#include "zbuild.h"

#include <assert.h>

#include <inttypes.h>

#ifdef ZLIB_COMPAT

#  include "zlib.h"

#else

#  include "zlib-ng.h"

#endif

#define CHECK_ERR(err, msg) { \

    if (err != Z_OK) { \

        fprintf(stderr, "%s error: %d\n", msg, err); \

        exit(1); \

    } \

}

static alloc_func zalloc = NULL;

static free_func zfree = NULL;

static unsigned int diff;

/* ===========================================================================

 * Test deflate() with large buffers and dynamic change of compression level

 */

void test_large_deflate(unsigned char *compr, size_t comprLen, unsigned char *uncompr, size_t uncomprLen) {

    PREFIX3(stream) c_stream; /* compression stream */

    int err;

    c_stream.zalloc = zalloc;

    c_stream.zfree = zfree;

    c_stream.opaque = (void *)0;

    err = PREFIX(deflateInit)(&c_stream, Z_BEST_COMPRESSION);

    CHECK_ERR(err, "deflateInit");

    c_stream.next_out = compr;

    c_stream.avail_out = (unsigned int)comprLen;

    /* At this point, uncompr is still mostly zeroes, so it should compress

     * very well:

     */

    c_stream.next_in = uncompr;

    c_stream.avail_in = (unsigned int)uncomprLen;

    err = PREFIX(deflate)(&c_stream, Z_NO_FLUSH);

    CHECK_ERR(err, "deflate large 1");

    if (c_stream.avail_in != 0) {

        fprintf(stderr, "deflate not greedy\n");

        exit(1);

    }

    /* Feed in already compressed data and switch to no compression: */

    PREFIX(deflateParams)(&c_stream, Z_NO_COMPRESSION, Z_DEFAULT_STRATEGY);

    c_stream.next_in = compr;

    diff = (unsigned int)(c_stream.next_out - compr);

    c_stream.avail_in = diff;

    err = PREFIX(deflate)(&c_stream, Z_NO_FLUSH);

    CHECK_ERR(err, "deflate large 2");

    /* Switch back to compressing mode: */

    PREFIX(deflateParams)(&c_stream, Z_BEST_COMPRESSION, Z_FILTERED);

    c_stream.next_in = uncompr;

    c_stream.avail_in = (unsigned int)uncomprLen;

    err = PREFIX(deflate)(&c_stream, Z_NO_FLUSH);

    CHECK_ERR(err, "deflate large 3");

    err = PREFIX(deflate)(&c_stream, Z_FINISH);

    if (err != Z_STREAM_END) {

        fprintf(stderr, "deflate large should report Z_STREAM_END\n");

        exit(1);

    }

    err = PREFIX(deflateEnd)(&c_stream);

    CHECK_ERR(err, "deflateEnd");

}

/* ===========================================================================

 * Test inflate() with large buffers

 */

void test_large_inflate(unsigned char *compr, size_t comprLen, unsigned char *uncompr, size_t uncomprLen) {

    int err;

    PREFIX3(stream) d_stream; /* decompression stream */

    d_stream.zalloc = zalloc;

    d_stream.zfree = zfree;

    d_stream.opaque = (void *)0;

    d_stream.next_in = compr;

    d_stream.avail_in = (unsigned int)comprLen;

    err = PREFIX(inflateInit)(&d_stream);

    CHECK_ERR(err, "inflateInit");

    for (;;) {

        d_stream.next_out = uncompr; /* discard the output */

        d_stream.avail_out = (unsigned int)uncomprLen;

        err = PREFIX(inflate)(&d_stream, Z_NO_FLUSH);

        if (err == Z_STREAM_END)

            break;

        CHECK_ERR(err, "large inflate");

    }

    err = PREFIX(inflateEnd)(&d_stream);

    CHECK_ERR(err, "inflateEnd");

    if (d_stream.total_out != 2 * uncomprLen + diff) {

        fprintf(stderr, "bad large inflate: %" PRIu64 "\n", (uint64_t)d_stream.total_out);

        exit(1);

    }

}

int LLVMFuzzerTestOneInput(const uint8_t *d, size_t size) {

    Z_UNUSED(d);

    size_t comprLen = 100 + 3 * size;

    size_t uncomprLen = comprLen;

    uint8_t *compr, *uncompr;

    /* Discard inputs larger than 512Kb. */

    static size_t kMaxSize = 512 * 1024;

    if (size < 1 || size > kMaxSize)

        return 0;

    compr = (uint8_t *)calloc(1, comprLen);

    uncompr = (uint8_t *)calloc(1, uncomprLen);

    test_large_deflate(compr, comprLen, uncompr, uncomprLen);

    test_large_inflate(compr, comprLen, uncompr, uncomprLen);

    free(compr);

    free(uncompr);

    /* This function must return 0. */

    return 0;

}