toaruos/apps/petty.c

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2018-11-08 12:02:54 +03:00
/* vim: tabstop=4 shiftwidth=4 noexpandtab
* This file is part of ToaruOS and is released under the terms
* of the NCSA / University of Illinois License - see LICENSE.md
* Copyright (C) 2018 K. Lange
*
* petty - Manage a TTY.
*
* Wraps a serial port (or other dumb connection) with a pty
* and manages a login for it.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <pty.h>
#include <sys/wait.h>
#include <sys/fswait.h>
int main(int argc, char * argv[]) {
int fd_master, fd_slave, fd_serial;
char * file = "/dev/ttyS0";
char * user = NULL;
if (getuid() != 0) {
fprintf(stderr, "%s: only root can do that\n", argv[0]);
return 1;
}
int opt;
while ((opt = getopt(argc, argv, "a:")) != -1) {
switch (opt) {
case 'a':
user = optarg;
break;
}
}
if (optind < argc) {
file = argv[optind];
}
openpty(&fd_master, &fd_slave, NULL, NULL, NULL);
fd_serial = open(file, O_RDWR);
pid_t child = fork();
if (!child) {
setsid();
dup2(fd_slave, 0);
dup2(fd_slave, 1);
dup2(fd_slave, 2);
system("ttysize -q");
char * tokens[] = {"/bin/login",NULL,NULL,NULL};
if (user) {
tokens[1] = "-f";
tokens[2] = user;
}
execvp(tokens[0], tokens);
exit(1);
} else {
int fds[2] = {fd_serial, fd_master};
while (1) {
int index = fswait2(2,fds,200);
char buf[1024];
int r;
switch (index) {
case 0: /* fd_serial */
r = read(fd_serial, buf, 1);
write(fd_master, buf, 1);
break;
case 1: /* fd_master */
r = read(fd_master, buf, 1024);
write(fd_serial, buf, r);
break;
default: /* timeout */
{
int result = waitpid(child, NULL, WNOHANG);
if (result > 0) {
/* Child login shell has returned (session ended) */
return 0;
}
}
break;
}
}
}
return 0;
}