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// 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.
#include "mojo/embedder/platform_channel_pair.h"
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "base/command_line.h"
#include "base/logging.h"
#include "base/posix/global_descriptors.h"
#include "base/strings/string_number_conversions.h"
#include "build/build_config.h"
#include "mojo/embedder/platform_handle.h"
namespace mojo {
namespace embedder {
namespace {
bool IsTargetDescriptorUsed(
const base::FileHandleMappingVector& file_handle_mapping,
int target_fd) {
for (size_t i = 0; i < file_handle_mapping.size(); i++) {
if (file_handle_mapping[i].second == target_fd)
return true;
}
return false;
}
} // namespace
PlatformChannelPair::PlatformChannelPair() {
// Create the Unix domain socket and set the ends to nonblocking.
int fds[2];
// TODO(vtl): Maybe fail gracefully if |socketpair()| fails.
PCHECK(socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0);
PCHECK(fcntl(fds[0], F_SETFL, O_NONBLOCK) == 0);
PCHECK(fcntl(fds[1], F_SETFL, O_NONBLOCK) == 0);
#if defined(OS_MACOSX)
// This turns off |SIGPIPE| when writing to a closed socket (causing it to
// fail with |EPIPE| instead). On Linux, we have to use |send...()| with
// |MSG_NOSIGNAL| -- which is not supported on Mac -- instead.
int no_sigpipe = 1;
PCHECK(setsockopt(fds[0], SOL_SOCKET, SO_NOSIGPIPE, &no_sigpipe,
sizeof(no_sigpipe)) == 0);
PCHECK(setsockopt(fds[1], SOL_SOCKET, SO_NOSIGPIPE, &no_sigpipe,
sizeof(no_sigpipe)) == 0);
#endif // defined(OS_MACOSX)
server_handle_.reset(PlatformHandle(fds[0]));
DCHECK(server_handle_.is_valid());
client_handle_.reset(PlatformHandle(fds[1]));
DCHECK(client_handle_.is_valid());
}
// static
ScopedPlatformHandle PlatformChannelPair::PassClientHandleFromParentProcess(
const CommandLine& command_line) {
std::string client_fd_string =
command_line.GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch);
int client_fd = -1;
if (client_fd_string.empty() ||
!base::StringToInt(client_fd_string, &client_fd) ||
client_fd < base::GlobalDescriptors::kBaseDescriptor) {
LOG(ERROR) << "Missing or invalid --" << kMojoPlatformChannelHandleSwitch;
return ScopedPlatformHandle();
}
return ScopedPlatformHandle(PlatformHandle(client_fd));
}
void PlatformChannelPair::PrepareToPassClientHandleToChildProcess(
CommandLine* command_line,
base::FileHandleMappingVector* handle_passing_info) const {
DCHECK(command_line);
DCHECK(handle_passing_info);
// This is an arbitrary sanity check. (Note that this guarantees that the loop
// below will terminate sanely.)
CHECK_LT(handle_passing_info->size(), 1000u);
DCHECK(client_handle_.is_valid());
// Find a suitable FD to map our client handle to in the child process.
// This has quadratic time complexity in the size of |*handle_passing_info|,
// but |*handle_passing_info| should be very small (usually/often empty).
int target_fd = base::GlobalDescriptors::kBaseDescriptor;
while (IsTargetDescriptorUsed(*handle_passing_info, target_fd))
target_fd++;
handle_passing_info->push_back(std::pair<int, int>(client_handle_.get().fd,
target_fd));
// Log a warning if the command line already has the switch, but "clobber" it
// anyway, since it's reasonably likely that all the switches were just copied
// from the parent.
LOG_IF(WARNING, command_line->HasSwitch(kMojoPlatformChannelHandleSwitch))
<< "Child command line already has switch --"
<< kMojoPlatformChannelHandleSwitch << "="
<< command_line->GetSwitchValueASCII(kMojoPlatformChannelHandleSwitch);
// (Any existing switch won't actually be removed from the command line, but
// the last one appended takes precedence.)
command_line->AppendSwitchASCII(kMojoPlatformChannelHandleSwitch,
base::IntToString(target_fd));
}
} // namespace embedder
} // namespace mojo
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