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