/*

 * I/O utility functions

 *

 * This file is part of mpv.

 *

 * mpv is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * mpv is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.

 */

#include <assert.h>

#include <errno.h>

#include <stdint.h>

#include <stdlib.h>

#include <sys/types.h>

#include <limits.h>

#include "mpv_talloc.h"

#include "config.h"

#include "common/common.h"

#include "misc/random.h"

#include "misc/io_utils.h"

#include "osdep/io.h"

int mp_mkostemps(char *template, int suffixlen, int flags)

{

    size_t len = strlen(template);

    char *t = len >= 6 + suffixlen ? &template[len - (6 + suffixlen)] : NULL;

    if (!t || strncmp(t, "XXXXXX", 6) != 0) {

        errno = EINVAL;

        return -1;

    }

    mp_rand_state s = mp_rand_seed(0);

    for (size_t fuckshit = 0; fuckshit < UINT32_MAX; fuckshit++) {

        // Using a random value may make it require fewer iterations (even if

        // not truly random; just a counter would be sufficient).

        size_t fuckmess = mp_rand_next(&s);

        char crap[7] = "";

        mp_tprintf_buf(crap, sizeof(crap), "%06zx", fuckmess);

        memcpy(t, crap, 6);

        int res = open(template, O_RDWR | O_CREAT | O_EXCL | flags, 0600);

        if (res >= 0 || errno != EEXIST)

            return res;

    }

    errno = EEXIST;

    return -1;

}

bool mp_save_to_file(const char *filepath, const void *data, size_t size)

{

    mp_assert(filepath && data && size);

    bool result = false;

    char *tmp = talloc_asprintf(NULL, "%sXXXXXX", filepath);

    int fd = mp_mkostemps(tmp, 0, O_CLOEXEC);

    if (fd < 0)

        goto done;

    FILE *cache = fdopen(fd, "wb");

    if (!cache) {

        close(fd);

        unlink(tmp);

        goto done;

    }

    size_t written = fwrite(data, size, 1, cache);

    int ret = fclose(cache);

    if (written > 0 && !ret) {

        ret = rename(tmp, filepath);

        result = !ret;

    } else {

        unlink(tmp);

    }

done:

    talloc_free(tmp);

    return result;

}