Testcase:

#define _GNU_SOURCE

#include <fcntl.h>

#include <unistd.h>

int

main (void)

{

  int dfd = open ("/tmp", O_RDONLY);

  int fd1 = openat (dfd, "abc", O_RDONLY);

  int fd2 = openat (0x12345678, "/tmp/abc", O_RDONLY);

  int fd3 = openat (AT_FDCWD, "abc", O_RDONLY);

  /* This is the only one that should warn.  */

  int fd4 = openat (0x12345678, "abc", O_RDONLY);

  return 0;

}

--- valgrind-3.2.3/include/vki-linux.h.jj	2006-08-28 15:38:37.000000000 +0200

+++ valgrind-3.2.3/include/vki-linux.h	2006-09-26 18:29:00.000000000 +0200

@@ -1223,6 +1223,8 @@ struct vki_dirent {

 #define VKI_F_NOTIFY	(VKI_F_LINUX_SPECIFIC_BASE+2)

+#define VKI_AT_FDCWD	-100

+

 //----------------------------------------------------------------------

 // From linux-2.6.8.1/include/linux/sysctl.h

 //----------------------------------------------------------------------

--- valgrind-3.2.3/coregrind/m_syswrap/syswrap-linux.c.jj	2006-08-28 15:38:57.000000000 +0200

+++ valgrind-3.2.3/coregrind/m_syswrap/syswrap-linux.c	2006-09-26 18:42:04.000000000 +0200

@@ -2350,10 +2350,15 @@ PRE(sys_openat)

                     int, dfd, const char *, filename, int, flags);

    }

-   if (!ML_(fd_allowed)(ARG1, "openat", tid, False))

+   PRE_MEM_RASCIIZ( "openat(filename)", ARG2 );

+

+   /* For absolute filenames, dfd is ignored.  If dfd is AT_FDCWD,

+      filename is relative to cwd.  */   

+   if (ML_(safe_to_deref)( (void*)ARG2, 1 )

+       && *(Char *)ARG2 != '/'

+       && ARG1 != VKI_AT_FDCWD

+       && !ML_(fd_allowed)(ARG1, "openat", tid, False))

       SET_STATUS_Failure( VKI_EBADF );

-   else

-      PRE_MEM_RASCIIZ( "openat(filename)", ARG2 );

    /* Handle the case where the open is of /proc/self/cmdline or

       /proc/<pid>/cmdline, and just give it a copy of the fd for the