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-rw-r--r--lib/pthread_sigmask.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/lib/pthread_sigmask.c b/lib/pthread_sigmask.c
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--- /dev/null
+++ b/lib/pthread_sigmask.c
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+/* POSIX compatible signal blocking for threads.
+ Copyright (C) 2011-2022 Free Software Foundation, Inc.
+
+ This file 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 2.1 of the
+ License, or (at your option) any later version.
+
+ This file 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 Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+/* Specification. */
+#include <signal.h>
+
+#include <errno.h>
+#include <stddef.h>
+
+#if PTHREAD_SIGMASK_INEFFECTIVE
+# include <string.h>
+#endif
+
+#if PTHREAD_SIGMASK_UNBLOCK_BUG
+# include <unistd.h>
+#endif
+
+int
+pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
+#undef pthread_sigmask
+{
+#if HAVE_PTHREAD_SIGMASK
+ int ret;
+
+# if PTHREAD_SIGMASK_INEFFECTIVE
+ sigset_t omask, omask_copy;
+ sigset_t *old_mask_ptr = &omask;
+ sigemptyset (&omask);
+ /* Add a signal unlikely to be blocked, so that OMASK_COPY
+ is unlikely to match the actual mask. */
+ sigaddset (&omask, SIGILL);
+ memcpy (&omask_copy, &omask, sizeof omask);
+# else
+ sigset_t *old_mask_ptr = old_mask;
+# endif
+
+ ret = pthread_sigmask (how, new_mask, old_mask_ptr);
+
+# if PTHREAD_SIGMASK_INEFFECTIVE
+ if (ret == 0)
+ {
+ /* Detect whether pthread_sigmask is currently ineffective.
+ Don't cache the information: libpthread.so could be dynamically
+ loaded after the program started and after pthread_sigmask was
+ called for the first time. */
+ if (memcmp (&omask_copy, &omask, sizeof omask) == 0
+ && pthread_sigmask (1729, &omask_copy, NULL) == 0)
+ {
+ /* pthread_sigmask is currently ineffective. The program is not
+ linked to -lpthread. So use sigprocmask instead. */
+ return (sigprocmask (how, new_mask, old_mask) < 0 ? errno : 0);
+ }
+
+ if (old_mask)
+ memcpy (old_mask, &omask, sizeof omask);
+ }
+# endif
+# if PTHREAD_SIGMASK_FAILS_WITH_ERRNO
+ if (ret == -1)
+ return errno;
+# endif
+# if PTHREAD_SIGMASK_UNBLOCK_BUG
+ if (ret == 0
+ && new_mask != NULL
+ && (how == SIG_UNBLOCK || how == SIG_SETMASK))
+ {
+ /* Give the OS the opportunity to raise signals that were pending before
+ the pthread_sigmask call and have now been unblocked. */
+ usleep (1);
+ }
+# endif
+ return ret;
+#else
+ int ret = sigprocmask (how, new_mask, old_mask);
+ return (ret < 0 ? errno : 0);
+#endif
+}