Enable passing pre-opened chardev socket FDs

The fd_is_socket() helper method is useful in a few places, so put it in the common sockets code.

Signed-off-by Daniel P. Berrange <[email protected]>

---
 include/qemu/sockets.h |  1 +
 io/channel-util.c      | 13 -------------
 util/qemu-sockets.c    | 13 +++++++++++++
 3 files changed, 14 insertions(+), 13 deletions(-)

include/qemu/sockets.h +1 -0

index 4f7311b52a..5680880f5a 100644
@@ -12,6 +12,7 @@ int inet_aton(const char *cp, struct in_addr *ia);
 #include "qapi-types.h"
 
 /* misc helpers */
+bool fd_is_socket(int fd);
 int qemu_socket(int domain, int type, int protocol);
 int qemu_accept(int s, struct sockaddr *addr, socklen_t *addrlen);
 int socket_set_cork(int fd, int v);

io/channel-util.c +0 -13

index 0fb4bd0837..423d79845a 100644
@@ -24,19 +24,6 @@
 #include "io/channel-socket.h"
 
 
-static bool fd_is_socket(int fd)
-{
-    int optval;
-    socklen_t optlen;
-    optlen = sizeof(optval);
-    return qemu_getsockopt(fd,
-                           SOL_SOCKET,
-                           SO_TYPE,
-                           (char *)&optval,
-                           &optlen) == 0;
-}
-
-
 QIOChannel *qio_channel_new_fd(int fd,
                                Error **errp)
 {

util/qemu-sockets.c +13 -1

index af4f01211a..1d23f0b742 100644
@@ -91,6 +91,19 @@ NetworkAddressFamily inet_netfamily(int family)
     return NETWORK_ADDRESS_FAMILY_UNKNOWN;
 }
 
+bool fd_is_socket(int fd)
+{
+    int optval;
+    socklen_t optlen;
+    optlen = sizeof(optval);
+    return qemu_getsockopt(fd,
+                           SOL_SOCKET,
+                           SO_TYPE,
+                           (char *)&optval,
+                           &optlen) == 0;
+}
+
+
 /*
  * Matrix we're trying to apply
  *
--

2.14.3

When starting QEMU management apps will usually setup a monitor socket, and then open it immediately after startup. If not using QEMU's own -daemonize arg, this process can be troublesome to handle correctly. The mgmt app will need to repeatedly call connect() until it succeeds, because it does not know when QEMU has created the listener socket. If can't retry connect()

forever though, because an error might have caused QEMU to exit before it even creates the monitor.

The obvious way to fix this kind of problem is to just pass in a pre-opened socket file descriptor for the QEMU monitor to listen on. The management app can now immediately call connect() just once. If connect() fails it knows that QEMU has exited with an error.

The SocketAddress(Legacy) structs allow for FD passing via the monitor, using the 'getfd' command, but only when using QMP JSON syntax. The HMP syntax has no way to initialize the SocketAddress(Legacy) 'fd' variant. So this patch first wires up the 'fd' parameter to refer to a monitor file descriptor, allowing HMP to use

getfd myfd
chardev-add socket,fd=myfd

The SocketAddress 'fd' variant is currently tied to the use of the monitor 'getfd' command, so we have a chicken & egg problem with reusing that at startup wher no monitor connection is available. We could define that the special fd name prefix '/dev/fdset' refers to a FD passed via the CLI, but magic strings feel unpleasant.

Instead we define a SocketAddress 'fdset' variant that takes an fd set number that works in combination with the 'add-fd' command line argument. e.g.

-add-fd fd=3,set=1
-chardev socket,fdset=1,id=mon
-mon chardev=mon,mode=control

Note that we do not wire this up in the legacy chardev syntax, so you cannot use FD passing with '-qmp', you must use the modern '-mon' + '-chardev' pair

An illustrative example of usage is:

#!/usr/bin/perl

use IO::Socket::UNIX;
use Fcntl;

unlink "/tmp/qmp";
my $srv = IO::Socket::UNIX->new(

    Type => SOCK_STREAM(),
    Local => "/tmp/qmp",
    Listen => 1,

);

  my $flags = fcntl $srv, F_GETFD, 0;
  fcntl $srv, F_SETFD, $flags & ~FD_CLOEXEC;

  my $fd = $srv->fileno();

  exec "qemu-system-x86_64", \
      "-add-fd", "fd=$fd,set=1", \
      "-chardev", "socket,fdset=1,server,nowait,id=mon", \
      "-mon", "chardev=mon,mode=control";

Signed-off-by Daniel P. Berrange <[email protected]>

---
 chardev/char-socket.c | 66 +++++++++++++++++++++++++++++++++++++++++++++------
 chardev/char.c        |  6 +++++
 monitor.c             |  5 ++++
 qapi/common.json      | 11 +++++++++
 qapi/sockets.json     | 14 ++++++++---
 util/qemu-sockets.c   | 36 ++++++++++++++++++++++++++++
 6 files changed, 128 insertions(+), 10 deletions(-)

chardev/char-socket.c +18 -0

index 6013972f72..c85298589f 100644
@@ -28,6 +28,7 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qapi/clone-visitor.h"
+#include "qemu/cutils.h"
 
 #include "chardev/char-io.h"
 

@@ -372,6 +373,10 @@ static char *SocketAddress_to_str(const char *prefix, SocketAddress *addr,
         return g_strdup_printf("%sfd:%s%s", prefix, addr->u.fd.str,
                                is_listen ? ",server" : "");
         break;
+    case SOCKET_ADDRESS_TYPE_FDSET:
+        return g_strdup_printf("%sfdset:%" PRId64 "%s", prefix, addr->u.fdset.i,
+                               is_listen ? ",server" : "");
+        break;
     case SOCKET_ADDRESS_TYPE_VSOCK:
         return g_strdup_printf("%svsock:%s:%s", prefix,
                                addr->u.vsock.cid,

@@ -983,25 +988,62 @@ static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend,
     const char *path = qemu_opt_get(opts, "path");
     const char *host = qemu_opt_get(opts, "host");
     const char *port = qemu_opt_get(opts, "port");
+    const char *fd = qemu_opt_get(opts, "fd");
+    const char *fdset = qemu_opt_get(opts, "fdset");
+    int64_t fdseti;
     const char *tls_creds = qemu_opt_get(opts, "tls-creds");
     SocketAddressLegacy *addr;
     ChardevSocket *sock;
+    int num = 0;
+
+    if (path) {
+        num++;
+    }
+    if (fd) {
+        num++;
+    }
+    if (fdset) {
+        num++;

chardev/char-socket.c +32 -7

     backend->type = CHARDEV_BACKEND_KIND_SOCKET;
-    if (!path) {
-        if (!host) {
-            error_setg(errp, "chardev: socket: no host given");
+    if (path) {
+        if (tls_creds) {
+            error_setg(errp, "TLS can only be used over TCP socket");
             return;
         }
+    } else if (host) {
         if (!port) {
             error_setg(errp, "chardev: socket: no port given");
             return;
         }
-    } else {
-        if (tls_creds) {
-            error_setg(errp, "TLS can only be used over TCP socket");
+    } else if (fd) {
+        /* We don't know what host to validate against when in client mode */
+        if (tls_creds && !is_listen) {
+            error_setg(errp, "TLS can not be used with pre-opened client FD");
+            return;
+        }
+    } else if (fdset) {
+        /* We don't know what host to validate against when in client mode */
+        if (tls_creds && !is_listen) {
+            error_setg(errp, "TLS can not be used with pre-opened client FD");
             return;
         }
+        if (qemu_strtoi64(fdset, NULL, 10, &fdseti) < 0) {
+            error_setg_errno(errp, errno,
+                             "Cannot parse fd set number %s", fdset);
+            return;
+        }
+    } else {
+        g_assert_not_reached();
     }
 
     sock = backend->u.socket.data = g_new0(ChardevSocket, 1);

@@ -1027,7 +1069,7 @@ static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend,
         addr->type = SOCKET_ADDRESS_LEGACY_KIND_UNIX;
         q_unix = addr->u.q_unix.data = g_new0(UnixSocketAddress, 1);
         q_unix->path = g_strdup(path);
-    } else {
+    } else if (host) {
         addr->type = SOCKET_ADDRESS_LEGACY_KIND_INET;
         addr->u.inet.data = g_new(InetSocketAddress, 1);
         *addr->u.inet.data = (InetSocketAddress) {

@@ -1040,6 +1082,16 @@ static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend,
             .has_ipv6 = qemu_opt_get(opts, "ipv6"),
             .ipv6 = qemu_opt_get_bool(opts, "ipv6", 0),
         };
+    } else if (fd) {
+        addr->type = SOCKET_ADDRESS_LEGACY_KIND_FD;
+        addr->u.fd.data = g_new(String, 1);
+        addr->u.fd.data->str = g_strdup(fd);
+    } else if (fdset) {
+        addr->type = SOCKET_ADDRESS_LEGACY_KIND_FDSET;
+        addr->u.fdset.data = g_new(Int, 1);
+        addr->u.fdset.data->i = fdseti;
+    } else {
+        g_assert_not_reached();
     }
     sock->addr = addr;
 }

chardev/char.c +6 -0

index 2ae4f465ec..db940fc40f 100644
@@ -798,6 +798,12 @@ QemuOptsList qemu_chardev_opts = {
         },{
             .name = "port",
             .type = QEMU_OPT_STRING,
+        },{
+            .name = "fd",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "fdset",
+            .type = QEMU_OPT_STRING,
         },{
             .name = "localaddr",
             .type = QEMU_OPT_STRING,

monitor.c +5 -0

index d682eee2d8..c7df558535 100644
@@ -1962,6 +1962,11 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
 {
     mon_fd_t *monfd;
 
+    if (mon == NULL) {
+        error_setg(errp, "No monitor is available to acquire FD");
+        return -1;
+    }
+
     QLIST_FOREACH(monfd, &mon->fds, next) {
         int fd;
 

qapi/common.json +11 -0

index 6eb01821ef..a15cdc36e9 100644
@@ -74,6 +74,17 @@
 { 'enum': 'OnOffSplit',
   'data': [ 'on', 'off', 'split' ] }
 
+##
+# @Int:
+#
+# A fat type wrapping 'int', to be embedded in lists.
+#
+# Since: 2.12
+##
+{ 'struct': 'Int',
+  'data': {
+    'i': 'int' } }
+
 ##
 # @String:
 #

qapi/sockets.json +11 -3

index ac022c6ad0..f3cac02166 100644
@@ -112,7 +112,8 @@
     'inet': 'InetSocketAddress',
     'unix': 'UnixSocketAddress',
     'vsock': 'VsockSocketAddress',
-    'fd': 'String' } }
+    'fd': 'String',
+    'fdset': 'Int' } }
 
 ##
 # @SocketAddressType:

@@ -123,10 +124,16 @@
 #
 # @unix:  Unix domain socket
 #
+# @vsock: VSOCK socket
+#
+# @fd: socket file descriptor passed over monitor
+#
+# @fdset: socket file descriptor passed via CLI (since 2.12)
+#
 # Since: 2.9
 ##
 { 'enum': 'SocketAddressType',
-  'data': [ 'inet', 'unix', 'vsock', 'fd' ] }
+  'data': [ 'inet', 'unix', 'vsock', 'fd', 'fdset' ] }
 
 ##
 # @SocketAddress:

@@ -144,4 +151,5 @@
   'data': { 'inet': 'InetSocketAddress',
             'unix': 'UnixSocketAddress',
             'vsock': 'VsockSocketAddress',
-            'fd': 'String' } }
+            'fd': 'String',
+            'fdset': 'Int' } }

util/qemu-sockets.c +36 -1

index 1d23f0b742..d623a9840c 100644
@@ -1049,6 +1049,22 @@ int socket_connect(SocketAddress *addr, Error **errp)
         fd = monitor_get_fd(cur_mon, addr->u.fd.str, errp);
         break;
 
+    case SOCKET_ADDRESS_TYPE_FDSET:
+        fd = monitor_fdset_get_fd(addr->u.fdset.i, O_RDWR);
+        if (fd < 0) {
+            error_setg_errno(errp, errno,
+                             "Unable to get FD from fdset %" PRId64,
+                             addr->u.fdset.i);
+            return -1;
+        }
+        if (!fd_is_socket(fd)) {
+            error_setg(errp, "Expected a socket FD from fdset %" PRId64,
+                       addr->u.fdset.i);
+            close(fd);
+            return -1;
+        }
+        break;
+
     case SOCKET_ADDRESS_TYPE_VSOCK:
         fd = vsock_connect_saddr(&addr->u.vsock, errp);
         break;

@@ -1076,6 +1092,22 @@ int socket_listen(SocketAddress *addr, Error **errp)
         fd = monitor_get_fd(cur_mon, addr->u.fd.str, errp);
         break;
 
+    case SOCKET_ADDRESS_TYPE_FDSET:
+        fd = monitor_fdset_get_fd(addr->u.fdset.i, O_RDWR);
+        if (fd < 0) {
+            error_setg_errno(errp, errno,
+                             "Unable to get FD from fdset %" PRId64,
+                             addr->u.fdset.i);
+            return -1;
+        }
+        if (!fd_is_socket(fd)) {
+            error_setg(errp, "Expected a socket FD from fdset %" PRId64,
+                       addr->u.fdset.i);
+            close(fd);
+            return -1;
+        }
+        break;
+
     case SOCKET_ADDRESS_TYPE_VSOCK:
         fd = vsock_listen_saddr(&addr->u.vsock, errp);
         break;

@@ -1293,6 +1325,10 @@ SocketAddress *socket_address_flatten(SocketAddressLegacy *addr_legacy)
         addr->type = SOCKET_ADDRESS_TYPE_FD;
         QAPI_CLONE_MEMBERS(String, &addr->u.fd, addr_legacy->u.fd.data);
         break;
+    case SOCKET_ADDRESS_LEGACY_KIND_FDSET:
+        addr->type = SOCKET_ADDRESS_TYPE_FDSET;
+        QAPI_CLONE_MEMBERS(Int, &addr->u.fdset, addr_legacy->u.fdset.data);
+        break;
     default:
         abort();
     }
--

2.14.3

Quoted 11 lines

      ChardevSocket *sock;

chardev/char-socket.c +9 -0

+    int num = 0;
+
+    if (path) {
+        num++;
+    }
+    if (fd) {
+        num++;
+    }
+    if (fdset) {

chardev/char-socket.c static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend, · line 1015

Quoted 10 lines

chardev/char-socket.c +10 -0

+        num++;
+    }
+    if (host) {
+        num++;
+    }
+    if (num != 1) {
+        error_setg(errp,
+                   "Exactly one of 'path', 'fd', 'fdset' or 'host' required");
+        return;
+    }

That could be shorter ;)

Quoted 5 lines

+++ b/qapi/common.json

qapi/common.json +0 -0

@@ -74,6 +74,17 @@
  { 'enum': 'OnOffSplit',
    'data': [ 'on', 'off', 'split' ] }
 

qapi/common.json line 87

Quoted 11 lines

qapi/common.json +11 -0

+##
+# @Int:
+#
+# A fat type wrapping 'int', to be embedded in lists.
+#
+# Since: 2.12
+##
+{ 'struct': 'Int',
+  'data': {
+    'i': 'int' } }
+

Quoted 6 lines

qapi/common.json +0 -0

  ##
  # @String:
  #

qapi/sockets.json +0 -1

index ac022c6ad0..f3cac02166 100644
--- a/qapi/sockets.json

qapi/sockets.json line 116

Quoted 8 lines

+++ b/qapi/sockets.json

qapi/sockets.json +2 -1

@@ -112,7 +112,8 @@
      'inet': 'InetSocketAddress',
      'unix': 'UnixSocketAddress',
      'vsock': 'VsockSocketAddress',
-    'fd': 'String' } }
+    'fd': 'String',
+    'fdset': 'Int' } }

Quoted 10 lines

qapi/sockets.json +3 -0

  ##
  # @SocketAddressType:

@@ -123,10 +124,16 @@
  #
  # @unix:  Unix domain socket
  #
+# @vsock: VSOCK socket
+#
+# @fd: socket file descriptor passed over monitor

qapi/sockets.json line 136

Quoted 8 lines

qapi/sockets.json +4 -1

+#
+# @fdset: socket file descriptor passed via CLI (since 2.12)
+#
  # Since: 2.9
  ##
  { 'enum': 'SocketAddressType',
-  'data': [ 'inet', 'unix', 'vsock', 'fd' ] }
+  'data': [ 'inet', 'unix', 'vsock', 'fd', 'fdset' ] }

qapi/sockets.json line 155

Quoted 10 lines

qapi/sockets.json +2 -1

  ##
  # @SocketAddress:

@@ -144,4 +151,5 @@
    'data': { 'inet': 'InetSocketAddress',
              'unix': 'UnixSocketAddress',
              'vsock': 'VsockSocketAddress',
-            'fd': 'String' } }
+            'fd': 'String',
+            'fdset': 'Int' } }

When starting QEMU management apps will usually setup a monitor socket, and then open it immediately after startup. If not using QEMU's own -daemonize arg, this process can be troublesome to handle correctly. The mgmt app will need to repeatedly call connect() until it succeeds, because it does not know when QEMU has created the listener socket. If can't retry connect() forever though, because an error might have caused QEMU to exit before it even creates the monitor.

The obvious way to fix this kind of problem is to just pass in a pre-opened socket file descriptor for the QEMU monitor to listen on. The management app can now immediately call connect() just once. If connect() fails it knows that QEMU has exited with an error.

The SocketAddress(Legacy) structs allow for FD passing via the monitor, using the 'getfd' command, but only when using QMP JSON syntax. The HMP syntax has no way to initialize the SocketAddress(Legacy) 'fd' variant. So this patch first wires up the 'fd' parameter to refer to a monitor file descriptor, allowing HMP to use

getfd myfd
chardev-add socket,fd=myfd

The SocketAddress 'fd' variant is currently tied to the use of the monitor 'getfd' command, so we have a chicken & egg problem with reusing that at startup wher no monitor connection is available. We could define that the special fd name prefix '/dev/fdset' refers to a FD passed via the CLI, but magic strings feel unpleasant.

Instead we define a SocketAddress 'fdset' variant that takes an fd set number that works in combination with the 'add-fd' command line argument. e.g.

-add-fd fd=3,set=1
-chardev socket,fdset=1,id=mon
-mon chardev=mon,mode=control

When starting QEMU management apps will usually setup a monitor socket, and then open it immediately after startup. If not using QEMU's own -daemonize arg, this process can be troublesome to handle correctly. The mgmt app will need to repeatedly call connect() until it succeeds, because it does not know when QEMU has created the listener socket. If can't retry connect() forever though, because an error might have caused QEMU to exit before it even creates the monitor.

The obvious way to fix this kind of problem is to just pass in a pre-opened socket file descriptor for the QEMU monitor to listen on. The management app can now immediately call connect() just once. If connect() fails it knows that QEMU has exited with an error.

The SocketAddress(Legacy) structs allow for FD passing via the monitor, using the 'getfd' command, but only when using QMP JSON syntax. The HMP syntax has no way to initialize the SocketAddress(Legacy) 'fd' variant. So this patch first wires up the 'fd' parameter to refer to a monitor file descriptor, allowing HMP to use

getfd myfd
chardev-add socket,fd=myfd

The SocketAddress 'fd' variant is currently tied to the use of the monitor 'getfd' command, so we have a chicken & egg problem with reusing that at startup wher no monitor connection is available. We could define that the

special fd name prefix '/dev/fdset' refers to a FD passed via the CLI, but magic strings feel unpleasant.

Instead we define a SocketAddress 'fdset' variant that takes an fd set number that works in combination with the 'add-fd' command line argument. e.g.

-add-fd fd=3,set=1
-chardev socket,fdset=1,id=mon
-mon chardev=mon,mode=control

Note that we do not wire this up in the legacy chardev syntax, so you cannot use FD passing with '-qmp', you must use the modern '-mon' + '-chardev' pair

An illustrative example of usage is:

#!/usr/bin/perl

use IO::Socket::UNIX;
use Fcntl;

unlink "/tmp/qmp";
my $srv = IO::Socket::UNIX->new(

    Type => SOCK_STREAM(),
    Local => "/tmp/qmp",
    Listen => 1,

);

  my $flags = fcntl $srv, F_GETFD, 0;
  fcntl $srv, F_SETFD, $flags & ~FD_CLOEXEC;

  my $fd = $srv->fileno();

  exec "qemu-system-x86_64", \
      "-add-fd", "fd=$fd,set=1", \
      "-chardev", "socket,fdset=1,server,nowait,id=mon", \
      "-mon", "chardev=mon,mode=control";

Signed-off-by Daniel P. Berrange <[email protected]>

qapi/common.json +7 -0

+#
+# Since: 2.12
+##
+{ 'struct': 'Int',
+  'data': {
+    'i': 'int' } }
+
 ##
 # @String:
 #

qapi/sockets.json +2 -1

index ac022c6ad0..f3cac02166 100644
@@ -112,7 +112,8 @@
     'inet': 'InetSocketAddress',
     'unix': 'UnixSocketAddress',
     'vsock': 'VsockSocketAddress',
-    'fd': 'String' } }
+    'fd': 'String',
+    'fdset': 'Int' } }
 
 ##
 # @SocketAddressType:

qapi/sockets.json +3 -2

 # Since: 2.9
 ##
 { 'enum': 'SocketAddressType',
-  'data': [ 'inet', 'unix', 'vsock', 'fd' ] }
+  'data': [ 'inet', 'unix', 'vsock', 'fd', 'fdset' ] }
 
 ##
 # @SocketAddress:

@@ -144,4 +151,5 @@
   'data': { 'inet': 'InetSocketAddress',
             'unix': 'UnixSocketAddress',
             'vsock': 'VsockSocketAddress',
-            'fd': 'String' } }
+            'fd': 'String',
+            'fdset': 'Int' } }

QAPI schema review only.

Quoted 19 lines · Daniel P. Berrange

When starting QEMU management apps will usually setup a monitor socket, and then open it immediately after startup. If not using QEMU's own -daemonize arg, this process can be troublesome to handle correctly. The mgmt app will need to repeatedly call connect() until it succeeds, because it does not know when QEMU has created the listener socket. If can't retry connect() forever though, because an error might have caused QEMU to exit before it even creates the monitor.

The obvious way to fix this kind of problem is to just pass in a pre-opened socket file descriptor for the QEMU monitor to listen on. The management app can now immediately call connect() just once. If connect() fails it knows that QEMU has exited with an error.

The SocketAddress(Legacy) structs allow for FD passing via the monitor, using the 'getfd' command, but only when using QMP JSON syntax. The HMP syntax has no way to initialize the SocketAddress(Legacy) 'fd' variant. So this patch first wires up the 'fd' parameter to refer to a monitor file descriptor, allowing HMP to use

Quoted 6 lines

getfd myfd
chardev-add socket,fd=myfd

The SocketAddress 'fd' variant is currently tied to the use of the monitor 'getfd' command, so we have a chicken & egg problem with reusing that at startup wher no monitor connection is available. We could define that the

s/wher/where/

Quoted 38 lines

special fd name prefix '/dev/fdset' refers to a FD passed via the CLI, but magic strings feel unpleasant.

Instead we define a SocketAddress 'fdset' variant that takes an fd set number that works in combination with the 'add-fd' command line argument. e.g.

-add-fd fd=3,set=1
-chardev socket,fdset=1,id=mon
-mon chardev=mon,mode=control

Note that we do not wire this up in the legacy chardev syntax, so you cannot use FD passing with '-qmp', you must use the modern '-mon' + '-chardev' pair

An illustrative example of usage is:

#!/usr/bin/perl

use IO::Socket::UNIX;
use Fcntl;

unlink "/tmp/qmp";
my $srv = IO::Socket::UNIX->new(

    Type => SOCK_STREAM(),
    Local => "/tmp/qmp",
    Listen => 1,

);

  my $flags = fcntl $srv, F_GETFD, 0;
  fcntl $srv, F_SETFD, $flags & ~FD_CLOEXEC;

  my $fd = $srv->fileno();

  exec "qemu-system-x86_64", \
      "-add-fd", "fd=$fd,set=1", \
      "-chardev", "socket,fdset=1,server,nowait,id=mon", \
      "-mon", "chardev=mon,mode=control";

Signed-off-by Daniel P. Berrange <[email protected]>

[...]

qapi/common.json line 80

Quoted 12 lines

qapi/common.json +4 -0

index 6eb01821ef..a15cdc36e9 100644
@@ -74,6 +74,17 @@
 { 'enum': 'OnOffSplit',
   'data': [ 'on', 'off', 'split' ] }
 
+##
+# @Int:
+#
+# A fat type wrapping 'int', to be embedded in lists.

I figure you got the "to be embedded in lists" part from @String. That one's occasionally used as list element type, but there are other uses. @Int has only such other uses so far. Let's drop this line from both types.

Quoted 25 lines

qapi/common.json +7 -0

+#
+# Since: 2.12
+##
+{ 'struct': 'Int',
+  'data': {
+    'i': 'int' } }
+
 ##
 # @String:
 #

qapi/sockets.json +2 -1

index ac022c6ad0..f3cac02166 100644
@@ -112,7 +112,8 @@
     'inet': 'InetSocketAddress',
     'unix': 'UnixSocketAddress',
     'vsock': 'VsockSocketAddress',
-    'fd': 'String' } }
+    'fd': 'String',
+    'fdset': 'Int' } }
 
 ##
 # @SocketAddressType:

qapi/sockets.json line 130

Quoted 7 lines

qapi/sockets.json +4 -0

@@ -123,10 +124,16 @@
 #
 # @unix:  Unix domain socket
 #
+# @vsock: VSOCK socket
+#
+# @fd: socket file descriptor passed over monitor
+#

Indepedent doc fix. I'd put it in a separate patch.

One inaccuracy: @fd is *not* a file descriptor, it's the *name* of a file descriptor. Please fix.

qapi/sockets.json line 132

Quoted 2 lines

qapi/sockets.json +2 -0

+# @fdset: socket file descriptor passed via CLI (since 2.12)
+#

I gather we have to ways to pass file descriptors. One way identifies them by name (member @fd), the other by numeric ID (member @fdset).

0. This is disgusting. Is there any way to unify the two, and deprecate the loser (hopefully the numeric one)?

1. What makes the second one a *set*?

2. What ties the second one to the CLI? Accidents of implementation or something deeper?

Quoted 7 lines

qapi/sockets.json +1 -1

 # Since: 2.9
 ##
 { 'enum': 'SocketAddressType',
-  'data': [ 'inet', 'unix', 'vsock', 'fd' ] }
+  'data': [ 'inet', 'unix', 'vsock', 'fd', 'fdset' ] }
 

Quoted 9 lines

qapi/sockets.json +2 -1

 ##
 # @SocketAddress:

@@ -144,4 +151,5 @@
   'data': { 'inet': 'InetSocketAddress',
             'unix': 'UnixSocketAddress',
             'vsock': 'VsockSocketAddress',
-            'fd': 'String' } }
+            'fd': 'String',
+            'fdset': 'Int' } }

[...]

QAPI schema review only.

qapi/sockets.json line 130

Quoted 8 lines

qapi/sockets.json +4 -0

@@ -123,10 +124,16 @@
  #
  # @unix:  Unix domain socket
  #
+# @vsock: VSOCK socket
+#
+# @fd: socket file descriptor passed over monitor
+#

Indepedent doc fix. I'd put it in a separate patch.

One inaccuracy: @fd is *not* a file descriptor, it's the *name* of a file descriptor. Please fix.

qapi/sockets.json line 132

Quoted 2 lines

qapi/sockets.json +2 -0

+# @fdset: socket file descriptor passed via CLI (since 2.12)
+#

I gather we have to ways to pass file descriptors. One way identifies them by name (member @fd), the other by numeric ID (member @fdset).

0. This is disgusting. Is there any way to unify the two, and deprecate the loser (hopefully the numeric one)?

1. What makes the second one a *set*?

2. What ties the second one to the CLI? Accidents of implementation or something deeper?