Add per-ctx custom engine options.

* src/gpgme.h.in (gpgme_ctx_set_engine_options): New prototype.
(gpgme_ctx_get_engine_options): Ditto.
* src/engine-backend.h (engine_ops): Add set_options and get_options.
* src/engine.c (gpgme_ctx_set_engine_options): New.
(gpgme_ctx_get_engine_options): Ditto.
* src/engine-gpg.c (gpg_set_options): New.
(gpg_get_options): Ditto.
* src/op-support.c (_gpgme_op_reset): Keep custom options.
* src/engine-gpg.c (_gpgme_engine_ops_gpg): Adjust for new members.
* src/engine-assuan.c (_gpgme_engine_ops_assuan): Ditto.
* src/engine-g13.c (_gpgme_engine_ops_g13): Ditto.
* src/engine-gpgconf.c (_gpgme_engine_ops_gpgconf): Ditto.
* src/engine-gpgsm.c (_gpgme_engine_ops_gpgsm): Ditto.
* src/engine-spawn.c (_gpgme_engine_ops_spawn): Ditto.
* src/engine-uiserver.c (_gpgme_engine_ops_uiserver): Ditto.
* src/gpgme.def: Export new symbols.
* src/libgpgme.vers: Ditto.
* doc/gpgme.texi: Document these new functions.

--
Not all of gpg2's features are exposed to libgpgme and adding these
functions makes it possible to do things like specify an --s2k-count,
etc.

doc/gpgme.texi

@@ -187,6 +187,7 @@ Context Attributes
 
 * Protocol Selection::            Selecting the protocol used by a context.
 * Crypto Engine::                 Configuring the crypto engine.
+* Custom Engine Options::         Adding command line options to an engine.
 * ASCII Armor::                   Requesting @acronym{ASCII} armored output.
 * Text Mode::                     Choosing canonical text mode.
 * Included Certificates::         Including a number of certificates.
@@ -2283,6 +2284,7 @@ started.  In fact, these references are accessed through the
 @menu
 * Protocol Selection::            Selecting the protocol used by a context.
 * Crypto Engine::                 Configuring the crypto engine.
+* Custom Engine Options::         Adding command line options to an engine.
 * ASCII Armor::                   Requesting @acronym{ASCII} armored output.
 * Text Mode::                     Choosing canonical text mode.
 * Included Certificates::         Including a number of certificates.
@@ -2362,6 +2364,29 @@ successful, or an eror code on failure.
 @end deftypefun
 
 
+@node Custom Engine Options
+@subsection Custom Engine Options
+@cindex context, configuring engine
+@cindex engine, configuration per context
+
+Since not all features of all engines may be exposed by @acronym{GPGME},
+additional command line arguments may be needed to allow the wanted
+functionality.
+
+@deftypefun gpgme_error_t gpgme_ctx_set_engine_options (@w{gpgme_ctx_t @var{ctx}}, @w{const char *@var{options}})
+The function @code{gpgme_ctx_set_engine_options} sets command line options for
+the configured engine in context @var{ctx} to @var{options}. The options are
+passed upon each op call and may be reset by setting @var{options} to
+@code{NULL}. This function returns @code{0} on success or an error on failure.
+@end deftypefun
+
+@deftypefun gpgme_error_t gpgme_ctx_get_engine_options (@w{gpgme_ctx_t @var{ctx}}, @w{char ** @var{result}})
+The function @code{gpgme_ctx_get_engine_options} returns the previously set
+engine options in @var{result}.  This function returns @code{0} on success or
+an error on failure.
+@end deftypefun
+
+
 @c FIXME: Unfortunately, using @acronym here breaks texi2dvi.
 @node ASCII Armor
 @subsection @acronym{ASCII} Armor

src/engine-assuan.c

@@ -759,6 +759,8 @@ struct engine_ops _gpgme_engine_ops_assuan =
     NULL,               /* set_colon_line_handler */
     llass_set_locale,
     NULL,		/* set_protocol */
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     NULL,               /* decrypt */
     NULL,               /* decrypt_verify */
     NULL,               /* delete */

src/engine-backend.h

@@ -59,6 +59,8 @@ struct engine_ops
 					   void *fnc_value);
   gpgme_error_t (*set_locale) (void *engine, int category, const char *value);
   gpgme_error_t (*set_protocol) (void *engine, gpgme_protocol_t protocol);
+  gpgme_error_t (*set_options) (void *engine, const char *options);
+  const char *(*get_options) (void *engine);
   gpgme_error_t (*decrypt) (void *engine, gpgme_data_t ciph,
 			    gpgme_data_t plain);
   gpgme_error_t (*decrypt_verify) (void *engine, gpgme_data_t ciph,

src/engine-g13.c

@@ -775,6 +775,8 @@ struct engine_ops _gpgme_engine_ops_g13 =
     NULL,               /* set_colon_line_handler */
     g13_set_locale,
     NULL,		/* set_protocol */
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     NULL,               /* decrypt */
     NULL,               /* decrypt_verify */
     NULL,               /* delete */

src/engine-gpg.c

@@ -115,6 +115,7 @@ struct engine_gpg
 
   char **argv;
   struct fd_data_map_s *fd_data_map;
+  char *options; /* gpgme_ctx_set_engine_options() */
 
   /* stuff needed for interactive (command) mode */
   struct
@@ -404,6 +405,7 @@ gpg_release (void *engine)
     free (gpg->status.buffer);
   if (gpg->colon.buffer)
     free (gpg->colon.buffer);
+  free (gpg->options);
   if (gpg->argv)
     free_argv (gpg->argv);
   if (gpg->cmd.keyword)
@@ -716,6 +718,43 @@ gpg_set_command_handler (void *engine, engine_command_handler_t fnc,
 }
 
 
+/* Custom command line options set with gpgme_ctx_set_engine_options() */
+static gpgme_error_t
+build_custom_argv (engine_gpg_t gpg, size_t *argc, char ***result)
+{
+  char *s, *options = gpg->options;
+  char **argv = NULL;
+  int total = 0;
+
+  if (!options)
+    return 0;
+
+  while ((s = strsep (&options, " ")))
+    {
+      char **tmp = realloc (argv, (total+2) * sizeof (char *));
+
+      if (!tmp)
+        {
+          free_argv (argv);
+          return GPG_ERR_ENOMEM;
+        }
+
+      argv = tmp;
+      argv[total] = strdup (s);
+      if (!argv[total++])
+        {
+          free_argv (argv);
+          return GPG_ERR_ENOMEM;
+        }
+
+      argv[total] = NULL;
+      (*argc)++;
+    }
+
+  *result = argv;
+  return 0;
+}
+
 static gpgme_error_t
 build_argv (engine_gpg_t gpg, const char *pgmname)
 {
@@ -723,7 +762,7 @@ build_argv (engine_gpg_t gpg, const char *pgmname)
   struct arg_and_data_s *a;
   struct fd_data_map_s *fd_data_map;
   size_t datac=0, argc=0;
-  char **argv;
+  char **argv, **custom_argv = NULL, **pp;
   int need_special = 0;
   int use_agent = 0;
   char *p;
@@ -780,6 +819,10 @@ build_argv (engine_gpg_t gpg, const char *pgmname)
     argc++;	/* --batch */
   argc += 1;	/* --no-sk-comments */
 
+  err = build_custom_argv (gpg, &argc, &custom_argv);
+  if (err)
+    return err;
+
   argv = calloc (argc + 1, sizeof *argv);
   if (!argv)
     return gpg_error_from_syserror ();
@@ -801,6 +844,14 @@ build_argv (engine_gpg_t gpg, const char *pgmname)
       return saved_err;
     }
   argc++;
+
+  if (custom_argv)
+    {
+      for (pp = custom_argv; pp && *pp; pp++)
+        argv[argc++] = *pp;
+      free (custom_argv);
+    }
+
   if (need_special)
     {
       argv[argc] = strdup ("--enable-special-filenames");
@@ -2449,6 +2500,30 @@ gpg_set_pinentry_mode (void *engine, gpgme_pinentry_mode_t mode)
   return 0;
 }
 
+static gpgme_error_t
+gpg_set_options (void *engine, const char *options)
+{
+  engine_gpg_t gpg = engine;
+
+  free (gpg->options);
+  gpg->options = NULL;
+  if (options)
+    {
+      gpg->options = strdup (options);
+      if (!gpg->options)
+        return GPG_ERR_ENOMEM;
+    }
+
+  return 0;
+}
+
+static const char *
+gpg_get_options (void *engine)
+{
+  engine_gpg_t gpg = engine;
+
+  return gpg->options;
+}
 
 
 struct engine_ops _gpgme_engine_ops_gpg =
@@ -2468,6 +2543,8 @@ struct engine_ops _gpgme_engine_ops_gpg =
     gpg_set_colon_line_handler,
     gpg_set_locale,
     NULL,				/* set_protocol */
+    gpg_set_options,
+    gpg_get_options,
     gpg_decrypt,
     gpg_decrypt,			/* decrypt_verify */
     gpg_delete,

src/engine-gpgconf.c

@@ -939,6 +939,8 @@ struct engine_ops _gpgme_engine_ops_gpgconf =
     NULL,		/* set_colon_line_handler */
     NULL,		/* set_locale */
     NULL,		/* set_protocol */
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     NULL,		/* decrypt */
     NULL,		/* decrypt_verify */
     NULL,		/* delete */

src/engine-gpgsm.c

@@ -1988,6 +1988,8 @@ struct engine_ops _gpgme_engine_ops_gpgsm =
     gpgsm_set_colon_line_handler,
     gpgsm_set_locale,
     NULL,		/* set_protocol */
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     gpgsm_decrypt,
     gpgsm_decrypt,
     gpgsm_delete,	/* decrypt_verify */

src/engine-spawn.c

@@ -445,6 +445,8 @@ struct engine_ops _gpgme_engine_ops_spawn =
     NULL,		/* set_colon_line_handler */
     NULL,		/* set_locale */
     NULL,		/* set_protocol */
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     NULL,		/* decrypt */
     NULL,		/* decrypt_verify */
     NULL,		/* delete */

src/engine-uiserver.c

@@ -1316,6 +1316,8 @@ struct engine_ops _gpgme_engine_ops_uiserver =
     uiserver_set_colon_line_handler,
     uiserver_set_locale,
     uiserver_set_protocol,
+    NULL,		/* set_options */
+    NULL,               /* get_options */
     uiserver_decrypt,
     uiserver_decrypt_verify,
     NULL,		/* delete */

src/engine.c

@@ -445,6 +445,37 @@ gpgme_set_engine_info (gpgme_protocol_t proto,
   return err;
 }
 
+/* Set custom command line options for the engine associated with a
+   context. */
+gpgme_error_t
+gpgme_ctx_set_engine_options (gpgme_ctx_t ctx, const char *options)
+{
+  if (!ctx || !ctx->engine)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
+  if (!ctx->engine->ops->set_options)
+    return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+
+  return (*ctx->engine->ops->set_options) (ctx->engine->engine, options);
+}
+
+/* Return previously set custom engine command line options. */
+gpgme_error_t
+gpgme_ctx_get_engine_options (gpgme_ctx_t ctx, const char **result)
+{
+  if (!ctx || !ctx->engine)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
+  if (!result)
+    return gpg_error (GPG_ERR_INV_ARG);
+
+  if (!ctx->engine->ops->get_options)
+    return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+
+  *result = (*ctx->engine->ops->get_options) (ctx->engine->engine);
+  return 0;
+}
+
 
 gpgme_error_t
 _gpgme_engine_new (gpgme_engine_info_t info, engine_t *r_engine)

src/gpgme.def

@@ -217,5 +217,7 @@ EXPORTS
 
     gpgme_op_spawn_start                  @163
     gpgme_op_spawn                        @164
+    gpgme_ctx_set_engine_options          @165
+    gpgme_ctx_get_engine_options          @166
 ; END
 

src/gpgme.h.in

@@ -947,6 +947,15 @@ gpgme_error_t gpgme_ctx_set_engine_info (gpgme_ctx_t ctx,
 					 const char *file_name,
 					 const char *home_dir);
 
+/* Set custom command line options for the engine associated with a
+   context. */
+gpgme_error_t gpgme_ctx_set_engine_options (gpgme_ctx_t ctx,
+                                            const char *options);
+
+/* Return previously set custom engine command line options. */
+gpgme_error_t gpgme_ctx_get_engine_options (gpgme_ctx_t ctx,
+                                            const char **result);
+
 
 /* Return a statically allocated string with the name of the public
    key algorithm ALGO, or NULL if that name is not known.  */

src/libgpgme.vers

@@ -92,6 +92,9 @@ GPGME_1.1 {
 
     gpgme_op_spawn_start;
     gpgme_op_spawn;
+
+    gpgme_ctx_set_engine_options;
+    gpgme_ctx_get_engine_options;
 };
 
 

src/op-support.c

@@ -83,9 +83,19 @@ _gpgme_op_reset (gpgme_ctx_t ctx, int type)
   struct gpgme_io_cbs io_cbs;
   int no_reset = (type & 256);
   int reuse_engine = 0;
+  char *options = NULL;
+  const char *tmp = NULL;
 
   type &= 255;
 
+  err = gpgme_ctx_get_engine_options (ctx, &tmp);
+  if (tmp)
+    {
+      options = strdup (tmp);
+      if (!options)
+        return GPG_ERR_ENOMEM;
+    }
+
   _gpgme_release_result (ctx);
   LOCK (ctx->lock);
   ctx->canceled = 0;
@@ -119,7 +129,21 @@ _gpgme_op_reset (gpgme_ctx_t ctx, int type)
       err = _gpgme_engine_new (info, &ctx->engine);
       if (err)
 	return err;
+
+      if (options)
+        {
+          err = gpgme_ctx_set_engine_options (ctx, options);
+          if (err && gpg_err_code (err) != GPG_ERR_NOT_IMPLEMENTED)
+            {
+              free (options);
+              _gpgme_engine_release (ctx->engine);
+              ctx->engine = NULL;
+              return err;
             }
+        }
+    }
+
+  free (options);
 
   if (!reuse_engine)
     {