Update from https://crrev.com/302630

sandbox/linux/syscall_broker/broker_client.h

+// Copyright 2014 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.
+
+#ifndef SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_
+#define SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_
+
+#include "base/macros.h"
+#include "sandbox/linux/syscall_broker/broker_common.h"
+
+namespace sandbox {
+
+namespace syscall_broker {
+
+class BrokerPolicy;
+
+// This class can be embedded in a sandboxed process and can be
+// used to perform certain system calls in another, presumably
+// non-sandboxed process (which embeds BrokerHost).
+// A key feature of this class is the ability to use some of its methods in a
+// thread-safe and async-signal safe way. The goal is to be able to use it to
+// replace the open() or access() system calls happening anywhere in a process
+// (as allowed for instance by seccomp-bpf's SIGSYS mechanism).
+class BrokerClient {
+ public:
+  // |policy| needs to match the policy used by BrokerHost. This
+  // allows to predict some of the requests which will be denied
+  // and save an IPC round trip.
+  // |ipc_channel| needs to be a suitable SOCK_SEQPACKET unix socket.
+  // |fast_check_in_client| should be set to true and
+  // |quiet_failures_for_tests| to false unless you are writing tests.
+  BrokerClient(const BrokerPolicy& policy,
+               int ipc_channel,
+               bool fast_check_in_client,
+               bool quiet_failures_for_tests);
+  ~BrokerClient();
+
+  // Can be used in place of access().
+  // X_OK will always return an error in practice since the broker process
+  // doesn't support execute permissions.
+  // It's similar to the access() system call and will return -errno on errors.
+  // This is async signal safe.
+  int Access(const char* pathname, int mode) const;
+  // Can be used in place of open().
+  // The implementation only supports certain white listed flags and will
+  // return -EPERM on other flags.
+  // It's similar to the open() system call and will return -errno on errors.
+  // This is async signal safe.
+  int Open(const char* pathname, int flags) const;
+
+ private:
+  const BrokerPolicy& broker_policy_;
+  const int ipc_channel_;
+  const bool fast_check_in_client_;  // Whether to forward a request that we
+                                     // know will be denied to the broker. (Used
+                                     // for tests).
+  const bool quiet_failures_for_tests_;  // Disable certain error message when
+                                         // testing for failures.
+
+  int PathAndFlagsSyscall(IPCCommand syscall_type,
+                          const char* pathname,
+                          int flags) const;
+
+  DISALLOW_COPY_AND_ASSIGN(BrokerClient);
+};
+
+}  // namespace syscall_broker
+
+}  // namespace sandbox
+
+#endif  //  SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_