Laszlo Ersek
2023-Mar-23 12:10 UTC
[Libguestfs] [libnbd PATCH v3 18/19] generator: Add APIs to get/set the socket activation socket name
From: "Richard W.M. Jones" <rjones at redhat.com>
To allow us to name the socket passed down to the NBD server when
calling nbd_connect_systemd_socket_activation(3), we need to add the
field to the handle and add access functions.
[Laszlo's note: originally posted by Rich at
<https://listman.redhat.com/archives/libguestfs/2023-January/030557.html>.
I've renamed "sa_name" to "sact_name", due to
<signal.h> reserving symbols
with the "sa_" prefix. This corresponds to earlier patches in this
series,
such as 'socket activation: rename sa_(tmpdir|sockpath) to
sact_(tmpdir|sockpath)' and 'ocaml: rename "sa_u" to
"saddr_u"'.]
Message-Id: <20230130225521.1771496-4-rjones at redhat.com>
Signed-off-by: Laszlo Ersek <lersek at redhat.com>
Reviewed-by: Richard W.M. Jones <rjones at redhat.com>
---
Notes:
v4:
- pick up Rich's R-b
lib/internal.h | 1 +
generator/API.ml | 49 +++++++++++++++++
lib/handle.c | 56 ++++++++++++++++++++
3 files changed, 106 insertions(+)
diff --git a/lib/internal.h b/lib/internal.h
index 35cb5e8994ee..2de8e4e5e043 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -101,6 +101,7 @@ struct nbd_handle {
_Atomic uintptr_t private_data;
char *export_name; /* Export name, never NULL. */
+ char *sact_name; /* Socket activation name, can be NULL. */
/* TLS settings. */
int tls; /* 0 = disable, 1 = enable, 2 = require */
diff --git a/generator/API.ml b/generator/API.ml
index 91e57a4c7c4f..24f97e647d2c 100644
--- a/generator/API.ml
+++ b/generator/API.ml
@@ -2036,15 +2036,62 @@ "connect_systemd_socket_activation", {
When the NBD handle is closed the server subprocess
is killed.
+
+=head3 Socket name
+
+The socket activation protocol lets you optionally give
+the socket a name. If used, the name is passed to the
+NBD server using the C<LISTEN_FDNAMES> environment
+variable. To provide a socket name, call
+L<nbd_set_socket_activation_name(3)> before calling
+the connect function.
" ^ blocking_connect_call_description;
see_also = [Link "aio_connect_systemd_socket_activation";
Link "connect_command"; Link
"kill_subprocess";
Link "set_opt_mode";
+ Link "set_socket_activation_name";
+ Link "get_socket_activation_name";
ExternalLink ("qemu-nbd", 1);
URLLink
"http://0pointer.de/blog/projects/socket-activation.html"];
example = Some "examples/open-qcow2.c";
};
+ "set_socket_activation_name", {
+ default_call with
+ args = [ String "socket_name" ]; ret = RErr;
+ shortdesc = "set the socket activation name";
+ longdesc = "\
+When running an NBD server using
+L<nbd_connect_systemd_socket_activation(3)> you can optionally
+name the socket. Call this function before connecting to the
+server.
+
+Some servers such as L<qemu-storage-daemon(1)>
+can use this information to associate the socket with a name
+used on the command line, but most servers will ignore it.
+The name is passed through the C<LISTEN_FDNAMES> environment
+variable.
+
+The parameter C<socket_name> can be a short alphanumeric string.
+If it is set to the empty string (also the default when the handle
+is created) then no name is passed to the server.";
+ see_also = [Link "connect_systemd_socket_activation";
+ Link "get_socket_activation_name"];
+ };
+
+ "get_socket_activation_name", {
+ default_call with
+ args = []; ret = RString;
+ shortdesc = "get the socket activation name";
+ longdesc = "\
+Return the socket name used when you call
+L<nbd_connect_systemd_socket_activation(3)> on the same
+handle. By default this will return the empty string
+meaning that no name is passed to the server.";
+ see_also = [Link "connect_systemd_socket_activation";
+ Link "set_socket_activation_name"];
+ };
+
"is_read_only", {
default_call with
args = []; ret = RBool;
@@ -3844,6 +3891,8 @@ "get_uri", {
"aio_opt_structured_reply", (1, 16);
"opt_starttls", (1, 16);
"aio_opt_starttls", (1, 16);
+ "set_socket_activation_name", (1, 16);
+ "get_socket_activation_name", (1, 16);
(* These calls are proposed for a future version of libnbd, but
* have not been added to any released version so far.
diff --git a/lib/handle.c b/lib/handle.c
index 8468b964240b..0f11bee56221 100644
--- a/lib/handle.c
+++ b/lib/handle.c
@@ -28,6 +28,7 @@
#include <sys/types.h>
#include <sys/wait.h>
+#include "ascii-ctype.h"
#include "internal.h"
static void
@@ -159,6 +160,7 @@ nbd_close (struct nbd_handle *h)
waitpid (h->pid, NULL, 0);
free (h->export_name);
+ free (h->sact_name);
free (h->tls_certificates);
free (h->tls_username);
free (h->tls_psk_file);
@@ -197,6 +199,60 @@ nbd_unlocked_get_handle_name (struct nbd_handle *h)
return copy;
}
+int
+nbd_unlocked_set_socket_activation_name (struct nbd_handle *h,
+ const char *name)
+{
+ size_t i, len;
+ char *new_name;
+
+ len = strlen (name);
+
+ /* Setting it to empty string stores NULL in the handle. */
+ if (len == 0) {
+ free (h->sact_name);
+ h->sact_name = NULL;
+ return 0;
+ }
+
+ /* Check the proposed name is short and alphanumeric. */
+ if (len > 32) {
+ set_error (ENAMETOOLONG, "socket activation name should be "
+ "<= 32 characters");
+ return -1;
+ }
+ for (i = 0; i < len; ++i) {
+ if (! ascii_isalnum (name[i])) {
+ set_error (EINVAL, "socket activation name should contain "
+ "only alphanumeric ASCII characters");
+ return -1;
+ }
+ }
+
+ new_name = strdup (name);
+ if (!new_name) {
+ set_error (errno, "strdup");
+ return -1;
+ }
+
+ free (h->sact_name);
+ h->sact_name = new_name;
+ return 0;
+}
+
+char *
+nbd_unlocked_get_socket_activation_name (struct nbd_handle *h)
+{
+ char *copy = strdup (h->sact_name ? h->sact_name : "");
+
+ if (!copy) {
+ set_error (errno, "strdup");
+ return NULL;
+ }
+
+ return copy;
+}
+
uintptr_t
nbd_unlocked_set_private_data (struct nbd_handle *h, uintptr_t data)
{
Eric Blake
2023-Mar-23 19:17 UTC
[Libguestfs] [libnbd PATCH v3 18/19] generator: Add APIs to get/set the socket activation socket name
On Thu, Mar 23, 2023 at 01:10:15PM +0100, Laszlo Ersek wrote:> From: "Richard W.M. Jones" <rjones at redhat.com> > > To allow us to name the socket passed down to the NBD server when > calling nbd_connect_systemd_socket_activation(3), we need to add the > field to the handle and add access functions. > > [Laszlo's note: originally posted by Rich at > <https://listman.redhat.com/archives/libguestfs/2023-January/030557.html>. > I've renamed "sa_name" to "sact_name", due to <signal.h> reserving symbols > with the "sa_" prefix. This corresponds to earlier patches in this series, > such as 'socket activation: rename sa_(tmpdir|sockpath) to > sact_(tmpdir|sockpath)' and 'ocaml: rename "sa_u" to "saddr_u"'.] > > Message-Id: <20230130225521.1771496-4-rjones at redhat.com> > Signed-off-by: Laszlo Ersek <lersek at redhat.com> > Reviewed-by: Richard W.M. Jones <rjones at redhat.com> > --- >> +++ b/generator/API.ml > @@ -2036,15 +2036,62 @@ "connect_systemd_socket_activation", { > > When the NBD handle is closed the server subprocess > is killed. > + > +=head3 Socket name > + > +The socket activation protocol lets you optionally give > +the socket a name. If used, the name is passed to the > +NBD server using the C<LISTEN_FDNAMES> environment > +variable. To provide a socket name, call > +L<nbd_set_socket_activation_name(3)> before calling > +the connect function. > " ^ blocking_connect_call_description; > see_also = [Link "aio_connect_systemd_socket_activation"; > Link "connect_command"; Link "kill_subprocess"; > Link "set_opt_mode"; > + Link "set_socket_activation_name"; > + Link "get_socket_activation_name"; > ExternalLink ("qemu-nbd", 1); > URLLink "http://0pointer.de/blog/projects/socket-activation.html"]; > example = Some "examples/open-qcow2.c"; > }; > > + "set_socket_activation_name", { > + default_call with > + args = [ String "socket_name" ]; ret = RErr; > + shortdesc = "set the socket activation name";I recommend adding permitted_states = [ Created ]; on this one - it makes no sense to change the socket name after connection.> + longdesc = "\ > +When running an NBD server using > +L<nbd_connect_systemd_socket_activation(3)> you can optionally > +name the socket. Call this function before connecting to the > +server. > + > +Some servers such as L<qemu-storage-daemon(1)> > +can use this information to associate the socket with a name > +used on the command line, but most servers will ignore it. > +The name is passed through the C<LISTEN_FDNAMES> environment > +variable.qemu-storage-daemon doesn't do it yet, but there's a strong likelihood of it moving that direction, so I don't mind leaving this statement as-is describing what we hope is the future state of things.> + > +The parameter C<socket_name> can be a short alphanumeric string. > +If it is set to the empty string (also the default when the handle > +is created) then no name is passed to the server."; > + see_also = [Link "connect_systemd_socket_activation"; > + Link "get_socket_activation_name"]; > + }; > + > + "get_socket_activation_name", { > + default_call with > + args = []; ret = RString; > + shortdesc = "get the socket activation name";Unlike set_ which only makes sense in Created, get_ makes sense over the entire life of the handle, so no permitted_state entry needed here. My suggested one-line addition is easy enough to add that I'm fine if you do that without needing a v5. 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