Simplify Linux sig{timed}wait{info} implementations

This patch simplifies sig{timed}wait{info} by:

  - Assuming __NR_rt_sigtimedwait existence on all architectures due minimum
    kernel version requirement (it pre-dates Linux git inclusion for Linux
    2.6.12).

  - Call __sigtimedwait on both sigwait and sigwaitinfo.

  - Now that sigwait is based on an internal sigtimedwait call and it is
    present of both libc.so and libpthread.so we need to add an external
    private definition of __sigtimedwait for libpthread.so call.

Checked on x86_64-linux-gnu.

	* sysdeps/unix/sysv/linux/Versions (libc) [GLIBC_PRIVATE]: Add
	__sigtimedwait.
	* sysdeps/unix/sysv/linux/sigtimedwait.c: Simplify includes and
	assume __NR_rt_sigtimedwait.
	* sysdeps/unix/sysv/linux/sigwait.c (__sigwait): Call __sigtimedwait
	and add LIBC_CANCEL_HANDLED for cancellation marking.
	* sysdeps/unix/sysv/linux/sigwaitinfo.c (__sigwaitinfo): Likewise.

Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Zack Weinberg <zackw@panix.com>

ChangeLog

@@ -1,5 +1,13 @@
 2017-11-06  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
+	* sysdeps/unix/sysv/linux/Versions (libc) [GLIBC_PRIVATE]: Add
+	__sigtimedwait.
+	* sysdeps/unix/sysv/linux/sigtimedwait.c: Simplify includes and
+	assume __NR_rt_sigtimedwait.
+	* sysdeps/unix/sysv/linux/sigwait.c (__sigwait): Call __sigtimedwait
+	and add LIBC_CANCEL_HANDLED for cancellation marking.
+	* sysdeps/unix/sysv/linux/sigwaitinfo.c (__sigwaitinfo): Likewise.
+
 	* sysdeps/arm/armv7/multiarch/Makefile [$(subdir) = string]
 	(sysdeps_routines): Add memchr_noneon.
 	* sysdeps/arm/armv7/multiarch/ifunc-memchr.h: New file.

sysdeps/unix/sysv/linux/Versions

@@ -172,6 +172,7 @@ libc {
     __open_nocancel;
     __read_nocancel;
     __close_nocancel;
+    __sigtimedwait;
     # functions used by nscd
     __netlink_assert_response;
   }

sysdeps/unix/sysv/linux/sigtimedwait.c

@@ -18,12 +18,7 @@
 #include <errno.h>
 #include <signal.h>
 #include <string.h>
-
-#include <nptl/pthreadP.h>
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-
-#ifdef __NR_rt_sigtimedwait
 
 int
 __sigtimedwait (const sigset_t *set, siginfo_t *info,
@@ -57,6 +52,3 @@ __sigtimedwait (const sigset_t *set, siginfo_t *info,
 }
 libc_hidden_def (__sigtimedwait)
 weak_alias (__sigtimedwait, sigtimedwait)
-#else
-# include <signal/sigtimedwait.c>
-#endif

sysdeps/unix/sysv/linux/sigwait.c

@@ -15,86 +15,21 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <signal.h>
-#define __need_NULL
-#include <stddef.h>
-#include <string.h>
-
-#include <nptl/pthreadP.h>
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-
-#ifdef __NR_rt_sigtimedwait
-
-/* Return any pending signal or wait for one for the given time.  */
-static int
-do_sigwait (const sigset_t *set, int *sig)
-{
-  int ret;
-
-  sigset_t tmpset;
-  if (set != NULL
-      && (__builtin_expect (__sigismember (set, SIGCANCEL), 0)
-	  || __builtin_expect (__sigismember (set, SIGSETXID), 0)))
-    {
-      /* Create a temporary mask without the bit for SIGCANCEL set.  */
-      // We are not copying more than we have to.
-      memcpy (&tmpset, set, _NSIG / 8);
-      __sigdelset (&tmpset, SIGCANCEL);
-      __sigdelset (&tmpset, SIGSETXID);
-      set = &tmpset;
-    }
-
-  /* XXX The size argument hopefully will have to be changed to the
-     real size of the user-level sigset_t.  */
-#ifdef INTERNAL_SYSCALL
-  INTERNAL_SYSCALL_DECL (err);
-  do
-    ret = INTERNAL_SYSCALL (rt_sigtimedwait, err, 4, set,
-			    NULL, NULL, _NSIG / 8);
-  while (INTERNAL_SYSCALL_ERROR_P (ret, err)
-	 && INTERNAL_SYSCALL_ERRNO (ret, err) == EINTR);
-  if (! INTERNAL_SYSCALL_ERROR_P (ret, err))
-    {
-      *sig = ret;
-      ret = 0;
-    }
-  else
-    ret = INTERNAL_SYSCALL_ERRNO (ret, err);
-#else
-  do
-    ret = INLINE_SYSCALL (rt_sigtimedwait, 4, set, NULL, NULL, _NSIG / 8);
-  while (ret == -1 && errno == EINTR);
-  if (ret != -1)
-    {
-      *sig = ret;
-      ret = 0;
-    }
-  else
-    ret = errno;
-#endif
-
-  return ret;
-}
 
 int
 __sigwait (const sigset_t *set, int *sig)
 {
-  if (SINGLE_THREAD_P)
+  siginfo_t si;
-    return do_sigwait (set, sig);
+  if (__sigtimedwait (set, &si, 0) < 0)
-
+    return -1;
-  int oldtype = LIBC_CANCEL_ASYNC ();
+  *sig = si.si_signo;
-
+  return 0;
-  int result = do_sigwait (set, sig);
-
-  LIBC_CANCEL_RESET (oldtype);
-
-  return result;
 }
 libc_hidden_def (__sigwait)
 weak_alias (__sigwait, sigwait)
-#else
-# include <sysdeps/posix/sigwait.c>
-#endif
 strong_alias (__sigwait, __libc_sigwait)
+
+/* __sigtimedwait handles cancellation.  */
+LIBC_CANCEL_HANDLED ();

sysdeps/unix/sysv/linux/sigwaitinfo.c

@@ -15,52 +15,19 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <signal.h>
-#define __need_NULL
-#include <stddef.h>
-#include <string.h>
-
-#include <nptl/pthreadP.h>
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-
-#ifdef __NR_rt_sigtimedwait
 
 /* Return any pending signal or wait for one for the given time.  */
 int
 __sigwaitinfo (const sigset_t *set, siginfo_t *info)
 {
-  sigset_t tmpset;
+  return __sigtimedwait (set, info, 0);
-  if (set != NULL
-      && (__builtin_expect (__sigismember (set, SIGCANCEL), 0)
-	  || __builtin_expect (__sigismember (set, SIGSETXID), 0)))
-    {
-      /* Create a temporary mask without the bit for SIGCANCEL set.  */
-      // We are not copying more than we have to.
-      memcpy (&tmpset, set, _NSIG / 8);
-      __sigdelset (&tmpset, SIGCANCEL);
-      __sigdelset (&tmpset, SIGSETXID);
-      set = &tmpset;
-    }
-
-  /* XXX The size argument hopefully will have to be changed to the
-     real size of the user-level sigset_t.  */
-  int result = SYSCALL_CANCEL (rt_sigtimedwait, set, info, NULL, _NSIG / 8);
-
-  /* The kernel generates a SI_TKILL code in si_code in case tkill is
-     used.  tkill is transparently used in raise().  Since having
-     SI_TKILL as a code is useful in general we fold the results
-     here.  */
-  if (result != -1 && info != NULL && info->si_code == SI_TKILL)
-    info->si_code = SI_USER;
-
-  return result;
 }
 
 libc_hidden_def (__sigwaitinfo)
 weak_alias (__sigwaitinfo, sigwaitinfo)
-#else
-# include <signal/sigwaitinfo.c>
-#endif
 strong_alias (__sigwaitinfo, __libc_sigwaitinfo)
+
+/* __sigtimedwait handles cancellation.  */
+LIBC_CANCEL_HANDLED ();