From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2155) id B38413858C27; Tue, 20 Apr 2021 08:47:01 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B38413858C27 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Corinna Vinschen To: cygwin-cvs@sourceware.org Subject: [newlib-cygwin] Cygwin: pty: Fix race issue in inheritance of pseudo console. X-Act-Checkin: newlib-cygwin X-Git-Author: Takashi Yano X-Git-Refname: refs/heads/master X-Git-Oldrev: b4fc81edcc25b5c313ab3805dc0bcd015c370e62 X-Git-Newrev: bb93c6d7c2c20d9edfb37d72ca3121cef05efde9 Message-Id: <20210420084701.B38413858C27@sourceware.org> Date: Tue, 20 Apr 2021 08:47:01 +0000 (GMT) X-BeenThere: cygwin-cvs@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Cygwin core component git logs List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Apr 2021 08:47:01 -0000 https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bb93c6d7c2c20d9edfb37d72ca3121cef05efde9 commit bb93c6d7c2c20d9edfb37d72ca3121cef05efde9 Author: Takashi Yano Date: Mon Apr 19 19:30:46 2021 +0900 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 Diff: --- winsup/cygwin/fhandler_tty.cc | 108 +++++++++++++++++++++++++----------------- winsup/cygwin/tty.cc | 15 ++---- winsup/cygwin/tty.h | 2 +- 3 files changed, 69 insertions(+), 56 deletions(-) diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc index 73aec2ade..ba9f4117f 100644 --- a/winsup/cygwin/fhandler_tty.cc +++ b/winsup/cygwin/fhandler_tty.cc @@ -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); @@ -1975,19 +1984,15 @@ 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); - DuplicateHandle (pcon_owner, get_ttyp ()->h_pcon_write_pipe, - GetCurrentProcess (), &hpcon_local.hWritePipe, - 0, TRUE, DUPLICATE_SAME_ACCESS); - ResizePseudoConsole ((HPCON) &hpcon_local, size); - CloseHandle (pcon_owner); - CloseHandle (hpcon_local.hWritePipe); - } + HPCON_INTERNAL hpcon_local; + HANDLE pcon_owner = + 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); + ResizePseudoConsole ((HPCON) &hpcon_local, size); + CloseHandle (pcon_owner); + CloseHandle (hpcon_local.hWritePipe); } void @@ -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; diff --git a/winsup/cygwin/tty.cc b/winsup/cygwin/tty.cc index 96acde387..2566f4c45 100644 --- a/winsup/cygwin/tty.cc +++ b/winsup/cygwin/tty.cc @@ -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); diff --git a/winsup/cygwin/tty.h b/winsup/cygwin/tty.h index 12c926ec0..8479dd2ec 100644 --- a/winsup/cygwin/tty.h +++ b/winsup/cygwin/tty.h @@ -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;