1 files changed, 115 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/linkat.c b/sysdeps/unix/sysv/linux/linkat.c
new file mode 100644
index 0000000..cfd0e18
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/linkat.c
@@ -0,0 +1,115 @@
+/* Copyright (C) 2005, 2006 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 <string.h>
+#include <stdio.h>
+#include <sysdep.h>
+#include <unistd.h>
+#include <kernel-features.h>
+
+
+/* Make a link to FROM named TO but relative paths in TO and FROM are
+   interpreted relative to FROMFD and TOFD respectively.  */
+int
+linkat (fromfd, from, tofd, to, flags)
+     int fromfd;
+     const char *from;
+     int tofd;
+     const char *to;
+     int flags;
+{
+  int result;
+
+#ifdef __NR_linkat
+# ifndef __ASSUME_ATFCTS
+  if (__have_atfcts >= 0)
+# endif
+    {
+      result = INLINE_SYSCALL (linkat, 5, fromfd, from, tofd, to, flags);
+# ifndef __ASSUME_ATFCTS
+      if (result == -1 && errno == ENOSYS)
+	__have_atfcts = -1;
+      else
+# endif
+	return result;
+    }
+#endif
+
+#ifndef __ASSUME_ATFCTS
+  /* Without kernel support we cannot handle AT_SYMLINK_FOLLOW.  */
+  if (flags != 0)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  static const char procfd[] = "/proc/self/fd/%d/%s";
+  char *buffrom = NULL;
+
+  if (fromfd != AT_FDCWD && from[0] != '/')
+    {
+      size_t filelen = strlen (from);
+      /* 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;
+      buffrom = alloca (buflen);
+
+      __snprintf (buffrom, buflen, procfd, fromfd, from);
+      from = buffrom;
+    }
+
+  char *bufto = NULL;
+
+  if (tofd != AT_FDCWD && to[0] != '/')
+    {
+      size_t filelen = strlen (to);
+      /* 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;
+      bufto = alloca (buflen);
+
+      __snprintf (bufto, buflen, procfd, tofd, to);
+      to = bufto;
+    }
+
+  INTERNAL_SYSCALL_DECL (err);
+
+  result = INTERNAL_SYSCALL (link, err, 2, from,  to);
+
+  if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
+    {
+      __atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), tofd, bufto,
+			  fromfd, buffrom);
+      result = -1;
+    }
+
+  return result;
+#endif
+}