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gnupg/dirmngr/workqueue.c

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/* workqueue.c - Maintain a queue of background tasks
* Copyright (C) 2017 Werner Koch
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GnuPG 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses/>.
*
* SPDX-License-Identifier: GPL-3.0+
*/
#include <config.h>
#include <stdlib.h>
#include <string.h>
#include "dirmngr.h"
/* An object for one item in the workqueue. */
struct wqitem_s
{
struct wqitem_s *next;
/* This flag is set if the task requires network access. */
unsigned int need_network:1;
/* The id of the session which created this task. If this is 0 the
* task is not associated with a specific session. */
unsigned int session_id;
/* The function to perform the backgrount task. */
wqtask_t func;
/* A string with the string argument for that task. */
char args[1];
};
typedef struct wqitem_s *wqitem_t;
/* The workque is a simple linked list. */
static wqitem_t workqueue;
/* Dump the queue using Assuan status comments. */
void
workqueue_dump_queue (ctrl_t ctrl)
{
wqitem_t saved_workqueue;
wqitem_t item;
unsigned int count;
/* Temporay detach the entiere workqueue so that other threads don't
* get into our way. */
saved_workqueue = workqueue;
workqueue = NULL;
for (count=0, item = saved_workqueue; item; item = item->next)
count++;
dirmngr_status_helpf (ctrl, "wq: number of entries: %u", count);
for (item = saved_workqueue; item; item = item->next)
dirmngr_status_helpf (ctrl, "wq: sess=%u net=%d %s(\"%.100s%s\")",
item->session_id, item->need_network,
item->func? item->func (NULL, NULL): "nop",
item->args, strlen (item->args) > 100? "[...]":"");
/* Restore then workqueue. Actually we append the saved queue do a
* possibly updated workqueue. */
if (!(item=workqueue))
workqueue = saved_workqueue;
else
{
while (item->next)
item = item->next;
item->next = saved_workqueue;
}
}
/* Append the task (FUNC,ARGS) to the work queue. FUNC shall return
* its name when called with (NULL, NULL). */
gpg_error_t
workqueue_add_task (wqtask_t func, const char *args, unsigned int session_id,
int need_network)
{
wqitem_t item, wi;
item = xtrycalloc (1, sizeof *item + strlen (args));
if (!item)
return gpg_error_from_syserror ();
strcpy (item->args, args);
item->func = func;
item->session_id = session_id;
item->need_network = !!need_network;
if (!(wi=workqueue))
workqueue = item;
else
{
while (wi->next)
wi = wi->next;
wi->next = item;
}
return 0;
}
/* Run the task described by ITEM. ITEM must have been detached from
* the workqueue; its ownership is transferred to this fucntion. */
static void
run_a_task (ctrl_t ctrl, wqitem_t item)
{
log_assert (!item->next);
if (opt.verbose)
log_info ("session %u: running %s(\"%s%s\")\n",
item->session_id,
item->func? item->func (NULL, NULL): "nop",
item->args, strlen (item->args) > 100? "[...]":"");
if (item->func)
item->func (ctrl, item->args);
xfree (item);
}
/* Run tasks not associated with a session. This is called from the
* ticker every few minutes. If WITH_NETWORK is not set tasks which
* require the network are not run. */
void
workqueue_run_global_tasks (ctrl_t ctrl, int with_network)
{
wqitem_t item, prev;
with_network = !!with_network;
if (opt.verbose)
log_info ("running scheduled tasks%s\n", with_network?" (with network)":"");
for (;;)
{
prev = NULL;
for (item = workqueue; item; prev = item, item = item->next)
if (!item->session_id
&& (!item->need_network || (item->need_network && with_network)))
break;
if (!item)
break; /* No more tasks to run. */
/* Detach that item from the workqueue. */
if (!prev)
workqueue = item->next;
else
prev->next = item->next;
item->next = NULL;
/* Run the task. */
run_a_task (ctrl, item);
}
}
/* Run tasks scheduled for running after a session. Those tasks are
* identified by the SESSION_ID. */
void
workqueue_run_post_session_tasks (unsigned int session_id)
{
struct server_control_s ctrlbuf;
ctrl_t ctrl = NULL;
wqitem_t item, prev;
if (!session_id)
return;
for (;;)
{
prev = NULL;
for (item = workqueue; item; prev = item, item = item->next)
if (item->session_id == session_id)
break;
if (!item)
break; /* No more tasks for this session. */
/* Detach that item from the workqueue. */
if (!prev)
workqueue = item->next;
else
prev->next = item->next;
item->next = NULL;
/* Create a CTRL object the first time we need it. */
if (!ctrl)
{
memset (&ctrlbuf, 0, sizeof ctrlbuf);
ctrl = &ctrlbuf;
dirmngr_init_default_ctrl (ctrl);
}
/* Run the task. */
run_a_task (ctrl, item);
}
dirmngr_deinit_default_ctrl (ctrl);
}