gpgconf: New option --chuid.

* tools/gpgconf.c (oChUid, opts): New option --chuid.
(main): Implement.
--

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

doc/DETAILS

@@ -1196,7 +1196,7 @@ pkd:0:1024:B665B1435F4C2 .... FF26ABB:
 *** MANUFACTURER <n> [<string>]
 
     This status returns the Manufactorer ID as the unsigned number N.
-    For OpenPGP this is weel defined; for other cards this is 0.  The
+    For OpenPGP this is well defined; for other cards this is 0.  The
     name of the manufacturer is also given as <string>; spaces are not
     escaped.  For PKCS#15 cards <string> is TokenInfo.manufactorerID.
 

doc/tools.texi

@@ -415,6 +415,16 @@ Try to be as quiet as possible.
 
 @include opt-homedir.texi
 
+@item --chuid @var{uid}
+@opindex chuid
+Change the current user to @var{uid} which may either be a number or a
+name.  This can be used from the root account to get information on
+the GnuPG environment of the specified user or to start or kill
+daemons.  If @var{uid} is not the current UID a standard PATH is set
+and the envvar GNUPGHOME is unset.  To override the latter the option
+@option{--homedir} can be used.  This option has currently no effect
+on Windows.
+
 @item -n
 @itemx --dry-run
 Do not actually change anything.  This is currently only implemented

tools/gpgconf.c

@@ -51,6 +51,7 @@ enum cmd_and_opt_values
     oBuilddir,
     oStatusFD,
     oShowSocket,
+    oChUid,
 
     aListComponents,
     aCheckPrograms,
@@ -113,6 +114,7 @@ static gpgrt_opt_t opts[] =
     { oNull, "null", 0, "@" },
     { oNoVerbose, "no-verbose",  0, "@"},
     ARGPARSE_s_n (oShowSocket, "show-socket", "@"),
+    ARGPARSE_s_s (oChUid, "chuid", "@"),
 
     ARGPARSE_end(),
   };
@@ -547,6 +549,7 @@ main (int argc, char **argv)
   enum cmd_and_opt_values cmd = 0;
   estream_t outfp = NULL;
   int show_socket = 0;
+  const char *changeuser = NULL;
 
   early_system_init ();
   gnupg_reopen_std (GPGCONF_NAME);
@@ -579,6 +582,7 @@ main (int argc, char **argv)
           set_status_fd (translate_sys2libc_fd_int (pargs.r.ret_int, 1));
           break;
         case oShowSocket: show_socket = 1; break;
+        case oChUid:      changeuser = pargs.r.ret_str; break;
 
 	case aListDirs:
         case aListComponents:
@@ -620,6 +624,10 @@ main (int argc, char **argv)
 
   fname = argc ? *argv : NULL;
 
+  /* If requested switch to the requested user or die.  */
+  if (changeuser && (err = gnupg_chuid (changeuser, 0)))
+    gpgconf_failure (err);
+
   /* Set the configuraton directories for use by gpgrt_argparser.  We
    * don't have a configuration file for this program but we have code
    * which reads the component's config files.  */