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// Copyright 2017 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.
#include "core/fpdfapi/parser/cpdf_read_validator.h"
#include <algorithm>
#include "third_party/base/logging.h"
namespace {
constexpr FX_FILESIZE kAlignBlockValue = 512;
FX_FILESIZE AlignDown(FX_FILESIZE offset) {
return offset > 0 ? (offset - offset % kAlignBlockValue) : 0;
}
FX_FILESIZE AlignUp(FX_FILESIZE offset) {
FX_SAFE_FILESIZE safe_result = AlignDown(offset);
safe_result += kAlignBlockValue;
if (safe_result.IsValid())
return safe_result.ValueOrDie();
return offset;
}
} // namespace
CPDF_ReadValidator::Session::Session(CPDF_ReadValidator* validator)
: validator_(validator) {
ASSERT(validator_);
saved_read_error_ = validator_->read_error_;
saved_has_unavailable_data_ = validator_->has_unavailable_data_;
validator_->ResetErrors();
}
CPDF_ReadValidator::Session::~Session() {
validator_->read_error_ |= saved_read_error_;
validator_->has_unavailable_data_ |= saved_has_unavailable_data_;
}
CPDF_ReadValidator::CPDF_ReadValidator(
const RetainPtr<IFX_SeekableReadStream>& file_read,
CPDF_DataAvail::FileAvail* file_avail)
: file_read_(file_read),
file_avail_(file_avail),
read_error_(false),
has_unavailable_data_(false),
whole_file_already_available_(false),
file_size_(file_read->GetSize()) {}
CPDF_ReadValidator::~CPDF_ReadValidator() {}
void CPDF_ReadValidator::ResetErrors() {
read_error_ = false;
has_unavailable_data_ = false;
}
bool CPDF_ReadValidator::ReadBlock(void* buffer,
FX_FILESIZE offset,
size_t size) {
FX_SAFE_FILESIZE end_offset = offset;
end_offset += size;
if (!end_offset.IsValid() || end_offset.ValueOrDie() > file_size_)
return false;
if (!CheckDataRangeAndRequestIfUnavailable(offset, size))
return false;
if (file_read_->ReadBlock(buffer, offset, size))
return true;
read_error_ = true;
ScheduleDownload(offset, size);
return false;
}
FX_FILESIZE CPDF_ReadValidator::GetSize() {
return file_size_;
}
void CPDF_ReadValidator::ScheduleDownload(FX_FILESIZE offset, size_t size) {
has_unavailable_data_ = true;
if (!hints_ || size == 0)
return;
const FX_FILESIZE start_segment_offset = AlignDown(offset);
FX_SAFE_FILESIZE end_segment_offset = offset;
end_segment_offset += size;
if (!end_segment_offset.IsValid()) {
NOTREACHED();
return;
}
end_segment_offset =
std::min(file_size_, AlignUp(end_segment_offset.ValueOrDie()));
FX_SAFE_SIZE_T segment_size = end_segment_offset;
segment_size -= start_segment_offset;
if (!segment_size.IsValid()) {
NOTREACHED();
return;
}
hints_->AddSegment(start_segment_offset, segment_size.ValueOrDie());
}
bool CPDF_ReadValidator::IsDataRangeAvailable(FX_FILESIZE offset,
size_t size) const {
return whole_file_already_available_ || !file_avail_ ||
file_avail_->IsDataAvail(offset, size);
}
bool CPDF_ReadValidator::IsWholeFileAvailable() {
const FX_SAFE_SIZE_T safe_size = file_size_;
whole_file_already_available_ =
whole_file_already_available_ ||
(safe_size.IsValid() ? IsDataRangeAvailable(0, safe_size.ValueOrDie())
: false);
return whole_file_already_available_;
}
bool CPDF_ReadValidator::CheckDataRangeAndRequestIfUnavailable(
FX_FILESIZE offset,
size_t size) {
if (IsDataRangeAvailable(offset, size))
return true;
ScheduleDownload(offset, size);
return false;
}
bool CPDF_ReadValidator::CheckWholeFileAndRequestIfUnavailable() {
if (IsWholeFileAvailable())
return true;
const FX_SAFE_SIZE_T safe_size = file_size_;
if (safe_size.IsValid())
ScheduleDownload(0, safe_size.ValueOrDie());
return false;
}
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