X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fareadlink.c;h=b4b856c5895a0c1f17ba506185b04412bdb6e262;hb=cd56634a4a8179fd5a4419fbb3e27211b042ab1c;hp=b506eb8bcab31b7f453e5871ca30d9b954f88cfb;hpb=2d4d7d9d00fe33b6f5291e00a30b6c1016775b74;p=gnulib.git

diff --git a/lib/areadlink.c b/lib/areadlink.c
index b506eb8bc..b4b856c58 100644
--- a/lib/areadlink.c
+++ b/lib/areadlink.c
@@ -1,7 +1,7 @@
 /* areadlink.c -- readlink wrapper to return the link name in malloc'd storage
    Unlike xreadlink and xreadlink_with_size, don't ever call exit.
 
-   Copyright (C) 2001, 2003-2007, 2009 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2003-2007, 2009-2014 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
@@ -24,96 +24,33 @@
 /* Specification.  */
 #include "areadlink.h"
 
-#include <errno.h>
-#include <limits.h>
-#include <stdint.h>
+#include "careadlinkat.h"
+
 #include <stdlib.h>
-#include <string.h>
 #include <unistd.h>
 
-#ifndef SSIZE_MAX
-# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
-#endif
-
-/* The initial buffer size for the link value.  A power of 2
-   detects arithmetic overflow earlier, but is not required.  */
-enum {
-  INITIAL_BUF_SIZE = 1024
-};
+/* Get the symbolic link value of FILENAME and put it into BUFFER, with
+   size BUFFER_SIZE.  This function acts like readlink but has
+   readlinkat's signature.  */
+static ssize_t
+careadlinkatcwd (int fd, char const *filename, char *buffer,
+                 size_t buffer_size)
+{
+  /* FD must be AT_FDCWD here, otherwise the caller is using this
+     function in contexts it was not meant for.  */
+  if (fd != AT_FDCWD)
+    abort ();
+  return readlink (filename, buffer, buffer_size);
+}
 
 /* Call readlink to get the symbolic link value of FILENAME.
    Return a pointer to that NUL-terminated string in malloc'd storage.
    If readlink fails, return NULL and set errno.
-   If realloc fails, or if the link value is longer than SIZE_MAX :-),
+   If allocation fails, or if the link value is longer than SIZE_MAX :-),
    return NULL and set errno to ENOMEM.  */
 
 char *
 areadlink (char const *filename)
 {
-  /* Allocate the initial buffer on the stack.  This way, in the common
-     case of a symlink of small size, we get away with a single small malloc()
-     instead of a big malloc() followed by a shrinking realloc().  */
-  char initial_buf[INITIAL_BUF_SIZE];
-
-  char *buffer = initial_buf;
-  size_t buf_size = sizeof initial_buf;
-
-  while (1)
-    {
-      /* Attempt to read the link into the current buffer.  */
-      ssize_t link_length = readlink (filename, buffer, buf_size);
-
-      /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1
-         with errno == ERANGE if the buffer is too small.  */
-      if (link_length < 0 && errno != ERANGE)
-        {
-          if (buffer != initial_buf)
-            {
-              int saved_errno = errno;
-              free (buffer);
-              errno = saved_errno;
-            }
-          return NULL;
-        }
-
-      if ((size_t) link_length < buf_size)
-        {
-          buffer[link_length++] = '\0';
-
-          /* Return it in a chunk of memory as small as possible.  */
-          if (buffer == initial_buf)
-            {
-              buffer = (char *) malloc (link_length);
-              if (buffer == NULL)
-                /* errno is ENOMEM.  */
-                return NULL;
-              memcpy (buffer, initial_buf, link_length);
-            }
-          else
-            {
-              /* Shrink buffer before returning it.  */
-              if ((size_t) link_length < buf_size)
-                {
-                  char *smaller_buffer = (char *) realloc (buffer, link_length);
-
-                  if (smaller_buffer != NULL)
-                    buffer = smaller_buffer;
-                }
-            }
-          return buffer;
-        }
-
-      if (buffer != initial_buf)
-        free (buffer);
-      buf_size *= 2;
-      if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
-        {
-          errno = ENOMEM;
-          return NULL;
-        }
-      buffer = (char *) malloc (buf_size);
-      if (buffer == NULL)
-        /* errno is ENOMEM.  */
-        return NULL;
-    }
+  return careadlinkat (AT_FDCWD, filename, NULL, 0, NULL, careadlinkatcwd);
 }