drivers/serial: add job-control TTY ioctls#19184
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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>
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acassis
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Jun 21, 2026
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@xiaoxiang781216 so Ctrl+Z will not "freeZe" a process the same way it does on Linux? For example on Linux: |
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@FelipeMdeO this patch may help you port dropbear. |
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Integrated SSH daemon authenticating against FSUTILS_PASSWD, with an ECDSA P-256 host key and an NSH session over a PTY per connection. Built from the upstream Dropbear tarball (pinned commit) and patched for NuttX, using Dropbear's bundled libtomcrypt for all crypto. setsid() is taken from NuttX libc (apache/nuttx#19184) instead of a local prototype. Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
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Integrated SSH daemon authenticating against FSUTILS_PASSWD, with an ECDSA P-256 host key and an NSH session over a PTY per connection. Built from the upstream Dropbear tarball (pinned commit) and patched for NuttX, using Dropbear's bundled libtomcrypt for all crypto. setsid() (apache/nuttx#19184) and link() now come from NuttX, not local stubs. Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
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Integrated SSH daemon authenticating against FSUTILS_PASSWD, with an ECDSA P-256 host key and an NSH session over a PTY per connection. Built from the upstream Dropbear tarball (pinned commit) and patched for NuttX, using Dropbear's bundled libtomcrypt for all crypto. setsid() (apache/nuttx#19184) and link() now come from NuttX, not local stubs. Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
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Integrated SSH daemon authenticating against FSUTILS_PASSWD, with an ECDSA P-256 host key and an NSH session over a PTY per connection. Built from the upstream Dropbear tarball (pinned commit) and patched for NuttX, using Dropbear's bundled libtomcrypt for all crypto. setsid() (apache/nuttx#19184) and link() now come from NuttX, not local stubs. Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
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Integrated SSH daemon authenticating against FSUTILS_PASSWD, with an ECDSA P-256 host key and an NSH session over a PTY per connection. Built from the upstream Dropbear tarball (pinned commit) and patched for NuttX, using Dropbear's bundled libtomcrypt for all crypto. setsid() (apache/nuttx#19184) and link() now come from NuttX, not local stubs. Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
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Summary
Add lightweight job-control/controlling-terminal support for serial and PTY drivers on systems without a real POSIX session/process-group model.
NuttX currently treats each task as its own process group. This patch keeps that model (
pgrp == pid) and adds the missing APIs/ioctls needed by portable software such as dropbear/socat:TIOCGPGRP,TIOCSPGRP, andTIOCGSIDioctl numbers.serial.candpty.cto support:TIOCSCTTY:arg > 0preserves the existing NuttX convention of passing an explicit target PID (used by NSH for foreground commands), whilearg == 0follows POSIX-style flag semantics and selects the calling task.TIOCGPGRP/TIOCGSID: return the current foreground PID.TIOCSPGRP: set the foreground PID (or caller when pgrp is zero).tcgetpgrp(),tcsetpgrp(),tcgetsid()over the new ioctls.setsid(),getsid(),setpgid()stubs consistent with the existing single-member process-group model.Documentation/components/drivers/character/serial.rst.Rationale
This avoids regressing existing NSH behavior where
TIOCSCTTYis used to register a spawned foreground command as the Ctrl-C/Ctrl-Z signal target, while also supporting the POSIX-styleioctl(fd, TIOCSCTTY, 0)pattern used by dropbear and similar software.Group-broadcast signaling (
kill(-pgrp, signo)) remains unsupported, so TTY-generated signals still target a single foreground PID.Testing
sim:nsh boot and ctrl+c work as before.