gecko-dev/mozglue/linker/SeekableZStream.cpp

271 lines
7.3 KiB
C++

/* 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 file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <algorithm>
#include "SeekableZStream.h"
#include "Logging.h"
#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif
#ifndef PAGE_MASK
#define PAGE_MASK (~ (PAGE_SIZE - 1))
#endif
bool
SeekableZStream::Init(const void *buf, size_t length)
{
const SeekableZStreamHeader *header = SeekableZStreamHeader::validate(buf);
if (!header) {
log("Not a seekable zstream");
return false;
}
buffer = reinterpret_cast<const unsigned char *>(buf);
totalSize = header->totalSize;
chunkSize = header->chunkSize;
lastChunkSize = header->lastChunkSize;
windowBits = header->windowBits;
dictionary.Init(buffer + sizeof(SeekableZStreamHeader), header->dictSize);
offsetTable.Init(buffer + sizeof(SeekableZStreamHeader) + header->dictSize,
header->nChunks);
filter = GetFilter(header->filter);
/* Sanity check */
if ((chunkSize == 0) ||
(chunkSize % PAGE_SIZE) ||
(chunkSize > 8 * PAGE_SIZE) ||
(offsetTable.numElements() < 1) ||
(lastChunkSize == 0) ||
(lastChunkSize > chunkSize) ||
(length < totalSize)) {
log("Malformed or broken seekable zstream");
return false;
}
return true;
}
bool
SeekableZStream::Decompress(void *where, size_t chunk, size_t length)
{
while (length) {
size_t len = std::min(length, static_cast<size_t>(chunkSize));
if (!DecompressChunk(where, chunk, len))
return false;
where = reinterpret_cast<unsigned char *>(where) + len;
length -= len;
chunk++;
}
return true;
}
bool
SeekableZStream::DecompressChunk(void *where, size_t chunk, size_t length)
{
if (chunk >= offsetTable.numElements()) {
log("DecompressChunk: chunk #%" PRIdSize " out of range [0-%" PRIdSize ")",
chunk, offsetTable.numElements());
return false;
}
bool isLastChunk = (chunk == offsetTable.numElements() - 1);
size_t chunkLen = isLastChunk ? lastChunkSize : chunkSize;
if (length == 0 || length > chunkLen)
length = chunkLen;
debug("DecompressChunk #%" PRIdSize " @%p (%" PRIdSize "/% " PRIdSize ")",
chunk, where, length, chunkLen);
z_stream zStream;
memset(&zStream, 0, sizeof(zStream));
zStream.avail_in = (isLastChunk ? totalSize : uint32_t(offsetTable[chunk + 1]))
- uint32_t(offsetTable[chunk]);
zStream.next_in = const_cast<Bytef *>(buffer + uint32_t(offsetTable[chunk]));
zStream.avail_out = length;
zStream.next_out = reinterpret_cast<Bytef *>(where);
/* Decompress chunk */
if (inflateInit2(&zStream, windowBits) != Z_OK) {
log("inflateInit failed: %s", zStream.msg);
return false;
}
if (dictionary && inflateSetDictionary(&zStream, dictionary,
dictionary.numElements()) != Z_OK) {
log("inflateSetDictionary failed: %s", zStream.msg);
return false;
}
if (inflate(&zStream, (length == chunkLen) ? Z_FINISH : Z_SYNC_FLUSH)
!= (length == chunkLen) ? Z_STREAM_END : Z_OK) {
log("inflate failed: %s", zStream.msg);
return false;
}
if (inflateEnd(&zStream) != Z_OK) {
log("inflateEnd failed: %s", zStream.msg);
return false;
}
if (filter)
filter(chunk * chunkSize, UNFILTER, (unsigned char *)where, chunkLen);
return true;
}
/* Branch/Call/Jump conversion filter for Thumb, derived from xz-utils
* by Igor Pavlov and Lasse Collin, published in the public domain */
static void
BCJ_Thumb_filter(off_t offset, SeekableZStream::FilterDirection dir,
unsigned char *buf, size_t size)
{
size_t i;
for (i = 0; i + 4 <= size; i += 2) {
if ((buf[i + 1] & 0xf8) == 0xf0 && (buf[i + 3] & 0xf8) == 0xf8) {
uint32_t src = (buf[i] << 11)
| ((buf[i + 1] & 0x07) << 19)
| buf[i + 2]
| ((buf[i + 3] & 0x07) << 8);
src <<= 1;
uint32_t dest;
if (dir == SeekableZStream::FILTER)
dest = offset + (uint32_t)(i) + 4 + src;
else
dest = src - (offset + (uint32_t)(i) + 4);
dest >>= 1;
buf[i] = dest >> 11;
buf[i + 1] = 0xf0 | ((dest >> 19) & 0x07);
buf[i + 2] = dest;
buf[i + 3] = 0xf8 | ((dest >> 8) & 0x07);
i += 2;
}
}
}
/* Branch/Call/Jump conversion filter for ARM, derived from xz-utils
* by Igor Pavlov and Lasse Collin, published in the public domain */
static void
BCJ_ARM_filter(off_t offset, SeekableZStream::FilterDirection dir,
unsigned char *buf, size_t size)
{
size_t i;
for (i = 0; i + 4 <= size; i += 4) {
if (buf[i + 3] == 0xeb) {
uint32_t src = buf[i]
| (buf[i + 1] << 8)
| (buf[i + 2] << 16);
src <<= 2;
uint32_t dest;
if (dir == SeekableZStream::FILTER)
dest = offset + (uint32_t)(i) + 8 + src;
else
dest = src - (offset + (uint32_t)(i) + 8);
dest >>= 2;
buf[i] = dest;
buf[i + 1] = dest >> 8;
buf[i + 2] = dest >> 16;
}
}
}
/* Branch/Call/Jump conversion filter for x86, derived from xz-utils
* by Igor Pavlov and Lasse Collin, published in the public domain */
#define Test86MSByte(b) ((b) == 0 || (b) == 0xff)
static void
BCJ_X86_filter(off_t offset, SeekableZStream::FilterDirection dir,
unsigned char *buf, size_t size)
{
static const bool MASK_TO_ALLOWED_STATUS[8] =
{ true, true, true, false, true, false, false, false };
static const uint32_t MASK_TO_BIT_NUMBER[8] =
{ 0, 1, 2, 2, 3, 3, 3, 3 };
uint32_t prev_mask = 0;
uint32_t prev_pos = 0;
for (size_t i = 0; i <= size - 5;) {
uint8_t b = buf[i];
if (b != 0xe8 && b != 0xe9) {
++i;
continue;
}
const uint32_t off = offset + (uint32_t)(i) - prev_pos;
prev_pos = offset + (uint32_t)(i);
if (off > 5) {
prev_mask = 0;
} else {
for (uint32_t i = 0; i < off; ++i) {
prev_mask &= 0x77;
prev_mask <<= 1;
}
}
b = buf[i + 4];
if (Test86MSByte(b) && MASK_TO_ALLOWED_STATUS[(prev_mask >> 1) & 0x7]
&& (prev_mask >> 1) < 0x10) {
uint32_t src = ((uint32_t)(b) << 24)
| ((uint32_t)(buf[i + 3]) << 16)
| ((uint32_t)(buf[i + 2]) << 8)
| (buf[i + 1]);
uint32_t dest;
while (true) {
if (dir == SeekableZStream::FILTER)
dest = src + (offset + (uint32_t)(i) + 5);
else
dest = src - (offset + (uint32_t)(i) + 5);
if (prev_mask == 0)
break;
const uint32_t i = MASK_TO_BIT_NUMBER[prev_mask >> 1];
b = (uint8_t)(dest >> (24 - i * 8));
if (!Test86MSByte(b))
break;
src = dest ^ ((1 << (32 - i * 8)) - 1);
}
buf[i + 4] = (uint8_t)(~(((dest >> 24) & 1) - 1));
buf[i + 3] = (uint8_t)(dest >> 16);
buf[i + 2] = (uint8_t)(dest >> 8);
buf[i + 1] = (uint8_t)(dest);
i += 5;
prev_mask = 0;
} else {
++i;
prev_mask |= 1;
if (Test86MSByte(b))
prev_mask |= 0x10;
}
}
}
SeekableZStream::ZStreamFilter
SeekableZStream::GetFilter(SeekableZStream::FilterId id)
{
switch (id) {
case BCJ_THUMB:
return BCJ_Thumb_filter;
case BCJ_ARM:
return BCJ_ARM_filter;
case BCJ_X86:
return BCJ_X86_filter;
default:
return NULL;
}
return NULL;
}