update from texinfo

[gnulib.git] / lib / xreadlink.c

diff --git a/lib/xreadlink.c b/lib/xreadlink.c
index e4c565f..2e66c07 100644 (file)
--- a/lib/xreadlink.c
+++ b/lib/xreadlink.c
@@ -1,6 +1,6 @@
 /* xreadlink.c -- readlink wrapper to return the link name in malloc'd storage
 
-   Copyright (C) 2001, 2003 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2003, 2004 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
@@ -23,19 +23,13 @@
 # include <config.h>
 #endif
 
+#include "xreadlink.h"
+
 #include <stdio.h>
 #include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
-
 #include <limits.h>
-#if HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#if HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
+#include <sys/types.h>
+#include <stdlib.h>
 #if HAVE_UNISTD_H
 # include <unistd.h>
 #endif
@@ -48,20 +42,21 @@ extern int errno;
 #endif
 
 #include "xalloc.h"
-#include "xreadlink.h"
 
 /* Call readlink to get the symbolic link value of FILENAME.
+   SIZE is a hint as to how long the link is expected to be;
+   typically it is taken from st_size.  It need not be correct.
    Return a pointer to that NUL-terminated string in malloc'd storage.
    If readlink fails, return NULL (caller may use errno to diagnose).
-   If realloc fails, or if the link value is longer than SIZE_MAX :-),
+   If malloc fails, or if the link value is longer than SSIZE_MAX :-),
    give a diagnostic and exit.  */
 
 char *
-xreadlink (char const *filename)
+xreadlink (char const *filename, size_t size)
 {
   /* The initial buffer size for the link value.  A power of 2
      detects arithmetic overflow earlier, but is not required.  */
-  size_t buf_size = 128;
+  size_t buf_size = size + 1;
 
   while (1)
     {
@@ -84,7 +79,7 @@ xreadlink (char const *filename)
 
       free (buffer);
       buf_size *= 2;
-      if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
+      if (! (0 < buf_size && buf_size <= SSIZE_MAX))
        xalloc_die ();
     }
 }