【转】vs2005下的dirent.h

http://www.analogcn.com/Article/wz3/200802/20080202211037.html

 

dirent.h是gcc下的一个头文件，而在VS2005中是没有的。这个文件中封装了几个对目录进行操作函数：

static DIR *opendir (const char *dirname);
static struct dirent *readdir (DIR *dirp);
static int closedir (DIR *dirp);

 对于在linux->windows之间进行程序移植来讲常常会造成一些困扰，在网上仔细搜了一下，发现原来已经有位好同志写了相应的移植代码，如下所示：

typedef struct dirent {
  /* name of current directory entry (a multi-byte character string) */
  char d_name[MAX_PATH + 1];

  /* file attributes */
  WIN32_FIND_DATA data;
} dirent;

typedef struct DIR {
  /* current directory entry */
  dirent current;

  /* is there an un-processed entry in current? */
  int cached;

  /* file search handle */
  HANDLE search_handle;

  /* search pattern (3 = zero terminator + pattern "\\*") */
  TCHAR patt[MAX_PATH + 3];
} DIR;

static DIR *opendir (const char *dirname);
static struct dirent *readdir (DIR *dirp);
static int closedir (DIR *dirp);

/* use the new safe string functions introduced in Visual Studio 2005 */
#if defined(_MSC_VER) && _MSC_VER >= 1400
# define STRNCPY(dest,src,size) strncpy_s((dest),(size),(src),_TRUNCATE)
#else
# define STRNCPY(dest,src,size) strncpy((dest),(src),(size))
#endif

/*
 * Open directory stream DIRNAME for read and return a pointer to the
 * internal working area that is used to retrieve individual directory
 * entries.
 */
static DIR*
opendir(
    const char *dirname)
{
  DIR *dirp;
  assert (dirname != NULL);
  assert (strlen (dirname) < MAX_PATH);

  /* construct new DIR structure */
  dirp = (DIR*) malloc (sizeof (struct DIR));
  if (dirp != NULL) {
    TCHAR *p;
   
    /* prepare search pattern */
#ifdef _UNICODE

    /* convert directory name to wide character string */
    MultiByteToWideChar(
        CP_ACP,                                /* code page */
        0,                                     /* conversion flags */
        dirname,                               /* mb-string to convert */
        -1,                                    /* length of mb-string */
        dirp->patt,                            /* wc-string to produce */
        MAX_PATH);                             /* max length of wc-string */
    dirp->patt[MAX_PATH] = '\0';
   
    /* append search pattern to directory name */
    p = wcschr (dirp->patt, '\0');
    if (dirp->patt < p  &&  *(p-1) != '\\'  &&  *(p-1) != ':') {
      *p++ = '\\';
    }
    *p++ = '*';
    *p = '\0';

#else /* !_UNICODE */
   
    /* take directory name... */
    STRNCPY (dirp->patt, dirname, sizeof(dirp->patt));
    dirp->patt[MAX_PATH] = '\0';
   
    /* ... and append search pattern to it */
    p = strchr (dirp->patt, '\0');
    if (dirp->patt < p  &&  *(p-1) != '\\'  &&  *(p-1) != ':') {
      *p++ = '\\';
    }
    *p++ = '*';
    *p = '\0';
   
#endif /* !_UNICODE */

    /* open stream and retrieve first file */
    dirp->search_handle = FindFirstFile (dirp->patt, &dirp->current.data);
    if (dirp->search_handle == INVALID_HANDLE_VALUE) {
      /* invalid search pattern? */
      free (dirp);
      return NULL;
    }

    /* there is an un-processed directory entry in memory now */
    dirp->cached = 1;
   
  }
  return dirp;
}

/*
 * Read a directory entry, and return a pointer to a dirent structure
 * containing the name of the entry in d_name field.  Individual directory
 * entries returned by this very function include regular files,
 * sub-directories, pseudo-directories "." and "..", but also volume labels,
 * hidden files and system files may be returned. 
 */
static struct dirent *
readdir(
    DIR *dirp)
{
  assert (dirp != NULL);

  if (dirp->search_handle == INVALID_HANDLE_VALUE) {
    /* directory stream was opened/rewound incorrectly or it ended normally */
    return NULL;
  }

  /* get next directory entry */
  if (dirp->cached != 0) {
    /* a valid directory entry already in memory */
    dirp->cached = 0;
  } else {
    /* read next directory entry from disk */
    if (FindNextFile (dirp->search_handle, &dirp->current.data) == FALSE) {
      /* the very last file has been processed or an error occured */
      FindClose (dirp->search_handle);
      dirp->search_handle = INVALID_HANDLE_VALUE;
      return NULL;
    }
  }

  /* copy directory entry to d_name */
#ifdef _UNICODE
 
  /* convert entry name to multibyte */
  WideCharToMultiByte(
      CP_ACP,                                  /* code page */
      0,                                       /* conversion flags */
      dirp->current.data.cFileName,            /* wc-string to convert */
      -1,                                      /* length of wc-string */
      dirp->current.d_name,                    /* mb-string to produce */
      MAX_PATH,                                /* max length of mb-string */
      NULL,                                    /* use sys default character */
      NULL);                                   /* don't care  */
  dirp->current.d_name[MAX_PATH] = '\0';
 
#else /* !_UNICODE */

  /* copy as a multibyte character string */
  STRNCPY (dirp->current.d_name, dirp->current.data.cFileName, sizeof(dirp->current.d_name));
  dirp->current.d_name[MAX_PATH] = '\0';

#endif /* !_UNICODE */
 
  return &dirp->current;
}

/*
 * Close directory stream opened by opendir() function.  Close of the
 * directory stream invalidates the DIR structure as well as any previously
 * read directory entry.
 */
static int
closedir(
    DIR *dirp)
{
  assert (dirp != NULL);
 
  /* release search handle */
  if (dirp->search_handle != INVALID_HANDLE_VALUE) {
    FindClose (dirp->search_handle);
    dirp->search_handle = INVALID_HANDLE_VALUE;
  }

  /* release directory handle */
  free (dirp);
  return 0;
}

此文件可从http://www.softagalleria.net/dirent/index.en.html下载得到，直接将它放在VS2005的include目录就OK 了！

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