/* Start reading the entries of a directory.

   Copyright (C) 2006-2018 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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <dirent.h>

#include <errno.h>

#include <stddef.h>

#if HAVE_OPENDIR

/* Override opendir(), to keep track of the open file descriptors.

   Needed because there is a function dirfd().  */

#else

# include <stdlib.h>

# include "dirent-private.h"

# include "filename.h"

#endif

#if REPLACE_FCHDIR

# include <unistd.h>

#endif

#ifdef __KLIBC__

# include <io.h>

# include <fcntl.h>

#endif

DIR *

opendir (const char *dir_name)

{

#if HAVE_OPENDIR

# undef opendir

  DIR *dirp;

  dirp = opendir (dir_name);

  if (dirp == NULL)

    return NULL;

# ifdef __KLIBC__

  {

    int fd = open (dir_name, O_RDONLY);

    if (fd == -1 || _gl_register_dirp_fd (fd, dirp))

      {

        int saved_errno = errno;

        close (fd);

        closedir (dirp);

        errno = saved_errno;

        return NULL;

      }

  }

# endif

#else

  char dir_name_mask[MAX_PATH + 1 + 1 + 1];

  int status;

  HANDLE current;

  WIN32_FIND_DATA entry;

  struct gl_directory *dirp;

  if (dir_name[0] == '\0')

    {

      errno = ENOENT;

      return NULL;

    }

  /* Make the dir_name absolute, so that we continue reading the same

     directory if the current directory changed between this opendir()

     call and a subsequent rewinddir() call.  */

  if (!GetFullPathName (dir_name, MAX_PATH, dir_name_mask, NULL))

    {

      errno = EINVAL;

      return NULL;

    }

  /* Append the mask.

     "*" and "*.*" appear to be equivalent.  */

  {

    char *p;

    p = dir_name_mask + strlen (dir_name_mask);

    if (p > dir_name_mask && !ISSLASH (p[-1]))

      *p++ = '\\';

    *p++ = '*';

    *p = '\0';

  }

  /* Start searching the directory.  */

  status = -1;

  current = FindFirstFile (dir_name_mask, &entry);

  if (current == INVALID_HANDLE_VALUE)

    {

      switch (GetLastError ())

        {

        case ERROR_FILE_NOT_FOUND:

          status = -2;

          break;

        case ERROR_PATH_NOT_FOUND:

          errno = ENOENT;

          return NULL;

        case ERROR_DIRECTORY:

          errno = ENOTDIR;

          return NULL;

        case ERROR_ACCESS_DENIED:

          errno = EACCES;

          return NULL;

        default:

          errno = EIO;

          return NULL;

        }

    }

  /* Allocate the result.  */

  dirp =

    (struct gl_directory *)

    malloc (offsetof (struct gl_directory, dir_name_mask[0])

            + strlen (dir_name_mask) + 1);

  if (dirp == NULL)

    {

      if (current != INVALID_HANDLE_VALUE)

        FindClose (current);

      errno = ENOMEM;

      return NULL;

    }

  dirp->status = status;

  dirp->current = current;

  if (status == -1)

    memcpy (&dirp->entry, &entry, sizeof (WIN32_FIND_DATA));

  strcpy (dirp->dir_name_mask, dir_name_mask);

#endif

#if REPLACE_FCHDIR

  {

    int fd = dirfd (dirp);

    if (0 <= fd && _gl_register_fd (fd, dir_name) != fd)

      {

        int saved_errno = errno;

        closedir (dirp);

        errno = saved_errno;

        return NULL;

      }

  }

#endif

  return dirp;

}