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#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::Stream::Stream() : fd_(-1) {}
Subprocess::Stream::~Stream() {
if (fd_ >= 0)
close(fd_);
}
Subprocess::Subprocess() : pid_(-1) {}
Subprocess::~Subprocess() {
// Reap child if forgotten.
if (pid_ != -1)
Finish();
}
bool Subprocess::Start(const string& command) {
int stdout_pipe[2];
if (pipe(stdout_pipe) < 0)
Fatal("pipe: %s", strerror(errno));
stdout_.fd_ = stdout_pipe[0];
int stderr_pipe[2];
if (pipe(stderr_pipe) < 0)
Fatal("pipe: %s", strerror(errno));
stderr_.fd_ = stderr_pipe[0];
pid_ = fork();
if (pid_ < 0)
Fatal("fork: %s", strerror(errno));
if (pid_ == 0) {
close(stdout_pipe[0]);
close(stderr_pipe[0]);
// Track which fd we use to report errors on.
int error_pipe = stderr_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(stdout_pipe[1], 1) < 0 ||
dup2(stderr_pipe[1], 2) < 0)
break;
// Now can use stderr for errors.
error_pipe = 2;
close(stdout_pipe[1]);
close(stderr_pipe[1]);
execl("/bin/sh", "/bin/sh", "-c", command.c_str(), NULL);
} while (false);
// If we get here, something went wrong; the execl should have
// replaced us.
char* err = strerror(errno);
write(error_pipe, err, strlen(err));
_exit(1);
}
close(stdout_pipe[1]);
close(stderr_pipe[1]);
return true;
}
void Subprocess::OnFDReady(int fd) {
char buf[4 << 10];
ssize_t len = read(fd, buf, sizeof(buf));
Stream* stream = fd == stdout_.fd_ ? &stdout_ : &stderr_;
if (len > 0) {
stream->buf_.append(buf, len);
} else {
if (len < 0)
Fatal("read: %s", strerror(errno));
close(stream->fd_);
stream->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;
}
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)->stdout_.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;
}
fd = (*i)->stderr_.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.data(), fds.size(), -1);
if (ret == -1) {
if (errno != EINTR)
perror("poll");
return;
}
for (size_t i = 0; i < fds.size(); ++i) {
if (fds[i].revents) {
Subprocess* subproc = fd_to_subprocess[fds[i].fd];
if (fds[i].revents) {
subproc->OnFDReady(fds[i].fd);
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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