/* xgetcwd.c -- return current directory with unlimited length
- Copyright (C) 1992, 1996, 2000 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
#endif
#include <sys/types.h>
-#include "pathmax.h"
+
+#if HAVE_STDLIB_H
+# include <stdlib.h>
+#endif
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
#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
-extern void *xmalloc ();
-extern char *xstrdup ();
-extern 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 *ret;
- unsigned path_max;
- char buf[1024];
+#if HAVE_GETCWD_NULL
+ char *cwd = getcwd (NULL, 0);
+ if (! cwd && errno == ENOMEM)
+ xalloc_die ();
+ return cwd;
+#else
- errno = 0;
- ret = getcwd (buf, sizeof (buf));
- if (ret != NULL)
- return xstrdup (buf);
- if (errno != ERANGE)
- return NULL;
+ /* 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
- path_max = (unsigned) PATH_MAX;
- path_max += 2; /* The getcwd docs say to do this. */
+ size_t buf_size = INITIAL_BUFFER_SIZE;
- for (;;)
+ while (1)
{
- char *cwd = (char *) xmalloc (path_max);
-
- errno = 0;
- ret = getcwd (cwd, path_max);
- if (ret != NULL)
- return ret;
- if (errno != ERANGE)
- {
- int save_errno = errno;
- free (cwd);
- errno = save_errno;
- return NULL;
- }
-
- free (cwd);
-
- path_max += path_max / 16;
- path_max += 32;
+ 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 ();
}
+#endif
}