From 25148dfa57d7dea44929d522812e964dad345a3e Mon Sep 17 00:00:00 2001
From: Eric Blake <ebb9@byu.net>
Date: Wed, 7 Oct 2009 10:39:29 -0600
Subject: [PATCH] xreadlinkat: new module

* modules/xreadlinkat: New module.
* lib/xreadlinkat.c (xreadlinkat): New file.
* lib/xreadlink.h (xreadlinkat): Declare it.
* MODULES.html.sh (File system functions): Mention it.

Signed-off-by: Eric Blake <ebb9@byu.net>
---
 ChangeLog           |  6 ++++++
 MODULES.html.sh     |  1 +
 lib/xreadlink.h     |  7 ++++++-
 lib/xreadlinkat.c   | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 modules/xreadlinkat | 25 +++++++++++++++++++++++++
 5 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 lib/xreadlinkat.c
 create mode 100644 modules/xreadlinkat

diff --git a/ChangeLog b/ChangeLog
index 0ac3c88e0..7a831c7c4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2009-10-07  Eric Blake  <ebb9@byu.net>
 
+	xreadlinkat: new module
+	* modules/xreadlinkat: New module.
+	* lib/xreadlinkat.c (xreadlinkat): New file.
+	* lib/xreadlink.h (xreadlinkat): Declare it.
+	* MODULES.html.sh (File system functions): Mention it.
+
 	areadlinkat: new module
 	* lib/at-func.c (FUNC_FAIL): New define.
 	(AT_FUNC_NAME, VALIDATE_FLAG): Use it rather than raw -1.
diff --git a/MODULES.html.sh b/MODULES.html.sh
index b418ab621..4f164ef20 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2495,6 +2495,7 @@ func_all_modules ()
   func_module write-any-file
   func_module xgetcwd
   func_module xreadlink
+  func_module xreadlinkat
   func_end_table
 
   element="File system as inode set"
diff --git a/lib/xreadlink.h b/lib/xreadlink.h
index 3eda90f6f..2a27689f3 100644
--- a/lib/xreadlink.h
+++ b/lib/xreadlink.h
@@ -1,6 +1,7 @@
 /* Reading symbolic links without size limitation.
 
-   Copyright (C) 2001, 2003, 2004, 2007 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2003, 2004, 2007, 2009 Free Software
+   Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -20,3 +21,7 @@
 #include <stddef.h>
 
 extern char *xreadlink (char const *filename);
+
+#if GNULIB_XREADLINKAT
+extern char *xreadlinkat (int fd, char const *filename);
+#endif
diff --git a/lib/xreadlinkat.c b/lib/xreadlinkat.c
new file mode 100644
index 000000000..471fc2ca1
--- /dev/null
+++ b/lib/xreadlinkat.c
@@ -0,0 +1,46 @@
+/* xreadlinkat.c -- readlink wrapper to return the link name in malloc'd storage
+
+   Copyright (C) 2001, 2003-2007, 2009 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Jim Meyering <jim@meyering.net>,
+   and Bruno Haible <bruno@clisp.org>,
+   and Eric Blake <ebb9@byu.net>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "xreadlink.h"
+
+#include <errno.h>
+
+#include "areadlink.h"
+#include "xalloc.h"
+
+/* Call readlinkat to get the symbolic link value of FILENAME relative to FD.
+   Return a pointer to that NUL-terminated string in malloc'd storage.
+   If readlinkat fails, return NULL and set errno (although failure to
+   change directory will issue a diagnostic and exit).
+   If realloc fails, or if the link value is longer than SIZE_MAX :-),
+   give a diagnostic and exit.  */
+
+char *
+xreadlinkat (int fd, char const *filename)
+{
+  char *result = areadlinkat (fd, filename);
+  if (result == NULL && errno == ENOMEM)
+    xalloc_die ();
+  return result;
+}
diff --git a/modules/xreadlinkat b/modules/xreadlinkat
new file mode 100644
index 000000000..81f87de47
--- /dev/null
+++ b/modules/xreadlinkat
@@ -0,0 +1,25 @@
+Description:
+Reading symbolic links without size limitation, relative to fd.
+
+Files:
+lib/xreadlink.h
+lib/xreadlinkat.c
+
+Depends-on:
+areadlinkat
+xalloc
+
+configure.ac:
+gl_MODULE_INDICATOR([xreadlinkat])
+
+Makefile.am:
+lib_SOURCES += xreadlinkat.c
+
+Include:
+"xreadlink.h"
+
+License:
+GPL
+
+Maintainer:
+Jim Meyering, Eric Blake
-- 
2.11.0