{bp-19184} drivers/serial: add job-control TTY ioctls and libc wrappers - #19708
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NuttX has no real session/process-group abstraction, so the TTY layer collapses the foreground process group onto the single dev->pid field (pgrp == pid, one member per group). Extend the controlling-terminal support so portable software (e.g. dropbear, socat) that relies on job-control primitives works without losing the existing NuttX-specific behaviour. Driver (serial.c, pty.c): - TIOCSCTTY now accepts a flag: arg > 0 keeps the historical "target PID in arg" semantics (NSH registers the foreground command it just spawned), while arg == 0 selects the calling task via nxsched_getpid(), matching the POSIX flag convention used by dropbear/socat/apue. This preserves all existing callers and makes the previously-dead arg==0 path deliver SIGINT correctly. - Add TIOCGPGRP/TIOCGSID (return dev->pid) and TIOCSPGRP (set it). - pty.c gains the same handlers against pd_pid and includes nuttx/sched.h for nxsched_getpid(). ioctl numbers (tioctl.h): TIOCGPGRP/TIOCSPGRP/TIOCGSID at 0x37-0x39. libc wrappers: - termios: tcgetpgrp(), tcsetpgrp(), tcgetsid() over the new ioctls. - unistd: setsid()/getsid()/setpgid() stubs consistent with the existing getpgrp()/getpgid() single-session model (sid == pgid == pid; setpgid only succeeds for pgid == pid). Declare the new prototypes in unistd.h (tcgetsid was already in termios.h) and register all sources in the Make.defs/CMakeLists. Group-broadcast signalling (kill(-pgrp)) remains unsupported, so tty signals still target the single dev->pid; a real session/process group model is left as a follow-up. Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
jerpelea
requested review from
Donny9,
GUIDINGLI,
acassis,
btashton,
hartmannathan and
xiaoxiang781216
as code owners
August 6, 2026 07:28
xiaoxiang781216
approved these changes
Aug 6, 2026
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Area: Drivers
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Summary
NuttX has no real session/process-group abstraction, so the TTY layer collapses the foreground process group onto the single dev->pid field (pgrp == pid, one member per group). Extend the controlling-terminal support so portable software (e.g. dropbear, socat) that relies on job-control primitives works without losing the existing NuttX-specific behaviour.
Driver (serial.c, pty.c):
ioctl numbers (tioctl.h): TIOCGPGRP/TIOCSPGRP/TIOCGSID at 0x37-0x39.
libc wrappers:
Declare the new prototypes in unistd.h (tcgetsid was already in termios.h) and register all sources in the Make.defs/CMakeLists.
Group-broadcast signalling (kill(-pgrp)) remains unsupported, so tty signals still target the single dev->pid; a real session/process group model is left as a follow-up.
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