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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <cups/cups.h>
#include <utility>
#include "base/functional/callback.h"
#include "base/logging.h"
#include "base/no_destructor.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/task_traits.h"
#include "base/task/thread_pool.h"
#include "base/threading/scoped_blocking_call.h"
#include "chrome/browser/chromeos/printing/cups_wrapper.h"
#include "printing/backend/cups_printer.h"
#include "url/gurl.h"
namespace chromeos {
namespace {
CupsWrapper::CupsWrapperFactory& GetCupsWrapperFactoryForTesting() {
static base::NoDestructor<CupsWrapper::CupsWrapperFactory>
factory_for_testing;
return *factory_for_testing;
}
} // namespace
// A wrapper around the CUPS connection to ensure that it's always accessed on
// the same sequence and run in the appropriate sequence off of the calling
// sequence.
class CupsWrapperImpl : public CupsWrapper {
public:
CupsWrapperImpl()
: backend_(std::make_unique<Backend>()),
backend_task_runner_(base::ThreadPool::CreateSequencedTaskRunner(
{base::MayBlock(), base::TaskPriority::BEST_EFFORT,
base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN})) {}
~CupsWrapperImpl() override {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
backend_task_runner_->DeleteSoon(FROM_HERE, backend_.release());
}
CupsWrapperImpl(const CupsWrapperImpl&) = delete;
CupsWrapperImpl& operator=(const CupsWrapperImpl&) = delete;
// CupsWrapper:
void QueryCupsPrintJobs(
const std::vector<std::string>& printer_ids,
base::OnceCallback<void(std::unique_ptr<CupsWrapperImpl::QueryResult>)>
callback) override {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// It's safe to pass unretained pointer here because we delete |backend_| on
// the same task runner.
backend_task_runner_->PostTaskAndReplyWithResult(
FROM_HERE,
base::BindOnce(&Backend::QueryCupsPrintJobs,
base::Unretained(backend_.get()), printer_ids),
std::move(callback));
}
void CancelJob(const std::string& printer_id, int job_id) override {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// It's safe to pass unretained pointer here because we delete |backend_| on
// the same task runner.
backend_task_runner_->PostTask(
FROM_HERE,
base::BindOnce(&Backend::CancelJob, base::Unretained(backend_.get()),
printer_id, job_id));
}
void QueryCupsPrinterStatus(
const std::string& printer_id,
base::OnceCallback<void(std::unique_ptr<::printing::PrinterStatus>)>
callback) override {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// It's safe to pass unretained pointer here because we delete |backend_| on
// the same task runner.
backend_task_runner_->PostTaskAndReplyWithResult(
FROM_HERE,
base::BindOnce(&Backend::QueryCupsPrinterStatus,
base::Unretained(backend_.get()), printer_id),
std::move(callback));
}
private:
class Backend {
public:
Backend() : cups_connection_(::printing::CupsConnection::Create()) {
DETACH_FROM_SEQUENCE(sequence_checker_);
}
~Backend() { DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); }
Backend(const Backend&) = delete;
Backend& operator=(const Backend&) = delete;
std::unique_ptr<QueryResult> QueryCupsPrintJobs(
const std::vector<std::string>& printer_ids) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
auto result = std::make_unique<CupsWrapperImpl::QueryResult>();
base::ScopedBlockingCall scoped_blocking_call(
FROM_HERE, base::BlockingType::MAY_BLOCK);
result->success = cups_connection_->GetJobs(printer_ids, &result->queues);
return result;
}
void CancelJob(const std::string& printer_id, int job_id) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::ScopedBlockingCall scoped_blocking_call(
FROM_HERE, base::BlockingType::MAY_BLOCK);
std::unique_ptr<::printing::CupsPrinter> printer =
cups_connection_->GetPrinter(printer_id);
if (!printer) {
LOG(WARNING) << "Printer not found: " << printer_id;
return;
}
if (!printer->CancelJob(job_id)) {
// This is not expected to fail but log it if it does.
LOG(WARNING) << "Cancelling job failed. Job may be stuck in queue.";
}
}
std::unique_ptr<::printing::PrinterStatus> QueryCupsPrinterStatus(
const std::string& printer_id) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
auto result = std::make_unique<::printing::PrinterStatus>();
base::ScopedBlockingCall scoped_blocking_call(
FROM_HERE, base::BlockingType::MAY_BLOCK);
if (!cups_connection_->GetPrinterStatus(printer_id, result.get()))
return nullptr;
return result;
}
private:
std::unique_ptr<::printing::CupsConnection> cups_connection_;
SEQUENCE_CHECKER(sequence_checker_);
};
// The |backend_| handles all communication with CUPS.
// It is instantiated on the thread |this| runs on but after that,
// must only be accessed and eventually destroyed via the
// |backend_task_runner_|.
std::unique_ptr<Backend> backend_;
scoped_refptr<base::SequencedTaskRunner> backend_task_runner_;
SEQUENCE_CHECKER(sequence_checker_);
};
// static
std::unique_ptr<CupsWrapper> CupsWrapper::Create() {
if (auto& testing_factory = GetCupsWrapperFactoryForTesting()) {
return testing_factory.Run();
}
return std::make_unique<CupsWrapperImpl>();
}
// static
void CupsWrapper::SetCupsWrapperFactoryForTesting(CupsWrapperFactory factory) {
GetCupsWrapperFactoryForTesting() = std::move(factory);
}
} // namespace chromeos
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