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/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkPDFConvertType1FontStream.h"
#include "SkTemplates.h"
#include "SkTo.h"
#include <ctype.h>
static bool parsePFBSection(const uint8_t** src, size_t* len, int sectionType,
size_t* size) {
// PFB sections have a two or six bytes header. 0x80 and a one byte
// section type followed by a four byte section length. Type one is
// an ASCII section (includes a length), type two is a binary section
// (includes a length) and type three is an EOF marker with no length.
const uint8_t* buf = *src;
if (*len < 2 || buf[0] != 0x80 || buf[1] != sectionType) {
return false;
} else if (buf[1] == 3) {
return true;
} else if (*len < 6) {
return false;
}
*size = (size_t)buf[2] | ((size_t)buf[3] << 8) | ((size_t)buf[4] << 16) |
((size_t)buf[5] << 24);
size_t consumed = *size + 6;
if (consumed > *len) {
return false;
}
*src = *src + consumed;
*len = *len - consumed;
return true;
}
static bool parsePFB(const uint8_t* src, size_t size, size_t* headerLen,
size_t* dataLen, size_t* trailerLen) {
const uint8_t* srcPtr = src;
size_t remaining = size;
return parsePFBSection(&srcPtr, &remaining, 1, headerLen) &&
parsePFBSection(&srcPtr, &remaining, 2, dataLen) &&
parsePFBSection(&srcPtr, &remaining, 1, trailerLen) &&
parsePFBSection(&srcPtr, &remaining, 3, nullptr);
}
/* The sections of a PFA file are implicitly defined. The body starts
* after the line containing "eexec," and the trailer starts with 512
* literal 0's followed by "cleartomark" (plus arbitrary white space).
*
* This function assumes that src is NUL terminated, but the NUL
* termination is not included in size.
*
*/
static bool parsePFA(const char* src, size_t size, size_t* headerLen,
size_t* hexDataLen, size_t* dataLen, size_t* trailerLen) {
const char* end = src + size;
const char* dataPos = strstr(src, "eexec");
if (!dataPos) {
return false;
}
dataPos += strlen("eexec");
while ((*dataPos == '\n' || *dataPos == '\r' || *dataPos == ' ') &&
dataPos < end) {
dataPos++;
}
*headerLen = dataPos - src;
const char* trailerPos = strstr(dataPos, "cleartomark");
if (!trailerPos) {
return false;
}
int zeroCount = 0;
for (trailerPos--; trailerPos > dataPos && zeroCount < 512; trailerPos--) {
if (*trailerPos == '\n' || *trailerPos == '\r' || *trailerPos == ' ') {
continue;
} else if (*trailerPos == '0') {
zeroCount++;
} else {
return false;
}
}
if (zeroCount != 512) {
return false;
}
*hexDataLen = trailerPos - src - *headerLen;
*trailerLen = size - *headerLen - *hexDataLen;
// Verify that the data section is hex encoded and count the bytes.
int nibbles = 0;
for (; dataPos < trailerPos; dataPos++) {
if (isspace(*dataPos)) {
continue;
}
if (!isxdigit(*dataPos)) {
return false;
}
nibbles++;
}
*dataLen = (nibbles + 1) / 2;
return true;
}
static int8_t hexToBin(uint8_t c) {
if (!isxdigit(c)) {
return -1;
} else if (c <= '9') {
return c - '0';
} else if (c <= 'F') {
return c - 'A' + 10;
} else if (c <= 'f') {
return c - 'a' + 10;
}
return -1;
}
sk_sp<SkData> SkPDFConvertType1FontStream(
std::unique_ptr<SkStreamAsset> srcStream, size_t* headerLen,
size_t* dataLen, size_t* trailerLen) {
size_t srcLen = srcStream ? srcStream->getLength() : 0;
SkASSERT(srcLen);
if (!srcLen) {
return nullptr;
}
// Flatten and Nul-terminate the source stream so that we can use
// strstr() to search it.
SkAutoTMalloc<uint8_t> sourceBuffer(SkToInt(srcLen + 1));
(void)srcStream->read(sourceBuffer.get(), srcLen);
sourceBuffer[SkToInt(srcLen)] = 0;
const uint8_t* src = sourceBuffer.get();
if (parsePFB(src, srcLen, headerLen, dataLen, trailerLen)) {
static const int kPFBSectionHeaderLength = 6;
const size_t length = *headerLen + *dataLen + *trailerLen;
SkASSERT(length > 0);
SkASSERT(length + (2 * kPFBSectionHeaderLength) <= srcLen);
sk_sp<SkData> data(SkData::MakeUninitialized(length));
const uint8_t* const srcHeader = src + kPFBSectionHeaderLength;
// There is a six-byte section header before header and data
// (but not trailer) that we're not going to copy.
const uint8_t* const srcData = srcHeader + *headerLen + kPFBSectionHeaderLength;
const uint8_t* const srcTrailer = srcData + *headerLen;
uint8_t* const resultHeader = (uint8_t*)data->writable_data();
uint8_t* const resultData = resultHeader + *headerLen;
uint8_t* const resultTrailer = resultData + *dataLen;
SkASSERT(resultTrailer + *trailerLen == resultHeader + length);
memcpy(resultHeader, srcHeader, *headerLen);
memcpy(resultData, srcData, *dataLen);
memcpy(resultTrailer, srcTrailer, *trailerLen);
return data;
}
// A PFA has to be converted for PDF.
size_t hexDataLen;
if (!parsePFA((const char*)src, srcLen, headerLen, &hexDataLen, dataLen,
trailerLen)) {
return nullptr;
}
const size_t length = *headerLen + *dataLen + *trailerLen;
SkASSERT(length > 0);
auto data = SkData::MakeUninitialized(length);
uint8_t* buffer = (uint8_t*)data->writable_data();
memcpy(buffer, src, *headerLen);
uint8_t* const resultData = &(buffer[*headerLen]);
const uint8_t* hexData = src + *headerLen;
const uint8_t* trailer = hexData + hexDataLen;
size_t outputOffset = 0;
uint8_t dataByte = 0; // To hush compiler.
bool highNibble = true;
for (; hexData < trailer; hexData++) {
int8_t curNibble = hexToBin(*hexData);
if (curNibble < 0) {
continue;
}
if (highNibble) {
dataByte = curNibble << 4;
highNibble = false;
} else {
dataByte |= curNibble;
highNibble = true;
resultData[outputOffset++] = dataByte;
}
}
if (!highNibble) {
resultData[outputOffset++] = dataByte;
}
SkASSERT(outputOffset == *dataLen);
uint8_t* const resultTrailer = &(buffer[SkToInt(*headerLen + outputOffset)]);
memcpy(resultTrailer, src + *headerLen + hexDataLen, *trailerLen);
return data;
}
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