dirname.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

// 
//  Visopsys
//  Copyright (C) 1998-2007 J. Andrew McLaughlin
//  
//  This library is free software; you can redistribute it and/or modify it
//  under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation; either version 2.1 of the License, or (at
//  your option) any later version.
//
//  This library 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 Lesser
//  General Public License for more details.
//
//  You should have received a copy of the GNU Lesser General Public License
//  along with this library; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  dirname.c
//

// This is the standard "dirname" function, as found in standard C libraries

#include <libgen.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>


char *dirname(char *path)
{
  // The GNU manual page says the following:
  //
  //   The functions dirname() and basename() break a null-terminated pathname
  //   string into directory and filename components.  In the usual case,
  //   dirname() returns the string up to, but not including, the final '/',
  //   and basename() returns the component following the final '/'.  Trailing
  //   '/' characters are not counted as part of the pathname.
  //
  //   If path does not contain a slash, dirname() returns the string "."
  //   while basename() returns a copy of path.  If path is the string  "/",
  //   then both dirname() and basename() return the string "/".  If path is a
  //   NULL pointer or points to an empty string, then both dirname() and
  //   basename() return the string ".".
  //
  // The GNU manual page also says that the POSIX versions might modify their
  // arguments or use statically allocated memory.  Our version will never
  // do either of these things; it will return a dynamically allocated string
  // which the caller is responsible for freeing.  Also, unlike GNU basename,
  // we will not return the empty string when path has a trailing '/'.

  char *newPath = NULL;
  char *lastSlash = NULL;
  int count;

  // Get the memory to return.  Always a maxed-out pathname.
  newPath = malloc(MAX_PATH_NAME_LENGTH);
  if (newPath == NULL)
    {
      // Nothing much we can do here.
      errno = ERR_MEMORY;
      return (newPath);
    }

  // Look for NULL, empty string, or no '/'
  if ((path == NULL) || (path[0] == '\0') || (strrchr(path, '/') == NULL))
    {
      newPath[0] = '.';
      newPath[1] = '\0';
      return (newPath);
    }

  strncpy(newPath, path, MAX_PATH_NAME_LENGTH);

  // Remove any trailing separators, not including the first character
  for (count = (strlen(newPath) - 1); ((count > 0) && (newPath[count] == '/'));
       count --)
    newPath[count] = '\0';

  // Look for the last instance of '/'
  lastSlash = strrchr(newPath, '/');

  if (lastSlash != newPath)
    // Terminate it there.
    lastSlash[0] = '\0';

  return (newPath);
}