X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fxreadlink.c;h=41f5242ea468c947cdb30fcaae3278899823ee9d;hb=10cf9b5e371bc4927b2b28354c19b62943dfe95e;hp=2fb389e98353db06426e4ba28c447031406476a0;hpb=962575377e90d3f74f6f5eb17fc87f30dfe802b9;p=gnulib.git

diff --git a/lib/xreadlink.c b/lib/xreadlink.c
index 2fb389e98..41f5242ea 100644
--- 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
@@ -23,6 +23,8 @@
 # include <config.h>
 #endif
 
+#include "xreadlink.h"
+
 #include <stdio.h>
 #include <errno.h>
 #ifndef errno
@@ -36,9 +38,6 @@ extern int errno;
 # include <unistd.h>
 #endif
 
-#include "xalloc.h"
-#include "xreadlink.h"
-
 #ifndef SIZE_MAX
 # define SIZE_MAX ((size_t) -1)
 #endif
@@ -46,18 +45,22 @@ extern int errno;
 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
 #endif
 
+#include "xalloc.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)
     {
@@ -80,7 +83,7 @@ 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 ();
     }
 }