[PATCH 2/2] agent: --supervised mode improvements when LISTEN_FDNAMES is unset

[Daniel Kahn Gillmor]

* agent/gpg-agent.c (map_supervised_socket): if the agent is running
  in --supervised mode and is not actually given LISTEN_FDNAMES
  directives, require at least fd 3 to be open for listening.

Signed-off-by: Daniel Kahn Gillmor <dkg at fifthhorseman.net>
---
 agent/gpg-agent.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/agent/gpg-agent.c b/agent/gpg-agent.c
index 16edae0..7fb85aa 100644
--- a/agent/gpg-agent.c
+++ b/agent/gpg-agent.c
@@ -716,12 +716,19 @@ map_supervised_sockets (gnupg_fd_t *r_fd,
   /* Assign the descriptors to the return values.  */
   if (!fdnames)
     {
+      struct stat statbuf;
       if (fd_count != 1)
         log_error ("no LISTEN_FDNAMES and LISTEN_FDS (%d) != 1"
                    " in --supervised mode."
                    " (ignoring all sockets but the first one)\n",
                    fd_count);
+      if (fstat (3, &statbuf) == -1 && errno ==EBADF)
+        log_fatal ("file descriptor 3 must be valid in --supervised mode (as the "
+                   "agent's standard socket) if LISTEN_FDNAMES is not set\n"); 
       *r_fd = 3;
+      socket_name = get_socket_name (3);
+      if (!socket_name)
+          log_error ("cannot learn socket name for fd 3\n");
     }
   else if (fd_count != nfdnames)
     {
-- 
2.9.3