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/* LIBGIMP - The GIMP Library
* Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
*
* This library 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 3 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <https://www.gnu.org/licenses/>.
*
* $Revision$
*/
#include "config.h"
#define _GNU_SOURCE /* for the sigaction stuff */
#include <glib.h>
#include "gimpsignal.h"
/**
* SECTION: gimpsignal
* @title: gimpsignal
* @short_description: Portable signal handling.
* @see_also: signal(2), signal(5 or 7), sigaction(2).
*
* Portable signal handling.
**/
/* Courtesy of Austin Donnelly 06-04-2000 to address bug #2742 */
/**
* gimp_signal_private:
* @signum: Selects signal to be handled see man 5 signal (or man 7 signal)
* @handler: Handler that maps to signum. Invoked by O/S.
* Handler gets signal that caused invocation. Corresponds
* to the @sa_handler field of the @sigaction struct.
* @flags: Preferences. OR'ed SA_<xxx>. See man sigaction. Corresponds
* to the @sa_flags field of the @sigaction struct.
*
* This function furnishes a workalike for signal(2) but
* which internally invokes sigaction(2) after certain
* sa_flags are set; these primarily to ensure restarting
* of interrupted system calls. See sigaction(2) It is a
* aid to transition and not new development: that effort
* should employ sigaction directly. [gosgood 18.04.2000]
*
* Cause @handler to be run when @signum is delivered. We
* use sigaction(2) rather than signal(2) so that we can control the
* signal handler's environment completely via @flags: some signal(2)
* implementations differ in their semantics, so we need to nail down
* exactly what we want. [austin 06.04.2000]
*
* Returns: A reference to the signal handling function which was
* active before the call to gimp_signal_private().
*/
GimpSignalHandlerFunc
gimp_signal_private (gint signum,
GimpSignalHandlerFunc handler,
gint flags)
{
#ifndef G_OS_WIN32
gint ret;
struct sigaction sa;
struct sigaction osa;
/* The sa_handler (mandated by POSIX.1) and sa_sigaction (a
* common extension) are often implemented by the OS as members
* of a union. This means you CAN NOT set both, you set one or
* the other. Caveat programmer!
*/
/* Passing gimp_signal_private a gimp_sighandler of NULL is not
* an error, and generally results in the action for that signal
* being set to SIG_DFL (default behavior). Many OSes define
* SIG_DFL as (void (*)()0, so setting sa_handler to NULL is
* the same thing as passing SIG_DFL to it.
*/
sa.sa_handler = handler;
/* Mask all signals while handler runs to avoid re-entrancy
* problems.
*/
sigfillset (&sa.sa_mask);
sa.sa_flags = flags;
ret = sigaction (signum, &sa, &osa);
if (ret < 0)
g_error ("unable to set handler for signal %d\n", signum);
return (GimpSignalHandlerFunc) osa.sa_handler;
#else
return NULL; /* Or g_error()? Should all calls to
* this function really be inside
* #ifdef G_OS_UNIX?
*/
#endif
}
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