/*
 * dirent.c
 *
 * 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>
 *
 * Martin Otter, 2001/01/06:
 *   - Call to "GetFileAttributes" and "#include <windows.h>"
 *     replaced by call to "_stat" because this is part of libc.a
 *   - If no more file found, _findnext sets errno.
 *     Since this is not an error, errno is reset to zero.
 *     (otherwise the calling routine cannot check, whether an error
 *     occurred within this function)
 *   - Initializing the search with findfirst is moved from "readdir"
 *     to "opendir", in order that in the calling function the
 *     current directory can be changed after "opendir".
 */

#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <io.h>
#include <direct.h>
#include <sys/types.h>
#include <sys/stat.h>

#include "win32_dirent.h"
#define SUFFIX "*"
#define  SLASH "\\"

/*
 * opendir
 *
 * Returns a pointer to a DIR structure appropriately filled in to begin
 * searching a directory.
 */
DIR *
opendir (const char *szPath)
{
    DIR *nd;

    errno = 0;

    if (!szPath)
    {
        errno = EFAULT;
        return (DIR *) 0;
    }

    if (szPath[0] == '\0')
    {
        errno = ENOTDIR;
        return (DIR *) 0;
    }

    /* Attempt to determine if the given path really is a directory. */
    {
#if defined(_MSC_VER)
        struct _stat fileInfo;
        if ( _stat(szPath, &fileInfo) != 0 ) {
#else
        struct stat fileInfo;
        if ( stat(szPath, &fileInfo) != 0 ) {
#endif
            /* call GetLastError for more error info */
            errno = ENOENT;
            return (DIR *) 0;
        }

        if ( !(fileInfo.st_mode & S_IFDIR) ) {
            /* Error, entry exists but not a directory. */
            errno = ENOTDIR;
            return (DIR *) 0;
        }
    }

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

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

    /* Create the search expression. */
    strcpy (nd->dd_name, szPath);

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

    /* Add on the search pattern */
    strcat (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;
    nd->dd_dir.d_name = nd->dd_dta.name;

    /* Start the search, in order that the user may still
       change the current directory afterwards
    */
    nd->dd_handle = (find_t)_findfirst (nd->dd_name, &(nd->dd_dta));
    if (nd->dd_handle == -1) {
        /* Whoops! Seems there are no files in that
         * directory. */
        nd->dd_stat = -1;
    } else {
        nd->dd_stat = 1;
    }

    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_dir.d_name != dirp->dd_dta.name)
    {
        /* The structure does not seem to be set up correctly. */
        errno = EINVAL;
        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
    {
        /* Get the next search entry. */
        if (_findnext (dirp->dd_handle, &(dirp->dd_dta)))
        {
            /* We are off the end */
            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 = (unsigned short)strlen (dirp->dd_dir.d_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))
            ;
    }
}
