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Import from coreutils.
[gnulib.git]
/
lib
/
xreadlink.c
diff --git
a/lib/xreadlink.c
b/lib/xreadlink.c
index
3194d31
..
41f5242
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, 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
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
@@
-23,39
+23,50
@@
# include <config.h>
#endif
# include <config.h>
#endif
+#include "xreadlink.h"
+
#include <stdio.h>
#include <stdio.h>
-#if HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#if HAVE_STDLIB_H
-# include <stdlib.h>
+#include <errno.h>
+#ifndef errno
+extern int errno;
#endif
#endif
+
+#include <limits.h>
+#include <sys/types.h>
+#include <stdlib.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#endif
#if HAVE_UNISTD_H
# 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 "xalloc.h"
-#include "xreadlink.h"
/* Call readlink to get the symbolic link value of FILENAME.
/* 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).
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 S
SIZE_MAX :-),
give a diagnostic and exit. */
char *
give a diagnostic and exit. */
char *
-xreadlink (char const *filename, size_t
*link_length_arg
)
+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. */
{
/* 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;
- char *buffer = NULL;
+ size_t buf_size = size + 1;
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)
{
int saved_errno = errno;
if (link_length < 0)
{
int saved_errno = errno;
@@
-63,14
+74,16
@@
xreadlink (char const *filename, size_t *link_length_arg)
errno = saved_errno;
return NULL;
}
errno = saved_errno;
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 (
! (0 < buf_size && buf_size <= SSIZE_MAX)
)
xalloc_die ();
}
}
xalloc_die ();
}
}