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// Copyright (c) 2016 The WebM project authors. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
#include "webm/file_reader.h"
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <limits>
#include <memory>
#include "webm/status.h"
namespace webm {
FileReader::FileReader(FILE* file) : file_(file) { assert(file); }
FileReader::FileReader(FileReader&& other)
: file_(std::move(other.file_)), position_(other.position_) {
other.position_ = 0;
}
FileReader& FileReader::operator=(FileReader&& other) {
if (this != &other) {
file_ = std::move(other.file_);
position_ = other.position_;
other.position_ = 0;
}
return *this;
}
Status FileReader::Read(std::size_t num_to_read, std::uint8_t* buffer,
std::uint64_t* num_actually_read) {
assert(num_to_read > 0);
assert(buffer != nullptr);
assert(num_actually_read != nullptr);
if (file_ == nullptr) {
*num_actually_read = 0;
return Status(Status::kEndOfFile);
}
std::size_t actual =
std::fread(static_cast<void*>(buffer), 1, num_to_read, file_.get());
*num_actually_read = static_cast<std::uint64_t>(actual);
position_ += *num_actually_read;
if (actual == 0) {
return Status(Status::kEndOfFile);
}
if (actual == num_to_read) {
return Status(Status::kOkCompleted);
} else {
return Status(Status::kOkPartial);
}
}
Status FileReader::Skip(std::uint64_t num_to_skip,
std::uint64_t* num_actually_skipped) {
assert(num_to_skip > 0);
assert(num_actually_skipped != nullptr);
*num_actually_skipped = 0;
if (file_ == nullptr) {
return Status(Status::kEndOfFile);
}
// Try seeking forward first.
long seek_offset = std::numeric_limits<long>::max(); // NOLINT
if (num_to_skip < static_cast<unsigned long>(seek_offset)) { // NOLINT
seek_offset = static_cast<long>(num_to_skip); // NOLINT
}
// TODO(mjbshaw): Use fseeko64/_fseeki64 if available.
if (!std::fseek(file_.get(), seek_offset, SEEK_CUR)) {
*num_actually_skipped = static_cast<std::uint64_t>(seek_offset);
position_ += static_cast<std::uint64_t>(seek_offset);
if (static_cast<unsigned long>(seek_offset) == num_to_skip) { // NOLINT
return Status(Status::kOkCompleted);
} else {
return Status(Status::kOkPartial);
}
}
std::clearerr(file_.get());
// Seeking doesn't work on things like pipes, so if seeking failed then fall
// back to reading the data into a junk buffer.
std::size_t actual = 0;
do {
std::uint8_t junk[1024];
std::size_t num_to_read = sizeof(junk);
if (num_to_skip < num_to_read) {
num_to_read = static_cast<std::size_t>(num_to_skip);
}
std::size_t actual =
std::fread(static_cast<void*>(junk), 1, num_to_read, file_.get());
*num_actually_skipped += static_cast<std::uint64_t>(actual);
position_ += static_cast<std::uint64_t>(actual);
num_to_skip -= static_cast<std::uint64_t>(actual);
} while (actual > 0 && num_to_skip > 0);
if (*num_actually_skipped == 0) {
return Status(Status::kEndOfFile);
}
if (num_to_skip == 0) {
return Status(Status::kOkCompleted);
} else {
return Status(Status::kOkPartial);
}
}
std::uint64_t FileReader::Position() const { return position_; }
} // namespace webm
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