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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_&lt;xxx&gt;. 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
+}