The aim of virNetSocketNewConnectCommand() is to execute passed
command and attach socket pair/pipe to it so that client socket
can be opened (this is used for connections with alternative
transports, e.g. ssh). The virCommand is created in a caller and
then passed to virNetSocketNewConnectCommand() where it is freed
using virCommandFree(). This approach is wrong on two levels:

1) The deallocation happens on a different level than allocation,
2) There's a WIN32 stub that just reports an error and doesn't
   free the command.

However, with g_autoptr() trickery the command can be freed in
caller.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/rpc/virnetsocket.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/rpc/virnetsocket.c b/src/rpc/virnetsocket.c
index 212089520d..50c0c4ecc8 100644
--- a/src/rpc/virnetsocket.c
+++ b/src/rpc/virnetsocket.c
@@ -821,8 +821,6 @@ int virNetSocketNewConnectCommand(virCommand *cmd,
     if (!(*retsock = virNetSocketNew(NULL, NULL, true, sv[0], errfd[0], pid, false)))
         goto error;
 
-    virCommandFree(cmd);
-
     return 0;
 
  error:
@@ -832,7 +830,6 @@ int virNetSocketNewConnectCommand(virCommand *cmd,
     VIR_FORCE_CLOSE(errfd[1]);
 
     virCommandAbort(cmd);
-    virCommandFree(cmd);
 
     return -1;
 }
@@ -856,7 +853,7 @@ int virNetSocketNewConnectSSH(const char *nodename,
                               const char *command,
                               virNetSocket **retsock)
 {
-    virCommand *cmd;
+    g_autoptr(virCommand) cmd = NULL;
 
     *retsock = NULL;
 
@@ -1154,7 +1151,7 @@ virNetSocketNewConnectLibssh(const char *host G_GNUC_UNUSED,
 int virNetSocketNewConnectExternal(const char **cmdargv,
                                    virNetSocket **retsock)
 {
-    virCommand *cmd;
+    g_autoptr(virCommand) cmd = NULL;
 
     *retsock = NULL;
 
-- 
2.32.0

On a Friday in 2021, Michal Privoznik wrote:
>The aim of virNetSocketNewConnectCommand() is to execute passed
>command and attach socket pair/pipe to it so that client socket
>can be opened (this is used for connections with alternative
>transports, e.g. ssh). The virCommand is created in a caller and
>then passed to virNetSocketNewConnectCommand() where it is freed
>using virCommandFree(). This approach is wrong on two levels:
>
>1) The deallocation happens on a different level than allocation,
>2) There's a WIN32 stub that just reports an error and doesn't
>   free the command.
>
>However, with g_autoptr() trickery the command can be freed in
>caller.
>
>Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
>---
> src/rpc/virnetsocket.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
>diff --git a/src/rpc/virnetsocket.c b/src/rpc/virnetsocket.c
>index 212089520d..50c0c4ecc8 100644
>--- a/src/rpc/virnetsocket.c
>+++ b/src/rpc/virnetsocket.c
>@@ -821,8 +821,6 @@ int virNetSocketNewConnectCommand(virCommand *cmd,
>     if (!(*retsock = virNetSocketNew(NULL, NULL, true, sv[0], errfd[0], pid, false)))
>         goto error;
>
>-    virCommandFree(cmd);
>-
>     return 0;
>
>  error:
>@@ -832,7 +830,6 @@ int virNetSocketNewConnectCommand(virCommand *cmd,
>     VIR_FORCE_CLOSE(errfd[1]);
>
>     virCommandAbort(cmd);
>-    virCommandFree(cmd);
>
>     return -1;
> }


The function is also called in tests/virnetsockettest.c

If you free the command there as well:

Reviewed-by: Ján Tomko <jtomko@redhat.com>

Jano