/*
 * Copyright (c) 2004, Richard Levitte <richard@levitte.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <stddef.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>
#ifndef LPDIR_H
# include "LPdir.h"
#endif

/*
 * The POSIXly macro for the maximum number of characters in a file path is
 * NAME_MAX.  However, some operating systems use PATH_MAX instead.
 * Therefore, it seems natural to first check for PATH_MAX and use that, and
 * if it doesn't exist, use NAME_MAX.
 */
#if defined(PATH_MAX)
# define LP_ENTRY_SIZE PATH_MAX
#elif defined(NAME_MAX)
# define LP_ENTRY_SIZE NAME_MAX
#endif

/*
 * Of course, there's the possibility that neither PATH_MAX nor NAME_MAX
 * exist.  It's also possible that NAME_MAX exists but is define to a very
 * small value (HP-UX offers 14), so we need to check if we got a result, and
 * if it meets a minimum standard, and create or change it if not.
 */
#if !defined(LP_ENTRY_SIZE) || LP_ENTRY_SIZE<255
# undef LP_ENTRY_SIZE
# define LP_ENTRY_SIZE 255
#endif

struct LP_dir_context_st {
    DIR *dir;
    char entry_name[LP_ENTRY_SIZE + 1];
};

const char *LP_find_file(LP_DIR_CTX **ctx, const char *directory)
{
    struct dirent *direntry = NULL;

    if (ctx == NULL || directory == NULL) {
        errno = EINVAL;
        return 0;
    }

    errno = 0;
    if (*ctx == NULL) {
        *ctx = (LP_DIR_CTX *)malloc(sizeof(LP_DIR_CTX));
        if (*ctx == NULL) {
            errno = ENOMEM;
            return 0;
        }
        memset(*ctx, '\0', sizeof(LP_DIR_CTX));

        (*ctx)->dir = opendir(directory);
        if ((*ctx)->dir == NULL) {
            int save_errno = errno; /* Probably not needed, but I'm paranoid */
            free(*ctx);
            *ctx = NULL;
            errno = save_errno;
            return 0;
        }
    }

    direntry = readdir((*ctx)->dir);
    if (direntry == NULL) {
        return 0;
    }

    strncpy((*ctx)->entry_name, direntry->d_name,
            sizeof((*ctx)->entry_name) - 1);
    (*ctx)->entry_name[sizeof((*ctx)->entry_name) - 1] = '\0';
    return (*ctx)->entry_name;
}

int LP_find_file_end(LP_DIR_CTX **ctx)
{
    if (ctx != NULL && *ctx != NULL) {
        int ret = closedir((*ctx)->dir);

        free(*ctx);
        switch (ret) {
        case 0:
            return 1;
        case -1:
            return 0;
        default:
            break;
        }
    }
    errno = EINVAL;
    return 0;
}
