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Cygwin: pty: Fix race issue in inheritance of pseudo console. 

- If multiple non-cygwin processes are started/ended simultaneously,
  inheritance of pseudo console sometimes fails. This patch fixes
  the issue.

  Addresses:
    https://cygwin.com/pipermail/cygwin/2021-April/248292.html
This commit is contained in:
Takashi Yano 2021-04-19 19:30:46 +09:00 committed by Corinna Vinschen
parent b4fc81edcc
commit bb93c6d7c2
3 changed files with 69 additions and 56 deletions
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92
winsup/cygwin/fhandler_tty.cc
View File

@ -1072,6 +1072,24 @@ fhandler_pty_slave::set_switch_to_pcon (void)
}
}
inline static bool
pcon_pid_alive (DWORD pid)
{
if (pid == 0)
return false;
HANDLE h = OpenProcess (SYNCHRONIZE, FALSE, pid);
if (h == NULL)
return false;
CloseHandle (h);
return true;
}
inline static bool
pcon_pid_self (DWORD pid)
{
return (pid == myself->exec_dwProcessId);
}
void
fhandler_pty_slave::reset_switch_to_pcon (void)
{
@ -1153,17 +1171,8 @@ fhandler_pty_slave::reset_switch_to_pcon (void)
if (isHybrid)
return;
WaitForSingleObject (pcon_mutex, INFINITE);
HANDLE h;
if (get_ttyp ()->pcon_pid > MAX_PID &&
(h = OpenProcess (SYNCHRONIZE, FALSE, get_ttyp ()->pcon_pid - MAX_PID)))
{
/* There is a process which is grabbing pseudo console. */
CloseHandle (h);
ReleaseMutex (pcon_mutex);
return;
}
if (get_ttyp ()->pcon_pid && get_ttyp ()->pcon_pid != myself->pid
&& !!pinfo (get_ttyp ()->pcon_pid))
if (!pcon_pid_self (get_ttyp ()->pcon_pid)
&& pcon_pid_alive (get_ttyp ()->pcon_pid))
{
/* There is a process which is grabbing pseudo console. */
ReleaseMutex (pcon_mutex);
@ -1975,12 +1984,9 @@ fhandler_pty_common::resize_pseudo_console (struct winsize *ws)
COORD size;
size.X = ws->ws_col;
size.Y = ws->ws_row;
pinfo p (get_ttyp ()->pcon_pid);
if (p)
{
HPCON_INTERNAL hpcon_local;
HANDLE pcon_owner =
OpenProcess (PROCESS_DUP_HANDLE, FALSE, p->exec_dwProcessId);
OpenProcess (PROCESS_DUP_HANDLE, FALSE, get_ttyp ()->pcon_pid);
DuplicateHandle (pcon_owner, get_ttyp ()->h_pcon_write_pipe,
GetCurrentProcess (), &hpcon_local.hWritePipe,
0, TRUE, DUPLICATE_SAME_ACCESS);
@ -1988,7 +1994,6 @@ fhandler_pty_common::resize_pseudo_console (struct winsize *ws)
CloseHandle (pcon_owner);
CloseHandle (hpcon_local.hWritePipe);
}
}
void
fhandler_pty_master::cleanup ()
@ -3085,9 +3090,8 @@ fhandler_pty_slave::setup_pseudoconsole (bool nopcon)
{
fhandler_pty_slave *ptys = (fhandler_pty_slave *) fh;
ptys->get_ttyp ()->switch_to_pcon_in = true;
if (ptys->get_ttyp ()->pcon_pid == 0
|| !pinfo (ptys->get_ttyp ()->pcon_pid))
ptys->get_ttyp ()->pcon_pid = myself->pid;
if (!pcon_pid_alive (ptys->get_ttyp ()->pcon_pid))
ptys->get_ttyp ()->pcon_pid = myself->exec_dwProcessId;
}
if (nopcon)
@ -3107,8 +3111,7 @@ fhandler_pty_slave::setup_pseudoconsole (bool nopcon)
}
HANDLE hpConIn, hpConOut;
if (get_ttyp ()->pcon_pid && get_ttyp ()->pcon_pid != myself->pid
&& !!pinfo (get_ttyp ()->pcon_pid) && get_ttyp ()->pcon_activated)
if (get_ttyp ()->pcon_activated)
{
if (GetStdHandle (STD_INPUT_HANDLE) == get_handle ())
{ /* Send CSI6n just for requesting transfer input. */
@ -3119,11 +3122,14 @@ fhandler_pty_slave::setup_pseudoconsole (bool nopcon)
get_ttyp ()->pcon_start_pid = myself->pid;
WriteFile (get_output_handle (), "\033[6n", 4, &n, NULL);
ReleaseMutex (input_mutex);
while (get_ttyp ()->pcon_start)
Sleep (1);
}
/* Attach to the pseudo console which already exits. */
pinfo p (get_ttyp ()->pcon_pid);
HANDLE pcon_owner =
OpenProcess (PROCESS_DUP_HANDLE, FALSE, p->exec_dwProcessId);
OpenProcess (PROCESS_DUP_HANDLE, FALSE, get_ttyp ()->pcon_pid);
if (pcon_owner == NULL)
return false;
DuplicateHandle (pcon_owner, get_ttyp ()->h_pcon_in,
GetCurrentProcess (), &hpConIn,
0, TRUE, DUPLICATE_SAME_ACCESS);
@ -3132,7 +3138,7 @@ fhandler_pty_slave::setup_pseudoconsole (bool nopcon)
0, TRUE, DUPLICATE_SAME_ACCESS);
CloseHandle (pcon_owner);
FreeConsole ();
AttachConsole (p->exec_dwProcessId);
AttachConsole (get_ttyp ()->pcon_pid);
goto skip_create;
}
@ -3287,10 +3293,10 @@ skip_create:
}
while (false);
if (get_ttyp ()->pcon_pid == 0 || !pinfo (get_ttyp ()->pcon_pid))
get_ttyp ()->pcon_pid = myself->pid;
if (!pcon_pid_alive (get_ttyp ()->pcon_pid))
get_ttyp ()->pcon_pid = myself->exec_dwProcessId;
if (hpcon && get_ttyp ()->pcon_pid == myself->pid)
if (hpcon && pcon_pid_self (get_ttyp ()->pcon_pid))
{
HPCON_INTERNAL *hp = (HPCON_INTERNAL *) hpcon;
get_ttyp ()->h_pcon_write_pipe = hp->hWritePipe;
@ -3381,15 +3387,14 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
if (force_switch_to)
{
switch_to_stub = force_switch_to;
new_pcon_pid = force_switch_to + MAX_PID;
ttyp->setpgid (new_pcon_pid);
new_pcon_pid = force_switch_to;
ttyp->setpgid (force_switch_to + MAX_PID);
}
else if (ttyp->pcon_pid == myself->pid)
else if (pcon_pid_self (ttyp->pcon_pid))
{
/* Search another process which attaches to the pseudo console */
DWORD current_pid = myself->exec_dwProcessId ?: myself->dwProcessId;
switch_to =
get_console_process_id (current_pid, false, true);
switch_to = get_console_process_id (current_pid, false, true);
if (switch_to)
{
pinfo p (cygwin_pid (switch_to));
@ -3397,15 +3402,21 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
{
if (p->exec_dwProcessId)
switch_to_stub = p->exec_dwProcessId;
new_pcon_pid = p->pid;
new_pcon_pid = p->exec_dwProcessId;
}
}
else
{
switch_to = get_console_process_id (current_pid, false, false);
if (switch_to)
new_pcon_pid = switch_to;
}
}
if (ttyp->pcon_activated)
{
ttyp->previous_code_page = GetConsoleCP ();
ttyp->previous_output_code_page = GetConsoleOutputCP ();
if (ttyp->pcon_pid == myself->pid)
if (pcon_pid_self (ttyp->pcon_pid))
{
switch_to = switch_to_stub ?: switch_to;
if (switch_to)
@ -3447,6 +3458,15 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
ttyp->h_pcon_conhost_process = new_conhost_process;
ttyp->h_pcon_in = new_pcon_in;
ttyp->h_pcon_out = new_pcon_out;
FreeConsole ();
pinfo p (myself->ppid);
if (p)
{
if (!AttachConsole (p->dwProcessId))
AttachConsole (ATTACH_PARENT_PROCESS);
}
else
AttachConsole (ATTACH_PARENT_PROCESS);
}
else
{ /* Close pseudo console */
@ -3462,7 +3482,7 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
/* Reconstruct pseudo console handler container here for close */
HPCON_INTERNAL *hp =
(HPCON_INTERNAL *) HeapAlloc (GetProcessHeap (), 0,
sizeof (*hp));
sizeof (HPCON_INTERNAL));
hp->hWritePipe = ttyp->h_pcon_write_pipe;
hp->hConDrvReference = ttyp->h_pcon_condrv_reference;
hp->hConHostProcess = ttyp->h_pcon_conhost_process;
@ -3489,7 +3509,7 @@ fhandler_pty_slave::close_pseudoconsole (tty *ttyp, DWORD force_switch_to)
AttachConsole (ATTACH_PARENT_PROCESS);
}
}
else if (ttyp->pcon_pid == myself->pid)
else if (pcon_pid_self (ttyp->pcon_pid))
{
if (switch_to_stub)
ttyp->pcon_pid = new_pcon_pid;

15
winsup/cygwin/tty.cc
View File

@ -327,25 +327,18 @@ tty_min::setpgid (int pid)
&& ttyp->pcon_input_state_eq (tty::to_nat))
{
bool attach_restore = false;
DWORD pcon_winpid = 0;
if (ttyp->pcon_pid)
{
pinfo p (ttyp->pcon_pid);
if (p)
pcon_winpid = p->exec_dwProcessId ?: p->dwProcessId;
}
HANDLE from = ptys->get_handle_nat ();
if (ttyp->pcon_activated && pcon_winpid
&& !ptys->get_console_process_id (pcon_winpid, true))
if (ttyp->pcon_activated && ttyp->pcon_pid
&& !ptys->get_console_process_id (ttyp->pcon_pid, true))
{
HANDLE pcon_owner =
OpenProcess (PROCESS_DUP_HANDLE, FALSE, pcon_winpid);
OpenProcess (PROCESS_DUP_HANDLE, FALSE, ttyp->pcon_pid);
DuplicateHandle (pcon_owner, ttyp->h_pcon_in,
GetCurrentProcess (), &from,
0, TRUE, DUPLICATE_SAME_ACCESS);
CloseHandle (pcon_owner);
FreeConsole ();
AttachConsole (pcon_winpid);
AttachConsole (ttyp->pcon_pid);
attach_restore = true;
}
WaitForSingleObject (ptys->input_mutex, INFINITE);

2
winsup/cygwin/tty.h
View File

@ -113,7 +113,7 @@ private:
bool pcon_start;
pid_t pcon_start_pid;
bool switch_to_pcon_in;
pid_t pcon_pid;
DWORD pcon_pid;
UINT term_code_page;
DWORD pcon_last_time;
HANDLE h_pcon_write_pipe;