/*
 * uce-dirent.h - operating system independent dirent implementation
 * 
 * Copyright (C) 1998-2002  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.
 * 
 * 
 * May 28 1998, Toni Ronkko <tronkko@messi.uku.fi>
 *
 * $Id: uce-dirent.h,v 1.7 2002/05/13 10:48:35 tr Exp $
 *
 * $Log: uce-dirent.h,v $
 * Revision 1.7  2002/05/13 10:48:35  tr
 * embedded some source code directly to the header so that no source
 * modules need to be included in the MS Visual C project using the
 * interface, removed all the dependencies to other headers of the `uce'
 * library so that the header can be made public
 *
 * Revision 1.6  2002/04/12 16:22:04  tr
 * Unified Compiling Environment (UCE) replaced `std' library
 *
 * Revision 1.5  2001/07/20 16:33:40  tr
 * moved to `std' library and re-named defines accordingly
 *
 * Revision 1.4  2001/07/10 16:47:18  tronkko
 * revised comments
 *
 * Revision 1.3  2001/01/11 13:16:43  tr
 * using ``uce-machine.h'' for finding out defines such as `FREEBSD'
 *
 * Revision 1.2  2000/10/08 16:00:41  tr
 * copy of FreeBSD man page
 *
 * Revision 1.1  2000/07/10 05:53:16  tr
 * Initial revision
 *
 * Revision 1.2  1998/07/19 18:29:14  tr
 * Added error reporting capabilities and some asserts.
 *
 * Revision 1.1  1998/07/04 16:27:51  tr
 * Initial revision
 *
 * 
 * MSVC 1.0 scans automatic dependencies incorrectly when your project
 * contains this very header.  The problem is that MSVC cannot handle
 * include directives inside #if..#endif block those are never entered.
 * Since this header ought to compile in many different operating systems,
 * there had to be several conditional blocks that are compiled only in
 * operating systems for what they were designed for.  MSVC 1.0 cannot
 * handle inclusion of sys/dir.h in a part that is compiled only in Apollo
 * operating system.  To fix the problem you need to insert DIR.H into
 * SYSINCL.DAT located in MSVC\BIN directory and restart visual C++.
 * Consult manuals for more informaton about the problem.
 *
 * Since many UNIX systems have dirent.h we assume to have one also.
 * However, if your UNIX system does not have dirent.h you can download one
 * for example at: http://ftp.uni-mannheim.de/ftp/GNU/dirent/dirent.tar.gz.
 * You can also see if you have one of dirent.h, direct.h, dir.h, ndir.h,
 * sys/dir.h and sys/ndir.h somewhere.  Try defining HAVE_DIRENT_H,
 * HAVE_DIRECT_H, HAVE_DIR_H, HAVE_NDIR_H, HAVE_SYS_DIR_H and
 * HAVE_SYS_NDIR_H according to the files found.
 */
#ifndef DIRENT_H
#define DIRENT_H
#define DIRENT_H_INCLUDED

/* find out platform */
#if defined(MSDOS)                             /* MS-DOS */
#elif defined(__MSDOS__)                       /* Turbo C/Borland */
# define MSDOS
#elif defined(__DOS__)                         /* Watcom */
# define MSDOS
#endif

#if defined(WIN32)                             /* MS-Windows */
#elif defined(__NT__)                          /* Watcom */
# define WIN32
#elif defined(_WIN32)                          /* Microsoft */
# define WIN32
#elif defined(__WIN32__)                       /* Borland */
# define WIN32
#endif

/*
 * See what kind of dirent interface we have unless autoconf has already
 * determinated that.
 */
#if !defined(HAVE_DIRENT_H) && !defined(HAVE_DIRECT_H) && !defined(HAVE_SYS_DIR_H) && !defined(HAVE_NDIR_H) && !defined(HAVE_SYS_NDIR_H) && !defined(HAVE_DIR_H)
# if defined(_MSC_VER)                         /* Microsoft C/C++ */
    /* no dirent.h */
# elif defined(__BORLANDC__)                   /* Borland C/C++ */
#   define HAVE_DIRENT_H
#   define VOID_CLOSEDIR
# elif defined(__TURBOC__)                     /* Borland Turbo C */
    /* no dirent.h */
# elif defined(__WATCOMC__)                    /* Watcom C/C++ */
#   define HAVE_DIRECT_H
# elif defined(__apollo)                       /* Apollo */
#   define HAVE_SYS_DIR_H
# elif defined(__hpux)                         /* HP-UX */
#   define HAVE_DIRENT_H
# elif (defined(__alpha) || defined(__alpha__)) && !defined(__linux__)  /* Alpha OSF1 */
#   error "not implemented"
# elif defined(__sgi)                          /* Silicon Graphics */
#   define HAVE_DIRENT_H
# elif defined(sun) || defined(_sun)           /* Sun Solaris */
#   define HAVE_DIRENT_H
# elif defined(__FreeBSD__)                    /* FreeBSD */
#   define HAVE_DIRENT_H
# elif defined(__linux__)                      /* Linux */
#   define HAVE_DIRENT_H
# elif defined(__GNUC__)                       /* GNU C/C++ */
#   define HAVE_DIRENT_H
# else
#   error "not implemented"
# endif
#endif

/* include proper interface headers */
#if defined(HAVE_DIRENT_H)
# include <dirent.h>
# ifdef FREEBSD
#   define NAMLEN(dp) ((int)((dp)->d_namlen))
# else
#   define NAMLEN(dp) ((int)(strlen((dp)->d_name)))
# endif

#elif defined(HAVE_NDIR_H)
# include <ndir.h>
# define NAMLEN(dp) ((int)((dp)->d_namlen))

#elif defined(HAVE_SYS_NDIR_H)
# include <sys/ndir.h>
# define NAMLEN(dp) ((int)((dp)->d_namlen))

#elif defined(HAVE_DIRECT_H)
# include <direct.h>
# define NAMLEN(dp) ((int)((dp)->d_namlen))

#elif defined(HAVE_DIR_H)
# include <dir.h>
# define NAMLEN(dp) ((int)((dp)->d_namlen))

#elif defined(HAVE_SYS_DIR_H)
# include <sys/types.h>
# include <sys/dir.h>
# ifndef dirent
#   define dirent direct
# endif
# define NAMLEN(dp) ((int)((dp)->d_namlen))

#elif defined(MSDOS) || defined(WIN32)

  /* figure out type of underlaying directory interface to be used */
# if defined(WIN32)
#   define DIRENT_WIN32_INTERFACE
# elif defined(MSDOS)
#   define DIRENT_MSDOS_INTERFACE
# else
#   error "missing native dirent interface"
# endif

  /*** WIN32 specifics ***/
# if defined(DIRENT_WIN32_INTERFACE)
#   include <windows.h>
#   if !defined(DIRENT_MAXNAMLEN)
#     define DIRENT_MAXNAMLEN (MAX_PATH)
#   endif


  /*** MS-DOS specifics ***/
# elif defined(DIRENT_MSDOS_INTERFACE)
#   include <dos.h>

    /* Borland defines file length macros in dir.h */
#   if defined(__BORLANDC__)
#     include <dir.h>
#     if !defined(DIRENT_MAXNAMLEN)
#       define DIRENT_MAXNAMLEN ((MAXFILE)+(MAXEXT))
#     endif
#     if !defined(_find_t)
#       define _find_t find_t
#     endif

    /* Turbo C defines ffblk structure in dir.h */
#   elif defined(__TURBOC__)
#     include <dir.h>
#     if !defined(DIRENT_MAXNAMLEN)
#       define DIRENT_MAXNAMLEN ((MAXFILE)+(MAXEXT))
#     endif
#     define DIRENT_USE_FFBLK

    /* MSVC */
#   elif defined(_MSC_VER)
#     if !defined(DIRENT_MAXNAMLEN)
#       define DIRENT_MAXNAMLEN (12)
#     endif

    /* Watcom */
#   elif defined(__WATCOMC__)
#     if !defined(DIRENT_MAXNAMLEN)
#       if defined(__OS2__) || defined(__NT__)
#         define DIRENT_MAXNAMLEN (255)
#       else
#         define DIRENT_MAXNAMLEN (12)
#       endif
#     endif

#   endif
# endif

  /*** generic MS-DOS and MS-Windows stuff ***/
# if !defined(NAME_MAX) && defined(DIRENT_MAXNAMLEN)
#   define NAME_MAX DIRENT_MAXNAMLEN
# endif
# if NAME_MAX < DIRENT_MAXNAMLEN
#   error "assertion failed: NAME_MAX >= DIRENT_MAXNAMLEN"
# endif


  /*
   * Substitute for real dirent structure.  Note that `d_name' field is a
   * true character array although we have it copied in the implementation
   * dependent data.  We could save some memory if we had declared `d_name'
   * as a pointer refering the name within implementation dependent data.
   * We have not done that since some code may rely on sizeof(d_name) to be
   * something other than four.  Besides, directory entries are typically so
   * small that it takes virtually no time to copy them from place to place.
   */
  typedef struct dirent {
    char d_name[NAME_MAX + 1];

    /*** Operating system specific part ***/
# if defined(DIRENT_WIN32_INTERFACE)       /*WIN32*/
    WIN32_FIND_DATA data;
# elif defined(DIRENT_MSDOS_INTERFACE)     /*MSDOS*/
#   if defined(DIRENT_USE_FFBLK)
    struct ffblk data;
#   else
    struct _find_t data;
#   endif
# endif
  } dirent;

  /* DIR substitute structure containing directory name.  The name is
   * essential for the operation of ``rewinndir'' function. */
  typedef struct DIR {
    char          *dirname;                    /* directory being scanned */
    dirent        current;                     /* current entry */
    int           dirent_filled;               /* is current un-processed? */

  /*** Operating system specific part ***/
#  if defined(DIRENT_WIN32_INTERFACE)
    HANDLE        search_handle;
#  elif defined(DIRENT_MSDOS_INTERFACE)
#  endif
  } DIR;

# ifdef __cplusplus
extern "C" {
# endif

/* supply prototypes for dirent functions */
static DIR *opendir (const char *dirname);
static struct dirent *readdir (DIR *dirp);
static int closedir (DIR *dirp);
static void rewinddir (DIR *dirp);

/*
 * Implement dirent interface as static functions so that the user does not
 * need to change his project in any way to use dirent function.  With this
 * it is sufficient to include this very header from source modules using
 * dirent functions and the functions will be pulled in automatically.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

/* use ffblk instead of _find_t if requested */
#if defined(DIRENT_USE_FFBLK)
# define _A_ARCH   (FA_ARCH)
# define _A_HIDDEN (FA_HIDDEN)
# define _A_NORMAL (0)
# define _A_RDONLY (FA_RDONLY)
# define _A_SUBDIR (FA_DIREC)
# define _A_SYSTEM (FA_SYSTEM)
# define _A_VOLID  (FA_LABEL)
# define _dos_findnext(dest) findnext(dest)
# define _dos_findfirst(name,flags,dest) findfirst(name,dest,flags)
#endif

static int _initdir (DIR *p);
static const char *_getdirname (const struct dirent *dp);
static void _setdirname (struct DIR *dirp);

/*
 * <function name="opendir">
 * <intro>open directory stream for reading
 * <syntax>DIR *opendir (const char *dirname);
 *
 * <desc>Open named directory stream for read and return pointer to the
 * internal working area that is used for retrieving individual directory
 * entries.  The internal working area has no fields of your interest.
 *
 * <ret>Returns a pointer to the internal working area or NULL in case the 
 * directory stream could not be opened.  Global `errno' variable will set
 * in case of error as follows:
 *
 * <table>
 * [EACESS  |Permission denied.
 * [EMFILE  |Too many open files used by the process.
 * [ENFILE  |Too many open files in system.
 * [ENOENT  |Directory does not exist.
 * [ENOMEM  |Insufficient memory.
 * [ENOTDIR |dirname does not refer to directory.  This value is not
 *           reliable on MS-DOS and MS-Windows platforms.  Many
 *           implementations return ENOENT even when the name refers to a
 *           file.]
 * </table>
 * </function>
 */
static DIR *opendir(const char *dirname)
{
  DIR *dirp;
  assert (dirname != NULL);
  
  dirp = (DIR*)malloc (sizeof (struct DIR));
  if (dirp != NULL) {
    char *p;
    
    /* allocate room for directory name */
    dirp->dirname = (char*) malloc (strlen (dirname) + 1 + strlen ("\\*.*"));
    if (dirp->dirname == NULL) {
      /* failed to duplicate directory name.  errno set by malloc() */
      free (dirp);
      return NULL;
    }
    /* Copy directory name while appending directory separator and "*.*".
     * Directory separator is not appended if the name already ends with
     * drive or directory separator.  Directory separator is assumed to be
     * '/' or '\' and drive separator is assumed to be ':'. */
    strcpy (dirp->dirname, dirname);
    p = strchr (dirp->dirname, '\0');
    if (dirp->dirname < p  &&
        *(p - 1) != '\\'  &&  *(p - 1) != '/'  &&  *(p - 1) != ':')
    {
      strcpy (p++, "\\");
    }
# ifdef DIRENT_WIN32_INTERFACE
    strcpy (p, "*"); /*scan files with and without extension in win32*/
# else
    strcpy (p, "*.*"); /*scan files with and without extension in DOS*/
# endif

    /* open stream */
    if (_initdir (dirp) == 0) {
      /* initialization failed */
      free (dirp->dirname);
      free (dirp);
      return NULL;
    }
  }
  return dirp;
}


/*
 * <function name="readdir">
 * <intro>read a directory entry
 * <syntax>struct dirent *readdir (DIR *dirp);
 *
 * <desc>Read individual directory entry and return pointer to a structure
 * containing the name of the entry.  Individual directory entries returned
 * include normal files, sub-directories, pseudo-directories "." and ".."
 * and also volume labels, hidden files and system files in MS-DOS and
 * MS-Windows.   You might want to use stat(2) function to determinate which
 * one are you dealing with.  Many dirent implementations already contain
 * equivalent information in dirent structure but you cannot depend on
 * this.
 *
 * The dirent structure contains several system dependent fields that
 * generally have no interest to you.  The only interesting one is char
 * d_name[] that is also portable across different systems.  The d_name
 * field contains the name of the directory entry without leading path.
 * While d_name is portable across different systems the actual storage
 * capacity of d_name varies from system to system and there is no portable
 * way to find out it at compile time as different systems define the
 * capacity of d_name with different macros and some systems do not define
 * capacity at all (besides actual declaration of the field). If you really
 * need to find out storage capacity of d_name then you might want to try
 * NAME_MAX macro. The NAME_MAX is defined in POSIX standard althought
 * there are many MS-DOS and MS-Windows implementations those do not define
 * it.  There are also systems that declare d_name as "char d_name[1]" and
 * then allocate suitable amount of memory at run-time.  Thanks to Alain
 * Decamps (Alain.Decamps@advalvas.be) for pointing it out to me.
 *
 * This all leads to the fact that it is difficult to allocate space
 * for the directory names when the very same program is being compiled on
 * number of operating systems.  Therefore I suggest that you always
 * allocate space for directory names dynamically.
 *
 * <ret>
 * Returns a pointer to a structure containing name of the directory entry
 * in `d_name' field or NULL if there was an error.  In case of an error the
 * global `errno' variable will set as follows:
 *
 * <table>
 * [EBADF  |dir parameter refers to an invalid directory stream.  This value
 *          is not set reliably on all implementations.]
 * </table>
 * </function>
 */
static struct dirent *
readdir (DIR *dirp)
{
  assert(dirp != NULL);
  if (dirp == NULL) {
    errno = EBADF;
    return NULL;
  }

#if defined(DIRENT_WIN32_INTERFACE)
  if (dirp->search_handle == INVALID_HANDLE_VALUE) {
    /* directory stream was opened/rewound incorrectly or it ended normally */
    errno = EBADF;
    return NULL;
  }
#endif

  if (dirp->dirent_filled != 0) {
    /*
     * Directory entry has already been retrieved and there is no need to
     * retrieve a new one.  Directory entry will be retrieved in advance
     * when the user calls readdir function for the first time.  This is so
     * because real dirent has separate functions for opening and reading
     * the stream whereas Win32 and DOS dirents open the stream
     * automatically when we retrieve the first file.  Therefore, we have to
     * save the first file when opening the stream and later we have to
     * return the saved entry when the user tries to read the first entry.
     */
    dirp->dirent_filled = 0;
  } else {
    /* fill in entry and return that */
#if defined(DIRENT_WIN32_INTERFACE)
    if (FindNextFile (dirp->search_handle, &dirp->current.data) == FALSE) {
      /* Last file has been processed or an error occured */
      FindClose (dirp->search_handle);
      dirp->search_handle = INVALID_HANDLE_VALUE;
      errno = ENOENT;
      return NULL;
    }

# elif defined(DIRENT_MSDOS_INTERFACE)
    if (_dos_findnext (&dirp->current.data) != 0) {
      /* _dos_findnext and findnext will set errno to ENOENT when no
       * more entries could be retrieved. */
      return NULL;
    }
# endif

    _setdirname (dirp);
    assert (dirp->dirent_filled == 0);
  }
  return &dirp->current;
}


/*
 * <function name="closedir">
 * <intro>close directory stream.
 * <syntax>int closedir (DIR *dirp);
 *
 * <desc>Close directory stream opened by the `opendir' function.  Close of
 * directory stream invalidates the DIR structure as well as previously read
 * dirent entry.
 *
 * <ret>The function typically returns 0 on success and -1 on failure but
 * the function may be declared to return void on same systems.  At least
 * Borland C/C++ and some UNIX implementations use void as a return type.
 * The dirent wrapper tries to define VOID_CLOSEDIR whenever closedir is
 * known to return nothing.  The very same definition is made by the GNU
 * autoconf if you happen to use it.
 *
 * The global `errno' variable will set to EBADF in case of error.
 * </function>
 */
static int
closedir (DIR *dirp)
{   
  int retcode = 0;

  /* make sure that dirp points to legal structure */
  assert (dirp != NULL);
  if (dirp == NULL) {
    errno = EBADF;
    return -1;
  }
 
  /* free directory name and search handles */
  if (dirp->dirname != NULL) free (dirp->dirname);

#if defined(DIRENT_WIN32_INTERFACE)
  if (dirp->search_handle != INVALID_HANDLE_VALUE) {
    if (FindClose (dirp->search_handle) == FALSE) {
      /* Unknown error */
      retcode = -1;
      errno = EBADF;
    }
  }
#endif                     

  /* clear dirp structure to make sure that it cannot be used anymore*/
  memset (dirp, 0, sizeof (*dirp));
# if defined(DIRENT_WIN32_INTERFACE)
  dirp->search_handle = INVALID_HANDLE_VALUE;
# endif

  free (dirp);
  return retcode;
}


/*
 * <function name="rewinddir">
 * <intro>rewind directory stream to the beginning
 * <syntax>void rewinddir (DIR *dirp);
 *
 * <desc>Rewind directory stream to the beginning so that the next call of
 * readdir() returns the very first directory entry again.  However, note
 * that next call of readdir() may not return the same directory entry as it
 * did in first time.  The directory stream may have been affected by newly
 * created files.
 *
 * Almost every dirent implementation ensure that rewinddir will update
 * the directory stream to reflect any changes made to the directory entries
 * since the previous ``opendir'' or ``rewinddir'' call.  Keep an eye on
 * this if your program depends on the feature.  I know at least one dirent
 * implementation where you are required to close and re-open the stream to
 * see the changes.
 *
 * <ret>Returns nothing.  If something went wrong while rewinding, you will
 * notice it later when you try to retrieve the first directory entry.
 */
static void
rewinddir (DIR *dirp)
{   
  /* make sure that dirp is legal */
  assert (dirp != NULL);
  if (dirp == NULL) {
    errno = EBADF;
    return;
  }
  assert (dirp->dirname != NULL);
  
  /* close previous stream */
#if defined(DIRENT_WIN32_INTERFACE)
  if (dirp->search_handle != INVALID_HANDLE_VALUE) {
    if (FindClose (dirp->search_handle) == FALSE) {
      /* Unknown error */
      errno = EBADF;
    }
  }
#endif

  /* re-open previous stream */
  if (_initdir (dirp) == 0) {
    /* initialization failed but we cannot deal with error.  User will notice
     * error later when she tries to retrieve first directory enty. */
    /*EMPTY*/;
  }
}


/*
 * Open native directory stream object and retrieve first file.
 * Be sure to close previous stream before opening new one.
 */
static int
_initdir (DIR *dirp)
{ 
  assert (dirp != NULL);
  assert (dirp->dirname != NULL);
  dirp->dirent_filled = 0;

# if defined(DIRENT_WIN32_INTERFACE)
  /* Open stream and retrieve first file */
  dirp->search_handle = FindFirstFile (dirp->dirname, &dirp->current.data);
  if (dirp->search_handle == INVALID_HANDLE_VALUE) {
    /* something went wrong but we don't know what.  GetLastError() could
     * give us more information about the error, but then we should map
     * the error code into errno. */
    errno = ENOENT;
    return 0;
  }

# elif defined(DIRENT_MSDOS_INTERFACE)
  if (_dos_findfirst (dirp->dirname,
          _A_SUBDIR | _A_RDONLY | _A_ARCH | _A_SYSTEM | _A_HIDDEN,
          &dirp->current.data) != 0)
  {
    /* _dos_findfirst and findfirst will set errno to ENOENT when no 
     * more entries could be retrieved. */
    return 0;
  }
# endif

  /* initialize DIR and it's first entry */
  _setdirname (dirp);
  dirp->dirent_filled = 1;
  return 1;
}


/*
 * Return implementation dependent name of the current directory entry.
 */
static const char *
_getdirname (const struct dirent *dp)
{
#if defined(DIRENT_WIN32_INTERFACE)
  return dp->data.cFileName;
  
#elif defined(DIRENT_USE_FFBLK)
  return dp->data.ff_name;
  
#else
  return dp->data.name;
#endif  
}


/*
 * Copy name of implementation dependent directory entry to the d_name field.
 */
static void
_setdirname (struct DIR *dirp) {
  /* make sure that d_name is long enough */
  assert (strlen (_getdirname (&dirp->current)) <= NAME_MAX);
  
  strncpy (dirp->current.d_name,
      _getdirname (&dirp->current),
      NAME_MAX);
  dirp->current.d_name[NAME_MAX] = '\0'; /*char d_name[NAME_MAX+1]*/
}
  
# ifdef __cplusplus
}
# endif
# define NAMLEN(dp) ((int)(strlen((dp)->d_name)))

#else
# error "missing dirent interface"
#endif


#endif /*DIRENT_H*/