Source code
Revision control
Copy as Markdown
Other Tools
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "FormatZlib.h"
#include "BaseAlgorithms.h"
#include "mozilla/dom/CompressionStreamBinding.h"
#include "mozilla/dom/TransformStreamDefaultController.h"
namespace mozilla::dom::compression {
NS_IMPL_CYCLE_COLLECTION_INHERITED(ZLibCompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_IMPL_ADDREF_INHERITED(ZLibCompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_IMPL_RELEASE_INHERITED(ZLibCompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ZLibCompressionStreamAlgorithms)
NS_INTERFACE_MAP_END_INHERITING(TransformerAlgorithmsBase)
NS_IMPL_CYCLE_COLLECTION_INHERITED(ZLibDecompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_IMPL_ADDREF_INHERITED(ZLibDecompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_IMPL_RELEASE_INHERITED(ZLibDecompressionStreamAlgorithms,
TransformerAlgorithmsBase)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ZLibDecompressionStreamAlgorithms)
NS_INTERFACE_MAP_END_INHERITING(TransformerAlgorithmsBase)
inline uint8_t intoZLibFlush(Flush aFlush) {
switch (aFlush) {
case Flush::No: {
return Z_NO_FLUSH;
}
case Flush::Yes: {
return Z_FINISH;
}
default: {
MOZ_ASSERT_UNREACHABLE("Unknown flush mode");
return Z_NO_FLUSH;
}
}
}
// From the docs in
inline int8_t ZLibWindowBits(CompressionFormat format) {
switch (format) {
case CompressionFormat::Deflate:
// The windowBits parameter is the base two logarithm of the window size
// (the size of the history buffer). It should be in the range 8..15 for
// this version of the library. Larger values of this parameter result
// in better compression at the expense of memory usage.
return 15;
case CompressionFormat::Deflate_raw:
// windowBits can also be –8..–15 for raw deflate. In this case,
// -windowBits determines the window size.
return -15;
case CompressionFormat::Gzip:
// windowBits can also be greater than 15 for optional gzip encoding.
// Add 16 to windowBits to write a simple gzip header and trailer around
// the compressed data instead of a zlib wrapper.
return 31;
default:
MOZ_ASSERT_UNREACHABLE("Unknown compression format");
return 0;
}
}
Result<already_AddRefed<ZLibCompressionStreamAlgorithms>, nsresult>
ZLibCompressionStreamAlgorithms::Create(CompressionFormat format) {
RefPtr<ZLibCompressionStreamAlgorithms> alg =
new ZLibCompressionStreamAlgorithms();
MOZ_TRY(alg->Init(format));
return alg.forget();
}
[[nodiscard]] nsresult ZLibCompressionStreamAlgorithms::Init(
CompressionFormat format) {
int8_t err = deflateInit2(&mZStream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
ZLibWindowBits(format), 8 /* default memLevel */,
Z_DEFAULT_STRATEGY);
if (err == Z_MEM_ERROR) {
return NS_ERROR_OUT_OF_MEMORY;
}
MOZ_ASSERT(err == Z_OK);
return NS_OK;
}
// Shared by:
void ZLibCompressionStreamAlgorithms::Compress(
JSContext* aCx, Span<const uint8_t> aInput,
JS::MutableHandleVector<JSObject*> aOutput, Flush aFlush,
ErrorResult& aRv) {
mZStream.avail_in = aInput.Length();
mZStream.next_in = const_cast<uint8_t*>(aInput.Elements());
do {
static uint16_t kBufferSize = 16384;
UniquePtr<uint8_t[], JS::FreePolicy> buffer(
static_cast<uint8_t*>(JS_malloc(aCx, kBufferSize)));
if (!buffer) {
aRv.ThrowTypeError("Out of memory");
return;
}
mZStream.avail_out = kBufferSize;
mZStream.next_out = buffer.get();
int8_t err = deflate(&mZStream, intoZLibFlush(aFlush));
// From the manual: deflate() returns ...
switch (err) {
case Z_OK:
case Z_STREAM_END:
case Z_BUF_ERROR:
// * Z_OK if some progress has been made
// * Z_STREAM_END if all input has been consumed and all output has
// been produced (only when flush is set to Z_FINISH)
// * Z_BUF_ERROR if no progress is possible (for example avail_in or
// avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
// deflate() can be called again with more input and more output space
// to continue compressing.
//
// (But of course no input should be given after Z_FINISH)
break;
case Z_STREAM_ERROR:
default:
// * Z_STREAM_ERROR if the stream state was inconsistent
// (which is fatal)
MOZ_ASSERT_UNREACHABLE("Unexpected compression error code");
aRv.ThrowTypeError("Unexpected compression error");
return;
}
// Stream should end only when flushed, see above
// The reverse is not true as zlib may have big data to be flushed that is
// larger than the buffer size
MOZ_ASSERT_IF(err == Z_STREAM_END, aFlush == Flush::Yes);
// At this point we either exhausted the input or the output buffer
MOZ_ASSERT(!mZStream.avail_in || !mZStream.avail_out);
size_t written = kBufferSize - mZStream.avail_out;
if (!written) {
break;
}
// Step 3: If buffer is empty, return.
// (We'll implicitly return when the array is empty.)
// Step 4: Split buffer into one or more non-empty pieces and convert them
// into Uint8Arrays.
// (The buffer is 'split' by having a fixed sized buffer above.)
JS::Rooted<JSObject*> view(aCx, nsJSUtils::MoveBufferAsUint8Array(
aCx, written, std::move(buffer)));
if (!view || !aOutput.append(view)) {
JS_ClearPendingException(aCx);
aRv.ThrowTypeError("Out of memory");
return;
}
} while (mZStream.avail_out == 0);
// From the manual:
// If deflate returns with avail_out == 0, this function must be called
// again with the same value of the flush parameter and more output space
// (updated avail_out)
}
ZLibCompressionStreamAlgorithms::~ZLibCompressionStreamAlgorithms() {
deflateEnd(&mZStream);
};
Result<already_AddRefed<ZLibDecompressionStreamAlgorithms>, nsresult>
ZLibDecompressionStreamAlgorithms::Create(CompressionFormat format) {
RefPtr<ZLibDecompressionStreamAlgorithms> alg =
new ZLibDecompressionStreamAlgorithms();
MOZ_TRY(alg->Init(format));
return alg.forget();
}
[[nodiscard]] nsresult ZLibDecompressionStreamAlgorithms::Init(
CompressionFormat format) {
int8_t err = inflateInit2(&mZStream, ZLibWindowBits(format));
if (err == Z_MEM_ERROR) {
return NS_ERROR_OUT_OF_MEMORY;
}
MOZ_ASSERT(err == Z_OK);
return NS_OK;
}
// Shared by:
// All data errors throw TypeError by step 2: If this results in an error,
// then throw a TypeError.
bool ZLibDecompressionStreamAlgorithms::Decompress(
JSContext* aCx, Span<const uint8_t> aInput,
JS::MutableHandleVector<JSObject*> aOutput, Flush aFlush,
ErrorResult& aRv) {
mZStream.avail_in = aInput.Length();
mZStream.next_in = const_cast<uint8_t*>(aInput.Elements());
do {
UniquePtr<uint8_t[], JS::FreePolicy> buffer(
static_cast<uint8_t*>(JS_malloc(aCx, kBufferSize)));
if (!buffer) {
aRv.ThrowTypeError("Out of memory");
return false;
}
mZStream.avail_out = kBufferSize;
mZStream.next_out = buffer.get();
int8_t err = inflate(&mZStream, intoZLibFlush(aFlush));
// From the manual: inflate() returns ...
switch (err) {
case Z_DATA_ERROR:
// Z_DATA_ERROR if the input data was corrupted (input stream not
// conforming to the zlib format or incorrect check value, in which
// case strm->msg points to a string with a more specific error)
aRv.ThrowTypeError("The input data is corrupted: "_ns +
nsDependentCString(mZStream.msg));
return false;
case Z_MEM_ERROR:
// Z_MEM_ERROR if there was not enough memory
aRv.ThrowTypeError("Out of memory");
return false;
case Z_NEED_DICT:
// Z_NEED_DICT if a preset dictionary is needed at this point
//
// From the `deflate` section of
// * The FDICT flag is not supported by these APIs, and will error the
// stream if set.
// And FDICT means preset dictionary per
aRv.ThrowTypeError(
"The stream needs a preset dictionary but such setup is "
"unsupported");
return false;
case Z_STREAM_END:
// Z_STREAM_END if the end of the compressed data has been reached and
// all uncompressed output has been produced
//
// conditions for each compression format when additional input comes
// after stream end.
// Note that additional calls for inflate() immediately emits
// Z_STREAM_END after this point.
mObservedStreamEnd = true;
break;
case Z_OK:
case Z_BUF_ERROR:
// * Z_OK if some progress has been made
// * Z_BUF_ERROR if no progress was possible or if there was not
// enough room in the output buffer when Z_FINISH is used. Note that
// Z_BUF_ERROR is not fatal, and inflate() can be called again with
// more input and more output space to continue decompressing.
//
// (But of course no input should be given after Z_FINISH)
break;
case Z_STREAM_ERROR:
default:
// * Z_STREAM_ERROR if the stream state was inconsistent
// (which is fatal)
MOZ_ASSERT_UNREACHABLE("Unexpected decompression error code");
aRv.ThrowTypeError("Unexpected decompression error");
return false;
}
// At this point we either exhausted the input or the output buffer, or
// met the stream end.
MOZ_ASSERT(!mZStream.avail_in || !mZStream.avail_out || mObservedStreamEnd);
size_t written = kBufferSize - mZStream.avail_out;
if (!written) {
break;
}
// Step 3: If buffer is empty, return.
// (We'll implicitly return when the array is empty.)
// Step 4: Split buffer into one or more non-empty pieces and convert them
// into Uint8Arrays.
// (The buffer is 'split' by having a fixed sized buffer above.)
JS::Rooted<JSObject*> view(aCx, nsJSUtils::MoveBufferAsUint8Array(
aCx, written, std::move(buffer)));
if (!view || !aOutput.append(view)) {
JS_ClearPendingException(aCx);
aRv.ThrowTypeError("Out of memory");
return false;
}
} while (mZStream.avail_out == 0 && !mObservedStreamEnd);
// From the manual:
// * It must update next_out and avail_out when avail_out has dropped to
// zero.
// * inflate() should normally be called until it returns Z_STREAM_END or an
// error.
return mZStream.avail_in == 0;
}
ZLibDecompressionStreamAlgorithms::~ZLibDecompressionStreamAlgorithms() {
inflateEnd(&mZStream);
}
} // namespace mozilla::dom::compression