6:39 a.m.
From: "Richard W.M. Jones" <rjones(a)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 notes:
- Originally posted by Rich at
<https://listman.redhat.com/archives/libguestfs/2023-January/030557.html>
(Message-Id: <20230130225521.1771496-4-rjones(a)redhat.com>).
- 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"'.
- Restricted "set_socket_activation_name" to the "Created" state, per
Eric's recommendation
<http://mid.mail-archive.com/n6lzl7ii5m4hu77n7rrzm3uih3tnx457e4y67rghki34b...;.
- Documented that we are going to pass "unknown" if "socket_name" is
set
to the empty string
<http://mid.mail-archive.com/oqwjnjvq4phqr76yum6zo5erfrm3tvmyewr5nxru3oxkl...]
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
Reviewed-by: Eric Blake <eblake(a)redhat.com>
---
Notes:
v5:
- restrict the set_socket_activation_name() API to the Created state
[Eric]
- Explain that not setting (or unsetting) the socket activation name
results (per update to the next patch) in the child NBD server seeing
"unknown" [Eric, Laszlo]
- update the commit message accordingly (as the commit message is still
based on Rich's original); also move the Message-Id tag (identifying
Rich's original patch) next to the mailing list archive URL
- drop Rich's R-b due to the above changes
- pick up Eric's R-b
v4:
- pick up Rich's R-b
lib/internal.h | 1 +
generator/API.ml | 50 +++++++++++++++++
lib/handle.c | 56 ++++++++++++++++++++
3 files changed, 107 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..bbb0b8a6e1ee 100644
--- a/generator/API.ml
+++ b/generator/API.ml
@@ -2036,15 +2036,63 @@ "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;
+ permitted_states = [ Created ];
+ 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 the name C<unknown> will be seen by 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 +3892,8 @@ "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)
{