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// Copyright 2014 PDFium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
#include "core/fxcodec/lgif/fx_gif.h"
#include <algorithm>
#include <utility>
#include "core/fxcodec/lbmp/fx_bmp.h"
#include "core/fxcodec/lgif/cgifcontext.h"
#include "third_party/base/logging.h"
#include "third_party/base/ptr_util.h"
#include "third_party/base/stl_util.h"
static_assert(sizeof(GifImageInfo) == 9,
"GifImageInfo should have a size of 9");
static_assert(sizeof(GifPalette) == 3, "GifPalette should have a size of 3");
static_assert(sizeof(GifPTE) == 13, "GifPTE should have a size of 13");
static_assert(sizeof(GifGCE) == 5, "GifGCE should have a size of 5");
static_assert(sizeof(GifHeader) == 6, "GifHeader should have a size of 6");
static_assert(sizeof(GifLSD) == 7, "GifLSD should have a size of 7");
GifImage::GifImage() {}
GifImage::~GifImage() {}
void CGifLZWDecoder::Input(uint8_t* src_buf, uint32_t src_size) {
next_in = src_buf;
avail_in = src_size;
}
uint32_t CGifLZWDecoder::GetAvailInput() {
return avail_in;
}
CGifLZWDecoder::CGifLZWDecoder(char* error_ptr)
: code_size(0),
code_size_cur(0),
code_clear(0),
code_end(0),
code_next(0),
code_first(0),
stack_size(0),
code_old(0),
next_in(nullptr),
avail_in(0),
bits_left(0),
code_store(0),
err_msg_ptr(error_ptr) {}
CGifLZWDecoder::~CGifLZWDecoder() {}
void CGifLZWDecoder::InitTable(uint8_t color_exp, uint8_t code_exp) {
// TODO(rharrison): Refactor all of this, so that initializing the table with
// bad values will kill the decompress.
ASSERT(code_exp <= GIF_MAX_LZW_EXP);
code_color_end = std::min(2 << color_exp, 1 << code_exp);
code_size = code_exp;
code_clear = 1 << code_exp;
code_end = code_clear + 1;
bits_left = 0;
code_store = 0;
next_in = nullptr;
avail_in = 0;
stack_size = 0;
code_first = 0;
ClearTable();
}
void CGifLZWDecoder::ClearTable() {
code_size_cur = code_size + 1;
code_next = code_end + 1;
code_old = static_cast<uint16_t>(-1);
memset(code_table, 0, sizeof(tag_Table) * GIF_MAX_LZW_CODE);
memset(stack, 0, GIF_MAX_LZW_CODE);
for (uint16_t i = 0; i < code_clear; i++)
code_table[i].suffix = static_cast<uint8_t>(i);
}
bool CGifLZWDecoder::DecodeString(uint16_t code) {
stack_size = 0;
while (code >= code_clear && code <= code_next) {
if (code == code_table[code].prefix || stack_size == GIF_MAX_LZW_CODE - 1)
return false;
stack[GIF_MAX_LZW_CODE - 1 - stack_size++] = code_table[code].suffix;
code = code_table[code].prefix;
}
if (code >= code_color_end)
return false;
stack[GIF_MAX_LZW_CODE - 1 - stack_size++] = static_cast<uint8_t>(code);
code_first = static_cast<uint8_t>(code);
return true;
}
void CGifLZWDecoder::AddCode(uint16_t prefix_code, uint8_t append_char) {
if (code_next == GIF_MAX_LZW_CODE)
return;
code_table[code_next].prefix = prefix_code;
code_table[code_next].suffix = append_char;
if (++code_next < GIF_MAX_LZW_CODE) {
if (code_next >> code_size_cur)
code_size_cur++;
}
}
GifDecodeStatus CGifLZWDecoder::Decode(uint8_t* des_buf, uint32_t* des_size) {
if (*des_size == 0)
return GifDecodeStatus::InsufficientDestSize;
uint32_t i = 0;
if (stack_size != 0) {
if (*des_size < stack_size) {
memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], *des_size);
stack_size -= static_cast<uint16_t>(*des_size);
return GifDecodeStatus::InsufficientDestSize;
}
memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], stack_size);
des_buf += stack_size;
i += stack_size;
stack_size = 0;
}
ASSERT(err_msg_ptr);
while (i <= *des_size && (avail_in > 0 || bits_left >= code_size_cur)) {
if (code_size_cur > GIF_MAX_LZW_EXP) {
strncpy(err_msg_ptr, "Code Length Out Of Range", GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
if (avail_in > 0) {
if (bits_left > 31) {
strncpy(err_msg_ptr, "Decode Error", GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
pdfium::base::CheckedNumeric<uint32_t> safe_code = *next_in++;
safe_code <<= bits_left;
safe_code |= code_store;
if (!safe_code.IsValid()) {
strncpy(err_msg_ptr, "Code Store Out Of Range", GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
code_store = safe_code.ValueOrDie();
--avail_in;
bits_left += 8;
}
while (bits_left >= code_size_cur) {
uint16_t code =
static_cast<uint16_t>(code_store) & ((1 << code_size_cur) - 1);
code_store >>= code_size_cur;
bits_left -= code_size_cur;
if (code == code_clear) {
ClearTable();
continue;
}
if (code == code_end) {
*des_size = i;
return GifDecodeStatus::Success;
}
if (code_old != static_cast<uint16_t>(-1)) {
if (code_next < GIF_MAX_LZW_CODE) {
if (code == code_next) {
AddCode(code_old, code_first);
if (!DecodeString(code)) {
strncpy(err_msg_ptr, "String Decoding Error",
GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
} else if (code > code_next) {
strncpy(err_msg_ptr, "Decode Error, Out Of Range",
GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
} else {
if (!DecodeString(code)) {
strncpy(err_msg_ptr, "String Decoding Error",
GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
uint8_t append_char = stack[GIF_MAX_LZW_CODE - stack_size];
AddCode(code_old, append_char);
}
}
} else {
if (!DecodeString(code)) {
strncpy(err_msg_ptr, "String Decoding Error", GIF_MAX_ERROR_SIZE - 1);
return GifDecodeStatus::Error;
}
}
code_old = code;
if (i + stack_size > *des_size) {
memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], *des_size - i);
stack_size -= static_cast<uint16_t>(*des_size - i);
return GifDecodeStatus::InsufficientDestSize;
}
memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], stack_size);
des_buf += stack_size;
i += stack_size;
stack_size = 0;
}
}
if (avail_in == 0) {
*des_size = i;
return GifDecodeStatus::Unfinished;
}
return GifDecodeStatus::Error;
}
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