//
// 03/10/2006 James Haley
//
// For this module only: 
// This code is public domain. No change sufficient enough to constitute a
// significant or original work has been made, and thus it remains as such.
//
//
// DESCRIPTION:
//
// Implementation of POSIX opendir for Visual C++.
// Derived from the MinGW C Library Extensions Source (released to the
// public domain). As with other Win32 modules, don't include most DOOM
// headers into this or conflicts will occur.
//
// Original Header:
//
// * dirent.c
// * This file has no copyright assigned and is placed in the Public Domain.
// * This file is a part of the mingw-runtime package.
// * No warranty is given; refer to the file DISCLAIMER within the package.
// *
// * Derived from DIRLIB.C by Matt J. Weinstein 
// * This note appears in the DIRLIB.H
// * DIRLIB.H by M. J. Weinstein   Released to public domain 1-Jan-89
// *
// * Updated by Jeremy Bettis <jeremy@hksys.com>
// * Significantly revised and rewinddir, seekdir and telldir added by Colin
// * Peters <colin@fu.is.saga-u.ac.jp>
//

#ifndef _MSC_VER
#error i_opndir.c is for Microsoft Visual C++ only
#endif

#include <stdlib.h>
#include <errno.h>
#include <string.h>

#define WIN32_LEAN_AND_MEAN
#include <windows.h> /* for GetFileAttributes */

#include <tchar.h>
#define SUFFIX	_T("*")
#define	SLASH	_T("\\")

#include "win_opendir.h"

//
// opendir
// 
// Returns a pointer to a DIR structure appropriately filled in to begin
// searching a directory.
//
DIR *opendir(const _TCHAR *szPath)
{
   DIR *nd;
   unsigned int rc;
   _TCHAR szFullPath[MAX_PATH];
	
   errno = 0;
   
   if(!szPath)
   {
      errno = EFAULT;
      return (DIR *)0;
   }
   
   if(szPath[0] == _T('\0'))
   {
      errno = ENOTDIR;
      return (DIR *)0;
   }

   /* Attempt to determine if the given path really is a directory. */
   rc = GetFileAttributes(szPath);
   if(rc == (unsigned int)-1)
   {
      /* call GetLastError for more error info */
      errno = ENOENT;
      return (DIR *)0;
   }
   if(!(rc & FILE_ATTRIBUTE_DIRECTORY))
   {
      /* Error, entry exists but not a directory. */
      errno = ENOTDIR;
      return (DIR *)0;
   }

   /* Make an absolute pathname.  */
   _tfullpath(szFullPath, szPath, MAX_PATH);

   /* Allocate enough space to store DIR structure and the complete
   * directory path given. */
   nd = (DIR *)(malloc(sizeof(DIR) + (_tcslen(szFullPath)
                                       + _tcslen(SLASH)
                                       + _tcslen(SUFFIX) + 1)
                                     * sizeof(_TCHAR)));

   if(!nd)
   {
      /* Error, out of memory. */
      errno = ENOMEM;
      return (DIR *)0;
   }

   /* Create the search expression. */
   _tcscpy(nd->dd_name, szFullPath);

   /* Add on a slash if the path does not end with one. */
   if(nd->dd_name[0] != _T('\0')
      && _tcsrchr(nd->dd_name, _T('/'))  != nd->dd_name
					    + _tcslen(nd->dd_name) - 1
      && _tcsrchr(nd->dd_name, _T('\\')) != nd->dd_name
      					    + _tcslen(nd->dd_name) - 1)
   {
      _tcscat(nd->dd_name, SLASH);
   }

   /* Add on the search pattern */
   _tcscat(nd->dd_name, SUFFIX);
   
   /* Initialize handle to -1 so that a premature closedir doesn't try
   * to call _findclose on it. */
   nd->dd_handle = -1;

   /* Initialize the status. */
   nd->dd_stat = 0;

   /* Initialize the dirent structure. ino and reclen are invalid under
    * Win32, and name simply points at the appropriate part of the
    * findfirst_t structure. */
   nd->dd_dir.d_ino = 0;
   nd->dd_dir.d_reclen = 0;
   nd->dd_dir.d_namlen = 0;
   memset(nd->dd_dir.d_name, 0, FILENAME_MAX);
  
   return nd;
}

//
// readdir
//
// Return a pointer to a dirent structure filled with the information on the
// next entry in the directory.
//
struct dirent *readdir(DIR *dirp)
{
   errno = 0;
   
   /* Check for valid DIR struct. */
   if(!dirp)
   {
      errno = EFAULT;
      return (struct dirent *)0;
   }

   if (dirp->dd_stat < 0)
   {
     /* We have already returned all files in the directory
      * (or the structure has an invalid dd_stat). */
      return (struct dirent *)0;
   }
   else if (dirp->dd_stat == 0)
   {
      /* We haven't started the search yet. */
      /* Start the search */
      dirp->dd_handle = _tfindfirst(dirp->dd_name, &(dirp->dd_dta));

      if(dirp->dd_handle == -1)
      {
         /* Whoops! Seems there are no files in that
          * directory. */
         dirp->dd_stat = -1;
      }
      else
      {
         dirp->dd_stat = 1;
      }
   }
   else
   {
      /* Get the next search entry. */
      if(_tfindnext(dirp->dd_handle, &(dirp->dd_dta)))
      {
         /* We are off the end or otherwise error.	
            _findnext sets errno to ENOENT if no more file
            Undo this. */ 
         DWORD winerr = GetLastError();
         if(winerr == ERROR_NO_MORE_FILES)
            errno = 0;
         _findclose(dirp->dd_handle);
         dirp->dd_handle = -1;
         dirp->dd_stat = -1;
      }
      else
      {
         /* Update the status to indicate the correct
          * number. */
         dirp->dd_stat++;
      }
   }

   if (dirp->dd_stat > 0)
   {
      /* Successfully got an entry. Everything about the file is
       * already appropriately filled in except the length of the
       * file name. */
      dirp->dd_dir.d_namlen = _tcslen(dirp->dd_dta.name);
      _tcscpy(dirp->dd_dir.d_name, dirp->dd_dta.name);
      return &dirp->dd_dir;
   }

   return (struct dirent *)0;
}


//
// closedir
//
// Frees up resources allocated by opendir.
//
int closedir(DIR *dirp)
{
   int rc;
   
   errno = 0;
   rc = 0;
   
   if(!dirp)
   {
      errno = EFAULT;
      return -1;
   }

   if(dirp->dd_handle != -1)
   {
      rc = _findclose(dirp->dd_handle);
   }

   /* Delete the dir structure. */
   free(dirp);
   
   return rc;
}

//
// rewinddir
//
// Return to the beginning of the directory "stream". We simply call findclose
// and then reset things like an opendir.
//
void rewinddir(DIR * dirp)
{
   errno = 0;
   
   if(!dirp)
   {
      errno = EFAULT;
      return;
   }

   if(dirp->dd_handle != -1)
   {
      _findclose(dirp->dd_handle);
   }
   
   dirp->dd_handle = -1;
   dirp->dd_stat = 0;
}

//
// telldir
//
// Returns the "position" in the "directory stream" which can be used with
// seekdir to go back to an old entry. We simply return the value in stat.
//
long telldir(DIR *dirp)
{
   errno = 0;
   
   if(!dirp)
   {
      errno = EFAULT;
      return -1;
   }
   return dirp->dd_stat;
}

//
// seekdir
//
// Seek to an entry previously returned by telldir. We rewind the directory
// and call readdir repeatedly until either dd_stat is the position number
// or -1 (off the end). This is not perfect, in that the directory may
// have changed while we weren't looking. But that is probably the case with
// any such system.
//
void seekdir(DIR *dirp, long lPos)
{
   errno = 0;
   
   if(!dirp)
   {
      errno = EFAULT;
      return;
   }

   if(lPos < -1)
   {
      /* Seeking to an invalid position. */
      errno = EINVAL;
      return;
   }
   else if(lPos == -1)
   {
      /* Seek past end. */
      if(dirp->dd_handle != -1)
      {
         _findclose(dirp->dd_handle);
      }
      dirp->dd_handle = -1;
      dirp->dd_stat = -1;
   }
   else
   {
      /* Rewind and read forward to the appropriate index. */
      rewinddir(dirp);
      
      while((dirp->dd_stat < lPos) && readdir(dirp))
         ; /* do-nothing loop */
   }
}

// EOF