/* xgetcwd.c -- return current directory with unlimited length
- Copyright (C) 1992 Free Software Foundation, Inc.
+ Copyright (C) 1992, 1996, 2000, 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
/* Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
-#ifdef HAVE_CONFIG_H
-#include <config.h>
+#if HAVE_CONFIG_H
+# include <config.h>
#endif
#include <stdio.h>
#ifndef errno
extern int errno;
#endif
+
#include <sys/types.h>
-#include "pathmax.h"
-#ifndef HAVE_GETCWD
-char *getwd ();
-#define getcwd(buf, max) getwd (buf)
-#else
-char *getcwd ();
+#if HAVE_STDLIB_H
+# include <stdlib.h>
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
#endif
-/* Amount to increase buffer size by in each try. */
-#define PATH_INCR 32
+#if HAVE_GETCWD
+char *getcwd ();
+#else
+# include "pathmax.h"
+# define INITIAL_BUFFER_SIZE (PATH_MAX + 1)
+char *getwd ();
+# define getcwd(Buf, Max) getwd (Buf)
+#endif
-char *xmalloc ();
-char *xrealloc ();
-void free ();
+#include "xalloc.h"
+#include "xgetcwd.h"
-/* Return the current directory, newly allocated, arbitrarily long.
- Return NULL and set errno on error. */
+/* Return the current directory, newly allocated, assuming it fits
+ within PATH_MAX bytes -- this is a common system-imposed limit
+ on how getcwd works.
+ Upon an out-of-memory error, call xalloc_die.
+ Upon any other type of error, return NULL. */
char *
-xgetcwd ()
+xgetcwd (void)
{
- char *cwd;
- char *ret;
- unsigned path_max;
-
- errno = 0;
- path_max = (unsigned) PATH_MAX;
- path_max += 2; /* The getcwd docs say to do this. */
+#if HAVE_GETCWD_NULL
+ char *cwd = getcwd (NULL, 0);
+ if (! cwd && errno == ENOMEM)
+ xalloc_die ();
+ return cwd;
+#else
- cwd = xmalloc (path_max);
+ /* The initial buffer size for the working directory. A power of 2
+ detects arithmetic overflow earlier, but is not required. */
+# ifndef INITIAL_BUFFER_SIZE
+# define INITIAL_BUFFER_SIZE 128
+# endif
- errno = 0;
- while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE)
- {
- path_max += PATH_INCR;
- cwd = xrealloc (cwd, path_max);
- errno = 0;
- }
+ size_t buf_size = INITIAL_BUFFER_SIZE;
- if (ret == NULL)
+ while (1)
{
- int save_errno = errno;
- free (cwd);
- errno = save_errno;
- return NULL;
+ char *buf = xmalloc (buf_size);
+ char *cwd = getcwd (buf, buf_size);
+ int saved_errno;
+ if (cwd)
+ return cwd;
+ saved_errno = errno;
+ free (buf);
+ if (saved_errno != ERANGE)
+ return NULL;
+ buf_size *= 2;
+ if (buf_size == 0)
+ xalloc_die ();
}
- return cwd;
+#endif
}