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| 1 // Copyright 2014 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "mojo/edk/embedder/platform_channel_pair.h" | |
| 6 | |
| 7 #include <fcntl.h> | |
| 8 #include <sys/socket.h> | |
| 9 #include <sys/types.h> | |
| 10 #include <unistd.h> | |
| 11 | |
| 12 #include "base/command_line.h" | |
| 13 #include "base/logging.h" | |
| 14 #include "base/posix/global_descriptors.h" | |
| 15 #include "base/strings/string_number_conversions.h" | |
| 16 #include "build/build_config.h" | |
| 17 #include "mojo/edk/embedder/platform_handle.h" | |
| 18 | |
| 19 namespace mojo { | |
| 20 namespace embedder { | |
| 21 | |
| 22 namespace { | |
| 23 | |
| 24 bool IsTargetDescriptorUsed( | |
| 25 const base::FileHandleMappingVector& file_handle_mapping, | |
| 26 int target_fd) { | |
| 27 for (size_t i = 0; i < file_handle_mapping.size(); i++) { | |
| 28 if (file_handle_mapping[i].second == target_fd) | |
| 29 return true; | |
| 30 } | |
| 31 return false; | |
| 32 } | |
| 33 | |
| 34 } // namespace | |
| 35 | |
| 36 PlatformChannelPair::PlatformChannelPair() { | |
| 37 // Create the Unix domain socket and set the ends to nonblocking. | |
| 38 int fds[2]; | |
| 39 // TODO(vtl): Maybe fail gracefully if |socketpair()| fails. | |
| 40 PCHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0); | |
| 41 PCHECK(fcntl(fds[0], F_SETFL, O_NONBLOCK) == 0); | |
| 42 PCHECK(fcntl(fds[1], F_SETFL, O_NONBLOCK) == 0); | |
| 43 | |
| 44 #if defined(OS_MACOSX) | |
| 45 // This turns off |SIGPIPE| when writing to a closed socket (causing it to | |
| 46 // fail with |EPIPE| instead). On Linux, we have to use |send...()| with | |
| 47 // |MSG_NOSIGNAL| -- which is not supported on Mac -- instead. | |
| 48 int no_sigpipe = 1; | |
| 49 PCHECK(setsockopt(fds[0], SOL_SOCKET, SO_NOSIGPIPE, &no_sigpipe, | |
| 50 sizeof(no_sigpipe)) == 0); | |
| 51 PCHECK(setsockopt(fds[1], SOL_SOCKET, SO_NOSIGPIPE, &no_sigpipe, | |
| 52 sizeof(no_sigpipe)) == 0); | |
| 53 #endif // defined(OS_MACOSX) | |
| 54 | |
| 55 server_handle_.reset(PlatformHandle(fds[0])); | |
| 56 DCHECK(server_handle_.is_valid()); | |
| 57 client_handle_.reset(PlatformHandle(fds[1])); | |
| 58 DCHECK(client_handle_.is_valid()); | |
| 59 } | |
| 60 | |
| 61 // static | |
| 62 ScopedPlatformHandle PlatformChannelPair::PassClientHandleFromParentProcess( | |
| 63 const base::CommandLine& command_line) { | |
| 64 std::string client_fd_string = | |
| 65 command_line.GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch); | |
| 66 int client_fd = -1; | |
| 67 if (client_fd_string.empty() || | |
| 68 !base::StringToInt(client_fd_string, &client_fd) || | |
| 69 client_fd < base::GlobalDescriptors::kBaseDescriptor) { | |
| 70 LOG(ERROR) << "Missing or invalid --" << kMojoPlatformChannelHandleSwitch; | |
| 71 return ScopedPlatformHandle(); | |
| 72 } | |
| 73 | |
| 74 return ScopedPlatformHandle(PlatformHandle(client_fd)); | |
| 75 } | |
| 76 | |
| 77 void PlatformChannelPair::PrepareToPassClientHandleToChildProcess( | |
| 78 base::CommandLine* command_line, | |
| 79 base::FileHandleMappingVector* handle_passing_info) const { | |
| 80 DCHECK(command_line); | |
| 81 DCHECK(handle_passing_info); | |
| 82 // This is an arbitrary sanity check. (Note that this guarantees that the loop | |
| 83 // below will terminate sanely.) | |
| 84 CHECK_LT(handle_passing_info->size(), 1000u); | |
| 85 | |
| 86 DCHECK(client_handle_.is_valid()); | |
| 87 | |
| 88 // Find a suitable FD to map our client handle to in the child process. | |
| 89 // This has quadratic time complexity in the size of |*handle_passing_info|, | |
| 90 // but |*handle_passing_info| should be very small (usually/often empty). | |
| 91 int target_fd = base::GlobalDescriptors::kBaseDescriptor; | |
| 92 while (IsTargetDescriptorUsed(*handle_passing_info, target_fd)) | |
| 93 target_fd++; | |
| 94 | |
| 95 handle_passing_info->push_back( | |
| 96 std::pair<int, int>(client_handle_.get().fd, target_fd)); | |
| 97 // Log a warning if the command line already has the switch, but "clobber" it | |
| 98 // anyway, since it's reasonably likely that all the switches were just copied | |
| 99 // from the parent. | |
| 100 LOG_IF(WARNING, command_line->HasSwitch(kMojoPlatformChannelHandleSwitch)) | |
| 101 << "Child command line already has switch --" | |
| 102 << kMojoPlatformChannelHandleSwitch << "=" | |
| 103 << command_line->GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch); | |
| 104 // (Any existing switch won't actually be removed from the command line, but | |
| 105 // the last one appended takes precedence.) | |
| 106 command_line->AppendSwitchASCII(kMojoPlatformChannelHandleSwitch, | |
| 107 base::IntToString(target_fd)); | |
| 108 } | |
| 109 | |
| 110 } // namespace embedder | |
| 111 } // namespace mojo | |
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