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/*
* Copyright (c) 2017 The WebRTC 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 "modules/desktop_capture/screen_drawer_lock_posix.h"
#include <fcntl.h>
#include <sys/stat.h>
#include "absl/strings/string_view.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
namespace webrtc {
namespace {
// A uuid as the name of semaphore.
static constexpr char kSemaphoreName[] = "GSDL54fe5552804711e6a7253f429a";
} // namespace
ScreenDrawerLockPosix::ScreenDrawerLockPosix()
: ScreenDrawerLockPosix(kSemaphoreName) {}
ScreenDrawerLockPosix::ScreenDrawerLockPosix(const char* name) {
semaphore_ = sem_open(name, O_CREAT, S_IRWXU | S_IRWXG | S_IRWXO, 1);
if (semaphore_ == SEM_FAILED) {
RTC_LOG_ERRNO(LS_ERROR) << "Failed to create named semaphore with " << name;
RTC_DCHECK_NOTREACHED();
}
sem_wait(semaphore_);
}
ScreenDrawerLockPosix::~ScreenDrawerLockPosix() {
if (semaphore_ == SEM_FAILED) {
return;
}
sem_post(semaphore_);
sem_close(semaphore_);
// sem_unlink a named semaphore won't wait until other clients to release the
// sem_t. So if a new process starts, it will sem_open a different kernel
// object with the same name and eventually breaks the cross-process lock.
}
// static
void ScreenDrawerLockPosix::Unlink(absl::string_view name) {
sem_unlink(std::string(name).c_str());
}
} // namespace webrtc
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