Add tcsetsid(3).

The entire world seems to use the non-standard TIOCSCTTY ioctl to make a
TTY a controlling terminal of a session. Even though tcsetsid(3) is also
non-standard, I think it's a lot better to use in our own source code,
mainly because it's similar to tcsetpgrp(), tcgetpgrp() and tcgetsid().

I stole the idea from QNX. They do it the other way around; their
TIOCSCTTY is just a wrapper around tcsetsid(). tcsetsid() then calls
into an IPC framework.

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/libc/gen/termios.c b/lib/libc/gen/termios.c
index 4c6dcff..85ca4e3 100644
--- a/lib/libc/gen/termios.c
+++ b/lib/libc/gen/termios.c
@@ -110,6 +110,18 @@ tcgetsid(int fd)
 	return ((pid_t)s);
 }
 
+int
+tcsetsid(int fd, pid_t pid)
+{
+
+	if (pid != getsid(0)) {
+		errno = EINVAL;
+		return (-1);
+	}
+
+	return (_ioctl(fd, TIOCSCTTY, NULL));
+}
+
 speed_t
 cfgetospeed(t)
 	const struct termios *t;