zlib.c

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/*
Copyright (C) 2012  Gregory Nietsky <gregory@distrotetch.co.za>
        http://www.distrotech.co.za

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <zlib.h>

#include "include/dtsapp.h"

static const unsigned char gzipMagicBytes[] = { 0x1f, 0x8b, 0x08, 0x00 };

static void zobj_free(void *data) {
    struct zobj *zdata = data;

    if (zdata->buff) {
        free(zdata->buff);
    }
}

extern struct zobj *zcompress(uint8_t *buff, uint16_t len, uint8_t level) {
    struct zobj *ret;

    if (!(ret = objalloc(sizeof(*ret), zobj_free))) {
        return (NULL);
    }

    ret->zlen = compressBound(len);
    ret->olen = len;

    if (!(ret->buff = malloc(ret->zlen))) {
        return (NULL);
    }
    compress2(ret->buff, (uLongf *)&ret->zlen, buff, len, level);

    return (ret);
}

extern void zuncompress(struct zobj *buff, uint8_t *obuff) {
    uLongf olen = buff->olen;

    if (!obuff) {
        return;
    }

    uncompress(obuff, &olen, buff->buff, buff->zlen);
}

extern int is_gzip(uint8_t *buf, int buf_size) {
    if (buf_size < 4) {
        return 0;
    }
    if (memcmp(buf, gzipMagicBytes, 4)) {
        return 0;
    }
    return 1;
}

extern uint8_t *gzinflatebuf(uint8_t *buf_in, int buf_size, uint32_t *len) {
    z_stream zdat;
    uint8_t *buf = NULL, *tmp;
    int res;

    zdat.opaque = NULL;
    zdat.zalloc = NULL;
    zdat.zfree = NULL;

    zdat.next_in = buf_in;
    zdat.avail_in = buf_size;
    zdat.next_out = buf;
    zdat.avail_out = 0;
    zdat.total_out = 0;

    if (inflateInit2(&zdat, 31)) {
        return NULL;
    }

    do {
        if (!(tmp = realloc(buf,zdat.total_out + (zdat.avail_in * 5) + 1))) {
            res = Z_MEM_ERROR;
            break;
        } else {
            buf = tmp;
        }
        buf[zdat.total_out] = '\0';
        zdat.next_out = &buf[zdat.total_out];
        zdat.avail_out += zdat.avail_in * 5;
    } while ((res = inflate(&zdat, Z_NO_FLUSH)) == Z_OK);

    if (res == Z_STREAM_END) {
        buf = realloc(buf, zdat.total_out);
        *len = zdat.total_out;
    } else {
        free(buf);
        *len = 0;
        buf = NULL;
    }
    inflateEnd(&zdat);

    return buf;
}