Add multi_process_lock to chrome/common

chrome/common/multi_process_lock_linux.cc

+// Copyright (c) 2010 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/common/multi_process_lock.h"
+
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "base/eintr_wrapper.h"
+#include "base/logging.h"
+
+class MultiProcessLockLinux : public MultiProcessLock {
+ public:
+  explicit MultiProcessLockLinux(const std::string& name)
+      : name_(name), fd_(-1), count_(0) { }
+
+  virtual ~MultiProcessLockLinux() {
+    if (count_ > 0) {
+      Unlock();
+    }
+  }
+
+  virtual bool TryLock() {
+    if (count_ > 0) {
+      count_ += 1;
+      return true;
+    }
+
+    struct sockaddr_un address;
+    // +2 because: 1 for terminator, and 1 for \0 at the front that makes
+    // this an abstract name port.
+    if (name_.length() + 2 > sizeof(address.sun_path)) {
+      DLOG(ERROR) << "Socket name too long " << name_;
+      return false;
+    }
+    memset(&address, 0, sizeof(address));
+    memcpy(&address.sun_path[1], name_.data(), name_.length());
+    address.sun_family = AF_LOCAL;
+    int socket_fd = socket(AF_LOCAL, SOCK_STREAM, 0);
+    if (socket_fd < 0) {
+      PLOG(ERROR) << "Couldn't create socket";
+      return false;
+    }
+    if (bind(socket_fd,
+             reinterpret_cast<sockaddr *>(&address),
+             sizeof(address)) == 0) {
+      fd_ = socket_fd;
+      count_ = 1;
+      return true;
+    } else {
+      NOTREACHED() << "Couldn't bind socket to " << address.sun_path;
+      HANDLE_EINTR(close(socket_fd));
+      return false;
+    }
+  }
+
+  virtual void Unlock() {
+    if (count_ == 0) {
+      DLOG(ERROR) << "Over unlocked MultiProcessLock " << name_;
+      return;
+    }
+    count_ -= 1;
+    if (count_ == 0) {
+      HANDLE_EINTR(close(fd_));
+      fd_ = -1;
+    }
+  }
+
+ private:
+  std::string name_;
+  int fd_;
+  int count_;
+  DISALLOW_COPY_AND_ASSIGN(MultiProcessLockLinux);
+};
+
+MultiProcessLock* MultiProcessLock::Create(const std::string &name) {
+  return new MultiProcessLockLinux(name);
+}