Function gzip_decompress

src/cli/cli.c:6096–6153

Decompress gzip data into a malloc'd buffer. Returns NULL on failure. * *out_total receives the decompressed size. Caller must free the result. */

/* Decompress gzip data into a malloc'd buffer. Returns NULL on failure.
 * *out_total receives the decompressed size. Caller must free the result. */
static unsigned char *gzip_decompress(const unsigned char *data, int data_len, size_t *out_total) {
    z_stream strm = {0};
    unsigned char *mutable_data;
    memcpy(&mutable_data, &data, sizeof(data));
    strm.next_in = mutable_data;
    strm.avail_in = (unsigned int)data_len;

    if (inflateInit2(&strm, 16 + MAX_WBITS) != Z_OK) {
        return NULL;
    }

    size_t buf_cap = (size_t)data_len * DECOMP_FACTOR;
    if (buf_cap < CLI_BUF_4K) {
        buf_cap = CLI_BUF_4K;
    }
    if (buf_cap > DECOMPRESS_MAX_BYTES) {
        buf_cap = DECOMPRESS_MAX_BYTES;
    }
    unsigned char *decompressed = malloc(buf_cap);
    if (!decompressed) {
        inflateEnd(&strm);
        return NULL;
    }

    size_t total = 0;
    int ret;
    do {
        if (total >= buf_cap) {
            size_t new_cap = buf_cap * GROWTH_FACTOR;
            if (new_cap > DECOMPRESS_MAX_BYTES) {
                free(decompressed);
                inflateEnd(&strm);
                return NULL;
            }
            unsigned char *nb = realloc(decompressed, new_cap);
            if (!nb) {
                free(decompressed);
                inflateEnd(&strm);
                return NULL;
            }
            decompressed = nb;
            buf_cap = new_cap;
        }
        strm.next_out = decompressed + total;
        strm.avail_out = (unsigned int)(buf_cap - total);
        ret = inflate(&strm, Z_NO_FLUSH);
        total = buf_cap - strm.avail_out;
    } while (ret == Z_OK);

    inflateEnd(&strm);

    if (ret != Z_STREAM_END) {
        free(decompressed);
        return NULL;
    }
    *out_total = total;
    return decompressed;
}