Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 0/7] Introduce filters.
This is still tentative and needs a lot of work, but: - partition filter works, supporting MBR & GPT - prepare and finalize methods fixed - open method can now be changed (allowing readonly flag to be modified) - thread_model can be limited I believe I made most of the changes which were previously suggested in email. I think the only one I didn't was preventing inclusion of both <nbdkit-plugin.h> and <nbdkit-filter.h> in the same file. Rich.
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 1/7] backend: Add prepare and finalize methods.
These methods are called just after open and just before close
respectively. They are unused in this commit, but make more sense
when used from filters.
---
src/connections.c | 40 ++++++++++++++++++++++++++++++++++++++++
src/internal.h | 2 ++
src/plugins.c | 18 ++++++++++++++++++
3 files changed, 60 insertions(+)
diff --git a/src/connections.c b/src/connections.c
index e225b5c..e2de180 100644
--- a/src/connections.c
+++ b/src/connections.c
@@ -93,6 +93,8 @@ static struct connection *new_connection (int sockin, int
sockout,
static void free_connection (struct connection *conn);
static int negotiate_handshake (struct connection *conn);
static int recv_request_send_reply (struct connection *conn);
+static int prepare (struct connection *conn);
+static int finalize (struct connection *conn);
/* Don't call these raw socket functions directly. Use conn->recv etc.
*/
static int raw_recv (struct connection *, void *buf, size_t len);
@@ -246,6 +248,10 @@ _handle_single_connection (int sockin, int sockout)
threadlocal_set_name (backend->plugin_name (backend));
+ /* Prepare (for filters), called just after open. */
+ if (prepare (conn) == -1)
+ goto done;
+
/* Handshake. */
if (negotiate_handshake (conn) == -1)
goto done;
@@ -300,6 +306,10 @@ _handle_single_connection (int sockin, int sockout)
free (workers);
}
+ /* Finalize (for filters), called just before close. */
+ if (finalize (conn) == -1)
+ goto done;
+
r = get_status (conn);
done:
debug ("connection cleanup with final status %d", r);
@@ -371,6 +381,36 @@ free_connection (struct connection *conn)
free (conn);
}
+static int
+prepare (struct connection *conn)
+{
+ int r;
+
+ lock_request (conn);
+ if (backend)
+ r = backend->prepare (backend, conn);
+ else
+ r = 0;
+ unlock_request (conn);
+
+ return r;
+}
+
+static int
+finalize (struct connection *conn)
+{
+ int r;
+
+ lock_request (conn);
+ if (backend)
+ r = backend->finalize (backend, conn);
+ else
+ r = 0;
+ unlock_request (conn);
+
+ return r;
+}
+
static int
compute_eflags (struct connection *conn, uint16_t *flags)
{
diff --git a/src/internal.h b/src/internal.h
index 8047b3b..dbcd89c 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -165,6 +165,8 @@ struct backend {
void (*config_complete) (struct backend *);
int (*errno_is_preserved) (struct backend *);
int (*open) (struct backend *, struct connection *conn, int readonly);
+ int (*prepare) (struct backend *, struct connection *conn);
+ int (*finalize) (struct backend *, struct connection *conn);
void (*close) (struct backend *, struct connection *conn);
int64_t (*get_size) (struct backend *, struct connection *conn);
int (*can_write) (struct backend *, struct connection *conn);
diff --git a/src/plugins.c b/src/plugins.c
index 137bae3..da11c2c 100644
--- a/src/plugins.c
+++ b/src/plugins.c
@@ -251,6 +251,22 @@ plugin_open (struct backend *b, struct connection *conn,
int readonly)
return 0;
}
+/* We don't expose .prepare and .finalize to plugins since they aren't
+ * necessary. Plugins can easily do the same work in .open and
+ * .close.
+ */
+static int
+plugin_prepare (struct backend *b, struct connection *conn)
+{
+ return 0;
+}
+
+static int
+plugin_finalize (struct backend *b, struct connection *conn)
+{
+ return 0;
+}
+
static void
plugin_close (struct backend *b, struct connection *conn)
{
@@ -503,6 +519,8 @@ static struct backend plugin_functions = {
.config_complete = plugin_config_complete,
.errno_is_preserved = plugin_errno_is_preserved,
.open = plugin_open,
+ .prepare = plugin_prepare,
+ .finalize = plugin_finalize,
.close = plugin_close,
.get_size = plugin_get_size,
.can_write = plugin_can_write,
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 2/7] include: Move some common functions out to <nbdkit-common.h>.
Functions such as nbdkit_error and nbdkit_debug which are not plugin
specific. Also the NBDKIT_THREAD_MODEL macros which will be shared
with filters.
---
include/Makefile.am | 4 ++-
include/nbdkit-common.h | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
include/nbdkit-plugin.h | 26 ++----------------
3 files changed, 75 insertions(+), 25 deletions(-)
diff --git a/include/Makefile.am b/include/Makefile.am
index 7d54215..bc8adff 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -30,4 +30,6 @@
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
-include_HEADERS = nbdkit-plugin.h
+include_HEADERS = \
+ nbdkit-common.h \
+ nbdkit-plugin.h
diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h
new file mode 100644
index 0000000..f8517d5
--- /dev/null
+++ b/include/nbdkit-common.h
@@ -0,0 +1,70 @@
+/* nbdkit
+ * Copyright (C) 2013-2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef NBDKIT_COMMON_H
+#define NBDKIT_COMMON_H
+
+#include <stdarg.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS 0
+#define NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS 1
+#define NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS 2
+#define NBDKIT_THREAD_MODEL_PARALLEL 3
+
+extern void nbdkit_error (const char *msg, ...)
+ __attribute__((format (printf, 1, 2)));
+extern void nbdkit_verror (const char *msg, va_list args);
+extern void nbdkit_debug (const char *msg, ...)
+ __attribute__((format (printf, 1, 2)));
+extern void nbdkit_vdebug (const char *msg, va_list args);
+
+extern char *nbdkit_absolute_path (const char *path);
+extern int64_t nbdkit_parse_size (const char *str);
+extern int nbdkit_read_password (const char *value, char **password);
+
+#ifdef __cplusplus
+}
+#endif
+
+#ifdef __cplusplus
+#define NBDKIT_CXX_LANG_C extern "C"
+#else
+#define NBDKIT_CXX_LANG_C /* nothing */
+#endif
+
+#endif /* NBDKIT_COMMON_H */
diff --git a/include/nbdkit-plugin.h b/include/nbdkit-plugin.h
index 2ec3b15..1981061 100644
--- a/include/nbdkit-plugin.h
+++ b/include/nbdkit-plugin.h
@@ -1,5 +1,5 @@
/* nbdkit
- * Copyright (C) 2013-2017 Red Hat Inc.
+ * Copyright (C) 2013-2018 Red Hat Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -36,18 +36,12 @@
#ifndef NBDKIT_PLUGIN_H
#define NBDKIT_PLUGIN_H
-#include <stdarg.h>
-#include <stdint.h>
+#include <nbdkit-common.h>
#ifdef __cplusplus
extern "C" {
#endif
-#define NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS 0
-#define NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS 1
-#define NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS 2
-#define NBDKIT_THREAD_MODEL_PARALLEL 3
-
#define NBDKIT_API_VERSION 1
struct nbdkit_plugin {
@@ -100,22 +94,6 @@ struct nbdkit_plugin {
};
extern void nbdkit_set_error (int err);
-extern void nbdkit_error (const char *msg, ...)
- __attribute__((format (printf, 1, 2)));
-extern void nbdkit_verror (const char *msg, va_list args);
-extern void nbdkit_debug (const char *msg, ...)
- __attribute__((format (printf, 1, 2)));
-extern void nbdkit_vdebug (const char *msg, va_list args);
-
-extern char *nbdkit_absolute_path (const char *path);
-extern int64_t nbdkit_parse_size (const char *str);
-extern int nbdkit_read_password (const char *value, char **password);
-
-#ifdef __cplusplus
-#define NBDKIT_CXX_LANG_C extern "C"
-#else
-#define NBDKIT_CXX_LANG_C /* nothing */
-#endif
#define NBDKIT_REGISTER_PLUGIN(plugin) \
NBDKIT_CXX_LANG_C \
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 3/7] Introduce filters.
Filters can be placed in front of plugins to modify their behaviour.
This commit adds the <nbdkit-filter.h> header file, the manual page,
the ‘filterdir’ directory (like ‘plugindir’), the ‘filters/’ source
directory which will contain the actual filters, the ‘--filters’
parameter, and the filters backend logic.
---
Makefile.am | 2 +-
TODO | 17 +-
configure.ac | 3 +-
docs/Makefile.am | 9 +-
docs/nbdkit-filter.pod | 510 ++++++++++++++++++++++++++++++++++++
docs/nbdkit-plugin.pod | 3 +-
docs/nbdkit.pod | 24 +-
filters/Makefile.am | 33 +++
include/Makefile.am | 3 +-
include/nbdkit-filter.h | 143 ++++++++++
nbdkit.in | 17 +-
src/Makefile.am | 6 +-
src/filters.c | 679 ++++++++++++++++++++++++++++++++++++++++++++++++
src/internal.h | 21 +-
src/main.c | 115 +++++++-
src/nbdkit.pc.in | 1 +
src/plugins.c | 11 +-
17 files changed, 1555 insertions(+), 42 deletions(-)
diff --git a/Makefile.am b/Makefile.am
index f3c88b0..9c5b4c3 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -49,7 +49,7 @@ SUBDIRS = \
src
if HAVE_PLUGINS
-SUBDIRS += plugins
+SUBDIRS += plugins filters
endif
SUBDIRS += tests
diff --git a/TODO b/TODO
index 0c027e2..0955db7 100644
--- a/TODO
+++ b/TODO
@@ -34,10 +34,8 @@ nbdkit there is no compelling reason unless the result is
better than
qemu-nbd. For the majority of users it would be better if they were
directed to qemu-nbd for these use cases.
-Filters
--------
-
-It should be possible to layer filters over plugins to do things like:
+Suggestions for filters
+-----------------------
* adding artificial delays (see wdelay/rdelay options in the file
plugin)
@@ -50,17 +48,6 @@ It should be possible to layer filters over plugins to do
things like:
* export a single partition (like qemu-nbd -P)
-A possible syntax would be:
-
- nbdkit --filter=delay [--filter=...] file file=foo wdelay=10
-
-The filter(s) intercept all plugin calls and can either return, return
-an error, or pass the call down to the next layer in the stack (and
-eventually to the plugin). By intercepting the .config call the
-filter can process its own parameters from the command line (wdelay=10
-in the example above), and by intercepting the .pread, .pwrite methods
-the filter could inject the delaying behaviour.
-
Composing nbdkit
----------------
diff --git a/configure.ac b/configure.ac
index a2950f6..7032614 100644
--- a/configure.ac
+++ b/configure.ac
@@ -181,7 +181,7 @@ AS_IF([test "x$POD2MAN" != "xno"],[
AM_CONDITIONAL([HAVE_POD2MAN], [test "x$POD2MAN" != "xno"])
AC_ARG_ENABLE([plugins],
- [AS_HELP_STRING([--disable-plugins], [disable all bundled plugins])])
+ [AS_HELP_STRING([--disable-plugins], [disable all bundled plugins and
filters])])
AM_CONDITIONAL([HAVE_PLUGINS], [test "x$enable_plugins" !=
"xno"])
dnl Check for Perl, for embedding in the perl plugin.
@@ -512,6 +512,7 @@ AC_CONFIG_FILES([Makefile
plugins/tar/Makefile
plugins/vddk/Makefile
plugins/xz/Makefile
+ filters/Makefile
src/Makefile
src/nbdkit.pc
tests/Makefile])
diff --git a/docs/Makefile.am b/docs/Makefile.am
index 323f48d..d2330fb 100644
--- a/docs/Makefile.am
+++ b/docs/Makefile.am
@@ -33,6 +33,7 @@
EXTRA_DIST = \
nbdkit.pod \
nbdkit-plugin.pod
+ nbdkit-filter.pod
CLEANFILES = *~
@@ -40,7 +41,8 @@ if HAVE_POD2MAN
man_MANS = \
nbdkit.1 \
- nbdkit-plugin.3
+ nbdkit-plugin.3 \
+ nbdkit-filter.3
CLEANFILES += $(man_MANS)
nbdkit.1: nbdkit.pod
@@ -53,4 +55,9 @@ nbdkit-plugin.3: nbdkit-plugin.pod
if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
mv $@.t $@
+nbdkit-filter.3: nbdkit-filter.pod
+ $(POD2MAN) $(POD2MAN_ARGS) --section=3 --name=nbdkit-filter $< $@.t
&& \
+ if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
+ mv $@.t $@
+
endif
diff --git a/docs/nbdkit-filter.pod b/docs/nbdkit-filter.pod
new file mode 100644
index 0000000..cec60c6
--- /dev/null
+++ b/docs/nbdkit-filter.pod
@@ -0,0 +1,510 @@
+=encoding utf8
+
+=head1 NAME
+
+nbdkit-filter - How to write nbdkit filters
+
+=head1 SYNOPSIS
+
+ #include <nbdkit-filter.h>
+
+ static int
+ myfilter_config (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value)
+ {
+ if (strcmp (key, "myparameter") == 0) {
+ // ...
+ return 0;
+ }
+ else {
+ // pass through to next filter or plugin
+ return next (nxdata, key, value);
+ }
+ }
+
+ static struct nbdkit_filter filter = {
+ .name = "filter",
+ .config = myfilter_config,
+ /* etc */
+ };
+
+ NBDKIT_REGISTER_FILTER(filter)
+
+When this has been compiled to a shared library, do:
+
+ nbdkit [--args ...] --filter=./myfilter.so plugin [key=value ...]
+
+When debugging, use the I<-fv> options:
+
+ nbdkit -fv --filter=./myfilter.so plugin [key=value ...]
+
+=head1 DESCRIPTION
+
+One or more nbdkit filters can be placed in front of an nbdkit plugin
+to modify the behaviour of the plugin. This manual page describes how
+to create an nbdkit filter.
+
+Filters can be used for example to limit requests to an offset/limit,
+add copy-on-write support, or inject delays or errors (for testing).
+
+Different filters can be stacked:
+
+ NBD ┌─────────┐ ┌─────────┐ ┌────────┐
+ client ───▶│ filter1 │───▶│ filter2 │── ─ ─ ──▶│ plugin │
+ request └─────────┘ └─────────┘ └────────┘
+
+Each filter intercepts plugin functions (see L<nbdkit-plugin(3)>) and
+can call the next filter or plugin in the chain, modifying parameters,
+calling before the filter function, in the middle or after. Filters
+may even short-cut the chain. As an example, to process its own
+parameters the filter can intercept the C<.config> method:
+
+ static int
+ myfilter_config (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value)
+ {
+ if (strcmp (key, "myparameter") == 0) {
+ // ...
+ // here you would handle this key, value
+ // ...
+ return 0;
+ }
+ else {
+ // pass through to next filter or plugin
+ return next (nxdata, key, value);
+ }
+ }
+
+ static struct nbdkit_filter filter = {
+ // ...
+ .config = myfilter_config,
+ // ...
+ };
+
+The call to C<next (nxdata, ...)> calls the C<.config> method of
the
+next filter or plugin in the chain. In the example above any
+instances of C<myparameter=...> on the command line would not be seen
+by the plugin.
+
+To see example filters, take a look at the source of nbdkit, in the
+C<filters> directory.
+
+Filters must be written in C and must be fully thread safe.
+
+=head1 C<nbdkit-filter.h>
+
+All filters should start by including this header file:
+
+ #include <nbdkit-filter.h>
+
+=head1 C<struct nbdkit_filter>
+
+All filters must define and register one C<struct nbdkit_filter>,
+which contains the name of the filter and pointers to plugin methods
+that the filter wants to intercept.
+
+ static struct nbdkit_filter filter = {
+ .name = "filter",
+ .longname = "My Filter",
+ .description = "This is my great filter for nbdkit",
+ .config = myfilter_config,
+ /* etc */
+ };
+
+ NBDKIT_REGISTER_FILTER(filter)
+
+The C<.name> field is the name of the filter. This is the only field
+which is required.
+
+=head1 NEXT PLUGIN
+
+F<nbdkit-filter.h> defines three function types
+(C<nbdkit_next_config>, C<nbdkit_next_config_complete>,
+C<nbdkit_next_open>) and a structure called C<struct
nbdkit_next_ops>.
+These abstract the next plugin or filter in the chain. There is also
+an opaque pointer C<nxdata> which must be passed along when calling
+these functions.
+
+The filter’s C<.config> and C<.config_complete> methods may only
call
+the next C<.config> or C<.config_complete> method in the chain
+(optionally).
+
+The filter’s C<.open> and C<.close> methods are called when a new
+connection is opened or an old connection closed, and these have no
+C<next> parameter because they cannot be short-circuited.
+
+The filter’s other methods like C<.get_size>, C<.pread> etc ―
always
+called in the context of a connection ― are passed a pointer to
+C<struct nbdkit_next_ops> which contains a subset of the plugin
+methods that can be called during a connection. It is possible for a
+filter to issue (for example) extra read calls in response to a single
+C<.pwrite> call.
+
+You can modify parameters when you call the C<next> function. However
+be careful when modifying strings because for some methods
+(eg. C<.config>) the plugin may save the string pointer that you pass
+along. So you may have to ensure that the string is not freed for the
+lifetime of the server.
+
+Note that if your filter registers a callback but in that callback it
+doesn't call the C<next> function then the corresponding method in
the
+plugin will never be called.
+
+=head1 CALLBACKS
+
+C<struct nbdkit_filter> has some static fields describing the filter
+and optional callback functions which can be used to intercept plugin
+methods.
+
+=head2 C<.name>
+
+ const char *name;
+
+This field (a string) is required, and B<must> contain only ASCII
+alphanumeric characters and be unique amongst all filters.
+
+=head2 C<.version>
+
+ const char *version;
+
+Filters may optionally set a version string which is displayed in help
+and debugging output.
+
+=head2 C<.longname>
+
+ const char *longname;
+
+An optional free text name of the filter. This field is used in error
+messages.
+
+=head2 C<.description>
+
+ const char *description;
+
+An optional multi-line description of the filter.
+
+=head2 C<.load>
+
+ void load (void);
+
+This is called once just after the filter is loaded into memory. You
+can use this to perform any global initialization needed by the
+filter.
+
+=head2 C<.unload>
+
+ void unload (void);
+
+This may be called once just before the filter is unloaded from
+memory. Note that it's not guaranteed that C<.unload> will always be
+called (eg. the server might be killed or segfault), so you should try
+to make the filter as robust as possible by not requiring cleanup.
+See also L<nbdkit-plugin(3)/SHUTDOWN>.
+
+=head2 C<.limit_thread_model>
+
+ int (*limit_thread_model) (void);
+
+A filter may define this to make the plugin thread model more limited
+if, for some reason, the filter is unable to handle parallel requests.
+The callback, if defined, should return one of the
+C<NBDKIT_THREAD_MODEL_*> values (see L<nbdkit-plugin(3)>).
+
+The final thread model is the smallest (ie. most serialized) out of
+all the filters and the plugin. Filters cannot alter the thread model
+to make it larger (more parallel).
+
+If this callback is not defined then the filter must be prepared to
+handle fully parallel requests (like C<NBDKIT_THREAD_MODEL_PARALLEL>),
+even multiple requests issued in parallel on the same connection.
+
+=head2 C<.config>
+
+ int (*config) (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value);
+
+This intercepts the plugin C<.config> method and can be used by the
+filter to parse its own command line parameters. You should try to
+make sure that command line parameter keys that the filter uses do not
+conflict with ones that could be used by a plugin.
+
+If there is an error, C<.config> should call C<nbdkit_error> with
an
+error message and return C<-1>.
+
+=head2 C<.config_complete>
+
+ int (*config_complete) (nbdkit_next_config_complete *next, void *nxdata);
+
+This intercepts the plugin C<.config_complete> method and can be used
+to ensure that all parameters needed by the filter were supplied on
+the command line.
+
+If there is an error, C<.config_complete> should call
C<nbdkit_error>
+with an error message and return C<-1>.
+
+=head2 C<.config_help>
+
+ const char *config_help;
+
+This optional multi-line help message should summarize any
+C<key=value> parameters that it takes. It does I<not> need to
repeat
+what already appears in C<.description>.
+
+If the filter doesn't take any config parameters you should probably
+omit this.
+
+=head2 C<.open>
+
+ void * (*open) (nbdkit_next_open *next, void *nxdata,
+ int readonly);
+
+This is called when a new client connection is opened and can be used
+to allocate any per-connection data structures needed by the filter.
+The handle (which is not the same as the plugin handle) is passed back
+to other filter callbacks and could be freed in the C<.close>
+callback.
+
+Note that the handle is completely opaque to nbdkit, but it must not
+be NULL.
+
+If there is an error, C<.open> should call C<nbdkit_error> with an
+error message and return C<NULL>.
+
+=head2 C<.close>
+
+ void (*close) (void *handle);
+
+This is called when the client closes the connection. It should clean
+up any per-connection resources used by the filter.
+
+=head2 C<.prepare>
+
+=head2 C<.finalize>
+
+ int (*prepare) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*finalize) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+These two methods can be used to perform any necessary operations just
+after opening the connection (C<.prepare>) or just before closing the
+connection (C<.finalize>).
+
+For example if you need to scan the underlying disk to check for a
+partition table, you could do it in your C<.prepare> method (calling
+the plugin's C<.pread> method via C<next_ops>). Or if you need
to
+cleanly update superblock data in the image on close you can do it in
+your C<.finalize> method (calling the plugin's C<.pwrite>
method).
+Doing these things in the filter's C<.open> or C<.close> method
is not
+possible.
+
+If there is an error, both callbacks should call C<nbdkit_error> with
+an error message and return C<-1>.
+
+=head2 C<.get_size>
+
+ int64_t (*get_size) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+This intercepts the plugin C<.get_size> method and can be used to read
+or modify the apparent size of the block device that the NBD client
+will see.
+
+The returned size must be E<ge> 0. If there is an error,
C<.get_size>
+should call C<nbdkit_error> with an error message and return C<-1>.
+
+=head2 C<.can_write>
+
+=head2 C<.can_flush>
+
+=head2 C<.is_rotational>
+
+=head2 C<.can_trim>
+
+ int (*can_write) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*can_flush) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*is_rotational) (struct nbdkit_next_ops *next_ops,
+ void *nxdata,
+ void *handle);
+ int (*can_trim) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+These intercept the corresponding plugin methods.
+
+If there is an error, the callback should call C<nbdkit_error> with an
+error message and return C<-1>.
+
+=head2 C<.pread>
+
+ int (*pread) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, void *buf, uint32_t count, uint64_t offset);
+
+This intercepts the plugin C<.pread> method and can be used to read or
+modify data read by the plugin.
+
+If there is an error (including a short read which couldn't be
+recovered from), C<.pread> should call C<nbdkit_error> with an
error
+message B<and> set C<errno>, then return C<-1>.
+
+=head2 C<.pwrite>
+
+ int (*pwrite) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle,
+ const void *buf, uint32_t count, uint64_t offset);
+
+This intercepts the plugin C<.pwrite> method and can be used to modify
+data written by the plugin.
+
+If there is an error (including a short write which couldn't be
+recovered from), C<.pwrite> should call C<nbdkit_error> with an
error
+message B<and> set C<errno>, then return C<-1>.
+
+=head2 C<.flush>
+
+ int (*flush) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+This intercepts the plugin C<.flush> method and can be used to modify
+flush requests.
+
+If there is an error, C<.flush> should call C<nbdkit_error> with an
+error message B<and> set C<errno>, then return C<-1>.
+
+=head2 C<.trim>
+
+ int (*trim) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset);
+
+This intercepts the plugin C<.trim> method and can be used to modify
+trim requests.
+
+If there is an error, C<.trim> should call C<nbdkit_error> with an
+error message B<and> set C<errno>, then return C<-1>.
+
+=head2 C<.zero>
+
+ int (*zero) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, int may_trim);
+
+This intercepts the plugin C<.zero> method and can be used to modify
+zero requests.
+
+If there is an error, C<.zero> should call C<nbdkit_error> with an
+error message B<and> set C<errno>, then return C<-1>.
+
+=head1 DEBUGGING
+
+Run the server with I<-f> and I<-v> options so it doesn't fork
and you
+can see debugging information:
+
+ nbdkit -fv --filter=./myfilter.so plugin [key=value [key=value [...]]]
+
+To print debugging information from within the filter, call
+C<nbdkit_debug>, which has the following prototype and works like
+L<printf(3)>:
+
+ void nbdkit_debug (const char *fs, ...);
+ void nbdkit_vdebug (const char *fs, va_list args);
+
+For convenience, C<nbdkit_debug> preserves the value of C<errno>.
+Note that C<nbdkit_debug> only prints things when the server is in
+verbose mode (I<-v> option).
+
+=head1 INSTALLING THE FILTER
+
+The filter is a C<*.so> file and possibly a manual page. You can of
+course install the filter C<*.so> file wherever you want, and users
+will be able to use it by running:
+
+ nbdkit --filter=/path/to/filter.so plugin [args]
+
+However B<if> the shared library has a name of the form
+C<nbdkit-I<name>-filter.so> B<and if> the library is
installed in the
+C<$filterdir> directory, then users can be run it by only typing:
+
+ nbdkit --filter=name plugin [args]
+
+The location of the C<$filterdir> directory is set when nbdkit is
+compiled and can be found by doing:
+
+ nbdkit --dump-config
+
+If using the pkg-config/pkgconf system then you can also find the
+filter directory at compile time by doing:
+
+ pkgconf nbdkit --variable=filterdir
+
+=head1 PKG-CONFIG/PKGCONF
+
+nbdkit provides a pkg-config/pkgconf file called C<nbdkit.pc> which
+should be installed on the correct path when the nbdkit development
+environment is installed. You can use this in autoconf
+F<configure.ac> scripts to test for the development environment:
+
+ PKG_CHECK_MODULES([NBDKIT], [nbdkit >= 1.2.3])
+
+The above will fail unless nbdkit E<ge> 1.2.3 and the header file is
+installed, and will set C<NBDKIT_CFLAGS> and C<NBDKIT_LIBS>
+appropriately for compiling filters.
+
+You can also run pkg-config/pkgconf directly, for example:
+
+ if ! pkgconf nbdkit --exists; then
+ echo "you must install the nbdkit development environment"
+ exit 1
+ fi
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-plugin(1)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright (C) 2013-2018 Red Hat Inc.
+
+=head1 LICENSE
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+=over 4
+
+=item *
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+=item *
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+=item *
+
+Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+=back
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS''
AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/docs/nbdkit-plugin.pod b/docs/nbdkit-plugin.pod
index 9abf75f..3cafc42 100644
--- a/docs/nbdkit-plugin.pod
+++ b/docs/nbdkit-plugin.pod
@@ -692,6 +692,7 @@ and then users will be able to run it like this:
=head1 SEE ALSO
L<nbdkit(1)>,
+L<nbdkit-filter(3)>,
L<nbdkit-example1-plugin(1)>,
L<nbdkit-example2-plugin(1)>,
L<nbdkit-example3-plugin(1)>,
@@ -711,7 +712,7 @@ Pino Toscano
=head1 COPYRIGHT
-Copyright (C) 2013-2017 Red Hat Inc.
+Copyright (C) 2013-2018 Red Hat Inc.
=head1 LICENSE
diff --git a/docs/nbdkit.pod b/docs/nbdkit.pod
index 1687ac9..636eedc 100644
--- a/docs/nbdkit.pod
+++ b/docs/nbdkit.pod
@@ -7,7 +7,7 @@ nbdkit - A toolkit for creating NBD servers
=head1 SYNOPSIS
nbdkit [-e EXPORTNAME] [--exit-with-parent] [-f]
- [-g GROUP] [-i IPADDR]
+ [--filter=FILTER ...] [-g GROUP] [-i IPADDR]
[--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT] [-r]
[--run CMD] [-s] [--selinux-label LABEL] [-t THREADS]
[--tls=off|on|require] [--tls-certificates /path/to/certificates]
@@ -119,6 +119,13 @@ not allowed with the oldstyle protocol.
I<Don't> fork into the background.
+=item B<--filter> FILTER
+
+Add a filter before the plugin. This option may be given one or more
+times to stack filters in front of the plugin. They are processed in
+the order they appear on the command line. See L</FILTERS> and
+L<nbdkit-filter(3)>.
+
=item B<-g> GROUP
=item B<--group> GROUP
@@ -354,6 +361,18 @@ languages. The file should be executable. For example:
(see L<nbdkit-perl-plugin(3)> for a full example).
+=head1 FILTERS
+
+One or more filters can be placed in front of an nbdkit plugin to
+modify the behaviour of the plugin, using the I<--filter> parameter.
+Filters can be used for example to limit requests to an offset/limit,
+add copy-on-write support, or inject delays or errors (for testing).
+
+Several existing filters are available in the C<$filterdir>. Use
+C<nbdkit --dump-config> to find the directory name.
+
+How to write filters is described in L<nbdkit-filter(3)>.
+
=head1 SOCKET ACTIVATION
nbdkit supports socket activation (sometimes called systemd socket
@@ -856,6 +875,7 @@ L</SOCKET ACTIVATION>.
Other nbdkit manual pages:
L<nbdkit-plugin(3)>,
+L<nbdkit-filter(3)>,
L<nbdkit-curl-plugin(1)>,
L<nbdkit-example1-plugin(1)>,
L<nbdkit-example2-plugin(1)>,
@@ -895,7 +915,7 @@ Pino Toscano
=head1 COPYRIGHT
-Copyright (C) 2013-2017 Red Hat Inc.
+Copyright (C) 2013-2018 Red Hat Inc.
=head1 LICENSE
diff --git a/filters/Makefile.am b/filters/Makefile.am
new file mode 100644
index 0000000..ed1580b
--- /dev/null
+++ b/filters/Makefile.am
@@ -0,0 +1,33 @@
+# nbdkit
+# Copyright (C) 2013-2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+#SUBDIRS diff --git a/include/Makefile.am b/include/Makefile.am
index bc8adff..eabe66f 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -32,4 +32,5 @@
include_HEADERS = \
nbdkit-common.h \
- nbdkit-plugin.h
+ nbdkit-plugin.h \
+ nbdkit-filter.h
diff --git a/include/nbdkit-filter.h b/include/nbdkit-filter.h
new file mode 100644
index 0000000..0dbe4fa
--- /dev/null
+++ b/include/nbdkit-filter.h
@@ -0,0 +1,143 @@
+/* nbdkit
+ * Copyright (C) 2013-2017 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* See nbdkit-filter(3) for documentation and how to write a filter. */
+
+#ifndef NBDKIT_FILTER_H
+#define NBDKIT_FILTER_H
+
+#include <nbdkit-common.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define NBDKIT_FILTER_API_VERSION 1
+
+typedef int nbdkit_next_config (void *nxdata,
+ const char *key, const char *value);
+typedef int nbdkit_next_config_complete (void *nxdata);
+typedef int nbdkit_next_open (void *nxdata,
+ int readonly);
+
+struct nbdkit_next_ops {
+ int64_t (*get_size) (void *nxdata);
+
+ int (*can_write) (void *nxdata);
+ int (*can_flush) (void *nxdata);
+ int (*is_rotational) (void *nxdata);
+ int (*can_trim) (void *nxdata);
+
+ int (*pread) (void *nxdata, void *buf, uint32_t count, uint64_t offset);
+ int (*pwrite) (void *nxdata,
+ const void *buf, uint32_t count, uint64_t offset);
+ int (*flush) (void *nxdata);
+ int (*trim) (void *nxdata, uint32_t count, uint64_t offset);
+ int (*zero) (void *nxdata, uint32_t count, uint64_t offset, int may_trim);
+};
+
+struct nbdkit_filter {
+ /* Do not set these fields directly; use NBDKIT_REGISTER_FILTER.
+ * They exist so that we can support filters compiled against
+ * one version of the header with a runtime compiled against a
+ * different version with more (or fewer) fields.
+ */
+ uint64_t _struct_size;
+ int _api_version;
+
+ /* New fields will only be added at the end of the struct. */
+ const char *name;
+ const char *longname;
+ const char *version;
+ const char *description;
+
+ void (*load) (void);
+ void (*unload) (void);
+
+ int (*limit_thread_model) (void);
+
+ int (*config) (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value);
+ int (*config_complete) (nbdkit_next_config_complete *next, void *nxdata);
+ const char *config_help;
+
+ void * (*open) (nbdkit_next_open *next, void *nxdata,
+ int readonly);
+ void (*close) (void *handle);
+
+ int (*prepare) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*finalize) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+ int64_t (*get_size) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+ int (*can_write) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*can_flush) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*is_rotational) (struct nbdkit_next_ops *next_ops,
+ void *nxdata,
+ void *handle);
+ int (*can_trim) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+
+ int (*pread) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, void *buf, uint32_t count, uint64_t offset);
+ int (*pwrite) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle,
+ const void *buf, uint32_t count, uint64_t offset);
+ int (*flush) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle);
+ int (*trim) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset);
+ int (*zero) (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, int may_trim);
+};
+
+#define NBDKIT_REGISTER_FILTER(filter) \
+ NBDKIT_CXX_LANG_C \
+ struct nbdkit_filter * \
+ filter_init (void) \
+ { \
+ (filter)._struct_size = sizeof (filter); \
+ (filter)._api_version = NBDKIT_FILTER_API_VERSION; \
+ return &(filter); \
+ }
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NBDKIT_FILTER_H */
diff --git a/nbdkit.in b/nbdkit.in
index 20bc9c0..d4fe4e0 100644
--- a/nbdkit.in
+++ b/nbdkit.in
@@ -1,7 +1,7 @@
#!/bin/bash -
# @configure_input@
-# Copyright (C) 2017 Red Hat Inc.
+# Copyright (C) 2017-2018 Red Hat Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
@@ -79,6 +79,21 @@ while [ $# -gt 0 ]; do
shift
;;
+ # Filters can be rewritten if purely alphanumeric.
+ --filter)
+ args[$i]="--filter"
+ ((++i))
+ if [[ "$2" =~ ^[a-zA-Z0-9]+$ ]]; then
+ if [ -x "$b/filters/$2/.libs/nbdkit-$2-filter.so" ];
then
+
args[$i]="$b/filters/$2/.libs/nbdkit-$2-filter.so"
+ else
+ args[$i]="$2"
+ fi
+ fi
+ ((++i))
+ shift 2
+ ;;
+
# Anything else can be rewritten if it's purely alphanumeric,
# but there is only one module name so only rewrite once.
*)
diff --git a/src/Makefile.am b/src/Makefile.am
index 1f05eab..ae16fde 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -31,6 +31,7 @@
# SUCH DAMAGE.
plugindir = $(libdir)/nbdkit/plugins
+filterdir = $(libdir)/nbdkit/filters
sbin_PROGRAMS = nbdkit
@@ -39,6 +40,7 @@ nbdkit_SOURCES = \
connections.c \
crypto.c \
errors.c \
+ filters.c \
internal.h \
locks.c \
main.c \
@@ -47,13 +49,15 @@ nbdkit_SOURCES = \
sockets.c \
threadlocal.c \
utils.c \
- $(top_srcdir)/include/nbdkit-plugin.h
+ $(top_srcdir)/include/nbdkit-plugin.h \
+ $(top_srcdir)/include/nbdkit-filter.h
nbdkit_CPPFLAGS = \
-Dbindir=\"$(bindir)\" \
-Dlibdir=\"$(libdir)\" \
-Dmandir=\"$(mandir)\" \
-Dplugindir=\"$(plugindir)\" \
+ -Dfilterdir=\"$(filterdir)\" \
-Dsbindir=\"$(sbindir)\" \
-Dsysconfdir=\"$(sysconfdir)\" \
-I$(top_srcdir)/include
diff --git a/src/filters.c b/src/filters.c
new file mode 100644
index 0000000..45c7794
--- /dev/null
+++ b/src/filters.c
@@ -0,0 +1,679 @@
+/* nbdkit
+ * Copyright (C) 2013-2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <inttypes.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <dlfcn.h>
+
+#include "nbdkit-filter.h"
+#include "internal.h"
+
+/* We extend the generic backend struct with extra fields relating
+ * to this filter.
+ */
+struct backend_filter {
+ struct backend backend;
+ char *filename;
+ void *dl;
+ struct nbdkit_filter filter;
+};
+
+/* Literally a backend + a connection pointer. This is the
+ * implementation of ‘void *nxdata’ in the filter API.
+ */
+struct b_conn {
+ struct backend *b;
+ struct connection *conn;
+};
+
+/* Note this frees the whole chain. */
+static void
+filter_free (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ f->backend.next->free (f->backend.next);
+
+ /* Acquiring this lock prevents any filter callbacks from running
+ * simultaneously.
+ */
+ lock_unload ();
+
+ debug ("%s: unload", f->filename);
+ if (f->filter.unload)
+ f->filter.unload ();
+
+ dlclose (f->dl);
+ free (f->filename);
+
+ unlock_unload ();
+
+ free (f);
+}
+
+static int
+filter_thread_model (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ int filter_thread_model = NBDKIT_THREAD_MODEL_PARALLEL;
+ int thread_model;
+
+ if (f->filter.limit_thread_model)
+ filter_thread_model = f->filter.limit_thread_model ();
+
+ thread_model = f->backend.next->thread_model (f->backend.next);
+ if (filter_thread_model < thread_model) /* more serialized */
+ thread_model = filter_thread_model;
+
+ return thread_model;
+}
+
+/* These are actually passing through to the final plugin, hence
+ * the function names.
+ */
+static int
+plugin_errno_is_preserved (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ return f->backend.next->errno_is_preserved (f->backend.next);
+}
+
+static const char *
+plugin_name (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ return f->backend.next->name (f->backend.next);
+}
+
+static const char *
+filter_name (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ return f->filter.name;
+}
+
+static const char *
+filter_version (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ return f->filter.version;
+}
+
+static void
+filter_usage (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ printf ("filter: %s", f->filter.name);
+ if (f->filter.longname)
+ printf (" (%s)", f->filter.longname);
+ printf ("\n");
+ printf ("(%s)", f->filename);
+ if (f->filter.description) {
+ printf ("\n");
+ printf ("%s\n", f->filter.description);
+ }
+ if (f->filter.config_help) {
+ printf ("\n");
+ printf ("%s\n", f->filter.config_help);
+ }
+}
+
+static void
+filter_dump_fields (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ f->backend.next->dump_fields (f->backend.next);
+}
+
+static int
+next_config (void *nxdata, const char *key, const char *value)
+{
+ struct backend *b = nxdata;
+ b->config (b, key, value);
+ return 0;
+}
+
+static void
+filter_config (struct backend *b, const char *key, const char *value)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ debug ("%s: config key=%s, value=%s",
+ f->filename, key, value);
+
+ if (f->filter.config) {
+ if (f->filter.config (next_config, f->backend.next, key, value) ==
-1)
+ exit (EXIT_FAILURE);
+ }
+ else
+ f->backend.next->config (f->backend.next, key, value);
+}
+
+static int
+next_config_complete (void *nxdata)
+{
+ struct backend *b = nxdata;
+ b->config_complete (b);
+ return 0;
+}
+
+static void
+filter_config_complete (struct backend *b)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+
+ debug ("%s: config_complete", f->filename);
+
+ if (f->filter.config_complete) {
+ if (f->filter.config_complete (next_config_complete, f->backend.next)
== -1)
+ exit (EXIT_FAILURE);
+ }
+ else
+ f->backend.next->config_complete (f->backend.next);
+}
+
+static int
+next_open (void *nxdata, int readonly)
+{
+ struct b_conn *b_conn = nxdata;
+
+ return b_conn->b->open (b_conn->b, b_conn->conn, readonly);
+}
+
+static int
+filter_open (struct backend *b, struct connection *conn, int readonly)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+ void *handle;
+
+ debug ("%s: open readonly=%d", f->filename, readonly);
+
+ if (f->filter.open) {
+ handle = f->filter.open (next_open, &nxdata, readonly);
+ if (handle == NULL)
+ return -1;
+ connection_set_handle (conn, f->backend.i, handle);
+ return 0;
+ }
+ else
+ return f->backend.next->open (f->backend.next, conn, readonly);
+}
+
+static void
+filter_close (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+
+ debug ("close");
+
+ if (f->filter.close)
+ f->filter.close (handle);
+ f->backend.next->close (f->backend.next, conn);
+}
+
+/* The next_functions structure contains pointers to backend
+ * functions. However because these functions are all expecting a
+ * backend and a connection, we cannot call them directly, but must
+ * write some next_* functions that unpack the two parameters from a
+ * single ‘void *nxdata’ struct pointer (‘b_conn’).
+ */
+
+static int64_t
+next_get_size (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->get_size (b_conn->b, b_conn->conn);
+}
+
+static int
+next_can_write (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->can_write (b_conn->b, b_conn->conn);
+}
+
+static int
+next_can_flush (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->can_flush (b_conn->b, b_conn->conn);
+}
+
+static int
+next_is_rotational (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->is_rotational (b_conn->b, b_conn->conn);
+}
+
+static int
+next_can_trim (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->can_trim (b_conn->b, b_conn->conn);
+}
+
+static int
+next_pread (void *nxdata, void *buf, uint32_t count, uint64_t offset)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->pread (b_conn->b, b_conn->conn, buf, count,
offset, 0);
+}
+
+static int
+next_pwrite (void *nxdata, const void *buf, uint32_t count, uint64_t offset)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->pwrite (b_conn->b, b_conn->conn, buf, count,
offset, 0);
+}
+
+static int
+next_flush (void *nxdata)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->flush (b_conn->b, b_conn->conn, 0);
+}
+
+static int
+next_trim (void *nxdata, uint32_t count, uint64_t offset)
+{
+ struct b_conn *b_conn = nxdata;
+ return b_conn->b->trim (b_conn->b, b_conn->conn, count, offset,
0);
+}
+
+static int
+next_zero (void *nxdata, uint32_t count, uint64_t offset, int may_trim)
+{
+ struct b_conn *b_conn = nxdata;
+ uint32_t f = 0;
+
+ if (may_trim)
+ f |= NBDKIT_FLAG_MAY_TRIM;
+
+ return b_conn->b->zero (b_conn->b, b_conn->conn, count, offset,
f);
+}
+
+static struct nbdkit_next_ops next_ops = {
+ .get_size = next_get_size,
+ .can_write = next_can_write,
+ .can_flush = next_can_flush,
+ .is_rotational = next_is_rotational,
+ .can_trim = next_can_trim,
+ .pread = next_pread,
+ .pwrite = next_pwrite,
+ .flush = next_flush,
+ .trim = next_trim,
+ .zero = next_zero,
+};
+
+static int
+filter_prepare (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("prepare");
+
+ if (f->filter.prepare)
+ return f->filter.prepare (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->prepare (f->backend.next, conn);
+}
+
+static int
+filter_finalize (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("finalize");
+
+ if (f->filter.finalize)
+ return f->filter.finalize (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->finalize (f->backend.next, conn);
+}
+
+static int64_t
+filter_get_size (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("get_size");
+
+ if (f->filter.get_size)
+ return f->filter.get_size (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->get_size (f->backend.next, conn);
+}
+
+static int
+filter_can_write (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("can_write");
+
+ if (f->filter.can_write)
+ return f->filter.can_write (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->can_write (f->backend.next, conn);
+}
+
+static int
+filter_can_flush (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("can_flush");
+
+ if (f->filter.can_flush)
+ return f->filter.can_flush (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->can_flush (f->backend.next, conn);
+}
+
+static int
+filter_is_rotational (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("is_rotational");
+
+ if (f->filter.is_rotational)
+ return f->filter.is_rotational (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->is_rotational (f->backend.next, conn);
+}
+
+static int
+filter_can_trim (struct backend *b, struct connection *conn)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ debug ("can_trim");
+
+ if (f->filter.can_trim)
+ return f->filter.can_trim (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->can_trim (f->backend.next, conn);
+}
+
+static int
+filter_pread (struct backend *b, struct connection *conn,
+ void *buf, uint32_t count, uint64_t offset,
+ uint32_t flags)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ assert (flags == 0);
+
+ debug ("pread count=%" PRIu32 " offset=%" PRIu64, count,
offset);
+
+ if (f->filter.pread)
+ return f->filter.pread (&next_ops, &nxdata, handle,
+ buf, count, offset);
+ else
+ return f->backend.next->pread (f->backend.next, conn,
+ buf, count, offset, flags);
+}
+
+static int
+filter_pwrite (struct backend *b, struct connection *conn,
+ const void *buf, uint32_t count, uint64_t offset,
+ uint32_t flags)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+ bool fua = flags & NBDKIT_FLAG_FUA;
+
+ assert (!(flags & ~NBDKIT_FLAG_FUA));
+
+ debug ("pwrite count=%" PRIu32 " offset=%" PRIu64 "
fua=%d",
+ count, offset, fua);
+
+ if (f->filter.pwrite)
+ return f->filter.pwrite (&next_ops, &nxdata, handle,
+ buf, count, offset);
+ else
+ return f->backend.next->pwrite (f->backend.next, conn,
+ buf, count, offset, flags);
+}
+
+static int
+filter_flush (struct backend *b, struct connection *conn, uint32_t flags)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ assert (flags == 0);
+
+ debug ("flush");
+
+ if (f->filter.flush)
+ return f->filter.flush (&next_ops, &nxdata, handle);
+ else
+ return f->backend.next->flush (f->backend.next, conn, flags);
+}
+
+static int
+filter_trim (struct backend *b, struct connection *conn,
+ uint32_t count, uint64_t offset,
+ uint32_t flags)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+
+ assert (flags == 0);
+
+ debug ("trim count=%" PRIu32 " offset=%" PRIu64, count,
offset);
+
+ if (f->filter.trim)
+ return f->filter.trim (&next_ops, &nxdata, handle, count,
offset);
+ else
+ return f->backend.next->trim (f->backend.next, conn, count,
offset, flags);
+}
+
+static int
+filter_zero (struct backend *b, struct connection *conn,
+ uint32_t count, uint64_t offset, uint32_t flags)
+{
+ struct backend_filter *f = container_of (b, struct backend_filter, backend);
+ void *handle = connection_get_handle (conn, f->backend.i);
+ struct b_conn nxdata = { .b = f->backend.next, .conn = conn };
+ int may_trim = (flags & NBDKIT_FLAG_MAY_TRIM) != 0;
+
+ assert (!(flags & ~(NBDKIT_FLAG_MAY_TRIM | NBDKIT_FLAG_FUA)));
+
+ debug ("zero count=%" PRIu32 " offset=%" PRIu64 "
may_trim=%d",
+ count, offset, may_trim);
+
+ if (f->filter.zero)
+ return f->filter.zero (&next_ops, &nxdata, handle,
+ count, offset, may_trim);
+ else
+ return f->backend.next->zero (f->backend.next, conn,
+ count, offset, flags);
+}
+
+static struct backend filter_functions = {
+ .free = filter_free,
+ .thread_model = filter_thread_model,
+ .name = filter_name,
+ .plugin_name = plugin_name,
+ .usage = filter_usage,
+ .version = filter_version,
+ .dump_fields = filter_dump_fields,
+ .config = filter_config,
+ .config_complete = filter_config_complete,
+ .errno_is_preserved = plugin_errno_is_preserved,
+ .open = filter_open,
+ .prepare = filter_prepare,
+ .finalize = filter_finalize,
+ .close = filter_close,
+ .get_size = filter_get_size,
+ .can_write = filter_can_write,
+ .can_flush = filter_can_flush,
+ .is_rotational = filter_is_rotational,
+ .can_trim = filter_can_trim,
+ .pread = filter_pread,
+ .pwrite = filter_pwrite,
+ .flush = filter_flush,
+ .trim = filter_trim,
+ .zero = filter_zero,
+};
+
+/* Register and load a filter. */
+struct backend *
+filter_register (struct backend *next, size_t index, const char *filename,
+ void *dl, struct nbdkit_filter *(*filter_init) (void))
+{
+ struct backend_filter *f;
+ const struct nbdkit_filter *filter;
+ size_t i, len, size;
+
+ f = calloc (1, sizeof *f);
+ if (f == NULL) {
+ out_of_memory:
+ perror ("strdup");
+ exit (EXIT_FAILURE);
+ }
+
+ f->backend = filter_functions;
+ f->backend.next = next;
+ f->backend.i = index;
+ f->filename = strdup (filename);
+ if (f->filename == NULL) goto out_of_memory;
+ f->dl = dl;
+
+ debug ("registering filter %s", f->filename);
+
+ /* Call the initialization function which returns the address of the
+ * filter's own 'struct nbdkit_filter'.
+ */
+ filter = filter_init ();
+ if (!filter) {
+ fprintf (stderr, "%s: %s: filter registration function failed\n",
+ program_name, f->filename);
+ exit (EXIT_FAILURE);
+ }
+
+ /* Check for incompatible future versions. */
+ if (filter->_api_version != 1) {
+ fprintf (stderr, "%s: %s: filter is incompatible with this version of
nbdkit (_api_version = %d)\n",
+ program_name, f->filename, filter->_api_version);
+ exit (EXIT_FAILURE);
+ }
+
+ /* Since the filter might be much older than the current version of
+ * nbdkit, only copy up to the self-declared _struct_size of the
+ * filter and zero out the rest. If the filter is much newer then
+ * we'll only call the "old" fields.
+ */
+ size = sizeof f->filter; /* our struct */
+ memset (&f->filter, 0, size);
+ if (size > filter->_struct_size)
+ size = filter->_struct_size;
+ memcpy (&f->filter, filter, size);
+
+ /* Only filter.name is required. */
+ if (f->filter.name == NULL) {
+ fprintf (stderr, "%s: %s: filter must have a .name field\n",
+ program_name, f->filename);
+ exit (EXIT_FAILURE);
+ }
+
+ len = strlen (f->filter.name);
+ if (len == 0) {
+ fprintf (stderr, "%s: %s: filter.name field must not be empty\n",
+ program_name, f->filename);
+ exit (EXIT_FAILURE);
+ }
+ for (i = 0; i < len; ++i) {
+ if (!((f->filter.name[i] >= '0' &&
f->filter.name[i] <= '9') ||
+ (f->filter.name[i] >= 'a' &&
f->filter.name[i] <= 'z') ||
+ (f->filter.name[i] >= 'A' &&
f->filter.name[i] <= 'Z'))) {
+ fprintf (stderr, "%s: %s: filter.name ('%s') field must
contain only ASCII alphanumeric characters\n",
+ program_name, f->filename, f->filter.name);
+ exit (EXIT_FAILURE);
+ }
+ }
+ /* Copy the module's name into local storage, so that filter.name
+ * survives past unload. */
+ if (!(f->filter.name = strdup (f->filter.name))) {
+ perror ("strdup");
+ exit (EXIT_FAILURE);
+ }
+
+ debug ("registered filter %s (name %s)", f->filename,
f->filter.name);
+
+ /* Call the on-load callback if it exists. */
+ debug ("%s: load", f->filename);
+ if (f->filter.load)
+ f->filter.load ();
+
+ return (struct backend *) f;
+}
diff --git a/src/internal.h b/src/internal.h
index dbcd89c..3cbfde5 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -41,6 +41,7 @@
#include <pthread.h>
#include "nbdkit-plugin.h"
+#include "nbdkit-filter.h"
#ifdef __APPLE__
#define UNIX_PATH_MAX 104
@@ -118,6 +119,7 @@ extern volatile int quit;
extern int quit_fd;
extern struct backend *backend;
+#define for_each_backend(b) for (b = backend; b != NULL; b = b->next)
/* cleanup.c */
extern void cleanup_free (void *ptr);
@@ -152,8 +154,19 @@ extern int crypto_negotiate_tls (struct connection *conn,
int sockin, int sockou
/* errors.c */
#define debug nbdkit_debug
-/* plugins.c */
struct backend {
+ /* Next filter or plugin in the chain. This is always NULL for
+ * plugins and never NULL for filters.
+ */
+ struct backend *next;
+
+ /* A unique index used to fetch the handle from the connections
+ * object. The plugin (last in the chain) has index 0, and the
+ * filters have index 1, 2, ... depending how "far" they are from
+ * the plugin.
+ */
+ size_t i;
+
void (*free) (struct backend *);
int (*thread_model) (struct backend *);
const char *(*name) (struct backend *);
@@ -180,7 +193,11 @@ struct backend {
int (*zero) (struct backend *, struct connection *conn, uint32_t count,
uint64_t offset, uint32_t flags);
};
-extern struct backend *plugin_register (const char *_filename, void *_dl,
struct nbdkit_plugin *(*plugin_init) (void));
+/* plugins.c */
+extern struct backend *plugin_register (size_t index, const char *filename,
void *dl, struct nbdkit_plugin *(*plugin_init) (void));
+
+/* filters.c */
+extern struct backend *filter_register (struct backend *next, size_t index,
const char *filename, void *dl, struct nbdkit_filter *(*filter_init) (void));
/* locks.c */
extern void lock_init_thread_model (void);
diff --git a/src/main.c b/src/main.c
index 90d464a..29332c4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -64,7 +64,8 @@
static int is_short_name (const char *);
static char *make_random_fifo (void);
-static struct backend *open_plugin_so (const char *filename, int short_name);
+static struct backend *open_plugin_so (size_t i, const char *filename, int
short_name);
+static struct backend *open_filter_so (struct backend *next, size_t i, const
char *filename, int short_name);
static void start_serving (void);
static void set_up_signals (void);
static void run_command (void);
@@ -120,6 +121,7 @@ static const struct option long_options[] = {
{ "export", 1, NULL, 'e' },
{ "export-name",1, NULL, 'e' },
{ "exportname", 1, NULL, 'e' },
+ { "filter", 1, NULL, 0 },
{ "foreground", 0, NULL, 'f' },
{ "no-fork", 0, NULL, 'f' },
{ "group", 1, NULL, 'g' },
@@ -154,7 +156,7 @@ usage (void)
{
printf ("nbdkit [--dump-config] [--dump-plugin]\n"
" [-e EXPORTNAME] [--exit-with-parent] [-f]\n"
- " [-g GROUP] [-i IPADDR]\n"
+ " [--filter=FILTER ...] [-g GROUP] [-i IPADDR]\n"
" [--newstyle] [--oldstyle] [-P PIDFILE] [-p PORT]
[-r]\n"
" [--run CMD] [-s] [--selinux-label LABEL] [-t
THREADS]\n"
" [--tls=off|on|require] [--tls-certificates
/path/to/certificates]\n"
@@ -179,6 +181,7 @@ dump_config (void)
printf ("%s=%s\n", "mandir", mandir);
printf ("%s=%s\n", "name", PACKAGE_NAME);
printf ("%s=%s\n", "plugindir", plugindir);
+ printf ("%s=%s\n", "filterdir", filterdir);
printf ("%s=%s\n", "root_tls_certificates_dir",
root_tls_certificates_dir);
printf ("%s=%s\n", "sbindir", sbindir);
#ifdef HAVE_LIBSELINUX
@@ -205,6 +208,11 @@ main (int argc, char *argv[])
int short_name;
const char *filename;
char *p;
+ static struct filter_filename {
+ struct filter_filename *next;
+ const char *filename;
+ } *filter_filenames = NULL;
+ size_t i;
threadlocal_init ();
@@ -244,6 +252,18 @@ main (int argc, char *argv[])
exit (EXIT_FAILURE);
#endif
}
+ else if (strcmp (long_options[option_index].name, "filter") ==
0) {
+ struct filter_filename *t;
+
+ t = malloc (sizeof *t);
+ if (t == NULL) {
+ perror ("malloc");
+ exit (EXIT_FAILURE);
+ }
+ t->next = filter_filenames;
+ t->filename = optarg;
+ filter_filenames = t;
+ }
else if (strcmp (long_options[option_index].name, "run") == 0)
{
if (socket_activation) {
fprintf (stderr, "%s: cannot use socket activation with --run
flag\n",
@@ -496,24 +516,47 @@ main (int argc, char *argv[])
}
}
- backend = open_plugin_so (filename, short_name);
+ /* Open the plugin (first) and then wrap the plugin with the
+ * filters. The filters are wrapped in reverse order that they
+ * appear on the command line so that in the end ‘backend’ points to
+ * the first filter on the command line.
+ */
+ backend = open_plugin_so (0, filename, short_name);
+ i = 1;
+ while (filter_filenames) {
+ struct filter_filename *t = filter_filenames;
+ const char *filename = t->filename;
+ int short_name = is_short_name (filename);
+
+ backend = open_filter_so (backend, i++, filename, short_name);
+
+ filter_filenames = t->next;
+ free (t);
+ }
lock_init_thread_model ();
if (help) {
+ struct backend *b;
+
usage ();
- printf ("\n%s:\n\n", filename);
- backend->usage (backend);
+ for_each_backend (b) {
+ printf ("\n");
+ b->usage (b);
+ }
exit (EXIT_SUCCESS);
}
if (version) {
const char *v;
+ struct backend *b;
display_version ();
- printf ("%s", backend->name (backend));
- if ((v = backend->version (backend)) != NULL)
- printf (" %s", v);
- printf ("\n");
+ for_each_backend (b) {
+ printf ("%s", b->name (b));
+ if ((v = b->version (b)) != NULL)
+ printf (" %s", v);
+ printf ("\n");
+ }
exit (EXIT_SUCCESS);
}
@@ -575,7 +618,7 @@ main (int argc, char *argv[])
exit (EXIT_SUCCESS);
}
-/* Is it a name relative to the plugindir? */
+/* Is it a plugin or filter name relative to the plugindir/filterdir? */
static int
is_short_name (const char *filename)
{
@@ -615,7 +658,7 @@ make_random_fifo (void)
}
static struct backend *
-open_plugin_so (const char *name, int short_name)
+open_plugin_so (size_t i, const char *name, int short_name)
{
struct backend *ret;
char *filename = (char *) name;
@@ -653,7 +696,55 @@ open_plugin_so (const char *name, int short_name)
}
/* Register the plugin. */
- ret = plugin_register (filename, dl, plugin_init);
+ ret = plugin_register (i, filename, dl, plugin_init);
+
+ if (free_filename)
+ free (filename);
+
+ return ret;
+}
+
+static struct backend *
+open_filter_so (struct backend *next, size_t i,
+ const char *name, int short_name)
+{
+ struct backend *ret;
+ char *filename = (char *) name;
+ int free_filename = 0;
+ void *dl;
+ struct nbdkit_filter *(*filter_init) (void);
+ char *error;
+
+ if (short_name) {
+ /* Short names are rewritten relative to the filterdir. */
+ if (asprintf (&filename,
+ "%s/nbdkit-%s-filter.so", filterdir, name) == -1) {
+ perror ("asprintf");
+ exit (EXIT_FAILURE);
+ }
+ free_filename = 1;
+ }
+
+ dl = dlopen (filename, RTLD_NOW|RTLD_GLOBAL);
+ if (dl == NULL) {
+ fprintf (stderr, "%s: %s: %s\n", program_name, filename, dlerror
());
+ exit (EXIT_FAILURE);
+ }
+
+ /* Initialize the filter. See dlopen(3) to understand C weirdness. */
+ dlerror ();
+ *(void **) (&filter_init) = dlsym (dl, "filter_init");
+ if ((error = dlerror ()) != NULL) {
+ fprintf (stderr, "%s: %s: %s\n", program_name, name, error);
+ exit (EXIT_FAILURE);
+ }
+ if (!filter_init) {
+ fprintf (stderr, "%s: %s: invalid filter_init\n", program_name,
name);
+ exit (EXIT_FAILURE);
+ }
+
+ /* Register the filter. */
+ ret = filter_register (next, i, filename, dl, filter_init);
if (free_filename)
free (filename);
diff --git a/src/nbdkit.pc.in b/src/nbdkit.pc.in
index cbb301d..fe8f511 100644
--- a/src/nbdkit.pc.in
+++ b/src/nbdkit.pc.in
@@ -3,6 +3,7 @@ exec_prefix=@exec_prefix@
libdir=@libdir@
includedir=@includedir@
plugindir=@libdir@/nbdkit/plugins
+filterdir=@libdir@/nbdkit/filters
Name: @PACKAGE_NAME@
Version: @PACKAGE_VERSION@
diff --git a/src/plugins.c b/src/plugins.c
index da11c2c..dac2280 100644
--- a/src/plugins.c
+++ b/src/plugins.c
@@ -102,10 +102,11 @@ plugin_usage (struct backend *b)
{
struct backend_plugin *p = container_of (b, struct backend_plugin, backend);
- printf ("%s", p->plugin.name);
+ printf ("plugin: %s", p->plugin.name);
if (p->plugin.longname)
printf (" (%s)", p->plugin.longname);
printf ("\n");
+ printf ("(%s)", p->filename);
if (p->plugin.description) {
printf ("\n");
printf ("%s\n", p->plugin.description);
@@ -536,7 +537,7 @@ static struct backend plugin_functions = {
/* Register and load a plugin. */
struct backend *
-plugin_register (const char *filename,
+plugin_register (size_t index, const char *filename,
void *dl, struct nbdkit_plugin *(*plugin_init) (void))
{
struct backend_plugin *p;
@@ -551,11 +552,13 @@ plugin_register (const char *filename,
}
p->backend = plugin_functions;
+ p->backend.next = NULL;
+ p->backend.i = index;
p->filename = strdup (filename);
if (p->filename == NULL) goto out_of_memory;
p->dl = dl;
- debug ("registering %s", p->filename);
+ debug ("registering plugin %s", p->filename);
/* Call the initialization function which returns the address of the
* plugin's own 'struct nbdkit_plugin'.
@@ -631,7 +634,7 @@ plugin_register (const char *filename,
exit (EXIT_FAILURE);
}
- debug ("registered %s (name %s)", p->filename,
p->plugin.name);
+ debug ("registered plugin %s (name %s)", p->filename,
p->plugin.name);
/* Call the on-load callback if it exists. */
debug ("%s: load", p->filename);
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 4/7] include: Prevent direct inclusion of <nbdkit-common.h>.
Thanks: Eric Blake. --- include/nbdkit-common.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h index f8517d5..3177878 100644 --- a/include/nbdkit-common.h +++ b/include/nbdkit-common.h @@ -34,6 +34,10 @@ #ifndef NBDKIT_COMMON_H #define NBDKIT_COMMON_H +#if !defined (NBDKIT_PLUGIN_H) && !defined (NBDKIT_FILTER_H) +#error this header file should not be directly included +#endif + #include <stdarg.h> #include <stdint.h> -- 2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 5/7] filters: Add nbdkit-offset-filter.
This very basic filter allows you to select an offset and range within
a plugin, for example:
nbdkit --filter=offset file file=foo offset=1M range=100M
which serves the byte range [ 1M .. 101M-1 ] from file ‘foo’.
---
TODO | 2 -
configure.ac | 1 +
filters/Makefile.am | 3 +-
filters/offset/Makefile.am | 62 ++++++++++++++
filters/offset/nbdkit-offset-filter.pod | 99 ++++++++++++++++++++++
filters/offset/offset.c | 142 ++++++++++++++++++++++++++++++++
6 files changed, 306 insertions(+), 3 deletions(-)
diff --git a/TODO b/TODO
index 0955db7..8eda0d7 100644
--- a/TODO
+++ b/TODO
@@ -44,8 +44,6 @@ Suggestions for filters
* copy-on-write, a popular feature in other servers
-* export a subset using offset/size
-
* export a single partition (like qemu-nbd -P)
Composing nbdkit
diff --git a/configure.ac b/configure.ac
index 7032614..4892dc4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -513,6 +513,7 @@ AC_CONFIG_FILES([Makefile
plugins/vddk/Makefile
plugins/xz/Makefile
filters/Makefile
+ filters/offset/Makefile
src/Makefile
src/nbdkit.pc
tests/Makefile])
diff --git a/filters/Makefile.am b/filters/Makefile.am
index ed1580b..91fbe6c 100644
--- a/filters/Makefile.am
+++ b/filters/Makefile.am
@@ -30,4 +30,5 @@
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
-#SUBDIRS +SUBDIRS = \
+ offset
diff --git a/filters/offset/Makefile.am b/filters/offset/Makefile.am
new file mode 100644
index 0000000..f6e253c
--- /dev/null
+++ b/filters/offset/Makefile.am
@@ -0,0 +1,62 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+EXTRA_DIST = nbdkit-offset-filter.pod
+
+CLEANFILES = *~
+
+filterdir = $(libdir)/nbdkit/filters
+
+filter_LTLIBRARIES = nbdkit-offset-filter.la
+
+nbdkit_offset_filter_la_SOURCES = \
+ offset.c \
+ $(top_srcdir)/include/nbdkit-filter.h
+
+nbdkit_offset_filter_la_CPPFLAGS = \
+ -I$(top_srcdir)/include
+nbdkit_offset_filter_la_CFLAGS = \
+ $(WARNINGS_CFLAGS)
+nbdkit_offset_filter_la_LDFLAGS = \
+ -module -avoid-version -shared
+
+if HAVE_POD2MAN
+
+man_MANS = nbdkit-offset-filter.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-offset-filter.1: nbdkit-offset-filter.pod
+ $(POD2MAN) $(POD2MAN_ARGS) --section=1 --name=`basename $@ .1` $< $@.t
&& \
+ if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
+ mv $@.t $@
+
+endif
diff --git a/filters/offset/nbdkit-offset-filter.pod
b/filters/offset/nbdkit-offset-filter.pod
new file mode 100644
index 0000000..a94170e
--- /dev/null
+++ b/filters/offset/nbdkit-offset-filter.pod
@@ -0,0 +1,99 @@
+=encoding utf8
+
+=head1 NAME
+
+nbdkit-offset-filter - nbdkit offset filter
+
+=head1 SYNOPSIS
+
+ nbdkit --filter=offset plugin offset=OFFSET range=LENGTH [plugin-args...]
+
+=head1 DESCRIPTION
+
+C<nbdkit-offset-filter> is a filter that limits requests to the byte
+range C<[offset .. offset+range-1]> within another plugin.
+
+=head1 PARAMETERS
+
+=over 4
+
+=item B<offset=OFFSET>
+
+The start offset. The offset must be E<ge> 0.
+
+This parameter is optional. If not given then C<offset=0> is assumed.
+
+=item B<range=LENGTH>
+
+The length of data to serve.
+
+This parameter is optional. If not given then the range is served
+starting from the offset through to the end of the underlying
+file/device.
+
+=back
+
+Note it is an error if the offset and/or range specify data which lies
+beyond the end of the underlying device.
+
+=head1 EXAMPLE
+
+Using L<nbdkit-file-plugin(1)>, serve the file C<disk.img> starting
at
+offset C<1M>. The total length served is C<100M> (the underlying
file
+must therefore be at least C<101M> in length):
+
+ nbdkit --filter=offset file file=disk.img offset=1M range=100M
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-file-plugin(1)>,
+L<nbdkit-filter(3)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright (C) 2018 Red Hat Inc.
+
+=head1 LICENSE
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+=over 4
+
+=item *
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+=item *
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+=item *
+
+Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+=back
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS''
AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/filters/offset/offset.c b/filters/offset/offset.c
new file mode 100644
index 0000000..573c0f4
--- /dev/null
+++ b/filters/offset/offset.c
@@ -0,0 +1,142 @@
+/* nbdkit
+ * Copyright (C) 2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <nbdkit-filter.h>
+
+static int64_t offset = 0, range = -1;
+
+/* Called for each key=value passed on the command line. */
+static int
+offset_config (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value)
+{
+ if (strcmp (key, "offset") == 0) {
+ offset = nbdkit_parse_size (value);
+ if (offset == -1)
+ return -1;
+ return 0;
+ }
+ else if (strcmp (key, "range") == 0) {
+ range = nbdkit_parse_size (value);
+ if (range == -1)
+ return -1;
+ return 0;
+ }
+ else
+ return next (nxdata, key, value);
+}
+
+/* Check the user did pass both parameters. */
+static int
+offset_config_complete (nbdkit_next_config_complete *next, void *nxdata)
+{
+ return next (nxdata);
+}
+
+#define offset_config_help \
+ "offset=<OFFSET> (required) The start offset to serve.\n"
\
+ "range=<LENGTH> The total size to serve."
+
+/* Get the file size. */
+static int64_t
+offset_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ int64_t real_size = next_ops->get_size (nxdata);
+
+ if (range >= 0) {
+ if (offset + range > real_size) {
+ nbdkit_error ("offset+range is larger than the real size of the
underlying file or device");
+ return -1;
+ }
+ return range;
+ }
+ else
+ return real_size - offset;
+}
+
+/* Read data. */
+static int
+offset_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, void *buf, uint32_t count, uint64_t offs)
+{
+ return next_ops->pread (nxdata, buf, count, offs + offset);
+}
+
+/* Write data. */
+static int
+offset_pwrite (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle,
+ const void *buf, uint32_t count, uint64_t offs)
+{
+ return next_ops->pwrite (nxdata, buf, count, offs + offset);
+}
+
+/* Trim data. */
+static int
+offset_trim (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offs)
+{
+ return next_ops->trim (nxdata, count, offs + offset);
+}
+
+/* Zero data. */
+static int
+offset_zero (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offs, int may_trim)
+{
+ return next_ops->zero (nxdata, count, offs + offset, may_trim);
+}
+
+static struct nbdkit_filter filter = {
+ .name = "offset",
+ .longname = "nbdkit offset filter",
+ .version = PACKAGE_VERSION,
+ .config = offset_config,
+ .config_complete = offset_config_complete,
+ .config_help = offset_config_help,
+ .get_size = offset_get_size,
+ .pread = offset_pread,
+ .pwrite = offset_pwrite,
+ .trim = offset_trim,
+ .zero = offset_zero,
+};
+
+NBDKIT_REGISTER_FILTER(filter)
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 6/7] filters: Move rdelay/wdelay from file plugin to new delay filter.
Previously the file plugin supported ‘rdelay’ and ‘wdelay’ parameters
for injecting delays (for testing) into read and write requests. This
moves the functionality to a new delay filter so that it can be used
with any plugin.
---
TODO | 3 -
configure.ac | 1 +
filters/Makefile.am | 1 +
filters/delay/Makefile.am | 62 +++++++++++++
filters/delay/delay.c | 161 ++++++++++++++++++++++++++++++++++
filters/delay/nbdkit-delay-filter.pod | 88 +++++++++++++++++++
plugins/file/file.c | 76 ++--------------
plugins/file/nbdkit-file-plugin.pod | 14 +--
tests/test-parallel-file.sh | 4 +-
tests/test-parallel-nbd.sh | 1 +
10 files changed, 324 insertions(+), 87 deletions(-)
diff --git a/TODO b/TODO
index 8eda0d7..3ec45fd 100644
--- a/TODO
+++ b/TODO
@@ -37,9 +37,6 @@ directed to qemu-nbd for these use cases.
Suggestions for filters
-----------------------
-* adding artificial delays (see wdelay/rdelay options in the file
- plugin)
-
* injecting artificial errors for testing clients
* copy-on-write, a popular feature in other servers
diff --git a/configure.ac b/configure.ac
index 4892dc4..9376a2e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -513,6 +513,7 @@ AC_CONFIG_FILES([Makefile
plugins/vddk/Makefile
plugins/xz/Makefile
filters/Makefile
+ filters/delay/Makefile
filters/offset/Makefile
src/Makefile
src/nbdkit.pc
diff --git a/filters/Makefile.am b/filters/Makefile.am
index 91fbe6c..d4aa6c0 100644
--- a/filters/Makefile.am
+++ b/filters/Makefile.am
@@ -31,4 +31,5 @@
# SUCH DAMAGE.
SUBDIRS = \
+ delay \
offset
diff --git a/filters/delay/Makefile.am b/filters/delay/Makefile.am
new file mode 100644
index 0000000..5b20b69
--- /dev/null
+++ b/filters/delay/Makefile.am
@@ -0,0 +1,62 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+EXTRA_DIST = nbdkit-delay-filter.pod
+
+CLEANFILES = *~
+
+filterdir = $(libdir)/nbdkit/filters
+
+filter_LTLIBRARIES = nbdkit-delay-filter.la
+
+nbdkit_delay_filter_la_SOURCES = \
+ delay.c \
+ $(top_srcdir)/include/nbdkit-filter.h
+
+nbdkit_delay_filter_la_CPPFLAGS = \
+ -I$(top_srcdir)/include
+nbdkit_delay_filter_la_CFLAGS = \
+ $(WARNINGS_CFLAGS)
+nbdkit_delay_filter_la_LDFLAGS = \
+ -module -avoid-version -shared
+
+if HAVE_POD2MAN
+
+man_MANS = nbdkit-delay-filter.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-delay-filter.1: nbdkit-delay-filter.pod
+ $(POD2MAN) $(POD2MAN_ARGS) --section=1 --name=`basename $@ .1` $< $@.t
&& \
+ if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
+ mv $@.t $@
+
+endif
diff --git a/filters/delay/delay.c b/filters/delay/delay.c
new file mode 100644
index 0000000..66b7e56
--- /dev/null
+++ b/filters/delay/delay.c
@@ -0,0 +1,161 @@
+/* nbdkit
+ * Copyright (C) 2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <time.h>
+
+#include <nbdkit-filter.h>
+
+static int rdelayms = 0; /* read delay (milliseconds) */
+static int wdelayms = 0; /* write delay (milliseconds) */
+
+static int
+parse_delay (const char *value)
+{
+ size_t len = strlen (value);
+ int r;
+
+ if (len > 2 && strcmp (&value[len-2], "ms") == 0) {
+ if (sscanf (value, "%d", &r) == 1)
+ return r;
+ else {
+ nbdkit_error ("cannot parse rdelay/wdelay milliseconds parameter:
%s",
+ value);
+ return -1;
+ }
+ }
+ else {
+ if (sscanf (value, "%d", &r) == 1)
+ return r * 1000;
+ else {
+ nbdkit_error ("cannot parse rdelay/wdelay seconds parameter:
%s",
+ value);
+ return -1;
+ }
+ }
+}
+
+static void
+delay (int ms)
+{
+ if (ms > 0) {
+ const struct timespec ts = {
+ .tv_sec = ms / 1000,
+ .tv_nsec = (ms * 1000000) % 1000000000
+ };
+ nanosleep (&ts, NULL);
+ }
+}
+
+static void
+read_delay (void)
+{
+ delay (rdelayms);
+}
+
+static void
+write_delay (void)
+{
+ delay (wdelayms);
+}
+
+/* Called for each key=value passed on the command line. */
+static int
+delay_config (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value)
+{
+ if (strcmp (key, "rdelay") == 0) {
+ rdelayms = parse_delay (value);
+ if (rdelayms == -1)
+ return -1;
+ return 0;
+ }
+ else if (strcmp (key, "wdelay") == 0) {
+ wdelayms = parse_delay (value);
+ if (wdelayms == -1)
+ return -1;
+ return 0;
+ }
+ else
+ return next (nxdata, key, value);
+}
+
+#define delay_config_help \
+ "rdelay=<NN>[ms] Read delay in
seconds/milliseconds.\n" \
+ "wdelay=<NN>[ms] Write delay in
seconds/milliseconds." \
+
+/* Read data. */
+static int
+delay_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, void *buf, uint32_t count, uint64_t offset)
+{
+ read_delay ();
+ return next_ops->pread (nxdata, buf, count, offset);
+}
+
+/* Write data. */
+static int
+delay_pwrite (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle,
+ const void *buf, uint32_t count, uint64_t offset)
+{
+ write_delay ();
+ return next_ops->pwrite (nxdata, buf, count, offset);
+}
+
+/* Zero data. */
+static int
+delay_zero (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offset, int may_trim)
+{
+ write_delay ();
+ return next_ops->zero (nxdata, count, offset, may_trim);
+}
+
+static struct nbdkit_filter filter = {
+ .name = "delay",
+ .longname = "nbdkit delay filter",
+ .version = PACKAGE_VERSION,
+ .config = delay_config,
+ .config_help = delay_config_help,
+ .pread = delay_pread,
+ .pwrite = delay_pwrite,
+ .zero = delay_zero,
+};
+
+NBDKIT_REGISTER_FILTER(filter)
diff --git a/filters/delay/nbdkit-delay-filter.pod
b/filters/delay/nbdkit-delay-filter.pod
new file mode 100644
index 0000000..10aba94
--- /dev/null
+++ b/filters/delay/nbdkit-delay-filter.pod
@@ -0,0 +1,88 @@
+=encoding utf8
+
+=head1 NAME
+
+nbdkit-delay-filter - nbdkit delay filter
+
+=head1 SYNOPSIS
+
+ nbdkit --filter=delay plugin rdelay=SECS wdelay=SECS [plugin-args...]
+
+ nbdkit --filter=delay plugin rdelay=<NN>ms wdelay=<NN>ms
[plugin-args...]
+
+=head1 DESCRIPTION
+
+C<nbdkit-delay-filter> is a filter that delays read and write requests
+by some seconds or milliseconds. This is used to simulate a slow or
+remote server, or to test certain kinds of race conditions in Linux.
+
+=head1 PARAMETERS
+
+=over 4
+
+=item B<rdelay=SECS>
+
+=item B<rdelay=E<lt>NNE<gt>ms>
+
+The optional read delay in seconds or milliseconds.
+
+=item B<wdelay=SECS>
+
+=item B<wdelay=E<lt>NNE<gt>ms>
+
+The optional write delay in seconds or milliseconds.
+
+=back
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-filter(3)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright (C) 2018 Red Hat Inc.
+
+=head1 LICENSE
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+=over 4
+
+=item *
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+=item *
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+=item *
+
+Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+=back
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS''
AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/plugins/file/file.c b/plugins/file/file.c
index 4a91251..1fe4191 100644
--- a/plugins/file/file.c
+++ b/plugins/file/file.c
@@ -40,7 +40,6 @@
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
-#include <time.h>
#include <errno.h>
#include <nbdkit-plugin.h>
@@ -50,8 +49,6 @@
#endif
static char *filename = NULL;
-static int rdelayms = 0; /* read delay (milliseconds) */
-static int wdelayms = 0; /* write delay (milliseconds) */
static void
file_unload (void)
@@ -59,56 +56,6 @@ file_unload (void)
free (filename);
}
-static int
-parse_delay (const char *value)
-{
- size_t len = strlen (value);
- int r;
-
- if (len > 2 && strcmp (&value[len-2], "ms") == 0) {
- if (sscanf (value, "%d", &r) == 1)
- return r;
- else {
- nbdkit_error ("cannot parse rdelay/wdelay milliseconds parameter:
%s",
- value);
- return -1;
- }
- }
- else {
- if (sscanf (value, "%d", &r) == 1)
- return r * 1000;
- else {
- nbdkit_error ("cannot parse rdelay/wdelay seconds parameter:
%s",
- value);
- return -1;
- }
- }
-}
-
-static void
-delay (int ms)
-{
- if (ms > 0) {
- const struct timespec ts = {
- .tv_sec = ms / 1000,
- .tv_nsec = (ms * 1000000) % 1000000000
- };
- nanosleep (&ts, NULL);
- }
-}
-
-static void
-read_delay (void)
-{
- delay (rdelayms);
-}
-
-static void
-write_delay (void)
-{
- delay (wdelayms);
-}
-
/* Called for each key=value passed on the command line. This plugin
* only accepts file=<filename>, which is required.
*/
@@ -122,15 +69,10 @@ file_config (const char *key, const char *value)
if (!filename)
return -1;
}
- else if (strcmp (key, "rdelay") == 0) {
- rdelayms = parse_delay (value);
- if (rdelayms == -1)
- return -1;
- }
- else if (strcmp (key, "wdelay") == 0) {
- wdelayms = parse_delay (value);
- if (wdelayms == -1)
- return -1;
+ else if (strcmp (key, "rdelay") == 0 ||
+ strcmp (key, "wdelay") == 0) {
+ nbdkit_error ("add --filter=delay on the command line");
+ return -1;
}
else {
nbdkit_error ("unknown parameter '%s'", key);
@@ -157,9 +99,7 @@ file_config_complete (void)
}
#define file_config_help \
- "file=<FILENAME> (required) The filename to serve.\n" \
- "rdelay=<NN>[ms] Read delay in
seconds/milliseconds.\n" \
- "wdelay=<NN>[ms] Write delay in
seconds/milliseconds." \
+ "file=<FILENAME> (required) The filename to serve." \
/* The per-connection handle. */
struct handle {
@@ -241,8 +181,6 @@ file_pread (void *handle, void *buf, uint32_t count,
uint64_t offset)
{
struct handle *h = handle;
- read_delay ();
-
while (count > 0) {
ssize_t r = pread (h->fd, buf, count, offset);
if (r == -1) {
@@ -267,8 +205,6 @@ file_pwrite (void *handle, const void *buf, uint32_t count,
uint64_t offset)
{
struct handle *h = handle;
- write_delay ();
-
while (count > 0) {
ssize_t r = pwrite (h->fd, buf, count, offset);
if (r == -1) {
@@ -292,8 +228,6 @@ file_zero (void *handle, uint32_t count, uint64_t offset,
int may_trim)
#endif
int r = -1;
- write_delay ();
-
#ifdef FALLOC_FL_PUNCH_HOLE
if (may_trim) {
r = fallocate (h->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
diff --git a/plugins/file/nbdkit-file-plugin.pod
b/plugins/file/nbdkit-file-plugin.pod
index a2d1e6a..016513a 100644
--- a/plugins/file/nbdkit-file-plugin.pod
+++ b/plugins/file/nbdkit-file-plugin.pod
@@ -31,21 +31,13 @@ This parameter is required.
=item B<rdelay=E<lt>NNE<gt>ms>
-Delay reads for C<SECS> seconds or C<NN> milliseconds.
-This is used to simulate a slow or remote server, or to
-test certain kinds of race conditions in Linux.
-
-The default is no delay.
-
=item B<wdelay=SECS>
=item B<wdelay=E<lt>NNE<gt>ms>
-Delay writes for C<SECS> seconds or C<NN> milliseconds.
-This is used to simulate a slow or remote server, or to
-test certain kinds of race conditions in Linux.
-
-The default is no delay.
+These plugin parameters have been moved to the
+L<nbdkit-delay-filter(1)> filter. Modify the command line to add
+I<--filter=delay> in order to use these parameters.
=back
diff --git a/tests/test-parallel-file.sh b/tests/test-parallel-file.sh
index 79a60ac..b9e5f40 100755
--- a/tests/test-parallel-file.sh
+++ b/tests/test-parallel-file.sh
@@ -49,7 +49,7 @@ $QEMU_IO -f raw -c "aio_write -P 2 1 1" -c
"aio_read -P 1 0 1" -c aio_flush \
trap 'rm -f test-parallel-file.out' 0 1 2 3 15
# With --threads=1, the write should complete first because it was issued first
-nbdkit -v -t 1 -U - file file=file-data wdelay=2 rdelay=1 --run '
+nbdkit -v -t 1 -U - --filter delay file file=file-data wdelay=2 rdelay=1 --run
'
$QEMU_IO -f raw -c "aio_write -P 2 1 1" -c "aio_read -P 1 0
1" -c aio_flush $nbd
' | tee test-parallel-file.out
if test "$(grep '1/1' test-parallel-file.out)" != \
@@ -59,7 +59,7 @@ read 1/1 bytes at offset 0"; then
fi
# With default --threads, the faster read should complete first
-nbdkit -v -U - file file=file-data wdelay=2 rdelay=1 --run '
+nbdkit -v -U - --filter delay file file=file-data wdelay=2 rdelay=1 --run '
$QEMU_IO -f raw -c "aio_write -P 2 1 1" -c "aio_read -P 1 0
1" -c aio_flush $nbd
' | tee test-parallel-file.out
if test "$(grep '1/1' test-parallel-file.out)" != \
diff --git a/tests/test-parallel-nbd.sh b/tests/test-parallel-nbd.sh
index f8e5071..d87573d 100755
--- a/tests/test-parallel-nbd.sh
+++ b/tests/test-parallel-nbd.sh
@@ -54,6 +54,7 @@ trap 'rm -f test-parallel-nbd.out
test-parallel-nbd.sock' 0 1 2 3 15
(
rm -f test-parallel-nbd.sock
nbdkit --exit-with-parent -v -U test-parallel-nbd.sock \
+ --filter delay \
file file=file-data wdelay=2 rdelay=1 &
# With --threads=1, the write should complete first because it was issued first
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:36 UTC
[Libguestfs] [PATCH nbdkit filters-v3 7/7] filters: Add nbdkit-partition-filter.
This can be used to filter a single partition from a disk image. It
supports MBR and GPT, but not MBR extended partitions because those
are crazy.
---
TODO | 2 -
configure.ac | 1 +
filters/Makefile.am | 3 +-
filters/offset/nbdkit-offset-filter.pod | 17 +-
filters/partition/Makefile.am | 62 +++++
filters/partition/nbdkit-partition-filter.pod | 99 ++++++++
filters/partition/partition.c | 351 ++++++++++++++++++++++++++
7 files changed, 531 insertions(+), 4 deletions(-)
diff --git a/TODO b/TODO
index 3ec45fd..b1f922e 100644
--- a/TODO
+++ b/TODO
@@ -41,8 +41,6 @@ Suggestions for filters
* copy-on-write, a popular feature in other servers
-* export a single partition (like qemu-nbd -P)
-
Composing nbdkit
----------------
diff --git a/configure.ac b/configure.ac
index 9376a2e..fd71ca6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -515,6 +515,7 @@ AC_CONFIG_FILES([Makefile
filters/Makefile
filters/delay/Makefile
filters/offset/Makefile
+ filters/partition/Makefile
src/Makefile
src/nbdkit.pc
tests/Makefile])
diff --git a/filters/Makefile.am b/filters/Makefile.am
index d4aa6c0..d918b81 100644
--- a/filters/Makefile.am
+++ b/filters/Makefile.am
@@ -32,4 +32,5 @@
SUBDIRS = \
delay \
- offset
+ offset \
+ partition
diff --git a/filters/offset/nbdkit-offset-filter.pod
b/filters/offset/nbdkit-offset-filter.pod
index a94170e..25bdbb9 100644
--- a/filters/offset/nbdkit-offset-filter.pod
+++ b/filters/offset/nbdkit-offset-filter.pod
@@ -36,7 +36,7 @@ file/device.
Note it is an error if the offset and/or range specify data which lies
beyond the end of the underlying device.
-=head1 EXAMPLE
+=head1 EXAMPLES
Using L<nbdkit-file-plugin(1)>, serve the file C<disk.img> starting
at
offset C<1M>. The total length served is C<100M> (the underlying
file
@@ -44,11 +44,26 @@ must therefore be at least C<101M> in length):
nbdkit --filter=offset file file=disk.img offset=1M range=100M
+One way to serve a single partition from a disk is to find the start
+and length of the partition, eg using:
+
+ $ parted disk.img -- unit b print
+ ...
+ Number Start End Size Type File system Flags
+ 1 65536B 104792575B 104727040B primary ext2
+
+You can then serve the partition only using:
+
+ nbdkit --filter=offset file file=disk.img offset=65536 range=104727040
+
+An easier way to do this is with L<nbdkit-partition-filter(1)>.
+
=head1 SEE ALSO
L<nbdkit(1)>,
L<nbdkit-file-plugin(1)>,
L<nbdkit-filter(3)>.
+L<nbdkit-partition-filter(1)>.
=head1 AUTHORS
diff --git a/filters/partition/Makefile.am b/filters/partition/Makefile.am
new file mode 100644
index 0000000..0464e7c
--- /dev/null
+++ b/filters/partition/Makefile.am
@@ -0,0 +1,62 @@
+# nbdkit
+# Copyright (C) 2018 Red Hat Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+#
+# * Neither the name of Red Hat nor the names of its contributors may be
+# used to endorse or promote products derived from this software without
+# specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+
+EXTRA_DIST = nbdkit-partition-filter.pod
+
+CLEANFILES = *~
+
+filterdir = $(libdir)/nbdkit/filters
+
+filter_LTLIBRARIES = nbdkit-partition-filter.la
+
+nbdkit_partition_filter_la_SOURCES = \
+ partition.c \
+ $(top_srcdir)/include/nbdkit-filter.h
+
+nbdkit_partition_filter_la_CPPFLAGS = \
+ -I$(top_srcdir)/include
+nbdkit_partition_filter_la_CFLAGS = \
+ $(WARNINGS_CFLAGS)
+nbdkit_partition_filter_la_LDFLAGS = \
+ -module -avoid-version -shared
+
+if HAVE_POD2MAN
+
+man_MANS = nbdkit-partition-filter.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-partition-filter.1: nbdkit-partition-filter.pod
+ $(POD2MAN) $(POD2MAN_ARGS) --section=1 --name=`basename $@ .1` $< $@.t
&& \
+ if grep 'POD ERROR' $@.t; then rm $@.t; exit 1; fi && \
+ mv $@.t $@
+
+endif
diff --git a/filters/partition/nbdkit-partition-filter.pod
b/filters/partition/nbdkit-partition-filter.pod
new file mode 100644
index 0000000..8ba2776
--- /dev/null
+++ b/filters/partition/nbdkit-partition-filter.pod
@@ -0,0 +1,99 @@
+=encoding utf8
+
+=head1 NAME
+
+nbdkit-partition-filter - nbdkit partition filter
+
+=head1 SYNOPSIS
+
+ nbdkit --filter=partition plugin partition=PART [plugin-args...]
+
+=head1 DESCRIPTION
+
+C<nbdkit-partition-filter> is a filter that limits requests to a
+single partition within a disk image that is served by another plugin.
+
+Partition numbers are specified by the required C<partition>
+parameter, and count from 1.
+
+This works like the C<qemu-nbd -P> option.
+
+=head1 NOTE
+
+Only MBR primary partitions and GPT partition tables are supported.
+MBR logical partitions are B<not> supported.
+
+=head1 PARAMETERS
+
+=over 4
+
+=item B<partition=PART>
+
+The partition number to serve, counting from 1.
+
+This parameter is required.
+
+=back
+
+=head1 EXAMPLE
+
+F<disk.img> is a partitioned disk image (eg. a virtual machine disk
+image). To serve the first partition only use:
+
+ nbdkit --filter=partition file file=disk.img partition=1
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-file-plugin(1)>,
+L<nbdkit-filter(3)>.
+L<nbdkit-offset-filter(1)>,
+L<parted(8)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright (C) 2018 Red Hat Inc.
+
+=head1 LICENSE
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+=over 4
+
+=item *
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+=item *
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+=item *
+
+Neither the name of Red Hat nor the names of its contributors may be
+used to endorse or promote products derived from this software without
+specific prior written permission.
+
+=back
+
+THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS''
AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGE.
diff --git a/filters/partition/partition.c b/filters/partition/partition.c
new file mode 100644
index 0000000..ddf6f93
--- /dev/null
+++ b/filters/partition/partition.c
@@ -0,0 +1,351 @@
+/* nbdkit
+ * Copyright (C) 2018 Red Hat Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS
IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <inttypes.h>
+#include <endian.h>
+
+#include <nbdkit-filter.h>
+
+static int partnum = -1;
+
+/* Called for each key=value passed on the command line. */
+static int
+partition_config (nbdkit_next_config *next, void *nxdata,
+ const char *key, const char *value)
+{
+ if (strcmp (key, "partition") == 0) {
+ if (sscanf (value, "%d", &partnum) != 1 || partnum <= 0) {
+ nbdkit_error ("invalid partition number");
+ return -1;
+ }
+ return 0;
+ }
+ else
+ return next (nxdata, key, value);
+}
+
+/* Check the user did pass partition number. */
+static int
+partition_config_complete (nbdkit_next_config_complete *next, void *nxdata)
+{
+ if (partnum == -1) {
+ nbdkit_error ("you must supply the partition parameter on the command
line");
+ return -1;
+ }
+
+ return next (nxdata);
+}
+
+#define partition_config_help \
+ "partition=<PART> (required) The partition number (counting
from 1)."
+
+struct handle {
+ int64_t offset;
+ int64_t range;
+};
+
+/* Open a connection. */
+static void *
+partition_open (nbdkit_next_open *next, void *nxdata, int readonly)
+{
+ struct handle *h;
+
+ if (next (nxdata, readonly) == -1)
+ return NULL;
+
+ h = malloc (sizeof *h);
+ if (h == NULL) {
+ nbdkit_error ("malloc: %m");
+ return NULL;
+ }
+
+ /* These are set in the prepare method. */
+ h->offset = h->range = -1;
+ return h;
+}
+
+static void
+partition_close (void *handle)
+{
+ struct handle *h = handle;
+
+ free (h);
+}
+
+/* Inspect the underlying partition table. partition_prepare is
+ * called before data processing.
+ */
+struct mbr_partition {
+ uint8_t part_type_byte;
+ uint32_t start_sector;
+ uint32_t nr_sectors;
+};
+
+static void
+get_mbr_partition (uint8_t *sector, int i, struct mbr_partition *part)
+{
+ int offset = 0x1BE + i*0x10;
+
+ part->part_type_byte = sector[offset+4];
+ memcpy (&part->start_sector, §or[offset+8], 4);
+ part->start_sector = le32toh (part->start_sector);
+ memcpy (&part->nr_sectors, §or[offset+0xC], 4);
+ part->nr_sectors = le32toh (part->nr_sectors);
+}
+
+static int
+find_mbr_partition (struct nbdkit_next_ops *next_ops, void *nxdata,
+ struct handle *h, int64_t size, uint8_t *mbr)
+{
+ int i;
+ struct mbr_partition partition;
+
+ if (partnum > 4) {
+ nbdkit_error ("MBR logical partitions are not supported");
+ return -1;
+ }
+
+ for (i = 0; i < 4; ++i) {
+ get_mbr_partition (mbr, i, &partition);
+ if (partition.nr_sectors > 0 &&
+ partition.part_type_byte != 0 &&
+ partnum == i+1) {
+ h->offset = partition.start_sector * 512;
+ h->range = partition.nr_sectors * 512;
+ return 0;
+ }
+ }
+
+ nbdkit_error ("MBR partition %d not found", partnum);
+ return -1;
+}
+
+struct gpt_header {
+ uint32_t nr_partitions;
+ uint32_t partition_entry_size;
+};
+
+static void
+get_gpt_header (uint8_t *sector, struct gpt_header *header)
+{
+ memcpy (&header->nr_partitions, §or[0x50], 4);
+ header->nr_partitions = le32toh (header->nr_partitions);
+ memcpy (&header->partition_entry_size, §or[0x54], 4);
+ header->partition_entry_size = le32toh (header->partition_entry_size);
+}
+
+struct gpt_partition {
+ uint8_t partition_type_guid[16];
+ uint64_t first_lba;
+ uint64_t last_lba;
+};
+
+static void
+get_gpt_partition (uint8_t *bytes, struct gpt_partition *part)
+{
+ memcpy (&part->partition_type_guid, &bytes[0], 16);
+ memcpy (&part->first_lba, &bytes[0x20], 8);
+ part->first_lba = le64toh (part->first_lba);
+ memcpy (&part->last_lba, &bytes[0x28], 8);
+ part->last_lba = le64toh (part->last_lba);
+}
+
+static int
+find_gpt_partition (struct nbdkit_next_ops *next_ops, void *nxdata,
+ struct handle *h, int64_t size, uint8_t *header_bytes)
+{
+ uint8_t partition_bytes[128];
+ struct gpt_header header;
+ struct gpt_partition partition;
+ int i;
+
+ if (partnum > 128) {
+ out_of_range:
+ nbdkit_error ("GPT partition number out of range");
+ return -1;
+ }
+ get_gpt_header (header_bytes, &header);
+ if (partnum > header.nr_partitions)
+ goto out_of_range;
+
+ if (header.partition_entry_size != 128) {
+ nbdkit_error ("GPT partition entry is not 128 bytes");
+ return -1;
+ }
+
+ for (i = 0; i < 128; ++i) {
+ /* We already checked these are within bounds in the
+ * partition_prepare call above.
+ */
+ if (next_ops->pread (nxdata, partition_bytes, sizeof partition_bytes,
+ 2*512 + i*128) == -1)
+ return -1;
+ get_gpt_partition (partition_bytes, &partition);
+ if (memcmp (partition.partition_type_guid,
+ "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 16) != 0
&&
+ partnum == i+1) {
+ h->offset = partition.first_lba * 512;
+ h->range = (1 + partition.last_lba - partition.first_lba) * 512;
+ return 0;
+ }
+ }
+
+ nbdkit_error ("GPT partition %d not found", partnum);
+ return -1;
+}
+
+static int
+partition_prepare (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+ int64_t size;
+ uint8_t lba01[1024]; /* LBA 0 and 1 */
+ int r;
+
+ size = next_ops->get_size (nxdata);
+ if (size == -1)
+ return -1;
+ if (size < 1024) {
+ nbdkit_error ("disk is too small to be a partitioned disk");
+ return -1;
+ }
+
+ nbdkit_debug ("disk size=%" PRIi64, size);
+
+ if (next_ops->pread (nxdata, lba01, sizeof lba01, 0) != 0)
+ return -1;
+
+ /* Is it GPT? */
+ if (size >= 2 * 34 * 512 && memcmp (&lba01[512], "EFI
PART", 8) == 0)
+ r = find_gpt_partition (next_ops, nxdata, h, size, &lba01[512]);
+ /* Is it MBR? */
+ else if (lba01[0x1fe] == 0x55 && lba01[0x1ff] == 0xAA)
+ r = find_mbr_partition (next_ops, nxdata, h, size, lba01);
+ else {
+ nbdkit_error ("disk does not contain MBR or GPT partition table
signature");
+ r = -1;
+ }
+ if (r == -1)
+ return -1;
+
+ /* The find_*_partition functions set h->offset & h->range in the
+ * handle to point to the partition boundaries. However we
+ * additionally check that they are inside the underlying disk.
+ */
+ if (h->offset < 0 || h->range < 0 || h->offset + h->range
> size) {
+ nbdkit_error ("partition is outside the disk");
+ return -1;
+ }
+
+ nbdkit_debug ("partition offset=%" PRIi64 " range=%"
PRIi64,
+ h->offset, h->range);
+
+ return 0;
+}
+
+/* Get the file size. */
+static int64_t
+partition_get_size (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle)
+{
+ struct handle *h = handle;
+
+ return h->range;
+}
+
+/* Read data. */
+static int
+partition_pread (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, void *buf, uint32_t count, uint64_t offs)
+{
+ struct handle *h = handle;
+
+ return next_ops->pread (nxdata, buf, count, offs + h->offset);
+}
+
+/* Write data. */
+static int
+partition_pwrite (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle,
+ const void *buf, uint32_t count, uint64_t offs)
+{
+ struct handle *h = handle;
+
+ return next_ops->pwrite (nxdata, buf, count, offs + h->offset);
+}
+
+/* Trim data. */
+static int
+partition_trim (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offs)
+{
+ struct handle *h = handle;
+
+ return next_ops->trim (nxdata, count, offs + h->offset);
+}
+
+/* Zero data. */
+static int
+partition_zero (struct nbdkit_next_ops *next_ops, void *nxdata,
+ void *handle, uint32_t count, uint64_t offs, int may_trim)
+{
+ struct handle *h = handle;
+
+ return next_ops->zero (nxdata, count, offs + h->offset, may_trim);
+}
+
+static struct nbdkit_filter filter = {
+ .name = "partition",
+ .longname = "nbdkit partition filter",
+ .version = PACKAGE_VERSION,
+ .config = partition_config,
+ .config_complete = partition_config_complete,
+ .config_help = partition_config_help,
+ .open = partition_open,
+ .prepare = partition_prepare,
+ .close = partition_close,
+ .get_size = partition_get_size,
+ .pread = partition_pread,
+ .pwrite = partition_pwrite,
+ .trim = partition_trim,
+ .zero = partition_zero,
+};
+
+NBDKIT_REGISTER_FILTER(filter)
--
2.15.1
Richard W.M. Jones
2018-Jan-19 22:51 UTC
Re: [Libguestfs] [PATCH nbdkit filters-v3 0/7] Introduce filters.
On Fri, Jan 19, 2018 at 10:36:21PM +0000, Richard W.M. Jones wrote:> This is still tentative and needs a lot of work, but: > > - partition filter works, supporting MBR & GPT > > - prepare and finalize methods fixed > > - open method can now be changed (allowing readonly flag to be modified)That should say "chained" ...> - thread_model can be limited > > I believe I made most of the changes which were previously suggested > in email. I think the only one I didn't was preventing inclusion of > both <nbdkit-plugin.h> and <nbdkit-filter.h> in the same file. > > Rich. > > _______________________________________________ > Libguestfs mailing list > Libguestfs@redhat.com > https://www.redhat.com/mailman/listinfo/libguestfs-- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v
Eric Blake
2018-Jan-19 23:27 UTC
Re: [Libguestfs] [PATCH nbdkit filters-v3 3/7] Introduce filters.
On 01/19/2018 04:36 PM, Richard W.M. Jones wrote:> Filters can be placed in front of plugins to modify their behaviour. > > This commit adds the <nbdkit-filter.h> header file, the manual page, > the ‘filterdir’ directory (like ‘plugindir’), the ‘filters/’ source > directory which will contain the actual filters, the ‘--filters’ > parameter, and the filters backend logic. > ---> + > +The filter’s C<.open> and C<.close> methods are called when a new > +connection is opened or an old connection closed, and these have no > +C<next> parameter because they cannot be short-circuited. > +Stale, given [1]> + > +=head2 C<.limit_thread_model> > + > + int (*limit_thread_model) (void);Does this need to be a callback, or can it just be a compile-time value the way plugins have a compile-time value? The backend has to have a function, to find the most restrictive model in the chain, but I'm not seeing how a filter would have a different model depending on how many times .open has been called, so exposing it as a function in the filter seems overkill.> + > +A filter may define this to make the plugin thread model more limited > +if, for some reason, the filter is unable to handle parallel requests. > +The callback, if defined, should return one of the > +C<NBDKIT_THREAD_MODEL_*> values (see L<nbdkit-plugin(3)>). > + > +The final thread model is the smallest (ie. most serialized) out of > +all the filters and the plugin. Filters cannot alter the thread model > +to make it larger (more parallel). > + > +If this callback is not defined then the filter must be prepared to > +handle fully parallel requests (like C<NBDKIT_THREAD_MODEL_PARALLEL>), > +even multiple requests issued in parallel on the same connection.This part is good, whether you go with a callback or a define.> +=head2 C<.open> > + > + void * (*open) (nbdkit_next_open *next, void *nxdata, > + int readonly);[1] this new signature.> + > +This is called when a new client connection is opened and can be used > +to allocate any per-connection data structures needed by the filter. > +The handle (which is not the same as the plugin handle) is passed back > +to other filter callbacks and could be freed in the C<.close> > +callback. > + > +Note that the handle is completely opaque to nbdkit, but it must not > +be NULL. > + > +If there is an error, C<.open> should call C<nbdkit_error> with an > +error message and return C<NULL>.No documentation about setting the underlying layers read-only (useful in a copy-on-write or copy-on-read filter)? Also, is it possible to write a filter that is read-only to the client, but must be able to write to the plugin?> +++ b/include/nbdkit-filter.h > +++ b/src/filters.c> +++ b/src/internal.h > @@ -41,6 +41,7 @@ > #include <pthread.h> > > #include "nbdkit-plugin.h" > +#include "nbdkit-filter.h"Hmm, my idea about preventing inclusion of both files at once won't work here. We may still want to prevent a single .so from declaring both a filter and a plugin, but that has to be done by means other than mutually-exclusive inclusion. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
Apparently Analagous Threads
- [PATCH nbdkit filters-v2 0/5] Introduce filters.
- [PATCH 0/9] Add filters to nbdkit.
- [nbdkit PATCH v3 00/15] Add FUA support to nbdkit
- [PATCH nbdkit] server: Implement extents/can_extents calls for plugins and filters.
- [PATCH nbdkit] server: Implement extents/can_extents calls for plugins and filters.