agent,dirmngr: New option --steal-socket

* agent/gpg-agent.c (oStealSocket): New.
(opts): Add option.
(steal_socket): New file global var.
(main): Set option.
(create_server_socket): Implement option.

* dirmngr/dirmngr.c (oStealSocket): New.
(opts): Add option.
(steal_socket): New file global var.
(main): Set option.  Add comment to eventually implement it.
--

Note that --steal-socket has currently no effect on dirmngr because
dirmngr does this anway.

Signed-off-by: Werner Koch <wk@gnupg.org>

agent/gpg-agent.c

@@ -119,6 +119,7 @@ enum cmd_and_opt_values
   oEnablePassphraseHistory,
   oDisableExtendedKeyFormat,
   oEnableExtendedKeyFormat,
+  oStealSocket,
   oUseStandardSocket,
   oNoUseStandardSocket,
   oExtraSocket,
@@ -173,6 +174,7 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_n (oQuiet,	  "quiet",     N_("be somewhat more quiet")),
   ARGPARSE_s_n (oSh,	  "sh",        N_("sh-style command output")),
   ARGPARSE_s_n (oCsh,	  "csh",       N_("csh-style command output")),
+  ARGPARSE_s_n (oStealSocket, "steal-socket", "@"),
   ARGPARSE_conffile (oOptions, "options", N_("|FILE|read options from FILE")),
 
   ARGPARSE_s_s (oDebug,	     "debug",       "@"),
@@ -362,6 +364,9 @@ static int disable_check_own_socket;
 /* Flag indicating that we are in supervised mode.  */
 static int is_supervised;
 
+/* Flag indicating to start the daemon even if one already runs.  */
+static int steal_socket;
+
 /* Flag to inhibit socket removal in cleanup.  */
 static int inhibit_socket_removal;
 
@@ -1211,6 +1216,7 @@ main (int argc, char **argv )
         case oSh: csh_style = 0; break;
         case oServer: pipe_server = 1; break;
         case oDaemon: is_daemon = 1; break;
+        case oStealSocket: steal_socket = 1; break;
         case oSupervised: is_supervised = 1; break;
 
         case oDisplay: default_display = xstrdup (pargs.r.ret_str); break;
@@ -2226,14 +2232,20 @@ create_server_socket (char *name, int primary, int cygwin,
          server is not yet operational; this would lead to a hang.  */
       if (primary && !check_for_running_agent (1))
         {
-          log_set_prefix (NULL, GPGRT_LOG_WITH_PREFIX);
-          log_set_file (NULL);
-          log_error (_("a gpg-agent is already running - "
-                       "not starting a new one\n"));
-          *name = 0; /* Inhibit removal of the socket by cleanup(). */
-          assuan_sock_close (fd);
-          xfree (unaddr);
-          agent_exit (2);
+          if (steal_socket)
+            log_info (N_("trying to steal socket from running %s\n"),
+                      "gpg-agent");
+          else
+            {
+              log_set_prefix (NULL, GPGRT_LOG_WITH_PREFIX);
+              log_set_file (NULL);
+              log_error (_("a gpg-agent is already running - "
+                           "not starting a new one\n"));
+              *name = 0; /* Inhibit removal of the socket by cleanup(). */
+              assuan_sock_close (fd);
+              xfree (unaddr);
+              agent_exit (2);
+            }
         }
       gnupg_remove (unaddr->sun_path);
       rc = assuan_sock_bind (fd, addr, len);

dirmngr/dirmngr.c

@@ -139,6 +139,7 @@ enum cmd_and_opt_values {
   oForce,
   oAllowOCSP,
   oAllowVersionCheck,
+  oStealSocket,
   oSocketName,
   oLDAPWrapperProgram,
   oHTTPWrapperProgram,
@@ -188,6 +189,7 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_s (oDebugLevel, "debug-level",
                 N_("|LEVEL|set the debugging level to LEVEL")),
   ARGPARSE_s_n (oNoDetach, "no-detach", N_("do not detach from the console")),
+  ARGPARSE_s_n (oStealSocket, "steal-socket", "@"),
   ARGPARSE_s_s (oLogFile,  "log-file",
                 N_("|FILE|write server mode logs to FILE")),
   ARGPARSE_s_n (oBatch,    "batch",       N_("run without asking a user")),
@@ -329,6 +331,10 @@ static volatile int shutdown_pending;
 /* Flags to indicate that we shall not watch our own socket. */
 static int disable_check_own_socket;
 
+/* Flag indicating to start the daemon even if one already runs.  */
+static int steal_socket;
+
+
 /* Flag to control the Tor mode.  */
 static enum
   { TOR_MODE_AUTO = 0,  /* Switch to NO or YES         */
@@ -1062,6 +1068,7 @@ main (int argc, char **argv)
         case oNoVerbose: opt.verbose = 0; break;
         case oHomedir: /* Ignore this option here. */; break;
         case oNoDetach: nodetach = 1; break;
+        case oStealSocket: steal_socket = 1; break;
         case oLogFile: logfile = pargs.r.ret_str; break;
         case oCsh: csh_style = 1; break;
         case oSh: csh_style = 0; break;
@@ -1323,7 +1330,11 @@ main (int argc, char **argv)
 #endif
               ))
 	{
-          /* Fixme: We should test whether a dirmngr is already running. */
+          /* Fixme: We should actually test whether a dirmngr is
+           * already running.  For now the steal option is a dummy. */
+          /* if (steal_socket) */
+          /*   log_info (N_("trying to steal socket from running %s\n"), */
+          /*             "dirmngr"); */
 	  gnupg_remove (redir_socket_name? redir_socket_name : socket_name);
 	  rc = assuan_sock_bind (fd, (struct sockaddr*) &serv_addr, len);
 	}

doc/gpg-agent.texi

@@ -316,6 +316,15 @@ Pinentry.  As of now it is only useful when used along with
 Don't detach the process from the console.  This is mainly useful for
 debugging.
 
+@item --steal-socket
+@opindex steal-socket
+In @option{--daemon} mode, gpg-agent detects an already running
+gpg-agent and does not allow to start a new instance. This option can
+be used to override this check: the new gpg-agent process will try to
+take over the communication sockets from the already running process
+and start anyway.  This option should in general not be used.
+
+
 @item -s
 @itemx --sh
 @itemx -c