mirror of https://github.com/GNOME/gimp.git
101 lines
3.5 KiB
C
101 lines
3.5 KiB
C
/* LIBGIMP - The GIMP Library
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* Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
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*
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* This library is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see
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* <http://www.gnu.org/licenses/>.
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*
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* $Revision$
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*/
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#include "config.h"
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#define _GNU_SOURCE /* for the sigaction stuff */
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#include <glib.h>
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#include "gimpsignal.h"
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/* Courtesy of Austin Donnelly 06-04-2000 to address bug #2742 */
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/**
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* gimp_signal_private:
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* @signum: Selects signal to be handled see man 5 signal (or man 7 signal)
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* @handler: Handler that maps to signum. Invoked by O/S.
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* Handler gets signal that caused invocation. Corresponds
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* to the @sa_handler field of the @sigaction struct.
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* @flags: Preferences. OR'ed SA_<xxx>. See man sigaction. Corresponds
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* to the @sa_flags field of the @sigaction struct.
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*
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* This function furnishes a workalike for signal(2) but
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* which internally invokes sigaction(2) after certain
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* sa_flags are set; these primarily to ensure restarting
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* of interrupted system calls. See sigaction(2) It is a
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* aid to transition and not new development: that effort
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* should employ sigaction directly. [gosgood 18.04.2000]
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*
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* Cause @handler to be run when @signum is delivered. We
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* use sigaction(2) rather than signal(2) so that we can control the
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* signal handler's environment completely via @flags: some signal(2)
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* implementations differ in their sematics, so we need to nail down
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* exactly what we want. [austin 06.04.2000]
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*
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* Returns: A reference to the signal handling function which was
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* active before the call to gimp_signal_private().
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*/
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GimpSignalHandlerFunc
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gimp_signal_private (gint signum,
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GimpSignalHandlerFunc handler,
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gint flags)
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{
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#ifndef G_OS_WIN32
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gint ret;
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struct sigaction sa;
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struct sigaction osa;
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/* The sa_handler (mandated by POSIX.1) and sa_sigaction (a
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* common extension) are often implemented by the OS as members
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* of a union. This means you CAN NOT set both, you set one or
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* the other. Caveat programmer!
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*/
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/* Passing gimp_signal_private a gimp_sighandler of NULL is not
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* an error, and generally results in the action for that signal
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* being set to SIG_DFL (default behavior). Many OSes define
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* SIG_DFL as (void (*)()0, so setting sa_handler to NULL is
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* the same thing as passing SIG_DFL to it.
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*/
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sa.sa_handler = handler;
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/* Mask all signals while handler runs to avoid re-entrancy
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* problems.
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*/
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sigfillset (&sa.sa_mask);
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sa.sa_flags = flags;
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ret = sigaction (signum, &sa, &osa);
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if (ret < 0)
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g_error ("unable to set handler for signal %d\n", signum);
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return (GimpSignalHandlerFunc) osa.sa_handler;
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#else
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return NULL; /* Or g_error()? Should all calls to
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* this function really be inside
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* #ifdef G_OS_UNIX?
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*/
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#endif
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}
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