xgetcwd.c

压缩包中包含LINUX下多个命令的源码

/* xgetcwd.c -- return current directory with unlimited length
   Copyright (C) 1992, 1996 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
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by David MacKenzie <[e-mail]>.  */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <errno.h>
#ifndef errno
extern int errno;
#endif

#include <sys/types.h>
#include "pathmax.h"

#if HAVE_GETCWD
extern char *getcwd __P ((char *buf, size_t size));
#else
extern char *getwd __P ((char *buf, size_t size));
# define getcwd(Buf, Max) getwd (Buf)
#endif

/* Amount to increase buffer size by in each try. */
#define PATH_INCR 32

extern char *xmalloc __P ((size_t n));
extern char *xrealloc __P ((void *p, size_t s));
extern void free __P ((void *));

/* Return the current directory, newly allocated, arbitrarily long.
   Return NULL and set errno on error. */

char *
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. */

  cwd = xmalloc (path_max);

  errno = 0;
  while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE)
    {
      path_max += PATH_INCR;
      cwd = xrealloc (cwd, path_max);
      errno = 0;
    }

  if (ret == NULL)
    {
      int save_errno = errno;
      free (cwd);
      errno = save_errno;
      return NULL;
    }
  return cwd;
}