Update and improve comments

diff --git a/ptyas.c b/ptyas.c
index 05170ec9ed7fd04f534476dfb2cae3bd307ea08a..1deda82a2e48cf265a73f5b86789bb98395fa2c9 100644 (file)
--- 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);