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[!USE_IN_LIBIO]: Omit this case; assume USE_IN_LIBIO is 1.
[gnulib.git]
/
lib
/
xreadlink.c
diff --git
a/lib/xreadlink.c
b/lib/xreadlink.c
index
333551f
..
f5cce16
100644
(file)
--- a/
lib/xreadlink.c
+++ b/
lib/xreadlink.c
@@
-1,6
+1,6
@@
-/*
exclude.c -- exclude file names
+/*
xreadlink.c -- readlink wrapper to return the link name in malloc'd storage
- Copyright
2001
Free Software Foundation, Inc.
+ Copyright
(C) 2001, 2003
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
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
@@
-24,9
+24,13
@@
#endif
#include <stdio.h>
#endif
#include <stdio.h>
-#if HAVE_SYS_TYPES_H
-# include <sys/types.h>
+#include <errno.h>
+#ifndef errno
+extern int errno;
#endif
#endif
+
+#include <limits.h>
+#include <sys/types.h>
#if HAVE_STDLIB_H
# include <stdlib.h>
#endif
#if HAVE_STDLIB_H
# include <stdlib.h>
#endif
@@
-34,39
+38,51
@@
# include <unistd.h>
#endif
# include <unistd.h>
#endif
+#ifndef SIZE_MAX
+# define SIZE_MAX ((size_t) -1)
+#endif
+#ifndef SSIZE_MAX
+# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
+#endif
+
#include "xalloc.h"
#include "xreadlink.h"
/* Call readlink to get the symbolic link value of FILENAME.
Return a pointer to that NUL-terminated string in malloc'd storage.
#include "xalloc.h"
#include "xreadlink.h"
/* 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 (use errno to diagnose).
+ If readlink fails, return NULL (
caller may
use errno to diagnose).
If realloc fails, or if the link value is longer than SIZE_MAX :-),
give a diagnostic and exit. */
char *
If realloc fails, or if the link value is longer than SIZE_MAX :-),
give a diagnostic and exit. */
char *
-xreadlink (char const *filename
, size_t *link_length_arg
)
+xreadlink (char const *filename)
{
{
- size_t buf_size = 128; /* must be a power of 2 */
- char *buffer = NULL;
+ /* 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;
while (1)
{
while (1)
{
-
int link_length
;
-
buffer = (char *) xrealloc (
buffer, buf_size);
- link_length = readlink (filename, buffer, buf_size);
+
char *buffer = xmalloc (buf_size)
;
+
ssize_t link_length = readlink (filename,
buffer, buf_size);
+
if (link_length < 0)
{
if (link_length < 0)
{
+ int saved_errno = errno;
free (buffer);
free (buffer);
+ errno = saved_errno;
return NULL;
}
return NULL;
}
- if (link_length < buf_size)
+
+ if ((size_t) link_length < buf_size)
{
{
- *link_length_arg = link_length;
buffer[link_length] = 0;
return buffer;
}
buffer[link_length] = 0;
return buffer;
}
+
+ free (buffer);
buf_size *= 2;
buf_size *= 2;
- if (
buf_size == 0
)
+ if (
SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0)
)
xalloc_die ();
}
}
xalloc_die ();
}
}