gpgconf: Enhance --list-dirs.

* tools/gpgconf.c (main) <aListDir>: Factor code out to ...
(list_dirs): new.  Rewrite to use a table.  Allow selection of a
items.  Add "agent-ssh-socket".
--

This change makes the use of gpgconf in scripts easier.  For example,
to set the envvar with the name of the socket used by ssh, it is now
possible to do this:

  SSH_AUTH_SOCK="$(gpgconf --list-dirs agent-ssh-socket)"

which guarantees that the right name is used.

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

doc/gpg-agent.texi

@@ -815,7 +815,7 @@ it by adding this to your init script:
 @example
 unset SSH_AGENT_PID
 if [ "$@{gnupg_SSH_AUTH_SOCK_by:-0@}" -ne $$ ]; then
-  export SSH_AUTH_SOCK="$@{HOME@}/.gnupg/S.gpg-agent.ssh"
+  export SSH_AUTH_SOCK="$(gpgconf --list-dirs agent-ssh-socket)"
 fi
 @end example
 @end cartouche

doc/tools.texi

@@ -280,7 +280,7 @@ Check the options for the component @var{component}.
 Update all configuration files with values taken from the global
 configuration file (usually @file{/etc/gnupg/gpgconf.conf}).
 
-@item --list-dirs
+@item --list-dirs [@var{names}]
 Lists the directories used by @command{gpgconf}.  One directory is
 listed per line, and each line consists of a colon-separated list where
 the first field names the directory type (for example @code{sysconfdir})
@@ -288,7 +288,9 @@ and the second field contains the percent-escaped directory.  Although
 they are not directories, the socket file names used by
 @command{gpg-agent} and @command{dirmngr} are printed as well.  Note
 that the socket file names and the @code{homedir} lines are the default
-names and they may be overridden by command line switches.
+names and they may be overridden by command line switches.  If
+@var{names} are given only the directories or file names specified by
+the list names are printed without any escaping.
 
 @item --list-config [@var{filename}]
 List the global configuration file in a colon separated format.  If

tools/gpgconf.c

@@ -147,6 +147,64 @@ get_outfp (estream_t *fp)
 }
 
 
+static void
+list_dirs (estream_t fp, char **names)
+{
+  static struct {
+    const char *name;
+    const char *(*fnc)(void);
+    const char *extra;
+    int special;
+  } list[] = {
+    { "sysconfdir",         gnupg_sysconfdir, NULL },
+    { "bindir",             gnupg_bindir,     NULL },
+    { "libexecdir",         gnupg_libexecdir, NULL },
+    { "libdir",             gnupg_libdir,     NULL },
+    { "datadir",            gnupg_datadir,    NULL },
+    { "localedir",          gnupg_localedir,  NULL },
+    { "dirmngr-socket",     dirmngr_user_socket_name, NULL, 1 },
+    { "dirmngr-socket",     dirmngr_sys_socket_name,  NULL, 2 },
+    { "dirmngr-sys-socket", dirmngr_sys_socket_name,  NULL, 1 },
+    { "agent-ssh-socket",   gnupg_socketdir,  GPG_AGENT_SSH_SOCK_NAME },
+    { "agent-socket",       gnupg_socketdir,  GPG_AGENT_SOCK_NAME },
+    { "homedir",            gnupg_homedir,    NULL }
+  };
+  int idx, j;
+  char *tmp;
+  const char *s;
+
+
+  for (idx = 0; idx < DIM (list); idx++)
+    {
+      if (list[idx].special == 1 && dirmngr_user_socket_name ())
+        ;
+      else if (list[idx].special == 2 && !dirmngr_user_socket_name ())
+        ;
+      else if (list[idx].special == 1 || list[idx].special == 2)
+        continue;
+
+      s = list[idx].fnc ();
+      if (list[idx].extra)
+        {
+          tmp = make_filename (s, list[idx].extra, NULL);
+          s = tmp;
+        }
+      else
+        tmp = NULL;
+      if (!names)
+        es_fprintf (fp, "%s:%s\n", list[idx].name, gc_percent_escape (s));
+      else
+        {
+          for (j=0; names[j]; j++)
+            if (!strcmp (names[j], list[idx].name))
+              es_fprintf (fp, "%s\n", s);
+        }
+
+      xfree (tmp);
+    }
+}
+
+
 /* gpgconf main. */
 int
 main (int argc, char **argv)
@@ -357,43 +415,7 @@ main (int argc, char **argv)
     case aListDirs:
       /* Show the system configuration directories for gpgconf.  */
       get_outfp (&outfp);
-      es_fprintf (outfp, "sysconfdir:%s\n",
-                  gc_percent_escape (gnupg_sysconfdir ()));
-      es_fprintf (outfp, "bindir:%s\n",
-                  gc_percent_escape (gnupg_bindir ()));
-      es_fprintf (outfp, "libexecdir:%s\n",
-                  gc_percent_escape (gnupg_libexecdir ()));
-      es_fprintf (outfp, "libdir:%s\n",
-                  gc_percent_escape (gnupg_libdir ()));
-      es_fprintf (outfp, "datadir:%s\n",
-                  gc_percent_escape (gnupg_datadir ()));
-      es_fprintf (outfp, "localedir:%s\n",
-                  gc_percent_escape (gnupg_localedir ()));
-
-      if (dirmngr_user_socket_name ())
-        {
-          es_fprintf (outfp, "dirmngr-socket:%s\n",
-                      gc_percent_escape (dirmngr_user_socket_name ()));
-          es_fprintf (outfp, "dirmngr-sys-socket:%s\n",
-                      gc_percent_escape (dirmngr_sys_socket_name ()));
-        }
-      else
-        {
-          es_fprintf (outfp, "dirmngr-socket:%s\n",
-                      gc_percent_escape (dirmngr_sys_socket_name ()));
-        }
-
-      {
-        char *tmp = make_filename (gnupg_socketdir (),
-                                   GPG_AGENT_SOCK_NAME, NULL);
-        es_fprintf (outfp, "agent-socket:%s\n", gc_percent_escape (tmp));
-        xfree (tmp);
-      }
-      {
-        char *tmp = xstrdup (gnupg_homedir ());
-        es_fprintf (outfp, "homedir:%s\n", gc_percent_escape (tmp));
-        xfree (tmp);
-      }
+      list_dirs (outfp, argc? argv : NULL);
       break;
 
     case aCreateSocketDir: