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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/utility/media_galleries/pmp_column_reader.h"
#include <cstring>
#include "base/file_util.h"
#include "base/files/file.h"
#include "base/logging.h"
#include "base/threading/thread_restrictions.h"
namespace picasa {
namespace {
COMPILE_ASSERT(sizeof(double) == 8, double_must_be_8_bytes_long);
const int64 kPmpMaxFilesize = 50*1024*1024; // Arbitrary maximum of 50 MB.
} // namespace
PmpColumnReader::PmpColumnReader()
: length_(0),
field_type_(PMP_TYPE_INVALID),
rows_read_(0) {}
PmpColumnReader::~PmpColumnReader() {}
bool PmpColumnReader::ReadFile(base::File* file,
const PmpFieldType expected_type) {
DCHECK(!data_.get());
base::ThreadRestrictions::AssertIOAllowed();
if (!file->IsValid())
return false;
base::File::Info info;
if (!file->GetInfo(&info))
return false;
length_ = info.size;
if (length_ < kPmpHeaderSize || length_ > kPmpMaxFilesize)
return false;
data_.reset(new uint8[length_]);
char* data_begin = reinterpret_cast<char*>(data_.get());
DCHECK(length_ < kint32max); // ReadFile expects an int.
bool success = file->Read(0, data_begin, length_) &&
ParseData(expected_type);
// If any of the reading or parsing fails, prevent Read* calls.
if (!success)
rows_read_ = 0;
return success;
}
bool PmpColumnReader::ReadString(const uint32 row, std::string* result) const {
DCHECK(data_.get() != NULL);
if (field_type_ != PMP_TYPE_STRING || row >= rows_read_)
return false;
DCHECK_LT(row, strings_.size());
*result = strings_[row];
return true;
}
bool PmpColumnReader::ReadUInt32(const uint32 row, uint32* result) const {
DCHECK(data_.get() != NULL);
if (field_type_ != PMP_TYPE_UINT32 || row >= rows_read_)
return false;
*result = reinterpret_cast<uint32*>(data_.get() + kPmpHeaderSize)[row];
return true;
}
bool PmpColumnReader::ReadDouble64(const uint32 row, double* result) const {
DCHECK(data_.get() != NULL);
if (field_type_ != PMP_TYPE_DOUBLE64 || row >= rows_read_)
return false;
*result = reinterpret_cast<double*>(data_.get() + kPmpHeaderSize)[row];
return true;
}
bool PmpColumnReader::ReadUInt8(const uint32 row, uint8* result) const {
DCHECK(data_.get() != NULL);
if (field_type_ != PMP_TYPE_UINT8 || row >= rows_read_)
return false;
*result = reinterpret_cast<uint8*>(data_.get() + kPmpHeaderSize)[row];
return true;
}
bool PmpColumnReader::ReadUInt64(const uint32 row, uint64* result) const {
DCHECK(data_.get() != NULL);
if (field_type_ != PMP_TYPE_UINT64 || row >= rows_read_)
return false;
*result = reinterpret_cast<uint64*>(data_.get() + kPmpHeaderSize)[row];
return true;
}
uint32 PmpColumnReader::rows_read() const {
DCHECK(data_.get() != NULL);
return rows_read_;
}
bool PmpColumnReader::ParseData(const PmpFieldType expected_type) {
DCHECK(data_.get() != NULL);
DCHECK_GE(length_, kPmpHeaderSize);
// Check all magic bytes.
if (memcmp(&kPmpMagic1, &data_[kPmpMagic1Offset], sizeof(kPmpMagic1)) != 0 ||
memcmp(&kPmpMagic2, &data_[kPmpMagic2Offset], sizeof(kPmpMagic2)) != 0 ||
memcmp(&kPmpMagic3, &data_[kPmpMagic3Offset], sizeof(kPmpMagic3)) != 0 ||
memcmp(&kPmpMagic4, &data_[kPmpMagic4Offset], sizeof(kPmpMagic4)) != 0) {
return false;
}
uint16 field_type_data =
*(reinterpret_cast<uint16*>(&data_[kPmpFieldType1Offset]));
// Verify if field type matches second declaration
if (field_type_data !=
*(reinterpret_cast<uint16*>(&data_[kPmpFieldType2Offset]))) {
return false;
}
field_type_ = static_cast<PmpFieldType>(field_type_data);
if (field_type_ != expected_type)
return false;
rows_read_ = *(reinterpret_cast<uint32*>(&data_[kPmpRowCountOffset]));
// Sanity check against malicious row field.
if (rows_read_ > (kPmpMaxFilesize - kPmpHeaderSize))
return false;
DCHECK_GE(length_, kPmpHeaderSize);
int64 body_length = length_ - kPmpHeaderSize;
int64 expected_body_length = 0;
switch (field_type_) {
case PMP_TYPE_STRING:
expected_body_length = IndexStrings();
break;
case PMP_TYPE_UINT32:
expected_body_length = static_cast<int64>(rows_read_) * sizeof(uint32);
break;
case PMP_TYPE_DOUBLE64:
expected_body_length = static_cast<int64>(rows_read_) * sizeof(double);
break;
case PMP_TYPE_UINT8:
expected_body_length = static_cast<int64>(rows_read_) * sizeof(uint8);
break;
case PMP_TYPE_UINT64:
expected_body_length = static_cast<int64>(rows_read_) * sizeof(uint64);
break;
default:
return false;
break;
}
return body_length == expected_body_length;
}
int64 PmpColumnReader::IndexStrings() {
DCHECK(data_.get() != NULL);
DCHECK_GE(length_, kPmpHeaderSize);
strings_.reserve(rows_read_);
int64 bytes_parsed = kPmpHeaderSize;
const uint8* data_cursor = data_.get() + kPmpHeaderSize;
while (strings_.size() < rows_read_) {
const uint8* string_end = static_cast<const uint8*>(
memchr(data_cursor, '\0', length_ - bytes_parsed));
// Fail if cannot find null termination. String runs on past file end.
if (string_end == NULL)
return -1;
// Length of string. (+1 to include the termination character).
ptrdiff_t length_in_bytes = string_end - data_cursor + 1;
strings_.push_back(reinterpret_cast<const char*>(data_cursor));
data_cursor += length_in_bytes;
bytes_parsed += length_in_bytes;
}
return bytes_parsed - kPmpHeaderSize;
}
} // namespace picasa
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