Re: [RFC PATCH 8/8] signals: Support BSD VSTATUS, KERNINFO and SIGINFO

[Arseny Maslennikov]

On Mon, Jan 03, 2022 at 10:19:56AM -0800, Walt Drummond wrote:
> Support TTY VSTATUS character, NOKERNINFO local control bit and the
> signal SIGINFO, all as in 4.3BSD.
> 
> Signed-off-by: Walt Drummond <walt@xxxxxxxxxxx>
> ---
>  arch/x86/include/asm/signal.h       |   2 +-
>  arch/x86/include/uapi/asm/signal.h  |   4 +-
>  drivers/tty/Makefile                |   2 +-
>  drivers/tty/n_tty.c                 |  21 +++++
>  drivers/tty/tty_io.c                |  10 ++-
>  drivers/tty/tty_ioctl.c             |   4 +
>  drivers/tty/tty_status.c            | 135 ++++++++++++++++++++++++++++
>  fs/proc/array.c                     |  29 +-----
>  include/asm-generic/termios.h       |   4 +-
>  include/linux/sched.h               |  52 ++++++++++-
>  include/linux/signal.h              |   4 +
>  include/linux/tty.h                 |   8 ++
>  include/uapi/asm-generic/ioctls.h   |   2 +
>  include/uapi/asm-generic/signal.h   |   6 +-
>  include/uapi/asm-generic/termbits.h |  34 +++----
>  15 files changed, 264 insertions(+), 53 deletions(-)
>  create mode 100644 drivers/tty/tty_status.c
> 
> diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h
> index d8e2efe6cd46..0a01877c11ab 100644
> --- a/arch/x86/include/asm/signal.h
> +++ b/arch/x86/include/asm/signal.h
> @@ -8,7 +8,7 @@
>  /* Most things should be clean enough to redefine this at will, if care
>     is taken to make libc match.  */
>  
> -#define _NSIG		64
> +#define _NSIG		65
>  
>  #ifdef __i386__
>  # define _NSIG_BPW	32
> diff --git a/arch/x86/include/uapi/asm/signal.h b/arch/x86/include/uapi/asm/signal.h
> index 164a22a72984..60dca62d3dcf 100644
> --- a/arch/x86/include/uapi/asm/signal.h
> +++ b/arch/x86/include/uapi/asm/signal.h
> @@ -60,7 +60,9 @@ typedef unsigned long sigset_t;
>  
>  /* These should not be considered constants from userland.  */
>  #define SIGRTMIN	32
> -#define SIGRTMAX	_NSIG
> +#define SIGRTMAX	64
> +
> +#define SIGINFO		65
>  
>  #define SA_RESTORER	0x04000000
>  
> diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
> index a2bd75fbaaa4..d50ba690bb87 100644
> --- a/drivers/tty/Makefile
> +++ b/drivers/tty/Makefile
> @@ -2,7 +2,7 @@
>  obj-$(CONFIG_TTY)		+= tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \
>  				   tty_buffer.o tty_port.o tty_mutex.o \
>  				   tty_ldsem.o tty_baudrate.o tty_jobctrl.o \
> -				   n_null.o
> +				   n_null.o tty_status.o
>  obj-$(CONFIG_LEGACY_PTYS)	+= pty.o
>  obj-$(CONFIG_UNIX98_PTYS)	+= pty.o
>  obj-$(CONFIG_AUDIT)		+= tty_audit.o
> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
> index 0ec93f1a61f5..b510e01289fd 100644
> --- a/drivers/tty/n_tty.c
> +++ b/drivers/tty/n_tty.c
> @@ -1334,6 +1334,24 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
>  			commit_echoes(tty);
>  			return;
>  		}
> +#ifdef VSTATUS
> +		if (c == STATUS_CHAR(tty)) {
> +			/* Do the status message first and then send
> +			 * the signal, otherwise signal delivery can
> +			 * change the process state making the status
> +			 * message misleading.  Also, use __isig() and
> +			 * not sig(), as if we flush the tty we can
> +			 * lose parts of the message.

...As well as the character input in the canonical mode's built-in line
editor.

> +			 */
> +
> +			if (!L_NOKERNINFO(tty))
> +				tty_status(tty);
> +# if defined(SIGINFO) && SIGINFO != SIGPWR
> +			__isig(SIGINFO, tty);
> +# endif
> +			return;
> +		}
> +#endif	/* VSTATUS */
>  		if (c == '\n') {
>  			if (L_ECHO(tty) || L_ECHONL(tty)) {
>  				echo_char_raw('\n', ldata);
> @@ -1763,6 +1781,9 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
>  			set_bit(EOF_CHAR(tty), ldata->char_map);
>  			set_bit('\n', ldata->char_map);
>  			set_bit(EOL_CHAR(tty), ldata->char_map);
> +#ifdef VSTATUS
> +			set_bit(STATUS_CHAR(tty), ldata->char_map);
> +#endif
>  			if (L_IEXTEN(tty)) {
>  				set_bit(WERASE_CHAR(tty), ldata->char_map);
>  				set_bit(LNEXT_CHAR(tty), ldata->char_map);
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 6616d4a0d41d..8e488ecba330 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -120,18 +120,26 @@
>  #define TTY_PARANOIA_CHECK 1
>  #define CHECK_TTY_COUNT 1
>  
> +/* Less ugly than an ifdef in the middle of the initalizer below, maybe? */
> +#ifdef NOKERNINFO
> +# define __NOKERNINFO NOKERNINFO
> +#else
> +# define __NOKERNINFO 0
> +#endif
> +
>  struct ktermios tty_std_termios = {	/* for the benefit of tty drivers  */
>  	.c_iflag = ICRNL | IXON,
>  	.c_oflag = OPOST | ONLCR,
>  	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
>  	.c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
> -		   ECHOCTL | ECHOKE | IEXTEN,
> +		   ECHOCTL | ECHOKE | IEXTEN | __NOKERNINFO,
>  	.c_cc = INIT_C_CC,
>  	.c_ispeed = 38400,
>  	.c_ospeed = 38400,
>  	/* .c_line = N_TTY, */
>  };
>  EXPORT_SYMBOL(tty_std_termios);
> +#undef __NOKERNINFO
>  
>  /* This list gets poked at by procfs and various bits of boot up code. This
>   * could do with some rationalisation such as pulling the tty proc function
> diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
> index 507a25d692bb..b250eabca1ba 100644
> --- a/drivers/tty/tty_ioctl.c
> +++ b/drivers/tty/tty_ioctl.c
> @@ -809,6 +809,10 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
>  		if (get_user(arg, (unsigned int __user *) arg))
>  			return -EFAULT;
>  		return tty_change_softcar(real_tty, arg);
> +#ifdef TIOCSTAT
> +	case TIOCSTAT:
> +		return tty_status(real_tty);
> +#endif
>  	default:
>  		return -ENOIOCTLCMD;
>  	}
> diff --git a/drivers/tty/tty_status.c b/drivers/tty/tty_status.c
> new file mode 100644

Nitpick: the new functionality is part of n_tty and not the generic tty
subsystem, so "tty_status.c" is a misleading name for the new file,
unlike e. g. "n_tty_status.c". It has no use in the various modem
drivers, for example.
Likewise for the tty_status() function.

> index 000000000000..a9600f5bd48c
> --- /dev/null
> +++ b/drivers/tty/tty_status.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-1.0+
> +/*
> + * tty_status.c --- implements VSTATUS and TIOCSTAT from BSD4.3/4.4
> + *
> + */
> +
> +#include <linux/sched.h>
> +#include <linux/mm.h>
> +#include <linux/tty.h>
> +#include <linux/sched/cputime.h>
> +#include <linux/sched/loadavg.h>
> +#include <linux/pid.h>
> +#include <linux/slab.h>
> +#include <linux/math64.h>
> +
> +#define MSGLEN (160 + TASK_COMM_LEN)
> +
> +inline unsigned long getRSSk(struct mm_struct *mm)
> +{
> +	if (mm == NULL)
> +		return 0;
> +	return get_mm_rss(mm) * PAGE_SIZE / 1024;
> +}
> +
> +inline long nstoms(long l)
> +{
> +	l /= NSEC_PER_MSEC * 10;
> +	if (l < 10)
> +		l *= 10;
> +	return l;
> +}
> +
> +inline struct task_struct *compare(struct task_struct *new,
> +				   struct task_struct *old)
> +{
> +	unsigned int ostate, nstate;
> +
> +	if (old == NULL)
> +		return new;
> +
> +	ostate = task_state_index(old);
> +	nstate = task_state_index(new);
> +
> +	if (ostate == nstate) {
> +		if (old->start_time > new->start_time)
> +			return old;
> +		return new;
> +	}
> +
> +	if (ostate < nstate)
> +		return old;
> +
> +	return new;
> +}
> +
> +struct task_struct *pick_process(struct pid *pgrp)
> +{
> +	struct task_struct *p, *winner = NULL;
> +
> +	read_lock(&tasklist_lock);
> +	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
> +		winner = compare(p, winner);
> +	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
> +	read_unlock(&tasklist_lock);
> +
> +	return winner;
> +}
> +
> +int tty_status(struct tty_struct *tty)
> +{
> +	char tname[TASK_COMM_LEN];
> +	unsigned long loadavg[3];
> +	uint64_t pcpu, cputime, wallclock;
> +	struct task_struct *p;
> +	struct rusage rusage;
> +	struct timespec64 utime, stime, rtime;
> +	char msg[MSGLEN] = {0};
> +	int len = 0;
> +
> +	if (tty == NULL)
> +		return -ENOTTY;
> +
> +	get_avenrun(loadavg, FIXED_1/200, 0);
> +	len += scnprintf((char *)&msg[len], MSGLEN - len, "load: %lu.%02lu  ",
> +		       LOAD_INT(loadavg[0]), LOAD_FRAC(loadavg[0]));
> +
> +	if (tty->ctrl.session == NULL) {
> +		len += scnprintf((char *)&msg[len], MSGLEN - len,
> +				 "not a controlling terminal");
> +		goto print;
> +	}
> +
> +	if (tty->ctrl.pgrp == NULL) {
> +		len += scnprintf((char *)&msg[len], MSGLEN - len,
> +				 "no foreground process group");
> +		goto print;
> +	}
> +
> +	p = pick_process(tty->ctrl.pgrp);
> +	if (p == NULL) {
> +		len += scnprintf((char *)&msg[len], MSGLEN - len,
> +				 "empty foreground process group");
> +		goto print;
> +	}
> +
> +	get_task_comm(tname, p);
> +	getrusage(p, RUSAGE_BOTH, &rusage);
> +	wallclock = ktime_get_ns() - p->start_time;
> +
> +	utime.tv_sec = rusage.ru_utime.tv_sec;
> +	utime.tv_nsec = rusage.ru_utime.tv_usec * NSEC_PER_USEC;
> +	stime.tv_sec = rusage.ru_stime.tv_sec;
> +	stime.tv_nsec = rusage.ru_stime.tv_usec * NSEC_PER_USEC;
> +	rtime = ns_to_timespec64(wallclock);
> +
> +	cputime = timespec64_to_ns(&utime) + timespec64_to_ns(&stime);
> +	pcpu = div64_u64(cputime * 100, wallclock);
> +
> +	len += scnprintf((char *)&msg[len], MSGLEN - len,
> +			 /* task, PID, task state */
> +			 "cmd: %s %d [%s] "
> +			 /* rtime,    utime,      stime,      %cpu,  rss */
> +			 "%llu.%02lur %llu.%02luu %llu.%02lus %llu%% %luk",
> +			 tname,	task_pid_vnr(p), (char *)get_task_state_name(p),
> +			 rtime.tv_sec, nstoms(rtime.tv_nsec),
> +			 utime.tv_sec, nstoms(utime.tv_nsec),
> +			 stime.tv_sec, nstoms(stime.tv_nsec),
> +			 pcpu, getRSSk(p->mm));
> +
> +print:
> +	len += scnprintf((char *)&msg[len], MSGLEN - len, "\r\n");
> +	tty_write_message(tty, msg);

tty_write_message() is quite risky to use; while writing my
implementation a couple of years ago I've found it easy to accidentally
set up deadlocks with this interface — in particular if the function is
called from the tty character receive path.
I hope you're testing the functionality with CONFIG_PROVE_LOCKING enabled.

> +
> +	return 0;
> +}
> diff --git a/fs/proc/array.c b/fs/proc/array.c
> index f37c03077b58..eb14306cdde2 100644
> --- a/fs/proc/array.c
> +++ b/fs/proc/array.c
> @@ -62,6 +62,7 @@
>  #include <linux/tty.h>
>  #include <linux/string.h>
>  #include <linux/mman.h>
> +#include <linux/sched.h>
>  #include <linux/sched/mm.h>
>  #include <linux/sched/numa_balancing.h>
>  #include <linux/sched/task_stack.h>
> @@ -111,34 +112,6 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
>  		seq_printf(m, "%.64s", tcomm);
>  }
>  
> -/*
> - * The task state array is a strange "bitmap" of
> - * reasons to sleep. Thus "running" is zero, and
> - * you can test for combinations of others with
> - * simple bit tests.
> - */
> -static const char * const task_state_array[] = {
> -
> -	/* states in TASK_REPORT: */
> -	"R (running)",		/* 0x00 */
> -	"S (sleeping)",		/* 0x01 */
> -	"D (disk sleep)",	/* 0x02 */
> -	"T (stopped)",		/* 0x04 */
> -	"t (tracing stop)",	/* 0x08 */
> -	"X (dead)",		/* 0x10 */
> -	"Z (zombie)",		/* 0x20 */
> -	"P (parked)",		/* 0x40 */
> -
> -	/* states beyond TASK_REPORT: */
> -	"I (idle)",		/* 0x80 */
> -};
> -
> -static inline const char *get_task_state(struct task_struct *tsk)
> -{
> -	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> -	return task_state_array[task_state_index(tsk)];
> -}
> -
>  static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
>  				struct pid *pid, struct task_struct *p)
>  {
> diff --git a/include/asm-generic/termios.h b/include/asm-generic/termios.h
> index b1398d0d4a1d..9b080e1a82d4 100644
> --- a/include/asm-generic/termios.h
> +++ b/include/asm-generic/termios.h
> @@ -10,9 +10,9 @@
>  	eof=^D		vtime=\0	vmin=\1		sxtc=\0
>  	start=^Q	stop=^S		susp=^Z		eol=\0
>  	reprint=^R	discard=^U	werase=^W	lnext=^V
> -	eol2=\0
> +	eol2=\0         status=^T
>  */
> -#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
> +#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
>  
>  /*
>   * Translate a "termio" structure into a "termios". Ugh.
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index c1a927ddec64..2171074ec8f5 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -70,7 +70,7 @@ struct task_group;
>  
>  /*
>   * Task state bitmask. NOTE! These bits are also
> - * encoded in fs/proc/array.c: get_task_state().
> + * encoded in get_task_state().
>   *
>   * We have two separate sets of flags: task->state
>   * is about runnability, while task->exit_state are
> @@ -1643,6 +1643,56 @@ static inline char task_state_to_char(struct task_struct *tsk)
>  	return task_index_to_char(task_state_index(tsk));
>  }
>  
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> +	static const char * const task_state_array[] = {
> +
> +		/* states in TASK_REPORT: */
> +		"running",		/* 0x00 */
> +		"sleeping",		/* 0x01 */
> +		"disk sleep",		/* 0x02 */
> +		"stopped",		/* 0x04 */
> +		"tracing stop",		/* 0x08 */
> +		"dead",			/* 0x10 */
> +		"zombie",		/* 0x20 */
> +		"parked",		/* 0x40 */
> +
> +		/* states beyond TASK_REPORT: */
> +		"idle",			/* 0x80 */
> +	};
> +
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> +	return task_state_array[task_state_index(tsk)];
> +}
> +
> +static inline const char *get_task_state(struct task_struct *tsk)
> +{
> +	/*
> +	 * The task state array is a strange "bitmap" of
> +	 * reasons to sleep. Thus "running" is zero, and
> +	 * you can test for combinations of others with
> +	 * simple bit tests.
> +	 */
> +	static const char * const task_state_array[] = {
> +
> +		/* states in TASK_REPORT: */
> +		"R (running)",		/* 0x00 */
> +		"S (sleeping)",		/* 0x01 */
> +		"D (disk sleep)",	/* 0x02 */
> +		"T (stopped)",		/* 0x04 */
> +		"t (tracing stop)",	/* 0x08 */
> +		"X (dead)",		/* 0x10 */
> +		"Z (zombie)",		/* 0x20 */
> +		"P (parked)",		/* 0x40 */
> +
> +		/* states beyond TASK_REPORT: */
> +		"I (idle)",		/* 0x80 */
> +	};
> +
> +	BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> +	return task_state_array[task_state_index(tsk)];
> +}
> +
>  /**
>   * is_global_init - check if a task structure is init. Since init
>   * is free to have sub-threads we need to check tgid.
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index b77f9472a37c..76bda1a20578 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -541,6 +541,7 @@ extern bool unhandled_signal(struct task_struct *tsk, int sig);
>   *	|  non-POSIX signal  |  default action  |
>   *	+--------------------+------------------+
>   *	|  SIGEMT            |  coredump	|
> + *	|  SIGINFO	     |	ignore		|
>   *	+--------------------+------------------+
>   *
>   * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
> @@ -567,6 +568,9 @@ static inline int sig_kernel_ignore(unsigned long sig)
>  	return	sig == SIGCONT	||
>  		sig == SIGCHLD	||
>  		sig == SIGWINCH ||
> +#if defined(SIGINFO) && SIGINFO != SIGPWR
> +		sig == SIGINFO  ||
> +#endif
>  		sig == SIGURG;
>  }
>  
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 168e57e40bbb..943d85aa471c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,9 @@
>  #define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE])
>  #define LNEXT_CHAR(tty)	((tty)->termios.c_cc[VLNEXT])
>  #define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2])
> +#ifdef VSTATUS
> +#define STATUS_CHAR(tty) ((tty)->termios.c_cc[VSTATUS])
> +#endif
>  
>  #define _I_FLAG(tty, f)	((tty)->termios.c_iflag & (f))
>  #define _O_FLAG(tty, f)	((tty)->termios.c_oflag & (f))
> @@ -114,6 +117,9 @@
>  #define L_PENDIN(tty)	_L_FLAG((tty), PENDIN)
>  #define L_IEXTEN(tty)	_L_FLAG((tty), IEXTEN)
>  #define L_EXTPROC(tty)	_L_FLAG((tty), EXTPROC)
> +#ifdef NOKERNINFO
> +#define L_NOKERNINFO(tty) _L_FLAG((tty), NOKERNINFO)
> +#endif
>  
>  struct device;
>  struct signal_struct;
> @@ -428,4 +434,6 @@ extern void tty_lock_slave(struct tty_struct *tty);
>  extern void tty_unlock_slave(struct tty_struct *tty);
>  extern void tty_set_lock_subclass(struct tty_struct *tty);
>  
> +extern int tty_status(struct tty_struct *tty);
> +
>  #endif
> diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
> index cdc9f4ca8c27..baa2b8d42679 100644
> --- a/include/uapi/asm-generic/ioctls.h
> +++ b/include/uapi/asm-generic/ioctls.h
> @@ -97,6 +97,8 @@
>  
>  #define TIOCMIWAIT	0x545C	/* wait for a change on serial input line(s) */
>  #define TIOCGICOUNT	0x545D	/* read serial port inline interrupt counts */
> +/* Some architectures use 0x545E for FIOQSIZE */
> +#define TIOCSTAT        0x545F	/* display process group stats on tty */
>  
>  /*
>   * Some arches already define FIOQSIZE due to a historical
> diff --git a/include/uapi/asm-generic/signal.h b/include/uapi/asm-generic/signal.h
> index 3c4cc9b8378e..0b771eb1db94 100644
> --- a/include/uapi/asm-generic/signal.h
> +++ b/include/uapi/asm-generic/signal.h
> @@ -4,7 +4,7 @@
>  
>  #include <linux/types.h>
>  
> -#define _NSIG		64
> +#define _NSIG		65
>  #define _NSIG_BPW	__BITS_PER_LONG
>  #define _NSIG_WORDS	((_NSIG + _NSIG_BPW - 1) / _NSIG_BPW)
>  
> @@ -49,9 +49,11 @@
>  /* These should not be considered constants from userland.  */
>  #define SIGRTMIN	32
>  #ifndef SIGRTMAX
> -#define SIGRTMAX	_NSIG
> +#define SIGRTMAX	64
>  #endif
>  
> +#define SIGINFO		65
> +
>  #if !defined MINSIGSTKSZ || !defined SIGSTKSZ
>  #define MINSIGSTKSZ	2048
>  #define SIGSTKSZ	8192
> diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
> index 2fbaf9ae89dd..cb4e9c6d629f 100644
> --- a/include/uapi/asm-generic/termbits.h
> +++ b/include/uapi/asm-generic/termbits.h
> @@ -58,6 +58,7 @@ struct ktermios {
>  #define VWERASE 14
>  #define VLNEXT 15
>  #define VEOL2 16
> +#define VSTATUS 17
>  
>  /* c_iflag bits */
>  #define IGNBRK	0000001
> @@ -164,22 +165,23 @@ struct ktermios {
>  #define IBSHIFT	  16		/* Shift from CBAUD to CIBAUD */
>  
>  /* c_lflag bits */
> -#define ISIG	0000001
> -#define ICANON	0000002
> -#define XCASE	0000004
> -#define ECHO	0000010
> -#define ECHOE	0000020
> -#define ECHOK	0000040
> -#define ECHONL	0000100
> -#define NOFLSH	0000200
> -#define TOSTOP	0000400
> -#define ECHOCTL	0001000
> -#define ECHOPRT	0002000
> -#define ECHOKE	0004000
> -#define FLUSHO	0010000
> -#define PENDIN	0040000
> -#define IEXTEN	0100000
> -#define EXTPROC	0200000
> +#define ISIG	   0000001
> +#define ICANON	   0000002
> +#define XCASE	   0000004
> +#define ECHO	   0000010
> +#define ECHOE	   0000020
> +#define ECHOK	   0000040
> +#define ECHONL	   0000100
> +#define NOFLSH	   0000200
> +#define TOSTOP	   0000400
> +#define ECHOCTL	   0001000
> +#define ECHOPRT	   0002000
> +#define ECHOKE	   0004000
> +#define FLUSHO	   0010000
> +#define PENDIN	   0040000
> +#define IEXTEN	   0100000
> +#define EXTPROC	   0200000
> +#define NOKERNINFO 0400000
>  
>  /* tcflow() and TCXONC use these */
>  #define	TCOOFF		0
> -- 
> 2.30.2
>

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