grab pselect from glibc

libc/sysdeps/linux/common/pselect.c

@@ -0,0 +1,66 @@
+/* Copyright (C) 1996-1998,2001,2002,2003,2006 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
+
+   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 <stddef.h>	/* For NULL.  */
+#include <sys/time.h>
+#include <sys/select.h>
+
+libc_hidden_proto(sigprocmask)
+libc_hidden_proto(select)
+
+
+/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
+   readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
+   (if not NULL) for exceptional conditions.  If TIMEOUT is not NULL, time out
+   after waiting the interval specified therein.  Additionally set the sigmask
+   SIGMASK for this call.  Returns the number of ready descriptors, or -1 for
+   errors.  */
+int
+pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
+	   const struct timespec *timeout, const sigset_t *sigmask)
+{
+  struct timeval tval;
+  int retval;
+  sigset_t savemask;
+
+  /* Change nanosecond number to microseconds.  This might mean losing
+     precision and therefore the `pselect` should be available.  But
+     for now it is hardly found.  */
+  if (timeout != NULL)
+    TIMESPEC_TO_TIMEVAL (&tval, timeout);
+
+  /* The setting and restoring of the signal mask and the select call
+     should be an atomic operation.  This can't be done without kernel
+     help.  */
+  if (sigmask != NULL)
+    sigprocmask (SIG_SETMASK, sigmask, &savemask);
+
+  /* Note the pselect() is a cancellation point.  But since we call
+     select() which itself is a cancellation point we do not have
+     to do anything here.  */
+  retval = select (nfds, readfds, writefds, exceptfds,
+		     timeout != NULL ? &tval : NULL);
+
+  if (sigmask != NULL)
+    sigprocmask (SIG_SETMASK, &savemask, NULL);
+
+  return retval;
+}