1 files changed, 110 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/openat.c b/sysdeps/unix/sysv/linux/openat.c
new file mode 100644
index 0000000000..a89f172b62
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/openat.c
@@ -0,0 +1,110 @@
+/* Copyright (C) 2005 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
+   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 <fcntl.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sysdep-cancel.h>
+
+
+#ifndef OPENAT
+# define OPENAT openat
+# define MORE_OFLAGS 0
+#endif
+
+/* Open FILE with access OFLAG.  Interpret relative paths relative to
+   the directory associated with FD.  If OFLAG includes O_CREAT, a
+   third argument is the file protection.  */
+int
+OPENAT (fd, file, oflag)
+     int fd;
+     const char *file;
+     int oflag;
+{
+  char *buf = NULL;
+
+  if (file[0] != '/')
+    {
+      size_t filelen = strlen (file);
+      static const char procfd[] = "/proc/self/fd/%d/%s";
+      /* Buffer for the path name we are going to use.  It consists of
+	 - the string /proc/self/fd/
+	 - the file descriptor number
+	 - the file name provided.
+	 The final NUL is included in the sizeof.   A bit of overhead
+	 due to the format elements compensates for possible negative
+	 numbers.  */
+      size_t buflen = sizeof (procfd) + sizeof (int) * 3 + filelen;
+      buf = alloca (buflen);
+
+      __snprintf (buf, buflen, procfd, fd, file);
+      file = buf;
+    }
+
+  mode_t mode = 0;
+  if (oflag & O_CREAT)
+    {
+      va_list arg;
+      va_start (arg, oflag);
+      mode = va_arg (arg, mode_t);
+      va_end (arg);
+    }
+
+  INTERNAL_SYSCALL_DECL (err);
+  int res;
+
+  if (SINGLE_THREAD_P)
+    res = INTERNAL_SYSCALL (open, err, 3, file, oflag | MORE_OFLAGS, mode);
+  else
+    {
+      int oldtype = LIBC_CANCEL_ASYNC ();
+
+      res = INTERNAL_SYSCALL (open, err, 3, file, oflag | MORE_OFLAGS, mode);
+
+      LIBC_CANCEL_RESET (oldtype);
+    }
+
+  if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (res, err), 0))
+    {
+      int errval = INTERNAL_SYSCALL_ERRNO (res, err);
+      if (buf != NULL && errval == ENOTDIR)
+	{
+	  /* This can mean either the file desriptor is invalid or
+	     /proc is not mounted.  */
+	  struct stat64 st;
+	  if (__fxstat64 (_STAT_VER, fd, &st) != 0)
+	    /* errno is already set correctly.  */
+	    goto out;
+
+	  /* If /proc is not mounted there is nothing we can do.  */
+	  if (S_ISDIR (st.st_mode)
+	      && (__xstat64 (_STAT_VER, "/proc/self/fd", &st) != 0
+		  || !S_ISDIR (st.st_mode)))
+	    errval = ENOSYS;
+	}
+
+      __set_errno (errval);
+    }
+
+ out:
+  return res;
+}