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Improvements for MachMultiprocess.

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This adds a pipe going in the other direction (parent to child).
Initially, I didn’t think this was necessary, but it turned out to be
needed for ProcessReader. Having the child wait on a pipe read is the
easiest way to keep it alive until the parent is done with it.

This also tests MachMultiprocess::ChildPID() in
mach_multiprocess_test.cc.

Both of these fell out of https://codereview.chromium.org/491963002/.

TEST=util_test MachMultiprocess.MachMultiprocess
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/491363002
This commit is contained in:
Mark Mentovai 2014-08-22 14:00:10 -04:00
parent b980a5984b
commit 4004e77ee9
3 changed files with 90 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

72
util/test/mac/mach_multiprocess.cc
View File

@ -67,19 +67,25 @@ namespace internal {
struct MachMultiprocessInfo {
MachMultiprocessInfo()
: service_name(),
read_pipe(-1),
write_pipe(-1),
pipe_c2p_read(-1),
pipe_c2p_write(-1),
pipe_p2c_read(-1),
pipe_p2c_write(-1),
child_pid(0),
pipe_fd(-1),
read_pipe_fd(-1),
write_pipe_fd(-1),
local_port(MACH_PORT_NULL),
remote_port(MACH_PORT_NULL),
child_task(MACH_PORT_NULL) {}
std::string service_name;
base::ScopedFD read_pipe;
base::ScopedFD write_pipe;
base::ScopedFD pipe_c2p_read; // child to parent
base::ScopedFD pipe_c2p_write; // child to parent
base::ScopedFD pipe_p2c_read; // parent to child
base::ScopedFD pipe_p2c_write; // parent to child
pid_t child_pid; // valid only in parent
int pipe_fd; // read_pipe in parent, write_pipe in child
int read_pipe_fd; // pipe_c2p_read in parent, pipe_p2c_read in child
int write_pipe_fd; // pipe_p2c_write in parent, pipe_c2p_write in child
base::mac::ScopedMachReceiveRight local_port;
base::mac::ScopedMachSendRight remote_port;
base::mac::ScopedMachSendRight child_task; // valid only in parent
@ -97,12 +103,19 @@ void MachMultiprocess::Run() {
base::AutoReset<internal::MachMultiprocessInfo*> reset_info(&info_,
info.get());
int pipe_fds[2];
int rv = pipe(pipe_fds);
int pipe_fds_c2p[2];
int rv = pipe(pipe_fds_c2p);
ASSERT_EQ(0, rv) << ErrnoMessage("pipe");
info_->read_pipe.reset(pipe_fds[0]);
info_->write_pipe.reset(pipe_fds[1]);
info_->pipe_c2p_read.reset(pipe_fds_c2p[0]);
info_->pipe_c2p_write.reset(pipe_fds_c2p[1]);
int pipe_fds_p2c[2];
rv = pipe(pipe_fds_p2c);
ASSERT_EQ(0, rv) << ErrnoMessage("pipe");
info_->pipe_p2c_read.reset(pipe_fds_p2c[0]);
info_->pipe_p2c_write.reset(pipe_fds_p2c[1]);
// Set up the parent port and register it with the bootstrap server before
// forking, so that it’s guaranteed to be there when the child attempts to
@ -169,9 +182,14 @@ pid_t MachMultiprocess::ChildPID() const {
return info_->child_pid;
}
int MachMultiprocess::PipeFD() const {
EXPECT_NE(-1, info_->pipe_fd);
return info_->pipe_fd;
int MachMultiprocess::ReadPipeFD() const {
EXPECT_NE(-1, info_->read_pipe_fd);
return info_->read_pipe_fd;
}
int MachMultiprocess::WritePipeFD() const {
EXPECT_NE(-1, info_->write_pipe_fd);
return info_->write_pipe_fd;
}
mach_port_t MachMultiprocess::LocalPort() const {
@ -190,9 +208,11 @@ mach_port_t MachMultiprocess::ChildTask() const {
}
void MachMultiprocess::RunParent() {
// The parent uses the read end of the pipe.
info_->write_pipe.reset();
info_->pipe_fd = info_->read_pipe.get();
// The parent uses the read end of c2p and the write end of p2c.
info_->pipe_c2p_write.reset();
info_->read_pipe_fd = info_->pipe_c2p_read.get();
info_->pipe_p2c_read.reset();
info_->write_pipe_fd = info_->pipe_p2c_write.get();
ReceiveHelloMessage message = {};
@ -284,8 +304,10 @@ void MachMultiprocess::RunParent() {
info_->remote_port.reset();
info_->local_port.reset();
info_->pipe_fd = -1;
info_->read_pipe.reset();
info_->read_pipe_fd = -1;
info_->pipe_c2p_read.reset();
info_->write_pipe_fd = -1;
info_->pipe_p2c_write.reset();
}
void MachMultiprocess::RunChild() {
@ -294,9 +316,11 @@ void MachMultiprocess::RunChild() {
// local_port is not valid in the forked child process.
ignore_result(info_->local_port.release());
// The child uses the write end of the pipe.
info_->read_pipe.reset();
info_->pipe_fd = info_->write_pipe.get();
// The child uses the write end of c2p and the read end of p2c.
info_->pipe_c2p_read.reset();
info_->write_pipe_fd = info_->pipe_c2p_write.get();
info_->pipe_p2c_write.reset();
info_->read_pipe_fd = info_->pipe_p2c_read.get();
mach_port_t local_port;
kern_return_t kr = mach_port_allocate(
@ -341,8 +365,10 @@ void MachMultiprocess::RunChild() {
info_->remote_port.reset();
info_->local_port.reset();
info_->pipe_fd = -1;
info_->write_pipe.reset();
info_->write_pipe_fd = -1;
info_->pipe_c2p_write.reset();
info_->read_pipe_fd = -1;
info_->pipe_p2c_read.reset();
if (Test::HasFailure()) {
// Trigger the ScopedNotReached destructor.

20
util/test/mac/mach_multiprocess.h
View File

@ -31,8 +31,7 @@ struct MachMultiprocessInfo;
//!
//! These tests are `fork()`-based. The parent process has access to the child
//! process’ task port. The parent and child processes are able to communicate
//! via Mach IPC, and the child process can also send messages to the parent
//! process via a POSIX pipe.
//! via Mach IPC, and via a pair of POSIX pipes.
//!
//! Subclasses are expected to implement the parent and child by overriding the
//! appropriate methods.
@ -79,12 +78,19 @@ class MachMultiprocess {
//! This method may only be called by the parent process.
pid_t ChildPID() const;
//! \brief Returns the pipe’s file descriptor.
//! \brief Returns the read pipe’s file descriptor.
//!
//! This method may be called by either the parent or the child process. In
//! the parent process, the pipe is read-only, and in the child process, it is
//! write-only.
int PipeFD() const;
//! This method may be called by either the parent or the child process.
//! Anything written to the write pipe in the partner process will appear
//! on the this file descriptor in this process.
int ReadPipeFD() const;
//! \brief Returns the write pipe’s file descriptor.
//!
//! This method may be called by either the parent or the child process.
//! Anything written to this file descriptor in this process will appear on
//! the read pipe in the partner process.
int WritePipeFD() const;
//! \brief Returns a receive right for the local port.
//!

35
util/test/mac/mach_multiprocess_test.cc
View File

@ -14,6 +14,8 @@
#include "util/test/mac/mach_multiprocess.h"
#include <unistd.h>
#include "base/basictypes.h"
#include "gtest/gtest.h"
#include "util/file/fd_io.h"
@ -32,27 +34,46 @@ class TestMachMultiprocess final : public MachMultiprocess {
protected:
// The base class will have already exercised the Mach ports for IPC and the
// child task port. Just make sure that the pipe is set up correctly.
// child task port. Just make sure that the pipe is set up correctly and that
// ChildPID() works as expected.
virtual void Parent() override {
int fd = PipeFD();
int read_fd = ReadPipeFD();
char c;
ssize_t rv = ReadFD(fd, &c, 1);
ssize_t rv = ReadFD(read_fd, &c, 1);
ASSERT_EQ(1, rv) << ErrnoMessage("read");
EXPECT_EQ('M', c);
pid_t pid;
rv = ReadFD(read_fd, &pid, sizeof(pid));
ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("read");
EXPECT_EQ(pid, ChildPID());
int write_fd = WritePipeFD();
c = 'm';
rv = WriteFD(write_fd, &c, 1);
ASSERT_EQ(1, rv) << ErrnoMessage("write");
// The child will close its end of the pipe and exit. Make sure that the
// parent sees EOF.
rv = ReadFD(fd, &c, 1);
rv = ReadFD(read_fd, &c, 1);
ASSERT_EQ(0, rv) << ErrnoMessage("read");
}
virtual void Child() override {
int fd = PipeFD();
int write_fd = WritePipeFD();
char c = 'M';
ssize_t rv = WriteFD(fd, &c, 1);
ssize_t rv = WriteFD(write_fd, &c, 1);
ASSERT_EQ(1, rv) << ErrnoMessage("write");
pid_t pid = getpid();
rv = WriteFD(write_fd, &pid, sizeof(pid));
ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("write");
int read_fd = ReadPipeFD();
rv = ReadFD(read_fd, &c, 1);
ASSERT_EQ(1, rv) << ErrnoMessage("read");
EXPECT_EQ('m', c);
}
private: