Hurd: readlinkat

2 files changed, 67 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index aee2aa5327..1591ca9e17 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2012-05-10  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
+        * sysdeps/mach/hurd/readlinkat.c: New file, heavily derived from
+        sysdeps/mach/hurd/readlink.c.
+
 	* posix/tst-sysconf.c (posix_options): Only use
 	_POSIX_PRIORITIZED_IO, _POSIX_PRIORITY_SCHEDULING, and
 	_POSIX_SYNCHRONIZED_IO when they are defined
@@ -16,8 +19,6 @@
 	(_POSIX_PRIORITIZED_IO): Undefine macro.
 	(_POSIX_SPIN_LOCKS): Define macro to -1.
 
-2012-05-10  Samuel Thibault  <samuel.thibault@ens-lyon.org>
-
 	* bits/sigaction.h [__USE_XOPEN2K8]: Define SA_RESTART,
 	SA_NODEFER, SA_RESETHAND.
 	* sysdeps/mach/hurd/bits/fcntl.h [__USE_XOPEN2K8]: Define
diff --git a/sysdeps/mach/hurd/readlinkat.c b/sysdeps/mach/hurd/readlinkat.c
new file mode 100644
index 0000000000..b70f9c8dea
--- /dev/null
+++ b/sysdeps/mach/hurd/readlinkat.c
@@ -0,0 +1,64 @@
+/* Copyright (C) 1991-2012 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 <unistd.h>
+#include <hurd.h>
+#include <hurd/paths.h>
+#include <hurd/fd.h>
+#include <fcntl.h>
+#include <string.h>
+
+/* Read the contents of the symbolic link FILE_NAME relative to FD into no more
+   than LEN bytes of BUF.  The contents are not null-terminated.
+   Returns the number of characters read, or -1 for errors.  */
+ssize_t
+readlinkat (fd, file_name, buf, len)
+     int fd;
+     const char *file_name;
+     char *buf;
+     size_t len;
+{
+  error_t err;
+  file_t file;
+  struct stat64 st;
+
+  file = __file_name_lookup_at (fd, 0, file_name, O_READ | O_NOLINK, 0);
+  if (file == MACH_PORT_NULL)
+    return -1;
+
+  err = __io_stat (file, &st);
+  if (! err)
+    if (S_ISLNK (st.st_mode))
+      {
+	char *rbuf = buf;
+
+	err = __io_read (file, &rbuf, &len, 0, len);
+	if (!err && rbuf != buf)
+	  {
+	    memcpy (buf, rbuf, len);
+	    __vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len);
+	  }
+      }
+    else
+      err = EINVAL;
+
+  __mach_port_deallocate (__mach_task_self (), file);
+
+  return err ? __hurd_fail (err) : len;
+}
+libc_hidden_def (readlinkat)