/* minigzip.c -- simulate gzip using the zlib compression library

 * Copyright (C) 1995-2006, 2010, 2011, 2016 Jean-loup Gailly

 * For conditions of distribution and use, see copyright notice in zlib.h

 */

/*

 * minigzip is a minimal implementation of the gzip utility. This is

 * only an example of using zlib and isn't meant to replace the

 * full-featured gzip. No attempt is made to deal with file systems

 * limiting names to 14 or 8+3 characters, etc... Error checking is

 * very limited. So use minigzip only for testing; use gzip for the

 * real thing.

 */

#include "zbuild.h"

#ifdef ZLIB_COMPAT

#  include "zlib.h"

#else

#  include "zlib-ng.h"

#endif

#include <stdio.h>

#include <assert.h>

#ifdef USE_MMAP

#  include <sys/types.h>

#  include <sys/mman.h>

#  include <sys/stat.h>

#endif

#if defined(_WIN32) || defined(__CYGWIN__)

#  include <fcntl.h>

#  include <io.h>

#  define SET_BINARY_MODE(file) setmode(fileno(file), O_BINARY)

#else

#  define SET_BINARY_MODE(file)

#endif

#if defined(_MSC_VER) && _MSC_VER < 1900

#  define snprintf _snprintf

#endif

#ifndef GZ_SUFFIX

#  define GZ_SUFFIX ".gz"

#endif

#define SUFFIX_LEN (sizeof(GZ_SUFFIX)-1)

#define BUFLEN      16384        /* read buffer size */

#define BUFLENW     (BUFLEN * 3) /* write buffer size */

#define MAX_NAME_LEN 1024

static const char *prog = "minigzip_fuzzer";

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

 * Display error message and exit

 */

static void error(const char *msg) {

    fprintf(stderr, "%s: %s\n", prog, msg);

    exit(1);

}

#ifdef USE_MMAP /* MMAP version, Miguel Albrecht <malbrech@eso.org> */

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

 * Try compressing the input file at once using mmap. Return Z_OK if

 * success, Z_ERRNO otherwise.

 */

static int gz_compress_mmap(FILE *in, gzFile out) {

    int err;

    int ifd = fileno(in);

    void *buf;      /* mmap'ed buffer for the entire input file */

    size_t buf_len; /* length of the input file */

    size_t len;

    struct stat sb;

    /* Determine the size of the file, needed for mmap: */

    if (fstat(ifd, &sb) < 0) return Z_ERRNO;

    /* Check size_t overflow */

    if (sb.st_size <= 0 || sb.st_size > PTRDIFF_MAX) return Z_ERRNO;

    buf_len = (size_t)sb.st_size;

    /* Now do the actual mmap: */

    buf = mmap(NULL, buf_len, PROT_READ, MAP_SHARED, ifd, (off_t)0);

    if (buf == MAP_FAILED) return Z_ERRNO;

    /* Compress the whole file at once: */

    len = PREFIX(gzfwrite)(buf, 1, buf_len, out);

    if (len != buf_len) error(PREFIX(gzerror)(out, &err));

    munmap(buf, buf_len);

    fclose(in);

    if (PREFIX(gzclose)(out) != Z_OK) error("failed gzclose");

    return Z_OK;

}

#endif /* USE_MMAP */

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

 * Compress input to output then close both files.

 */

static void gz_compress(FILE *in, gzFile out) {

    char buf[BUFLEN];

    int len;

    int err;

#ifdef USE_MMAP

    /* Try first compressing with mmap. If mmap fails (minigzip used in a

     * pipe), use the normal fread loop.

     */

    if (gz_compress_mmap(in, out) == Z_OK) return;

#endif

    /* Clear out the contents of buf before reading from the file to avoid

       MemorySanitizer: use-of-uninitialized-value warnings. */

    memset(buf, 0, sizeof(buf));

    for (;;) {

        len = (int)fread(buf, 1, sizeof(buf), in);

        if (ferror(in)) {

            perror("fread");

            exit(1);

        }

        if (len == 0) break;

        if (PREFIX(gzwrite)(out, buf, (unsigned)len) != len) error(PREFIX(gzerror)(out, &err));

    }

    fclose(in);

    if (PREFIX(gzclose)(out) != Z_OK) error("failed gzclose");

}

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

 * Uncompress input to output then close both files.

 */

static void gz_uncompress(gzFile in, FILE *out) {

    char buf[BUFLENW];

    int len;

    int err;

    for (;;) {

        len = PREFIX(gzread)(in, buf, sizeof(buf));

        if (len < 0) error (PREFIX(gzerror)(in, &err));

        if (len == 0) break;

        if ((int)fwrite(buf, 1, (unsigned)len, out) != len) {

            error("failed fwrite");

        }

    }

    if (fclose(out)) error("failed fclose");

    if (PREFIX(gzclose)(in) != Z_OK) error("failed gzclose");

}

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

 * Compress the given file: create a corresponding .gz file and remove the

 * original.

 */

static void file_compress(char *file, char *mode) {

    char outfile[MAX_NAME_LEN];

    FILE *in;

    gzFile out;

    if (strlen(file) + strlen(GZ_SUFFIX) >= sizeof(outfile)) {

        fprintf(stderr, "%s: filename too long\n", prog);

        exit(1);

    }

    snprintf(outfile, sizeof(outfile), "%s%s", file, GZ_SUFFIX);

    in = fopen(file, "rb");

    if (in == NULL) {

        perror(file);

        exit(1);

    }

    out = PREFIX(gzopen)(outfile, mode);

    if (out == NULL) {

        fprintf(stderr, "%s: can't gzopen %s\n", prog, outfile);

        exit(1);

    }

    gz_compress(in, out);

    unlink(file);

}

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

 * Uncompress the given file and remove the original.

 */

static void file_uncompress(char *file) {

    char buf[MAX_NAME_LEN];

    char *infile, *outfile;

    FILE *out;

    gzFile in;

    size_t len = strlen(file);

    if (len + strlen(GZ_SUFFIX) >= sizeof(buf)) {

        fprintf(stderr, "%s: filename too long\n", prog);

        exit(1);

    }

    snprintf(buf, sizeof(buf), "%s", file);

    if (len > SUFFIX_LEN && strcmp(file+len-SUFFIX_LEN, GZ_SUFFIX) == 0) {

        infile = file;

        outfile = buf;

        outfile[len-3] = '\0';

    } else {

        outfile = file;

        infile = buf;

        snprintf(buf + len, sizeof(buf) - len, "%s", GZ_SUFFIX);

    }

    in = PREFIX(gzopen)(infile, "rb");

    if (in == NULL) {

        fprintf(stderr, "%s: can't gzopen %s\n", prog, infile);

        exit(1);

    }

    out = fopen(outfile, "wb");

    if (out == NULL) {

        perror(file);

        exit(1);

    }

    gz_uncompress(in, out);

    unlink(infile);

}

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataLen) {

    char *inFileName = "minigzip_fuzzer.out";

    char *outFileName = "minigzip_fuzzer.out.gz";

    char outmode[20];

    FILE *in;

    char buf[BUFLEN];

    uint32_t offset = 0;

    /* Discard inputs larger than 1Mb. */

    static size_t kMaxSize = 1024 * 1024;

    if (dataLen < 1 || dataLen > kMaxSize)

        return 0;

    in = fopen(inFileName, "wb");

    if (fwrite(data, 1, (unsigned)dataLen, in) != dataLen)

        error("failed fwrite");

    if (fclose(in))

        error("failed fclose");

    memset(outmode, 0, sizeof(outmode));

    snprintf(outmode, sizeof(outmode), "%s", "wb");

    /* Compression level: [0..9]. */

    outmode[2] = '0' + (data[0] % 10);

    switch (data[dataLen-1] % 6) {

    default:

    case 0:

        outmode[3] = 0;

        break;

    case 1:

        /* compress with Z_FILTERED */

        outmode[3] = 'f';

        break;

    case 2:

        /* compress with Z_HUFFMAN_ONLY */

        outmode[3] = 'h';

        break;

    case 3:

        /* compress with Z_RLE */

        outmode[3] = 'R';

        break;

    case 4:

        /* compress with Z_FIXED */

        outmode[3] = 'F';

        break;

    case 5:

        /* direct */

        outmode[3] = 'T';

        break;

    }

    file_compress(inFileName, outmode);

    /* gzopen does not support reading in direct mode */

    if (outmode[3] == 'T')

        inFileName = outFileName;

    else

        file_uncompress(outFileName);

    /* Check that the uncompressed file matches the input data. */

    in = fopen(inFileName, "rb");

    if (in == NULL) {

        perror(inFileName);

        exit(1);

    }

    memset(buf, 0, sizeof(buf));

    for (;;) {

        int len = (int)fread(buf, 1, sizeof(buf), in);

        if (ferror(in)) {

            perror("fread");

            exit(1);

        }

        if (len == 0)

            break;

        int c = memcmp(data + offset, buf, len);

        assert(0 == c);

        Z_UNUSED(c); // in Release build, assert() is a no-op.

        offset += len;

    }

    if (fclose(in))

        error("failed fclose");

    /* This function must return 0. */

    return 0;

}