From 825f5f0f639d76e5ef05687408eb3225ba9c93fa Mon Sep 17 00:00:00 2001 From: Simon Ruderich Date: Tue, 29 Nov 2016 15:30:22 +0100 Subject: [PATCH] Update and improve comments --- ptyas.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/ptyas.c b/ptyas.c index 05170ec..1deda82 100644 --- a/ptyas.c +++ b/ptyas.c @@ -79,7 +79,6 @@ static void open_pty_or_die(int *pty_master, int *pty_slave, uid_t uid) { /* The user must be able to write to the new TTY. Normally grantpt() would * do this for us, but we don't trust the user and thus don't want to pass * the pty_master to a process running under that uid. */ - // TODO: is this a problem? if (chown(slave_path, uid, (gid_t)-1) != 0) { die("chown slave tty"); } @@ -206,7 +205,7 @@ static void proxy_input_between_ttys(int pty_master, int ctty, volatile pid_t *p while (*pid_to_wait_for != 0) { /* * If a signal happens here _and_ the child hasn't closed pty_slave, - * we will hang in poll(); therefore ppoll() is requred. + * we would hang in poll(); therefore ppoll() is necessary. */ nfds_t nfds = sizeof(fds)/sizeof(*fds); if (ppoll(fds, nfds, NULL /* no timeout */, &sigset_old) == -1) { @@ -218,7 +217,8 @@ static void proxy_input_between_ttys(int pty_master, int ctty, volatile pid_t *p break; } - /* Handle errors first. */ + /* Handle errors first. (Data available before the error occurred + * might be skipped, but shouldn't matter here.) */ if (fds[0].revents & (POLLERR | POLLNVAL)) { fprintf(stderr, "poll: error on master: %d\n", fds[0].revents); break; @@ -228,7 +228,7 @@ static void proxy_input_between_ttys(int pty_master, int ctty, volatile pid_t *p break; } - /* Then read data if available. */ + /* Read data if available. */ if (fds[0].revents & POLLIN) { if (!read_from_write_to(pty_master, ctty)) { perror("read from master write to ctty"); @@ -254,7 +254,10 @@ static void proxy_input_between_ttys(int pty_master, int ctty, volatile pid_t *p } -/* Not sig_atomic_t but I don't know how to do that any other way. */ +/* + * Not sig_atomic_t (as required by POSIX) but I don't know how to do that any + * other way. + */ static volatile pid_t pid_to_wait_for; static int pid_to_wait_for_status; @@ -321,6 +324,8 @@ int main(int argc, char **argv) { if (pid == -1) { die("fork parent"); } else if (pid == 0) { + /* child, will become a session leader */ + if (sigprocmask(SIG_SETMASK, &sigset_old, NULL) != 0) { die("sigprocmask setmask child"); } @@ -386,7 +391,7 @@ int main(int argc, char **argv) { close_or_die(STDOUT_FILENO); close_or_die(STDERR_FILENO); - // TODO: EINTR? + /* TODO: EINTR? */ int status; if (waitpid(pid, &status, 0) <= 0) { die("waitpid child"); @@ -414,7 +419,7 @@ int main(int argc, char **argv) { die("tcgetattr"); } term = old_term; - /* From man 3 cfmakeraw which is non-standard. */ + /* From man 3 cfmakeraw; cfmakeraw is non-standard so set it manually. */ term.c_iflag &= ~(tcflag_t)(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON); term.c_oflag &= ~(tcflag_t)(OPOST); term.c_lflag &= ~(tcflag_t)(ECHO | ECHONL | ICANON | ISIG | IEXTEN); -- 2.45.2