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Cygwin: termios: Add comments to the code refactored recently. 

- This patch adds some comments to the source code whose intent may
  not be clear enough from the code which is refactored recently.
This commit is contained in:
Takashi Yano 2022-02-27 20:40:24 +09:00
parent d857df6f08
commit 33d8578feb
2 changed files with 52 additions and 21 deletions
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13
winsup/cygwin/fhandler.h
View File

@ -1902,12 +1902,15 @@ class fhandler_termios: public fhandler_base
virtual void release_input_mutex_if_necessary (void) {};
virtual void discard_input () {};
/* Result status of processing keys in process_sigs(). */
enum process_sig_state {
signalled,
not_signalled,
not_signalled_but_done,
not_signalled_with_nat_reader,
done_with_debugger
signalled, /* Signalled normally */
not_signalled, /* Not signalled at all */
not_signalled_but_done, /* Not signalled, but CTRL_C_EVENT was sent. */
not_signalled_with_nat_reader, /* Not signalled, but detected non-cygwin
process may be reading the tty. */
done_with_debugger /* The key was processed (CTRL_C_EVENT was sent)
for inferior of GDB. */
};
public:

60
winsup/cygwin/fhandler_termios.cc
View File

@ -149,7 +149,8 @@ tty_min::kill_pgrp (int sig, pid_t target_pgid)
if (!p || !p->exists () || p->ctty != ntty || p->pgid != target_pgid)
continue;
if (p->process_state & PID_NOTCYGWIN)
continue;
continue; /* Do not send signal to non-cygwin process to prevent
cmd.exe from crash. */
if (p == myself)
killself = sig != __SIGSETPGRP && !exit_state;
else
@ -309,32 +310,52 @@ fhandler_termios::echo_erase (int force)
doecho ("\b \b", 3);
}
/* The basic policy is as follows:
- The signal generated by key press will be sent only to cygwin process.
- For non-cygwin process, CTRL_C_EVENT will be sent on Ctrl-C. */
/* The inferior of GDB is an exception. GDB does not support to hook signal
even if the inferior is a cygwin app. As a result, inferior cannot be
continued after interruption by Ctrl-C if SIGINT was sent. Therefore,
CTRL_C_EVENT rather than SIGINT is sent to the inferior of GDB. */
fhandler_termios::process_sig_state
fhandler_termios::process_sigs (char c, tty* ttyp, fhandler_termios *fh)
{
termios &ti = ttyp->ti;
pid_t pgid = ttyp->pgid;
/* The name *_nat stands for 'native' which means non-cygwin apps. */
pinfo leader (pgid);
bool cyg_leader = leader && !(leader->process_state & PID_NOTCYGWIN);
bool cyg_leader = /* The process leader is a cygwin process. */
leader && !(leader->process_state & PID_NOTCYGWIN);
bool ctrl_c_event_sent = false;
bool need_discard_input = false;
bool pg_with_nat = false;
bool need_send_sig = false;
bool nat_shell = false;
bool cyg_reader = false;
bool with_debugger = false;
bool with_debugger_nat = false;
bool pg_with_nat = false; /* The process group has non-cygwin processes. */
bool need_send_sig = false; /* There is process which need the signal. */
bool nat_shell = false; /* The shell seems to be a non-cygwin process. */
bool cyg_reader = false; /* Cygwin process is reading the tty. */
bool with_debugger = false; /* GDB is debugging cygwin app. */
bool with_debugger_nat = false; /* GDB is debugging non-cygwin app. */
winpids pids ((DWORD) 0);
for (unsigned i = 0; i < pids.npids; i++)
{
_pinfo *p = pids[i];
/* PID_NOTCYGWIN: check this for non-cygwin process.
PID_NEW_PG: check this ofr GDB with non-cygwin inferior in pty
without pcon enabled. In this case, the inferior is not
cygwin process list. PID_NEW_PG is set as a marker for
GDB with non-cygwin inferior in pty code.
!PID_CYGPARENT: check this for GDB with cygwin inferior. */
if (c == '\003' && p && p->ctty == ttyp->ntty && p->pgid == pgid
&& ((p->process_state & PID_NOTCYGWIN)
|| (p->process_state & PID_NEW_PG)
|| !(p->process_state & PID_CYGPARENT)))
{
/* Ctrl-C event will be sent only to the processes attaching
to the same console. Therefore, attach to the console to
which the target process is attaching before sending the
CTRL_C_EVENT. After sending the event, reattach to the
console to which the process was previously attached. */
pinfo pinfo_resume = pinfo (myself->ppid);
DWORD resume_pid = 0;
if (pinfo_resume)
@ -361,7 +382,8 @@ fhandler_termios::process_sigs (char c, tty* ttyp, fhandler_termios *fh)
&& (p->process_state & PID_NOTCYGWIN))
GenerateConsoleCtrlEvent (CTRL_BREAK_EVENT, p->dwProcessId);
else if ((!fh || fh->need_send_ctrl_c_event () || cyg_leader)
&& !ctrl_c_event_sent)
&& !ctrl_c_event_sent) /* cyg_leader is needed by GDB
with non-cygwin inferior */
{
GenerateConsoleCtrlEvent (CTRL_C_EVENT, 0);
ctrl_c_event_sent = true;
@ -378,13 +400,13 @@ fhandler_termios::process_sigs (char c, tty* ttyp, fhandler_termios *fh)
if (p && p->ctty == ttyp->ntty && p->pgid == pgid)
{
if (p->process_state & PID_NOTCYGWIN)
pg_with_nat = true;
pg_with_nat = true; /* The process group has non-cygwin process */
if (!(p->process_state & PID_NOTCYGWIN))
need_send_sig = true;
need_send_sig = true; /* Process which needs signal exists */
if (!p->cygstarted)
nat_shell = true;
nat_shell = true; /* The shell seems to a non-cygwin shell */
if (p->process_state & PID_TTYIN)
cyg_reader = true;
cyg_reader = true; /* Theh process is reading the tty */
if (!p->cygstarted && !(p->process_state & PID_NOTCYGWIN)
&& (p != myself || being_debugged ())
&& cyg_leader) /* inferior is cygwin app */
@ -406,8 +428,12 @@ fhandler_termios::process_sigs (char c, tty* ttyp, fhandler_termios *fh)
return done_with_debugger;
}
if (with_debugger_nat)
return not_signalled;
/* Send SIGQUIT to non-cygwin process. */
return not_signalled; /* Do not process slgnal keys further.
The non-cygwin inferior of GDB cannot receive
the signals. */
/* Send SIGQUIT to non-cygwin process. Non-cygwin app will not be alerted
by kill_pgrp(), however, QUIT key should quit the non-cygwin app
if it is started along with cygwin process from cygwin shell. */
if ((ti.c_lflag & ISIG) && CCEQ (ti.c_cc[VQUIT], c)
&& pg_with_nat && need_send_sig && !nat_shell)
{
@ -426,7 +452,9 @@ fhandler_termios::process_sigs (char c, tty* ttyp, fhandler_termios *fh)
sig = SIGINT;
else if (CCEQ (ti.c_cc[VQUIT], c))
sig = SIGQUIT;
else if (pg_with_nat)
else if (pg_with_nat) /* If the process group has a non-cygwin process,
it cannot be suspended correctly. Therefore,
do not send SIGTSTP. */
goto not_a_sig;
else if (CCEQ (ti.c_cc[VSUSP], c))
sig = SIGTSTP;