michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  * vim: set ts=8 sts=4 et sw=4 tw=99:
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "vm/Compression.h"
michael@0: 
michael@0: #include "js/Utility.h"
michael@0: 
michael@0: using namespace js;
michael@0: 
michael@0: #if USE_ZLIB
michael@0: static void *
michael@0: zlib_alloc(void *cx, uInt items, uInt size)
michael@0: {
michael@0:     return js_calloc(items, size);
michael@0: }
michael@0: 
michael@0: static void
michael@0: zlib_free(void *cx, void *addr)
michael@0: {
michael@0:     js_free(addr);
michael@0: }
michael@0: 
michael@0: Compressor::Compressor(const unsigned char *inp, size_t inplen)
michael@0:     : inp(inp),
michael@0:       inplen(inplen),
michael@0:       outbytes(0),
michael@0:       initialized(false)
michael@0: {
michael@0:     JS_ASSERT(inplen > 0);
michael@0:     zs.opaque = nullptr;
michael@0:     zs.next_in = (Bytef *)inp;
michael@0:     zs.avail_in = 0;
michael@0:     zs.next_out = nullptr;
michael@0:     zs.avail_out = 0;
michael@0:     zs.zalloc = zlib_alloc;
michael@0:     zs.zfree = zlib_free;
michael@0: }
michael@0: 
michael@0: 
michael@0: Compressor::~Compressor()
michael@0: {
michael@0:     if (initialized) {
michael@0:         int ret = deflateEnd(&zs);
michael@0:         if (ret != Z_OK) {
michael@0:             // If we finished early, we can get a Z_DATA_ERROR.
michael@0:             JS_ASSERT(ret == Z_DATA_ERROR);
michael@0:             JS_ASSERT(uInt(zs.next_in - inp) < inplen || !zs.avail_out);
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: bool
michael@0: Compressor::init()
michael@0: {
michael@0:     if (inplen >= UINT32_MAX)
michael@0:         return false;
michael@0:     // zlib is slow and we'd rather be done compression sooner
michael@0:     // even if it means decompression is slower which penalizes
michael@0:     // Function.toString()
michael@0:     int ret = deflateInit(&zs, Z_BEST_SPEED);
michael@0:     if (ret != Z_OK) {
michael@0:         JS_ASSERT(ret == Z_MEM_ERROR);
michael@0:         return false;
michael@0:     }
michael@0:     initialized = true;
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: void
michael@0: Compressor::setOutput(unsigned char *out, size_t outlen)
michael@0: {
michael@0:     JS_ASSERT(outlen > outbytes);
michael@0:     zs.next_out = out + outbytes;
michael@0:     zs.avail_out = outlen - outbytes;
michael@0: }
michael@0: 
michael@0: Compressor::Status
michael@0: Compressor::compressMore()
michael@0: {
michael@0:     JS_ASSERT(zs.next_out);
michael@0:     uInt left = inplen - (zs.next_in - inp);
michael@0:     bool done = left <= CHUNKSIZE;
michael@0:     if (done)
michael@0:         zs.avail_in = left;
michael@0:     else if (zs.avail_in == 0)
michael@0:         zs.avail_in = CHUNKSIZE;
michael@0:     Bytef *oldout = zs.next_out;
michael@0:     int ret = deflate(&zs, done ? Z_FINISH : Z_NO_FLUSH);
michael@0:     outbytes += zs.next_out - oldout;
michael@0:     if (ret == Z_MEM_ERROR) {
michael@0:         zs.avail_out = 0;
michael@0:         return OOM;
michael@0:     }
michael@0:     if (ret == Z_BUF_ERROR || (done && ret == Z_OK)) {
michael@0:         JS_ASSERT(zs.avail_out == 0);
michael@0:         return MOREOUTPUT;
michael@0:     }
michael@0:     JS_ASSERT_IF(!done, ret == Z_OK);
michael@0:     JS_ASSERT_IF(done, ret == Z_STREAM_END);
michael@0:     return done ? DONE : CONTINUE;
michael@0: }
michael@0: 
michael@0: bool
michael@0: js::DecompressString(const unsigned char *inp, size_t inplen, unsigned char *out, size_t outlen)
michael@0: {
michael@0:     JS_ASSERT(inplen <= UINT32_MAX);
michael@0:     z_stream zs;
michael@0:     zs.zalloc = zlib_alloc;
michael@0:     zs.zfree = zlib_free;
michael@0:     zs.opaque = nullptr;
michael@0:     zs.next_in = (Bytef *)inp;
michael@0:     zs.avail_in = inplen;
michael@0:     zs.next_out = out;
michael@0:     JS_ASSERT(outlen);
michael@0:     zs.avail_out = outlen;
michael@0:     int ret = inflateInit(&zs);
michael@0:     if (ret != Z_OK) {
michael@0:         JS_ASSERT(ret == Z_MEM_ERROR);
michael@0:         return false;
michael@0:     }
michael@0:     ret = inflate(&zs, Z_FINISH);
michael@0:     JS_ASSERT(ret == Z_STREAM_END);
michael@0:     ret = inflateEnd(&zs);
michael@0:     JS_ASSERT(ret == Z_OK);
michael@0:     return true;
michael@0: }
michael@0: #endif /* USE_ZLIB */
michael@0: