Richard W.M. Jones
2023-May-17 10:06 UTC
[Libguestfs] [PATCH nbdkit v2 5/6] New plugin: ones
Returns a fully allocated disk containing all 0xff (all ones), or
another byte of your choice.
---
plugins/data/nbdkit-data-plugin.pod | 1 +
plugins/full/nbdkit-full-plugin.pod | 1 +
plugins/null/nbdkit-null-plugin.pod | 1 +
plugins/ones/nbdkit-ones-plugin.pod | 77 +++++++
plugins/pattern/nbdkit-pattern-plugin.pod | 4 +-
plugins/random/nbdkit-random-plugin.pod | 1 +
.../nbdkit-sparse-random-plugin.pod | 1 +
plugins/zero/nbdkit-zero-plugin.pod | 1 +
configure.ac | 2 +
plugins/ones/Makefile.am | 70 +++++++
tests/Makefile.am | 4 +
plugins/ones/ones.c | 191 ++++++++++++++++++
tests/test-ones.sh | 53 +++++
13 files changed, 406 insertions(+), 1 deletion(-)
diff --git a/plugins/data/nbdkit-data-plugin.pod
b/plugins/data/nbdkit-data-plugin.pod
index cec1af7f7..46daa859e 100644
--- a/plugins/data/nbdkit-data-plugin.pod
+++ b/plugins/data/nbdkit-data-plugin.pod
@@ -404,6 +404,7 @@ L<nbdkit-plugin(3)>,
L<nbdkit-info-plugin(1)>,
L<nbdkit-memory-plugin(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-partitioning-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-random-plugin(1)>,
diff --git a/plugins/full/nbdkit-full-plugin.pod
b/plugins/full/nbdkit-full-plugin.pod
index 5664aa2da..18c86a327 100644
--- a/plugins/full/nbdkit-full-plugin.pod
+++ b/plugins/full/nbdkit-full-plugin.pod
@@ -65,6 +65,7 @@ L<nbdkit(1)>,
L<nbdkit-plugin(3)>,
L<nbdkit-error-filter(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-random-plugin(1)>.
L<nbdkit-sparse-random-plugin(1)>,
diff --git a/plugins/null/nbdkit-null-plugin.pod
b/plugins/null/nbdkit-null-plugin.pod
index 27fe68746..c71dc2c6f 100644
--- a/plugins/null/nbdkit-null-plugin.pod
+++ b/plugins/null/nbdkit-null-plugin.pod
@@ -55,6 +55,7 @@ C<nbdkit-null-plugin> first appeared in nbdkit 1.2.
L<nbdkit(1)>,
L<nbdkit-plugin(3)>,
L<nbdkit-full-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-random-plugin(1)>.
L<nbdkit-sparse-random-plugin(1)>,
diff --git a/plugins/ones/nbdkit-ones-plugin.pod
b/plugins/ones/nbdkit-ones-plugin.pod
new file mode 100644
index 000000000..50ccfe272
--- /dev/null
+++ b/plugins/ones/nbdkit-ones-plugin.pod
@@ -0,0 +1,77 @@
+=head1 NAME
+
+nbdkit-ones-plugin - nbdkit plugin filled with repeated 0xff or other bytes
+
+=head1 SYNOPSIS
+
+ nbdkit ones [[size=]SIZE] [byte=N]
+
+=head1 DESCRIPTION
+
+C<nbdkit-ones-plugin> is a plugin for L<nbdkit(1)>. Any read
returns
+a repeating pattern of C<0xff> (all ones) bytes, or another repeating
+byte if you use the C<byte> parameter. Everything written to the
+virtual device is discarded.
+
+Most NBD consumers will be very confused by this device. It is mainly
+useful for testing. L<nbdkit-data-plugin(1)> can be used to create a
+modifiable RAM disk initialized with fixed data.
+
+=head1 PARAMETERS
+
+=over 4
+
+=item B<byte=>N
+
+Set the repeating byte to C<N>. The default is C<0xff> (all ones).
+
+Instead of C<byte=0> it is more efficient to use
+L<nbdkit-null-plugin(1)>.
+
+=item [B<size=>]SIZE
+
+Specify the virtual size of the disk image.
+
+This parameter is optional. If omitted then a zero-sized device is
+created.
+
+C<size=> is a magic config key and may be omitted in most cases.
+See L<nbdkit(1)/Magic parameters>.
+
+=back
+
+=head1 FILES
+
+=over 4
+
+=item F<$plugindir/nbdkit-ones-plugin.so>
+
+The plugin.
+
+Use C<nbdkit --dump-config> to find the location of C<$plugindir>.
+
+=back
+
+=head1 VERSION
+
+C<nbdkit-ones-plugin> first appeared in nbdkit 1.36.
+
+=head1 SEE ALSO
+
+L<nbdkit(1)>,
+L<nbdkit-plugin(3)>,
+L<nbdkit-data-plugin(1)>,
+L<nbdkit-full-plugin(1)>,
+L<nbdkit-null-plugin(1)>,
+L<nbdkit-pattern-plugin(1)>,
+L<nbdkit-random-plugin(1)>.
+L<nbdkit-sparse-random-plugin(1)>,
+L<nbdkit-zero-plugin(1)>.
+
+=head1 AUTHORS
+
+Richard W.M. Jones
+
+=head1 COPYRIGHT
+
+Copyright Red Hat
diff --git a/plugins/pattern/nbdkit-pattern-plugin.pod
b/plugins/pattern/nbdkit-pattern-plugin.pod
index c5d4f0d36..f4ae324ed 100644
--- a/plugins/pattern/nbdkit-pattern-plugin.pod
+++ b/plugins/pattern/nbdkit-pattern-plugin.pod
@@ -11,7 +11,8 @@ nbdkit-pattern-plugin - plugin to serve a fixed pattern of
data for testing
C<nbdkit-pattern-plugin> is a plugin for L<nbdkit(1)> which serves
a
fixed pattern of data, read only. This is used for testing nbdkit
filters and NBD clients. To create test disks filled with other
-repeated patterns use L<nbdkit-data-plugin(1)> instead.
+repeated patterns use L<nbdkit-data-plugin(1)> or
+L<nbdkit-ones-plugin(1)> instead.
The fixed pattern is the offset, as a 64 bit big endian integer, every
8 bytes. In hexadecimal this looks like:
@@ -88,6 +89,7 @@ L<nbdkit-plugin(3)>,
L<nbdkit-data-plugin(1)>,
L<nbdkit-full-plugin(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-offset-filter(1)>,
L<nbdkit-random-plugin(1)>,
L<nbdkit-sparse-random-plugin(1)>,
diff --git a/plugins/random/nbdkit-random-plugin.pod
b/plugins/random/nbdkit-random-plugin.pod
index 040d86bfc..0d6da8d5f 100644
--- a/plugins/random/nbdkit-random-plugin.pod
+++ b/plugins/random/nbdkit-random-plugin.pod
@@ -76,6 +76,7 @@ L<nbdkit-plugin(3)>,
L<nbdkit-data-plugin(1)>,
L<nbdkit-full-plugin(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-sparse-random-plugin(1)>,
L<nbdkit-zero-plugin(1)>,
diff --git a/plugins/sparse-random/nbdkit-sparse-random-plugin.pod
b/plugins/sparse-random/nbdkit-sparse-random-plugin.pod
index 03e98ee16..5636e76c4 100644
--- a/plugins/sparse-random/nbdkit-sparse-random-plugin.pod
+++ b/plugins/sparse-random/nbdkit-sparse-random-plugin.pod
@@ -110,6 +110,7 @@ L<nbdkit-plugin(3)>,
L<nbdkit-data-plugin(1)>,
L<nbdkit-full-plugin(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-random-plugin(1)>,
L<nbdkit-zero-plugin(1)>,
diff --git a/plugins/zero/nbdkit-zero-plugin.pod
b/plugins/zero/nbdkit-zero-plugin.pod
index 03544ad6e..2ac846027 100644
--- a/plugins/zero/nbdkit-zero-plugin.pod
+++ b/plugins/zero/nbdkit-zero-plugin.pod
@@ -37,6 +37,7 @@ L<nbdkit-plugin(3)>,
L<nbdkit-data-plugin(1)>,
L<nbdkit-full-plugin(1)>,
L<nbdkit-null-plugin(1)>,
+L<nbdkit-ones-plugin(1)>,
L<nbdkit-pattern-plugin(1)>,
L<nbdkit-random-plugin(1)>,
L<nbdkit-sparse-random-plugin(1)>.
diff --git a/configure.ac b/configure.ac
index dafddcc29..310de7ac1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -95,6 +95,7 @@ non_lang_plugins="\
nbd \
null \
ondemand \
+ ones \
partitioning \
pattern \
random \
@@ -1500,6 +1501,7 @@ AC_CONFIG_FILES([Makefile
plugins/null/Makefile
plugins/ocaml/Makefile
plugins/ondemand/Makefile
+ plugins/ones/Makefile
plugins/partitioning/Makefile
plugins/pattern/Makefile
plugins/perl/Makefile
diff --git a/plugins/ones/Makefile.am b/plugins/ones/Makefile.am
new file mode 100644
index 000000000..9f8cbc4e2
--- /dev/null
+++ b/plugins/ones/Makefile.am
@@ -0,0 +1,70 @@
+# nbdkit
+# Copyright Red Hat
+#
+# 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 $(top_srcdir)/common-rules.mk
+
+EXTRA_DIST = nbdkit-ones-plugin.pod
+
+plugin_LTLIBRARIES = nbdkit-ones-plugin.la
+
+nbdkit_ones_plugin_la_SOURCES = \
+ ones.c \
+ $(top_srcdir)/include/nbdkit-plugin.h \
+ $(NULL)
+
+nbdkit_ones_plugin_la_CPPFLAGS = \
+ -I$(top_srcdir)/include \
+ -I$(top_builddir)/include \
+ $(NULL)
+nbdkit_ones_plugin_la_CFLAGS = $(WARNINGS_CFLAGS)
+nbdkit_ones_plugin_la_LIBADD = \
+ $(IMPORT_LIBRARY_ON_WINDOWS) \
+ $(NULL)
+nbdkit_ones_plugin_la_LDFLAGS = \
+ -module -avoid-version -shared $(NO_UNDEFINED_ON_WINDOWS) \
+ $(NULL)
+if USE_LINKER_SCRIPT
+nbdkit_ones_plugin_la_LDFLAGS += \
+ -Wl,--version-script=$(top_srcdir)/plugins/plugins.syms
+endif
+
+if HAVE_POD
+
+man_MANS = nbdkit-ones-plugin.1
+CLEANFILES += $(man_MANS)
+
+nbdkit-ones-plugin.1: nbdkit-ones-plugin.pod \
+ $(top_builddir)/podwrapper.pl
+ $(PODWRAPPER) --section=1 --man $@ \
+ --html $(top_builddir)/html/$@.html \
+ $<
+
+endif HAVE_POD
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 3c8123f45..3ae13d660 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -955,6 +955,10 @@ EXTRA_DIST += \
test-ondemand-locking.sh \
$(NULL)
+# ones plugin test.
+TESTS += test-ones.sh
+EXTRA_DIST += test-ones.sh
+
# partitioning plugin test.
TESTS += \
test-partitioning1.sh \
diff --git a/plugins/ones/ones.c b/plugins/ones/ones.c
new file mode 100644
index 000000000..2ff1ed028
--- /dev/null
+++ b/plugins/ones/ones.c
@@ -0,0 +1,191 @@
+/* nbdkit
+ * Copyright Red Hat
+ *
+ * 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 <errno.h>
+
+#define NBDKIT_API_VERSION 2
+
+#include <nbdkit-plugin.h>
+
+/* The size of disk in bytes (initialized by size=<SIZE> parameter). */
+static int64_t size = 0;
+
+/* Repeating byte. */
+static uint8_t byte = 0xff;
+
+static int
+ones_config (const char *key, const char *value)
+{
+ int64_t r;
+
+ if (strcmp (key, "size") == 0) {
+ r = nbdkit_parse_size (value);
+ if (r == -1)
+ return -1;
+ size = r;
+ }
+ else if (strcmp (key, "byte") == 0) {
+ if (nbdkit_parse_uint8_t ("byte", value, &byte) == -1)
+ return -1;
+ }
+ else {
+ nbdkit_error ("unknown parameter '%s'", key);
+ return -1;
+ }
+
+ return 0;
+}
+
+#define ones_config_help \
+ "byte=<BYTE> Repeating byte to use (default:
0xff).\n" \
+ "size=<SIZE> Size of the backing disk."
+
+/* Create the per-connection handle. */
+static void *
+ones_open (int readonly)
+{
+ return NBDKIT_HANDLE_NOT_NEEDED;
+}
+
+#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
+
+/* Get the disk size. */
+static int64_t
+ones_get_size (void *handle)
+{
+ return size;
+}
+
+/* Serves the same data over multiple connections. */
+static int
+ones_can_multi_conn (void *handle)
+{
+ return 1;
+}
+
+/* Cache. */
+static int
+ones_can_cache (void *handle)
+{
+ /* Everything is already in memory, returning this without
+ * implementing .cache lets nbdkit do the correct no-op.
+ */
+ return NBDKIT_CACHE_NATIVE;
+}
+
+/* Read data. */
+static int
+ones_pread (void *handle, void *buf, uint32_t count, uint64_t offset,
+ uint32_t flags)
+{
+ memset (buf, byte, count);
+ return 0;
+}
+
+/* Write data. */
+static int
+ones_pwrite (void *handle, const void *buf, uint32_t count, uint64_t offset,
+ uint32_t flags)
+{
+ /* nothing */
+ return 0;
+}
+
+/* Write zeroes. */
+static int
+ones_zero (void *handle, uint32_t count, uint64_t offset, uint32_t flags)
+{
+ /* nothing */
+ return 0;
+}
+
+/* Flush is a no-op, so advertise native FUA support */
+static int
+ones_can_fua (void *handle)
+{
+ return NBDKIT_FUA_NATIVE;
+}
+
+/* Trim. */
+static int
+ones_trim (void *handle, uint32_t count, uint64_t offset, uint32_t flags)
+{
+ /* nothing */
+ return 0;
+}
+
+/* Nothing is persistent, so flush is trivially supported */
+static int
+ones_flush (void *handle, uint32_t flags)
+{
+ return 0;
+}
+
+/* Extents. */
+static int
+ones_extents (void *handle, uint32_t count, uint64_t offset, uint32_t flags,
+ struct nbdkit_extents *extents)
+{
+ /* Return a fully allocated data extent covering the entire disk. */
+ return nbdkit_add_extent (extents, 0, size, 0);
+}
+
+static struct nbdkit_plugin plugin = {
+ .name = "ones",
+ .version = PACKAGE_VERSION,
+ .config = ones_config,
+ .config_help = ones_config_help,
+ .magic_config_key = "size",
+ .open = ones_open,
+ .get_size = ones_get_size,
+ .can_multi_conn = ones_can_multi_conn,
+ .can_cache = ones_can_cache,
+ .pread = ones_pread,
+ .pwrite = ones_pwrite,
+ .zero = ones_zero,
+ .trim = ones_trim,
+ .can_fua = ones_can_fua,
+ .flush = ones_flush,
+ .extents = ones_extents,
+ /* In this plugin, errno is preserved properly along error return
+ * paths from failed system calls.
+ */
+ .errno_is_preserved = 1,
+};
+
+NBDKIT_REGISTER_PLUGIN (plugin)
diff --git a/tests/test-ones.sh b/tests/test-ones.sh
new file mode 100755
index 000000000..1a2b22caf
--- /dev/null
+++ b/tests/test-ones.sh
@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+# nbdkit
+# Copyright Red Hat
+#
+# 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.
+
+source ./functions.sh
+set -e
+set -x
+
+requires_plugin ones
+requires_nbdsh_uri
+requires_nbdinfo
+
+# Check the disk contains 0xff by default.
+nbdkit -U - ones 1024 --run '
+nbdsh -u "$uri" -c "assert (h.pread(1024,0) ==
b\"\\xff\"*1024)"
+'
+
+# Change the byte.
+nbdkit -U - ones 1024 byte=0x5a --run '
+nbdsh -u "$uri" -c "assert (h.pread(1024,0) ==
b\"\\x5a\"*1024)"
+'
+
+# Check the disk is fully allocated.
+nbdkit -U - ones 1G --run 'nbdinfo --map "$uri"' | \
+ grep -E '0[[:space:]]+1073741824[[:space:]]+0[[:space:]]+data'
--
2.39.2
On Wed, May 17, 2023 at 11:06:58AM +0100, Richard W.M. Jones wrote:> Returns a fully allocated disk containing all 0xff (all ones), or > another byte of your choice. > --- > + > +=item B<byte=>N > + > +Set the repeating byte to C<N>. The default is C<0xff> (all ones). > + > +Instead of C<byte=0> it is more efficient to use > +L<nbdkit-null-plugin(1)>.Good catch. On v1, I suggested nbdkit-zero-plugin, but re-reading the difference between those two, I see you got the one I meant. (For the casual reader: zero-plugin has size zero, while the null plugin has non-zero size that reads as zero) Reviewed-by: Eric Blake <eblake at redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
On Wed, May 17, 2023 at 11:06:58AM +0100, Richard W.M. Jones wrote:> Returns a fully allocated disk containing all 0xff (all ones), or > another byte of your choice. > --- > plugins/data/nbdkit-data-plugin.pod | 1 + > plugins/full/nbdkit-full-plugin.pod | 1 + > plugins/null/nbdkit-null-plugin.pod | 1 + > plugins/ones/nbdkit-ones-plugin.pod | 77 +++++++ > plugins/pattern/nbdkit-pattern-plugin.pod | 4 +- > plugins/random/nbdkit-random-plugin.pod | 1 + > .../nbdkit-sparse-random-plugin.pod | 1 + > plugins/zero/nbdkit-zero-plugin.pod | 1 + > configure.ac | 2 + > plugins/ones/Makefile.am | 70 +++++++ > tests/Makefile.am | 4 + > plugins/ones/ones.c | 191 ++++++++++++++++++ > tests/test-ones.sh | 53 +++++ > 13 files changed, 406 insertions(+), 1 deletion(-) > > +++ b/plugins/ones/ones.c > @@ -0,0 +1,191 @@> + > +/* Write zeroes. */ > +static int > +ones_zero (void *handle, uint32_t count, uint64_t offset, uint32_t flags) > +{ > + /* nothing */ > + return 0; > +}Since writing zeroes is a no-op...> +static struct nbdkit_plugin plugin = { > + .name = "ones", > + .version = PACKAGE_VERSION, > + .config = ones_config, > + .config_help = ones_config_help, > + .magic_config_key = "size", > + .open = ones_open, > + .get_size = ones_get_size, > + .can_multi_conn = ones_can_multi_conn, > + .can_cache = ones_can_cache, > + .pread = ones_pread, > + .pwrite = ones_pwrite, > + .zero = ones_zero, > + .trim = ones_trim, > + .can_fua = ones_can_fua, > + .flush = ones_flush, > + .extents = ones_extents, > + /* In this plugin, errno is preserved properly along error return > + * paths from failed system calls. > + */ > + .errno_is_preserved = 1, > +};...we probably also want to supply .can_fast_zero with a function that returns true. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org