Compatibility of signalfd/eventfd with older kernels.

1 files changed, 12 insertions, 3 deletions

diff --git a/sysdeps/unix/sysv/linux/signalfd.c b/sysdeps/unix/sysv/linux/signalfd.c
index 9898f29231..c2d974a45d 100644
--- a/sysdeps/unix/sysv/linux/signalfd.c
+++ b/sysdeps/unix/sysv/linux/signalfd.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2007, 2008, 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
@@ -20,14 +20,21 @@
 #include <signal.h>
 #include <sys/signalfd.h>
 #include <sysdep.h>
+#include <kernel-features.h>
 
 
 int
 signalfd (int fd, const sigset_t *mask, int flags)
 {
 #ifdef __NR_signalfd4
-  return INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
-#else
+  int res = INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
+# ifndef __ASSUME_SIGNALFD4
+  if (res != -1 || errno != ENOSYS)
+# endif
+    return res;
+#endif
+
+#ifndef __ASSUME_SIGNALFD4
   /* The old system call has no flag parameter which is bad.  So we have
      to wait until we have to support to pass additional values to the
      kernel (sys_indirect) before implementing setting flags like
@@ -44,5 +51,7 @@ signalfd (int fd, const sigset_t *mask, int flags)
   __set_errno (ENOSYS);
   return -1;
 # endif
+#elif !defined __NR_signalfd4
+# error "__ASSUME_SIGNALFD4 defined but not __NR_signalfd4"
 #endif
 }