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/*****************************************************************************
* dirent.h - dirent API for Microsoft Visual Studio
*
* Copyright (C) 2006 Toni Ronkko
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* ``Software''), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL TONI RONKKO BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Dec 15, 2009, John Cunningham
* Added rewinddir member function
*
* Jan 18, 2008, Toni Ronkko
* Using FindFirstFileA and WIN32_FIND_DATAA to avoid converting string
* between multi-byte and unicode representations.  This makes the
* code simpler and also allows the code to be compiled under MingW.  Thanks
* to Azriel Fasten for the suggestion.
*
* Mar 4, 2007, Toni Ronkko
* Bug fix: due to the strncpy_s() function this file only compiled in
* Visual Studio 2005.  Using the new string functions only when the
* compiler version allows.
*
* Nov  2, 2006, Toni Ronkko
* Major update: removed support for Watcom C, MS-DOS and Turbo C to
* simplify the file, updated the code to compile cleanly on Visual
* Studio 2005 with both unicode and multi-byte character strings,
* removed rewinddir() as it had a bug.
*
* Aug 20, 2006, Toni Ronkko
* Removed all remarks about MSVC 1.0, which is antiqued now.  Simplified
* comments by removing SGML tags.
*
* May 14 2002, Toni Ronkko
* Embedded the function definitions directly to the header so that no
* source modules need to be included in the Visual Studio project.  Removed
* all the dependencies to other projects so that this very header can be
* used independently.
*
* May 28 1998, Toni Ronkko
* First version.
*****************************************************************************/
#ifndef DIRENT_H
#define DIRENT_H

#include <windows.h>
#include <string.h>
#include <assert.h>

typedef struct dirent
{
    char d_name[ MAX_PATH + 1 ]; /* current dir entry (multi-byte char string) */
    WIN32_FIND_DATAA data; /* file attributes */
} dirent;


typedef struct DIR
{
    dirent current; /* Current directory entry */
    int cached; /* Indicates un-processed entry in memory */
    HANDLE search_handle; /* File search handle */
    char patt[ MAX_PATH + 3 ]; /* search pattern (3 = pattern + "\\*\0") */
} DIR;


/* Forward declarations */
static DIR * opendir( const char * dirname );
static struct dirent * readdir( DIR * dirp );
static int closedir( DIR * dirp );
static void rewinddir( 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 ) {
        char * p;
       
        /* 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';
       
        /* open stream and retrieve first file */
        dirp->search_handle = FindFirstFileA( 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 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( FindNextFileA( 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 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';
   
    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;
}


/*****************************************************************************
* Resets the position of the directory stream to which dirp refers to the
* beginning of the directory. It also causes the directory stream to refer
* to the current state of the corresponding directory, as a call to opendir()
* would have done. If dirp does not refer to a directory stream, the effect
* is undefined.
*/
static void rewinddir( DIR * dirp )
{
    /* release search handle */
    if( dirp->search_handle != INVALID_HANDLE_VALUE ) {
        FindClose( dirp->search_handle );
        dirp->search_handle = INVALID_HANDLE_VALUE;
    }
   
    /* open new search handle and retrieve first file */
    dirp->search_handle = FindFirstFileA( dirp->patt, & dirp->current.data );
    if( dirp->search_handle == INVALID_HANDLE_VALUE ) {
        /* invalid search pattern? */
        free( dirp );
        return;
    }
   
    /* there is an un-processed directory entry in memory now */
    dirp->cached = 1;
}


#endif /*DIRENT_H*/