Implement IPC::ChannelFactory, a class that accept()s on a UNIX socket.

ipc/unix_domain_socket_util.h

Index: ipc/unix_domain_socket_util.h
diff --git a/ipc/unix_domain_socket_util.h b/ipc/unix_domain_socket_util.h
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+// Copyright 2013 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 IPC_UNIX_DOMAIN_SOCKET_UTIL_H_
+#define IPC_UNIX_DOMAIN_SOCKET_UTIL_H_
+
+#include <sys/types.h>
+
+#include <string>
+
+#include "ipc/ipc_export.h"
+
+namespace base {
+class FilePath;
+}  // namespace base
+
+namespace IPC {
+
+// Creates a UNIX-domain socket at |socket_name| and bind()s it, then listen()s
+// on it. If successful, |server_listen_fd| will be set to the new file
+// descriptor, and the function will return true. Otherwise returns false.
+//
+// This function also effectively performs `mkdir -p` on the dirname of
+// |socket_name| to ensure that all the directories up to |socket_name| exist.
+// As a result of which this function must be run on a thread that allows
+// blocking I/O, e.g. the FILE thread in Chrome's browser process.
+IPC_EXPORT bool CreateServerUnixDomainSocket(const base::FilePath& socket_name,
+                                             int* server_listen_fd);
+
+// Opens a UNIX-domain socket at |socket_name| and connect()s to it. If
+// successful, |client_socket| will be set to the new file descriptor, and the
+// function will return true. Otherwise returns false.
+IPC_EXPORT bool CreateClientUnixDomainSocket(const base::FilePath& socket_name,
+                                             int* client_socket);
+
+// Gets the effective user ID of the other end of the UNIX-domain socket
+// specified by |fd|. If successful, sets |peer_euid| to the uid, and returns
+// true. Otherwise returns false.
+IPC_EXPORT bool GetPeerEuid(int fd, uid_t* peer_euid);
+
+// Checks that the process on the other end of the UNIX domain socket
+// represented by |peer_fd| shares the same EUID as this process.
+IPC_EXPORT bool IsPeerAuthorized(int peer_fd);
+
+// Accepts a client attempting to connect to |server_listen_fd|, storing the
+// new file descriptor for the connection in |server_socket|.
+//
+// Returns false if |server_listen_fd| encounters an unrecoverable error.
+// Returns true if it's valid to keep listening on |server_listen_fd|. In this
+// case, it's possible that a connection wasn't successfully established; then,
+// |server_socket| will be set to -1.
+IPC_EXPORT bool ServerAcceptConnection(int server_listen_fd,
+                                       int* server_socket);
+
+// The maximum length of the name of a socket for MODE_NAMED_SERVER or
+// MODE_NAMED_CLIENT if you want to pass in your own socket.
+// The standard size on linux is 108, mac is 104. To maintain consistency
+// across platforms we standardize on the smaller value.
+static const size_t kMaxSocketNameLength = 104;
+
+}  // namespace IPC
+
+#endif  // IPC_UNIX_DOMAIN_SOCKET_UTIL_H_