doc/

2004-02-24  Marcus Brinkmann  <marcus@g10code.de>

	* gpgme.texi (cancellation): New section.

gpgme/
2004-02-24  Marcus Brinkmann  <marcus@g10code.de>

	* gpgme.c (gpgme_cancel): New function.
	* engine-backend.h (struct engine_ops): New member cancel.
	* engine.h (_gpgme_engine_cancel): New prototype.
	* engine.c (_gpgme_engine_cancel): New function.
	* engine-gpgsm.c: Add new member cancel.
	(gpgsm_cancel): New function.
	(gpgsm_release): Use it.
	* rungpg.c: Add new member cancel.

NEWS

@@ -54,16 +54,19 @@ Noteworthy changes in version 0.4.5 (unreleased)
    needed.  Still, it is there if necessary.  If in doubt, contact us
    and we will give our advise for your specific situation.
 
- * A new key listing mode for validation of the key has been added.
-   See the manual.
+ * New key listing mode GPGME_KEYLIST_MODE_VALIDATE for validation of
+   the listed keys.
+
+ * New interface gpgme_cancel() that can be used to cancel
+   asynchronous operations.
 
  * Interface changes relative to the 0.4.4 release:
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 gpgme_data_seek_cb_t		CHANGED: off_t is now a largefile type.
 gpgme_data_seek			CHANGED: off_t is now a largefile type.
 gpgme_data_new_from_filepart	CHANGED: off_t is now a largefile type.
-GPGME_KEYLIST_MODE_VALIDATE     NEW.
-
+GPGME_KEYLIST_MODE_VALIDATE     NEW
+gpgme_cancel			NEW
 
 Noteworthy changes in version 0.4.4 (2004-01-12)
 ------------------------------------------------

doc/ChangeLog

@@ -1,3 +1,7 @@
+2004-02-24  Marcus Brinkmann  <marcus@g10code.de>
+
+	* gpgme.texi (cancellation): New section.
+
 2004-02-17  Werner Koch  <wk@gnupg.org>
 
 	* gpgme.texi (Key Listing Mode): Doc KEYLIST_MODE_VALIDATE.

doc/gpgme.texi

@@ -201,6 +201,7 @@ Run Control
 
 * Waiting For Completion::        Waiting until an operation is completed.
 * Using External Event Loops::    Advanced control over what happens when.
+* Cancellation::                  How to end pending operations prematurely.
 
 Using External Event Loops
 
@@ -4315,6 +4316,7 @@ time.
 @menu
 * Waiting For Completion::        Waiting until an operation is completed.
 * Using External Event Loops::    Advanced control over what happens when.
+* Cancellation::                  How to end pending operations prematurely.
 @end menu
 
 
@@ -4898,6 +4900,43 @@ my_gpgme_register_io_callback (void *data, int fd, int dir, gpgme_io_cb_t fnc,
 @end example
 
 
+@node Cancellation
+@subsection Cancellation
+@cindex cryptographic operation, aborting
+@cindex cryptographic operation, cancelling
+@cindex aborting operations
+@cindex cancelling operations
+
+Sometimes you do not want to wait for an operation to finish.  If you
+use external I/O callbacks, you can cancel a pending operation.
+However, you must ensure that no other thread is currently using the
+context in which the operation you want to cancel runs.  This includes
+callback handlers.  So your external event loop must either be halted
+or otherwise it must be guaranteed that no installed I/O callbacks are
+run for this context.
+
+@deftypefun gpgme_ctx_t gpgme_cancel (@w{gpgme_ctx_t @var{ctx}})
+The function @code{gpgme_cancel} attempts to cancel a pending
+operation in the context @var{ctx}.  This only works if you use the
+global event loop or your own event loop.
+
+If you use the global event loop, you must not call @code{gpgme_wait}
+or @code{gpgme_wait} during cancellation.  After successful
+cancellation, you can call @code{gpgme_wait} (optionally waiting on
+@var{ctx}), and the context @var{ctx} will appear as if it had
+finished with the error code @code{GPG_ERR_CANCEL}.
+
+If you use your an external event loop, you must ensure that no I/O
+callbacks are invoked for this context (for example by halting the
+event loop).  On successful cancellation, all registered I/O callbacks
+for this context will be unregistered, and a @code{GPGME_EVENT_DONE}
+event with the error code @code{GPG_ERR_CANCEL} will be signaled.
+
+The function returns an error code if the cancellation failed (in this
+case the state of @var{ctx} is not modified).
+@end deftypefun
+
+
 @include gpl.texi
 
 

gpgme/ChangeLog

@@ -1,3 +1,14 @@
+2004-02-24  Marcus Brinkmann  <marcus@g10code.de>
+
+	* gpgme.c (gpgme_cancel): New function.
+	* engine-backend.h (struct engine_ops): New member cancel.
+	* engine.h (_gpgme_engine_cancel): New prototype.
+	* engine.c (_gpgme_engine_cancel): New function.
+	* engine-gpgsm.c: Add new member cancel.
+	(gpgsm_cancel): New function.
+	(gpgsm_release): Use it.
+	* rungpg.c: Add new member cancel.
+
 2004-02-17  Werner Koch  <wk@gnupg.org>
 
 	* gpgme.h: Add GPGME_KEYLIST_MODE_VALIDATE. 

gpgme/engine-backend.h

@@ -84,6 +84,8 @@ struct engine_ops
   
   void (*set_io_cbs) (void *engine, gpgme_io_cbs_t io_cbs);
   void (*io_event) (void *engine, gpgme_event_io_t type, void *type_data);
+
+  gpgme_error_t (*cancel) (void *engine);
 };
 
 

gpgme/engine-gpgsm.c

@@ -272,8 +272,8 @@ map_assuan_error (AssuanError err)
 }
 
 
-static void
-gpgsm_release (void *engine)
+static gpgme_error_t
+gpgsm_cancel (void *engine)
 {
   engine_gpgsm_t gpgsm = engine;
 
@@ -290,6 +290,18 @@ gpgsm_release (void *engine)
     _gpgme_io_close (gpgsm->message_cb.fd);
 
   assuan_disconnect (gpgsm->assuan_ctx);
+}
+
+
+static void
+gpgsm_release (void *engine)
+{
+  engine_gpgsm_t gpgsm = engine;
+
+  if (!gpgsm)
+    return;
+
+  gpgsm_cancel (engine);
 
   free (gpgsm->colon.attic.line);
   free (gpgsm);
@@ -1540,5 +1552,6 @@ struct engine_ops _gpgme_engine_ops_gpgsm =
     NULL,		/* trustlist */
     gpgsm_verify,
     gpgsm_set_io_cbs,
-    gpgsm_io_event
+    gpgsm_io_event,
+    gpgsm_cancel
   };

gpgme/engine.c

@@ -484,3 +484,16 @@ _gpgme_engine_io_event (engine_t engine,
 
   (*engine->ops->io_event) (engine->engine, type, type_data);
 }
+
+
+gpgme_error_t
+_gpgme_engine_cancel (engine_t engine)
+{
+  if (!engine)
+    return gpg_error (GPG_ERR_INV_VALUE);
+
+  if (!engine->ops->cancel)
+    return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+
+  return (*engine->ops->cancel) (engine->engine);
+}

gpgme/engine.h

@@ -110,4 +110,6 @@ void _gpgme_engine_set_io_cbs (engine_t engine,
 void _gpgme_engine_io_event (engine_t engine,
 			     gpgme_event_io_t type, void *type_data);
 
+gpgme_error_t _gpgme_engine_cancel (engine_t engine);
+
 #endif /* ENGINE_H */

gpgme/gpgme.c

@@ -90,6 +90,22 @@ gpgme_new (gpgme_ctx_t *r_ctx)
 }
 
 
+/* Cancel a pending asynchronous operation.  */
+gpgme_error_t
+gpgme_cancel (gpgme_ctx_t ctx)
+{
+  gpgme_error_t err;
+
+  err = _gpgme_engine_cancel (ctx->engine);
+  if (err)
+    return err;
+
+  err = gpg_error (GPG_ERR_CANCELED);
+  _gpgme_engine_io_event (ctx->engine, GPGME_EVENT_DONE, &err);
+
+  return 0;
+}
+
 /* Release all resources associated with the given context.  */
 void
 gpgme_release (gpgme_ctx_t ctx)

gpgme/gpgme.h

@@ -995,6 +995,10 @@ unsigned long gpgme_key_sig_get_ulong_attr (gpgme_key_t key, int uid_idx,
 
 /* Crypto Operations.  */
 
+/* Cancel a pending asynchronous operation.  */
+gpgme_error_t gpgme_cancel (gpgme_ctx_t ctx);
+
+
 struct _gpgme_invalid_key
 {
   struct _gpgme_invalid_key *next;

gpgme/rungpg.c

@@ -1664,5 +1664,6 @@ struct engine_ops _gpgme_engine_ops_gpg =
     gpg_trustlist,
     gpg_verify,
     gpg_set_io_cbs,
-    gpg_io_event
+    gpg_io_event,
+    NULL
   };