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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "subprocess.h"
#include <algorithm>
#include <map>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
#include "util.h"
Subprocess::Subprocess() : fd_(-1), pid_(-1) {
}
Subprocess::~Subprocess() {
if (fd_ >= 0)
close(fd_);
// Reap child if forgotten.
if (pid_ != -1)
Finish();
}
bool Subprocess::Start(SubprocessSet* set, const string& command) {
int output_pipe[2];
if (pipe(output_pipe) < 0)
Fatal("pipe: %s", strerror(errno));
fd_ = output_pipe[0];
SetCloseOnExec(fd_);
pid_ = fork();
if (pid_ < 0)
Fatal("fork: %s", strerror(errno));
if (pid_ == 0) {
close(output_pipe[0]);
// Track which fd we use to report errors on.
int error_pipe = output_pipe[1];
do {
// Open /dev/null over stdin.
int devnull = open("/dev/null", O_WRONLY);
if (devnull < 0)
break;
if (dup2(devnull, 0) < 0)
break;
close(devnull);
if (dup2(output_pipe[1], 1) < 0 ||
dup2(output_pipe[1], 2) < 0)
break;
// Now can use stderr for errors.
error_pipe = 2;
close(output_pipe[1]);
execl("/bin/sh", "/bin/sh", "-c", command.c_str(), (char *) NULL);
} while (false);
// If we get here, something went wrong; the execl should have
// replaced us.
char* err = strerror(errno);
if (write(error_pipe, err, strlen(err)) < 0) {
// If the write fails, there's nothing we can do.
// But this block seems necessary to silence the warning.
}
_exit(1);
}
close(output_pipe[1]);
return true;
}
void Subprocess::OnPipeReady() {
char buf[4 << 10];
ssize_t len = read(fd_, buf, sizeof(buf));
if (len > 0) {
buf_.append(buf, len);
} else {
if (len < 0)
Fatal("read: %s", strerror(errno));
close(fd_);
fd_ = -1;
}
}
bool Subprocess::Finish() {
assert(pid_ != -1);
int status;
if (waitpid(pid_, &status, 0) < 0)
Fatal("waitpid(%d): %s", pid_, strerror(errno));
pid_ = -1;
if (WIFEXITED(status)) {
int exit = WEXITSTATUS(status);
if (exit == 0)
return true;
}
return false;
}
bool Subprocess::Done() const {
return fd_ == -1;
}
const string& Subprocess::GetOutput() const {
return buf_;
}
SubprocessSet::SubprocessSet() {}
SubprocessSet::~SubprocessSet() {}
void SubprocessSet::Add(Subprocess* subprocess) {
running_.push_back(subprocess);
}
void SubprocessSet::DoWork() {
vector<pollfd> fds;
map<int, Subprocess*> fd_to_subprocess;
for (vector<Subprocess*>::iterator i = running_.begin();
i != running_.end(); ++i) {
int fd = (*i)->fd_;
if (fd >= 0) {
fd_to_subprocess[fd] = *i;
fds.resize(fds.size() + 1);
pollfd* newfd = &fds.back();
newfd->fd = fd;
newfd->events = POLLIN;
newfd->revents = 0;
}
}
int ret = poll(&fds.front(), fds.size(), -1);
if (ret == -1) {
if (errno != EINTR)
perror("ninja: poll");
return;
}
for (size_t i = 0; i < fds.size(); ++i) {
if (fds[i].revents) {
Subprocess* subproc = fd_to_subprocess[fds[i].fd];
subproc->OnPipeReady();
if (subproc->Done()) {
finished_.push(subproc);
std::remove(running_.begin(), running_.end(), subproc);
running_.resize(running_.size() - 1);
}
}
}
}
Subprocess* SubprocessSet::NextFinished() {
if (finished_.empty())
return NULL;
Subprocess* subproc = finished_.front();
finished_.pop();
return subproc;
}
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