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-rw-r--r--src/wait-global.c378
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diff --git a/src/wait-global.c b/src/wait-global.c
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+/* wait-global.c
+ Copyright (C) 2000 Werner Koch (dd9jn)
+ Copyright (C) 2001, 2002, 2003, 2004, 2005 g10 Code GmbH
+
+ This file is part of GPGME.
+
+ GPGME is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of
+ the License, or (at your option) any later version.
+
+ GPGME is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ 02111-1307, USA. */
+
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include <errno.h>
+
+#include "gpgme.h"
+#include "sema.h"
+#include "util.h"
+#include "context.h"
+#include "wait.h"
+#include "priv-io.h"
+#include "ops.h"
+
+/* The global event loop is used for all asynchronous operations
+ (except key listing) for which no user I/O callbacks are specified.
+
+ A context sets up its initial I/O callbacks and then sends the
+ GPGME_EVENT_START event. After that, it is added to the global
+ list of active contexts.
+
+ The gpgme_wait function contains a select() loop over all file
+ descriptors in all active contexts. If an error occurs, it closes
+ all fds in that context and moves the context to the global done
+ list. Likewise, if a context has removed all I/O callbacks, it is
+ moved to the global done list.
+
+ All contexts in the global done list are eligible for being
+ returned by gpgme_wait if requested by the caller. */
+
+/* The ctx_list_lock protects the list of active and done contexts.
+ Insertion into any of these lists is only allowed when the lock is
+ held. This allows a muli-threaded program to loop over gpgme_wait
+ and in parallel start asynchronous gpgme operations.
+
+ However, the fd tables in the contexts are not protected by this
+ lock. They are only allowed to change either before the context is
+ added to the active list (ie, before the start event is signalled)
+ or in a callback handler. */
+DEFINE_STATIC_LOCK (ctx_list_lock);
+
+/* A ctx_list_item is an item in the global list of active or done
+ contexts. */
+struct ctx_list_item
+{
+ /* Every ctx_list_item is an element in a doubly linked list. The
+ list pointers are protected by the ctx_list_lock. */
+ struct ctx_list_item *next;
+ struct ctx_list_item *prev;
+
+ gpgme_ctx_t ctx;
+ /* The status is set when the ctx is moved to the done list. */
+ gpgme_error_t status;
+};
+
+/* The active list contains all contexts that are in the global event
+ loop, have active I/O callbacks, and have already seen the start
+ event. */
+static struct ctx_list_item *ctx_active_list;
+
+/* The done list contains all contexts that have previously been
+ active but now are not active any longer, either because they
+ finished successfully or an I/O callback returned an error. The
+ status field in the list item contains the error value (or 0 if
+ successful). */
+static struct ctx_list_item *ctx_done_list;
+
+
+/* Enter the context CTX into the active list. */
+static gpgme_error_t
+ctx_active (gpgme_ctx_t ctx)
+{
+ struct ctx_list_item *li = malloc (sizeof (struct ctx_list_item));
+ if (!li)
+ return gpg_error_from_errno (errno);
+ li->ctx = ctx;
+
+ LOCK (ctx_list_lock);
+ /* Add LI to active list. */
+ li->next = ctx_active_list;
+ li->prev = NULL;
+ if (ctx_active_list)
+ ctx_active_list->prev = li;
+ ctx_active_list = li;
+ UNLOCK (ctx_list_lock);
+ return 0;
+}
+
+
+/* Enter the context CTX into the done list with status STATUS. */
+static void
+ctx_done (gpgme_ctx_t ctx, gpgme_error_t status)
+{
+ struct ctx_list_item *li;
+
+ LOCK (ctx_list_lock);
+ li = ctx_active_list;
+ while (li && li->ctx != ctx)
+ li = li->next;
+ assert (li);
+
+ /* Remove LI from active list. */
+ if (li->next)
+ li->next->prev = li->prev;
+ if (li->prev)
+ li->prev->next = li->next;
+ else
+ ctx_active_list = li->next;
+
+ li->status = status;
+
+ /* Add LI to done list. */
+ li->next = ctx_done_list;
+ li->prev = NULL;
+ if (ctx_done_list)
+ ctx_done_list->prev = li;
+ ctx_done_list = li;
+ UNLOCK (ctx_list_lock);
+}
+
+
+/* Find finished context CTX (or any context if CTX is NULL) and
+ return its status in STATUS after removing it from the done list.
+ If a matching context could be found, return it. Return NULL if no
+ context could be found. */
+static gpgme_ctx_t
+ctx_wait (gpgme_ctx_t ctx, gpgme_error_t *status)
+{
+ struct ctx_list_item *li;
+
+ LOCK (ctx_list_lock);
+ li = ctx_done_list;
+ if (ctx)
+ {
+ /* A specific context is requested. */
+ while (li && li->ctx != ctx)
+ li = li->next;
+ }
+ if (li)
+ {
+ ctx = li->ctx;
+ if (status)
+ *status = li->status;
+
+ /* Remove LI from done list. */
+ if (li->next)
+ li->next->prev = li->prev;
+ if (li->prev)
+ li->prev->next = li->next;
+ else
+ ctx_done_list = li->next;
+ free (li);
+ }
+ else
+ ctx = NULL;
+ UNLOCK (ctx_list_lock);
+ return ctx;
+}
+
+
+/* Internal I/O callback functions. */
+
+/* The add_io_cb and remove_io_cb handlers are shared with the private
+ event loops. */
+
+void
+_gpgme_wait_global_event_cb (void *data, gpgme_event_io_t type,
+ void *type_data)
+{
+ gpgme_ctx_t ctx = (gpgme_ctx_t) data;
+
+ assert (ctx);
+
+ switch (type)
+ {
+ case GPGME_EVENT_START:
+ {
+ gpgme_error_t err = ctx_active (ctx);
+
+ if (err)
+ /* An error occured. Close all fds in this context, and
+ send the error in a done event. */
+ _gpgme_cancel_with_err (ctx, err);
+ }
+ break;
+
+ case GPGME_EVENT_DONE:
+ {
+ gpgme_error_t *errp = (gpgme_error_t *) type_data;
+ assert (errp);
+ ctx_done (ctx, *errp);
+ }
+ break;
+
+ case GPGME_EVENT_NEXT_KEY:
+ assert (!"Unexpected event GPGME_EVENT_NEXT_KEY");
+ break;
+
+ case GPGME_EVENT_NEXT_TRUSTITEM:
+ assert (!"Unexpected event GPGME_EVENT_NEXT_TRUSTITEM");
+ break;
+
+ default:
+ assert (!"Unexpected event");
+ break;
+ }
+}
+
+
+
+/* Perform asynchronous operations in the global event loop (ie, any
+ asynchronous operation except key listing and trustitem listing
+ operations). If CTX is not a null pointer, the function will
+ return if the asynchronous operation in the context CTX finished.
+ Otherwise the function will return if any asynchronous operation
+ finished. If HANG is zero, the function will not block for a long
+ time. Otherwise the function does not return until an operation
+ matching CTX finished.
+
+ If a matching context finished, it is returned, and *STATUS is set
+ to the error value of the operation in that context. Otherwise, if
+ the timeout expires, NULL is returned and *STATUS is 0. If an
+ error occurs, NULL is returned and *STATUS is set to the error
+ value. */
+gpgme_ctx_t
+gpgme_wait (gpgme_ctx_t ctx, gpgme_error_t *status, int hang)
+{
+ do
+ {
+ unsigned int i = 0;
+ struct ctx_list_item *li;
+ struct fd_table fdt;
+ int nr;
+
+ /* Collect the active file descriptors. */
+ LOCK (ctx_list_lock);
+ for (li = ctx_active_list; li; li = li->next)
+ i += li->ctx->fdt.size;
+ fdt.fds = malloc (i * sizeof (struct io_select_fd_s));
+ if (!fdt.fds)
+ {
+ int saved_errno = errno;
+ UNLOCK (ctx_list_lock);
+ if (status)
+ *status = gpg_error_from_errno (saved_errno);
+ return NULL;
+ }
+ fdt.size = i;
+ i = 0;
+ for (li = ctx_active_list; li; li = li->next)
+ {
+ memcpy (&fdt.fds[i], li->ctx->fdt.fds,
+ li->ctx->fdt.size * sizeof (struct io_select_fd_s));
+ i += li->ctx->fdt.size;
+ }
+ UNLOCK (ctx_list_lock);
+
+ nr = _gpgme_io_select (fdt.fds, fdt.size, 0);
+ if (nr < 0)
+ {
+ int saved_errno = errno;
+ free (fdt.fds);
+ if (status)
+ *status = gpg_error_from_errno (saved_errno);
+ return NULL;
+ }
+
+ for (i = 0; i < fdt.size && nr; i++)
+ {
+ if (fdt.fds[i].fd != -1 && fdt.fds[i].signaled)
+ {
+ gpgme_ctx_t ictx;
+ gpgme_error_t err = 0;
+ struct wait_item_s *item;
+
+ assert (nr);
+ nr--;
+
+ item = (struct wait_item_s *) fdt.fds[i].opaque;
+ assert (item);
+ ictx = item->ctx;
+ assert (ictx);
+
+ LOCK (ctx->lock);
+ if (ctx->canceled)
+ err = gpg_error (GPG_ERR_CANCELED);
+ UNLOCK (ctx->lock);
+
+ if (!err)
+ err = _gpgme_run_io_cb (&fdt.fds[i], 0);
+ if (err)
+ {
+ /* An error occured. Close all fds in this context,
+ and signal it. */
+ _gpgme_cancel_with_err (ictx, err);
+
+ /* Break out of the loop, and retry the select()
+ from scratch, because now all fds should be
+ gone. */
+ break;
+ }
+ }
+ }
+ free (fdt.fds);
+
+ /* Now some contexts might have finished successfully. */
+ LOCK (ctx_list_lock);
+ retry:
+ for (li = ctx_active_list; li; li = li->next)
+ {
+ gpgme_ctx_t actx = li->ctx;
+
+ for (i = 0; i < actx->fdt.size; i++)
+ if (actx->fdt.fds[i].fd != -1)
+ break;
+ if (i == actx->fdt.size)
+ {
+ gpgme_error_t err = 0;
+
+ /* FIXME: This does not perform too well. We have to
+ release the lock because the I/O event handler
+ acquires it to remove the context from the active
+ list. Two alternative strategies are worth
+ considering: Either implement the DONE event handler
+ here in a lock-free manner, or save a list of all
+ contexts to be released and call the DONE events
+ afterwards. */
+ UNLOCK (ctx_list_lock);
+ _gpgme_engine_io_event (actx->engine, GPGME_EVENT_DONE, &err);
+ LOCK (ctx_list_lock);
+ goto retry;
+ }
+ }
+ UNLOCK (ctx_list_lock);
+
+ {
+ gpgme_ctx_t dctx = ctx_wait (ctx, status);
+
+ if (dctx)
+ {
+ ctx = dctx;
+ hang = 0;
+ }
+ else if (!hang)
+ {
+ ctx = NULL;
+ if (status)
+ *status = 0;
+ }
+ }
+ }
+ while (hang);
+
+ return ctx;
+}
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