zsh pty test

pty-test.c

#define _XOPEN_SOURCE 600

#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <string.h>

// #define SUDO

#ifdef SUDO
char *child_argv[] = { "zsh", "-c", "sudo touch /tmp/sudo", NULL };
#else
char *child_argv[] = { "zsh", "-c", "touch /tmp/fork &", NULL };
#endif

int main(int argc, char *argv[])
{
	int ret, master, slave;
#ifdef SUDO
	const char *pwd;

	pwd = getenv("PASSWORD");
	if (!pwd) {
		fprintf(stderr, "Missing PASSWORD env variable\n");
		exit(1);
	}
#endif

	if (argc >= 1) child_argv[0] = argv[1];

	master = posix_openpt(O_RDWR | O_NOCTTY);
	unlockpt(master);

#ifdef TIOCGPTPEER
	slave = ioctl(master, TIOCGPTPEER, O_RDWR | O_NOCTTY);
#else
	slave = open(ptsname(master), O_RDWR | O_NOCTTY);
#endif

	pid_t pid = fork();
	if (pid) {
		fd_set rfds;
		int status;

		close(slave);

		FD_ZERO(&rfds);
		FD_SET(master, &rfds);

		select(master + 1, &rfds, NULL, NULL, NULL);

		if (FD_ISSET(master, &rfds)) {
			char input[0x1000];
			ret = read(master, input, sizeof(input));
			if (ret > 0)
				fprintf(stdout, "out: %.*s\n", ret, input);
		}

#ifdef SUDO
		write(master, pwd, strlen(pwd));
		write(master, "\n", 1);
#endif

		waitpid(pid, &status, 0);
		return (WEXITSTATUS(status));
	} else {
		setsid();
		ioctl(slave, TIOCSCTTY, NULL);
		signal(SIGHUP, SIG_IGN);

		close(master);

		dup2(slave, 0);
		dup2(slave, 1);
		dup2(slave, 2);
		close(slave);

		execvp(child_argv[0], child_argv);
	}

	return 0;
}