Implement pthread_sigqueue.

The kernel from 2.3.31 on supports the rt_tgsigqueueinfo syscall.
Use it to implement the non-standard extension which, like
sigqueue, can pass additional data to the receiving thread.

2 files changed, 90 insertions, 1 deletions

diff --git a/nptl/sysdeps/pthread/bits/sigthread.h b/nptl/sysdeps/pthread/bits/sigthread.h
index 960bde18a9..9a524e57db 100644
--- a/nptl/sysdeps/pthread/bits/sigthread.h
+++ b/nptl/sysdeps/pthread/bits/sigthread.h
@@ -1,5 +1,5 @@
 /* Signal handling function for threaded programs.
-   Copyright (C) 1998, 1999, 2000, 2002 Free Software Foundation, Inc.
+   Copyright (C) 1998, 1999, 2000, 2002, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -35,4 +35,10 @@ extern int pthread_sigmask (int __how,
 /* Send signal SIGNO to the given thread. */
 extern int pthread_kill (pthread_t __threadid, int __signo) __THROW;
 
+#ifdef __USE_GNU
+/* Queue signal and data to a thread.  */
+extern int pthread_sigqueue (pthread_t __threadid, int __signo,
+			     const union sigval __value) __THROW;
+#endif
+
 #endif	/* bits/sigthread.h */
diff --git a/nptl/sysdeps/unix/sysv/linux/pthread_sigqueue.c b/nptl/sysdeps/unix/sysv/linux/pthread_sigqueue.c
new file mode 100644
index 0000000000..4440703b6a
--- /dev/null
+++ b/nptl/sysdeps/unix/sysv/linux/pthread_sigqueue.c
@@ -0,0 +1,83 @@
+/* Copyright (C) 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2009.
+
+   The GNU C 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 2.1 of the License, or (at your option) any later version.
+
+   The GNU C 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <errno.h>
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+#include <pthreadP.h>
+#include <tls.h>
+#include <sysdep.h>
+#include <kernel-features.h>
+
+
+int
+pthread_sigqueue (threadid, signo, value)
+     pthread_t threadid;
+     int signo;
+     const union sigval value;
+{
+#ifdef __NR_rt_tgsigqueueinfo
+  struct pthread *pd = (struct pthread *) threadid;
+
+  /* Make sure the descriptor is valid.  */
+  if (DEBUGGING_P && INVALID_TD_P (pd))
+    /* Not a valid thread handle.  */
+    return ESRCH;
+
+  /* Force load of pd->tid into local variable or register.  Otherwise
+     if a thread exits between ESRCH test and tgkill, we might return
+     EINVAL, because pd->tid would be cleared by the kernel.  */
+  pid_t tid = atomic_forced_read (pd->tid);
+  if (__builtin_expect (tid <= 0, 0))
+    /* Not a valid thread handle.  */
+    return ESRCH;
+
+  /* Disallow sending the signal we use for cancellation, timers, for
+     for the setxid implementation.  */
+  if (signo == SIGCANCEL || signo == SIGTIMER || signo == SIGSETXID)
+    return EINVAL;
+
+  /* Set up the siginfo_t structure.  */
+  siginfo_t info;
+  memset (&info, '\0', sizeof (siginfo_t));
+  info.si_signo = signo;
+  info.si_code = SI_QUEUE;
+  info.si_pid = THREAD_GETMEM (THREAD_SELF, pid);
+  info.si_uid = getuid ();
+  info.si_value = value;
+
+  /* We have a special syscall to do the work.  */
+  INTERNAL_SYSCALL_DECL (err);
+
+  /* One comment: The PID field in the TCB can temporarily be changed
+     (in fork).  But this must not affect this code here.  Since this
+     function would have to be called while the thread is executing
+     fork, it would have to happen in a signal handler.  But this is
+     no allowed, pthread_sigqueue is not guaranteed to be async-safe.  */
+  int val = INTERNAL_SYSCALL (rt_tgsigqueueinfo, err, 4,
+			      THREAD_GETMEM (THREAD_SELF, pid),
+			      tid, signo, &info);
+
+  return (INTERNAL_SYSCALL_ERROR_P (val, err)
+	  ? INTERNAL_SYSCALL_ERRNO (val, err) : 0);
+#else
+  return ENOSYS;
+#endif
+}