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#include "child_process.h"
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
namespace util {
void ChildProcess::ParseCommandline(vector<char *> *args) {
char *p = commandline_;
bool in_quote;
do {
// Find the start of a chunk.
while(*p && isspace(*p)) p++;
if (!*p) break;
args->push_back(p);
in_quote = false;
// Find the end of the chunk.
while (*p) {
if (*p == '"') {
in_quote = !in_quote;
} else if (isspace(*p) && !in_quote) {
break;
}
p++;
}
if (!*p) break;
*p = '\0';
p++;
} while(1);
args->push_back(NULL);
}
static volatile bool _child_ready = false;
static void SignalHandler(int signo) {
printf("SIGNAL!\n");
_child_ready = true;
}
void ChildProcess::Start() {
Stop();
vector<char *> args;
ParseCommandline(&args);
if (args.size() > 1) {
if (pipe(read_pipe_) != 0) {
perror("pipe");
exit(-1);
}
if (pipe(write_pipe_) != 0) {
perror("pipe");
exit(-1);
}
// Prepare a signal handler to tell us when the child process is
// ready.
_child_ready = false;
if (signal(SIGUSR1, SignalHandler) == SIG_ERR) {
perror("signal");
exit(-1);
}
sigset_t zeromask, mask, orig;
sigemptyset(&zeromask);
sigemptyset(&mask);
sigaddset(&mask, SIGUSR1);
if (sigprocmask(SIG_BLOCK, &mask, &orig) < 0) {
perror("sigprocmask");
exit(-1);
}
// Fork.
pid_ = fork();
if (pid_ < 0) {
perror("fork");
exit(-1);
}
if (pid_ == 0) {
printf("In the child process...\n");
// In the child process we do not need the pipes for parent
// reads and writes.
close(write_pipe_[1]);
close(read_pipe_[0]);
if (dup2(write_pipe_[0], fileno(stdin)) < 0) {
perror("dup2");
exit(-1);
}
close(write_pipe_[0]);
if (dup2(read_pipe_[1], fileno(stdout)) < 0) {
perror("dup2");
exit(-1);
}
if (dup2(fileno(stdout), fileno(stderr)) < 0) {
perror("dup2");
exit(-1);
}
close(read_pipe_[1]);
// Tell the parent that the pipes are set up then exec the child
// image.
kill(getppid(), SIGUSR1);
execvp(args[0], &(args[0]));
perror("exec");
exit(-1);
} else {
printf("In the parent process waiting...\n");
while(!_child_ready) {
sigsuspend(&zeromask);
}
printf("PARENT WAKEUP!\n");
_child_ready = false;
if (sigprocmask(SIG_SETMASK, &orig, NULL) < 0) {
perror("sigprocmask");
exit(-1);
}
close(write_pipe_[0]);
close(read_pipe_[1]);
from_ = fdopen(read_pipe_[0], "r");
to_ = fdopen(write_pipe_[1], "w");
setbuf(from_, NULL);
setbuf(to_, NULL);
running_ = true;
name_ = args[0];
}
}
}
void ChildProcess::Stop() {
if (!running_) {
return;
}
fclose(to_);
fclose(from_);
close(write_pipe_[1]);
close(read_pipe_[0]);
kill(pid_, SIGTERM);
int x;
waitpid(pid_, &x, 0);
}
void ChildProcess::Send(char *line) {
if (!running_) {
return;
}
fprintf(to_, "%s", line);
printf("%s sent: %s", name_, line);
}
void ChildProcess::Receive(char *line, int size) {
if (!size) return;
*line = '\0';
if (!running_) {
return;
}
if (!Poll()) {
return;
}
fgets(line, size, from_);
printf("%s recv: %s\n", name_, line);
}
bool ChildProcess::Poll() {
fd_set myset;
FD_ZERO(&myset);
FD_SET(read_pipe_[0], &myset);
timeval mytime;
mytime.tv_sec = 0;
mytime.tv_usec = 0;
return select(read_pipe_[0] + 1, &myset, NULL, NULL, &mytime) > 0;
}
void ChildProcess::Flush() {
static char line[1000];
while (Poll()) {
Receive(line, 1000);
printf("flush: %s", line);
if (!line[0]) {
break;
}
}
}
} // namespace
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