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Diffstat (limited to 'libgimpbase/gimpsignal.c')
| -rw-r--r-- | libgimpbase/gimpsignal.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/libgimpbase/gimpsignal.c b/libgimpbase/gimpsignal.c new file mode 100644 index 0000000..a0221f3 --- /dev/null +++ b/libgimpbase/gimpsignal.c @@ -0,0 +1,110 @@ +/* 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 +} |