/* sigproc.cc: inter/intra signal and sub process handler Copyright 1997, 1998, 1999, 2000 Cygnus Solutions. Written by Christopher Faylor This file is part of Cygwin. This software is a copyrighted work licensed under the terms of the Cygwin license. Please consult the file "CYGWIN_LICENSE" for details. */ #include "winsup.h" #include #include #include #include #include #include #include "cygerrno.h" #include "sync.h" #include "sigproc.h" #include "pinfo.h" #include "cygheap.h" #include "child_info.h" #include "perthread.h" #include #include "shared_info.h" #include "security.h" /* * Convenience defines */ #define WSSC 60000 // Wait for signal completion #define WPSP 40000 // Wait for proc_subproc mutex #define WSPX 20000 // Wait for wait_sig to terminate #define WWSP 20000 // Wait for wait_subproc to terminate #define WAIT_SIG_PRIORITY THREAD_PRIORITY_NORMAL #define TOTSIGS (NSIG + __SIGOFFSET) #define wake_wait_subproc() SetEvent (events[0]) #define no_signals_available() (!hwait_sig || !sig_loop_wait) /* * Global variables */ const char *__sp_fn ; int __sp_ln; char NO_COPY myself_nowait_dummy[1] = {'0'};// Flag to sig_send that signal goes to // current process but no wait is required char NO_COPY myself_nowait_nonmain_dummy[1] = {'1'};// Flag to sig_send that signal goes to // current process but no wait is required // if this is not the main thread. HANDLE NO_COPY signal_arrived; // Event signaled when a signal has // resulted in a user-specified // function call /* * Common variables */ /* How long to wait for message/signals. Normally this is infinite. * On termination, however, these are set to zero as a flag to exit. */ #define Static static NO_COPY Static DWORD proc_loop_wait = 500; // Wait for subprocesses to exit Static DWORD sig_loop_wait = 500; // Wait for signals to arrive Static HANDLE sigcatch_nonmain = NULL; // The semaphore signaled when // signals are available for // processing from non-main thread Static HANDLE sigcatch_main = NULL; // Signalled when main thread sends a // signal Static HANDLE sigcatch_nosync = NULL; // Signal wait_sig to scan sigtodo // but not to bother with any // synchronization Static HANDLE sigcomplete_main = NULL; // Event signaled when a signal has // finished processing for the main // thread Static HANDLE sigcomplete_nonmain = NULL;// Semaphore raised for non-main // threads when a signal has finished // processing Static HANDLE hwait_sig = NULL; // Handle of wait_sig thread Static HANDLE hwait_subproc = NULL; // Handle of sig_subproc thread Static HANDLE wait_sig_inited = NULL; // Control synchronization of // message queue startup /* Used by WaitForMultipleObjects. These are handles to child processes. */ Static HANDLE events[PSIZE + 1] = {0}; // All my children's handles++ #define hchildren (events + 1) // Where the children handles begin Static pinfo pchildren[PSIZE] = {pinfo ()};// All my children info Static pinfo zombies[PSIZE] = {pinfo ()}; // All my deceased children info Static int nchildren = 0; // Number of active children Static int nzombies = 0; // Number of deceased children Static waitq waitq_head = {0, 0, 0, 0, 0, 0, 0};// Start of queue for wait'ing threads Static waitq waitq_main; // Storage for main thread muto NO_COPY *sync_proc_subproc = NULL; // Control access to subproc stuff DWORD NO_COPY sigtid = 0; // ID of the signal thread int NO_COPY pending_signals = 0; // TRUE if signals pending /* Functions */ static int __stdcall checkstate (waitq *); static __inline__ BOOL get_proc_lock (DWORD, DWORD); static HANDLE __stdcall getsem (_pinfo *, const char *, int, int); static void __stdcall remove_child (int); static void __stdcall remove_zombie (int); static DWORD WINAPI wait_sig (VOID *arg); static int __stdcall stopped_or_terminated (waitq *, _pinfo *); static DWORD WINAPI wait_subproc (VOID *); /* Determine if the parent process is alive. */ BOOL __stdcall my_parent_is_alive () { DWORD res; if (!parent_alive) { debug_printf ("No parent_alive mutex"); res = FALSE; } else for (int i = 0; i < 2; i++) switch (res = WaitForSingleObject (parent_alive, 0)) { case WAIT_OBJECT_0: debug_printf ("parent dead."); res = FALSE; goto out; case WAIT_TIMEOUT: debug_printf ("parent still alive"); res = TRUE; goto out; case WAIT_FAILED: DWORD werr = GetLastError (); if (werr == ERROR_INVALID_HANDLE && i == 0) continue; system_printf ("WFSO for parent_alive(%p) failed, error %d", parent_alive, werr); res = FALSE; goto out; } out: return res; } __inline static void wait_for_me () { /* See if this is the first signal call after initialization. * If so, wait for notification that all initialization has completed. * Then set the handle to NULL to avoid checking this again. */ if (wait_sig_inited) { (void) WaitForSingleObject (wait_sig_inited, INFINITE); (void) ForceCloseHandle (wait_sig_inited); wait_sig_inited = NULL; } } static BOOL __stdcall proc_can_be_signalled (_pinfo *p) { if (p == myself_nowait || p == myself_nowait_nonmain || p == myself) { wait_for_me (); return 1; } return ISSTATE (p, PID_INITIALIZING) || (((p)->process_state & (PID_ACTIVE | PID_IN_USE)) == (PID_ACTIVE | PID_IN_USE)); } BOOL __stdcall pid_exists (pid_t pid) { pinfo p (pid); return proc_exists (p); } /* Test to determine if a process really exists and is processing * signals. */ BOOL __stdcall proc_exists (_pinfo *p) { HANDLE h; if (p == NULL) return FALSE; if (p == myself || p == myself_nowait_nonmain || p == myself_nowait) return TRUE; if (p->process_state == PID_NOT_IN_USE || !p->dwProcessId) return FALSE; sigproc_printf ("checking for existence of pid %d, window pid %d", p->pid, p->dwProcessId); if (p->ppid == myself->pid && p->hProcess != NULL) { sigproc_printf ("it's mine, process_state %x", p->process_state); return proc_can_be_signalled (p); } /* Note: Process is alive if OpenProcess() call fails due to permissions */ if (((h = OpenProcess (STANDARD_RIGHTS_REQUIRED, FALSE, p->dwProcessId)) != NULL) || (GetLastError () == ERROR_ACCESS_DENIED)) { sigproc_printf ("it exists, %p", h); if (h) { DWORD rc = WaitForSingleObject (h, 0); CloseHandle (h); if (rc == WAIT_OBJECT_0) return 0; } return proc_can_be_signalled (p); } sigproc_printf ("it doesn't exist"); #if 0 /* If the parent pid does not exist, clean this process out of the pinfo * table. It must have died abnormally. */ if ((p->pid == p->ppid) || (p->ppid == 1) || !pid_exists (p->ppid)) { p->hProcess = NULL; p->process_state = PID_NOT_IN_USE; } #endif return FALSE; } /* Return 1 if this is one of our children, zero otherwise. FIXME: This really should be integrated with the rest of the proc_subproc testing. Scanning these lists twice is inefficient. */ int __stdcall mychild (int pid) { for (int i = 0; i < nchildren; i++) if (pchildren[i]->pid == pid) return 1; for (int i = 0; i < nzombies; i++) if (zombies[i]->pid == pid) return 1; return 0; } /* Handle all subprocess requests */ #define vchild (*((pinfo *) val)) int __stdcall proc_subproc (DWORD what, DWORD val) { int rc = 1; int potential_match; _pinfo *child; int clearing; waitq *w; #define wval ((waitq *) val) sigproc_printf ("args: %x, %d", what, val); if (!get_proc_lock (what, val)) // Serialize access to this function { sigproc_printf ("I am not ready"); goto out1; } switch (what) { /* Add a new subprocess to the children arrays. * (usually called from the main thread) */ case PROC_ADDCHILD: if (nchildren >= PSIZE - 1) system_printf ("nchildren too large %d", nchildren); if (WaitForSingleObject (vchild->hProcess, 0) != WAIT_TIMEOUT) { system_printf ("invalid process handle %p. pid %d, win pid %d", vchild->hProcess, vchild->pid, vchild->dwProcessId); rc = 0; break; } pchildren[nchildren] = vchild; hchildren[nchildren] = vchild->hProcess; ProtectHandle1 (vchild->hProcess, childhProc); nchildren++; if (!DuplicateHandle (hMainProc, vchild->hProcess, hMainProc, &vchild->pid_handle, 0, 0, DUPLICATE_SAME_ACCESS)) system_printf ("Couldn't duplicate child handle for pid %d, %E", vchild->pid); ProtectHandle1 (vchild->pid_handle, pid_handle); sigproc_printf ("added pid %d to wait list, slot %d, winpid %p, handle %p", vchild->pid, nchildren, vchild->dwProcessId, vchild->hProcess); wake_wait_subproc (); break; /* A child process had terminated. * Possibly this is just due to an exec(). Cygwin implements an exec() * as a "handoff" from one windows process to another. If child->hProcess * is different from what is recorded in hchildren, then this is an exec(). * Otherwise this is a normal child termination event. * (called from wait_subproc thread) */ case PROC_CHILDTERMINATED: rc = 0; if (hchildren[val] != pchildren[val]->hProcess) { sigproc_printf ("pid %d[%d], reparented old hProcess %p, new %p", pchildren[val]->pid, val, hchildren[val], pchildren[val]->hProcess); ForceCloseHandle1 (hchildren[val], childhProc); hchildren[val] = pchildren[val]->hProcess; /* Filled out by child */ ProtectHandle1 (pchildren[val]->hProcess, childhProc); break; // This was an exec() } sigproc_printf ("pid %d[%d] terminated, handle %p, nchildren %d, nzombies %d", pchildren[val]->pid, val, hchildren[val], nchildren, nzombies); zombies[nzombies] = pchildren[val]; // Add to zombie array zombies[nzombies++]->process_state = PID_ZOMBIE;// Walking dead remove_child (val); // Remove from children array if (!proc_loop_wait) // Don't bother if wait_subproc is break; // exiting /* Send a SIGCHLD to myself. */ rc = sig_send (myself_nowait, SIGCHLD); // Send a SIGCHLD break; /* A child is in the stopped state. Scan wait() queue to see if anyone * should be notified. (Called from wait_sig thread) */ case PROC_CHILDSTOPPED: child = myself; // Just to avoid accidental NULL dereference sigproc_printf ("Received stopped notification"); clearing = 0; goto scan_wait; /* Handle a wait4() operation. Allocates an event for the calling * thread which is signaled when the appropriate pid exits or stops. * (usually called from the main thread) */ case PROC_WAIT: wval->ev = NULL; // Don't know event flag yet if (wval->pid <= 0) child = NULL; // Not looking for a specific pid else if (!mychild (wval->pid)) goto out; // invalid pid. flag no such child wval->status = 0; // Don't know status yet sigproc_printf ("wval->pid %d, wval->options %d", wval->pid, wval->options); /* If the first time for this thread, create a new event, otherwise * reset the event. */ if ((wval->ev = wval->thread_ev) == NULL) { wval->ev = wval->thread_ev = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL); ProtectHandle (wval->ev); } ResetEvent (wval->ev); w = waitq_head.next; waitq_head.next = wval; /* Add at the beginning. */ wval->next = w; /* Link in rest of the list. */ clearing = 0; goto scan_wait; /* Clear all waiting threads. Called from exceptions.cc prior to * the main thread's dispatch to a signal handler function. * (called from wait_sig thread) */ case PROC_CLEARWAIT: /* Clear all "wait"ing threads. */ if (val) sigproc_printf ("clear waiting threads"); else sigproc_printf ("looking for processes to reap"); clearing = val; scan_wait: /* Scan the linked list of wait()ing threads. If a wait's parameters * match this pid, then activate it. */ for (w = &waitq_head; w->next != NULL; w = w->next) { if ((potential_match = checkstate (w)) > 0) sigproc_printf ("released waiting thread"); else if (!clearing && !(w->next->options & WNOHANG) && potential_match < 0) sigproc_printf ("only found non-terminated children"); else if (potential_match <= 0) // nothing matched { sigproc_printf ("waiting thread found no children"); HANDLE oldw = w->next->ev; w->next->pid = 0; if (clearing) w->next->status = -1; /* flag that a signal was received */ else w->next->ev = NULL; if (!SetEvent (oldw)) system_printf ("couldn't wake up wait event %p, %E", oldw); w->next = w->next->next; } if (w->next == NULL) break; } if (!clearing) sigproc_printf ("finished processing terminated/stopped child"); else { waitq_head.next = NULL; sigproc_printf ("finished clearing"); } break; } out: sync_proc_subproc->release (); // Release the lock out1: sigproc_printf ("returning %d", rc); return rc; } /* Terminate the wait_subproc thread. * Called on process exit. * Also called by spawn_guts to disassociate any subprocesses from this * process. Subprocesses will then know to clean up after themselves and * will not become zombies. */ void __stdcall proc_terminate (void) { sigproc_printf ("nchildren %d, nzombies %d", nchildren, nzombies); /* Signal processing is assumed to be blocked in this routine. */ if (hwait_subproc) { int rc; proc_loop_wait = 0; // Tell wait_subproc thread to exit wake_wait_subproc (); // Wake wait_subproc loop /* Wait for wait_subproc thread to exit (but not *too* long) */ if ((rc = WaitForSingleObject (hwait_subproc, WWSP)) != WAIT_OBJECT_0) if (rc == WAIT_TIMEOUT) system_printf ("WFSO(hwait_subproc) timed out"); else system_printf ("WFSO(hwait_subproc), rc %d, %E", rc); HANDLE h = hwait_subproc; hwait_subproc = NULL; ForceCloseHandle1 (h, hwait_subproc); sync_proc_subproc->acquire(WPSP); (void) proc_subproc (PROC_CLEARWAIT, 1); /* Clean out zombie processes from the pid list. */ int i; for (i = 0; i < nzombies; i++) { if (zombies[i]->hProcess) { ForceCloseHandle1 (zombies[i]->hProcess, childhProc); ForceCloseHandle1 (zombies[i]->pid_handle, pid_handle); } zombies[i]->process_state = PID_NOT_IN_USE; /* CGF FIXME - still needed? */ zombies[i].release(); // FIXME: this breaks older gccs for some reason } /* Disassociate my subprocesses */ for (i = 0; i < nchildren; i++) { if (pchildren[i]->process_state == PID_NOT_IN_USE) continue; // Should never happen if (!pchildren[i]->hProcess) sigproc_printf ("%d(%d) hProcess cleared already?", pchildren[i]->pid, pchildren[i]->dwProcessId); else { ForceCloseHandle1 (pchildren[i]->hProcess, childhProc); if (!proc_exists (pchildren[i])) { sigproc_printf ("%d(%d) doesn't exist", pchildren[i]->pid, pchildren[i]->dwProcessId); pchildren[i]->process_state = PID_NOT_IN_USE; /* a reaped child CGF FIXME -- still needed? */ } else { sigproc_printf ("%d(%d) closing active child handle", pchildren[i]->pid, pchildren[i]->dwProcessId); pchildren[i]->ppid = 1; if (pchildren[i]->pgid == myself->pid) pchildren[i]->process_state |= PID_ORPHANED; } } pchildren[i].release (); // FIXME: this breaks older gccs for some reason } nchildren = nzombies = 0; /* Just zero sync_proc_subproc as the delete below seems to cause problems for older gccs. */ #if 1 sync_proc_subproc = NULL; #else /* Attempt to close and release sync_proc_subproc in a * non-raceable manner. */ muto *m = sync_proc_subproc; if (m) { sync_proc_subproc = NULL; // delete m; } #endif } sigproc_printf ("leaving"); } /* Clear pending signal from the sigtodo array */ void __stdcall sig_clear (int sig) { (void) InterlockedExchange (myself->getsigtodo(sig), 0L); return; } /* Force the wait_sig thread to wake up and scan the sigtodo array. */ extern "C" int __stdcall sig_dispatch_pending (int justwake) { if (!hwait_sig) return 0; int was_pending = pending_signals; #ifdef DEBUGGING sigproc_printf ("pending_signals %d", was_pending); #endif if (!was_pending && !justwake) #ifdef DEBUGGING sigproc_printf ("no need to wake anything up"); #else ; #endif else { wait_for_me (); if (!justwake) (void) sig_send (myself, __SIGFLUSH); else if (ReleaseSemaphore (sigcatch_nosync, 1, NULL)) #ifdef DEBUGGING sigproc_printf ("woke up wait_sig"); #else ; #endif else if (no_signals_available ()) /*sigproc_printf ("I'm going away now")*/; else system_printf ("%E releasing sigcatch_nosync(%p)", sigcatch_nosync); } return was_pending; } /* Message initialization. Called from dll_crt0_1 * * This routine starts the signal handling thread. The wait_sig_inited * event is used to signal that the thread is ready to handle signals. * We don't wait for this during initialization but instead detect it * in sig_send to gain a little concurrency. */ void __stdcall sigproc_init () { wait_sig_inited = CreateEvent (&sec_none_nih, TRUE, FALSE, NULL); ProtectHandle (wait_sig_inited); /* local event signaled when main thread has been dispatched to a signal handler function. */ signal_arrived = CreateEvent(&sec_none_nih, TRUE, FALSE, NULL); if (!(hwait_sig = makethread (wait_sig, NULL, 0, "sig"))) { system_printf ("cannot create wait_sig thread, %E"); api_fatal ("terminating"); } ProtectHandle (hwait_sig); /* sync_proc_subproc is used by proc_subproc. It serialises * access to the children and zombie arrays. */ sync_proc_subproc = new_muto (FALSE, "sync_proc_subproc"); /* Initialize waitq structure for main thread. A waitq structure is * allocated for each thread that executes a wait to allow multiple threads * to perform waits. Pre-allocate a waitq structure for the main thread. */ waitq *w; if ((w = (waitq *)waitq_storage.get ()) == NULL) { w = &waitq_main; waitq_storage.set (w); } memset (w, 0, sizeof *w); // Just to be safe sigproc_printf ("process/signal handling enabled(%x)", myself->process_state); return; } /* Called on process termination to terminate signal and process threads. */ void __stdcall sigproc_terminate (void) { HANDLE h = hwait_sig; hwait_sig = NULL; if (GetCurrentThreadId () == sigtid) { ForceCloseHandle (sigcomplete_main); for (int i = 0; i < 20; i++) (void) ReleaseSemaphore (sigcomplete_nonmain, 1, NULL); ForceCloseHandle (sigcomplete_nonmain); ForceCloseHandle (sigcatch_main); ForceCloseHandle (sigcatch_nonmain); ForceCloseHandle (sigcatch_nosync); } proc_terminate (); // Terminate process handling thread if (!sig_loop_wait) sigproc_printf ("sigproc_terminate: sigproc handling not active"); else { sigproc_printf ("entering"); sig_loop_wait = 0; // Tell wait_sig to exit when it is // finished with anything it is doing sig_dispatch_pending (TRUE); // wake up and die /* If !hwait_sig, then the process probably hasn't even finished * its initialization phase. */ if (hwait_sig) { if (GetCurrentThreadId () != sigtid) WaitForSingleObject (h, 10000); ForceCloseHandle1 (h, hwait_sig); /* Exiting thread. Cleanup. Don't set to inactive if a child has been execed with the same pid. */ if (!myself->dwProcessId || myself->dwProcessId == GetCurrentProcessId ()) myself->process_state &= ~PID_ACTIVE; else sigproc_printf ("Did not clear PID_ACTIVE since %d != %d", myself->dwProcessId, GetCurrentProcessId ()); /* In case of a sigsuspend */ SetEvent (signal_arrived); if (GetCurrentThreadId () != sigtid) { ForceCloseHandle (sigcomplete_main); ForceCloseHandle (sigcomplete_nonmain); ForceCloseHandle (sigcatch_main); ForceCloseHandle (sigcatch_nonmain); ForceCloseHandle (sigcatch_nosync); } } sigproc_printf ("done"); } /* Set this so that subsequent tests will succeed. */ if (!myself->dwProcessId) myself->dwProcessId = GetCurrentProcessId (); return; } /* Send a signal to another process by raising its signal semaphore. * If pinfo *p == NULL, send to the current process. * If sending to this process, wait for notification that a signal has * completed before returning. */ int __stdcall sig_send (_pinfo *p, int sig, DWORD ebp) { int rc = 1; DWORD tid = GetCurrentThreadId (); BOOL its_me; HANDLE thiscatch = NULL; HANDLE thiscomplete = NULL; BOOL wait_for_completion; sigframe thisframe; if (p == myself_nowait_nonmain) p = (tid == mainthread.id) ? (_pinfo *) myself : myself_nowait; if (!(its_me = (p == NULL || p == myself || p == myself_nowait))) wait_for_completion = FALSE; else { if (no_signals_available ()) goto out; // Either exiting or not yet initializing wait_for_me (); wait_for_completion = p != myself_nowait; p = myself; } /* It is possible that the process is not yet ready to receive messages * or that it has exited. Detect this. */ if (!proc_can_be_signalled (p)) /* Is the process accepting messages? */ { sigproc_printf ("invalid pid %d(%x), signal %d", p->pid, p->process_state, sig); set_errno (ESRCH); goto out; } sigproc_printf ("pid %d, signal %d, its_me %d", p->pid, sig, its_me); if (its_me) { if (!wait_for_completion) thiscatch = sigcatch_nosync; else if (tid != mainthread.id) { thiscatch = sigcatch_nonmain; thiscomplete = sigcomplete_nonmain; } else { thiscatch = sigcatch_main; thiscomplete = sigcomplete_main; thisframe.set (mainthread, ebp); } } else if (!(thiscatch = getsem (p, "sigcatch", 0, 0))) goto out; // Couldn't get the semaphore. getsem issued // an error, if appropriate. #if WHEN_MULTI_THREAD_SIGNALS_WORK signal_dispatch *sd; sd = signal_dispatch_storage.get (); if (sd == NULL) sd = signal_dispatch_storage.create (); #endif /* Increment the sigtodo array to signify which signal to assert. */ (void) InterlockedIncrement (p->getsigtodo(sig)); /* Notify the process that a signal has arrived. */ SetLastError (0); #if 0 int prio; prio = GetThreadPriority (GetCurrentThread ()); (void) SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_TIME_CRITICAL); #endif if (!ReleaseSemaphore (thiscatch, 1, NULL) && (int) GetLastError () > 0) { /* Couldn't signal the semaphore. This probably means that the * process is exiting. */ if (!its_me) ForceCloseHandle (thiscatch); else { if (no_signals_available ()) sigproc_printf ("I'm going away now"); else if ((int) GetLastError () == -1) rc = WaitForSingleObject (thiscomplete, 500); else system_printf ("error sending signal %d to pid %d, semaphore %p, %E", sig, p->pid, thiscatch); } goto out; } /* No need to wait for signal completion unless this was a signal to * this process. * * If it was a signal to this process, wait for a dispatched signal. * Otherwise just wait for the wait_sig to signal that it has finished * processing the signal. */ if (!wait_for_completion) { rc = WAIT_OBJECT_0; sigproc_printf ("Not waiting for sigcomplete. its_me %d sig %d", its_me, sig); if (!its_me) ForceCloseHandle (thiscatch); } else { sigproc_printf ("Waiting for thiscomplete %p", thiscomplete); SetLastError (0); rc = WaitForSingleObject (thiscomplete, WSSC); /* Check for strangeness due to this thread being redirected by the signal handler. Sometimes a WAIT_TIMEOUT will occur when the thread hasn't really timed out. So, check again. FIXME: This isn't foolproof. */ if (rc != WAIT_OBJECT_0 && WaitForSingleObject (thiscomplete, 0) == WAIT_OBJECT_0) rc = WAIT_OBJECT_0; } #if 0 SetThreadPriority (GetCurrentThread (), prio); #endif if (rc == WAIT_OBJECT_0) rc = 0; // Successful exit else { /* It's an error unless sig_loop_wait == 0 (the process is exiting). */ if (!no_signals_available ()) system_printf ("wait for sig_complete event failed, sig %d, rc %d, %E", sig, rc); set_errno (ENOSYS); rc = -1; } out: sigproc_printf ("returning %d from sending signal %d", rc, sig); return rc; } /* Set pending signal from the sigtodo array */ void __stdcall sig_set_pending (int sig) { (void) InterlockedIncrement (myself->getsigtodo(sig)); return; } /* Initialize the wait_subproc thread. * Called from fork() or spawn() to initialize the handling of subprocesses. */ void __stdcall subproc_init (void) { if (hwait_subproc) return; /* A "wakeup" handle which can be toggled to make wait_subproc reexamine * the hchildren array. */ events[0] = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL); if (!(hwait_subproc = makethread (wait_subproc, NULL, 0, "+proc"))) system_printf ("cannot create wait_subproc thread, %E"); ProtectHandle (events[0]); ProtectHandle (hwait_subproc); sigproc_printf ("started wait_subproc thread %p", hwait_subproc); } /* Initialize some of the memory block passed to child processes by fork/spawn/exec. */ void __stdcall init_child_info (DWORD chtype, child_info *ch, pid_t pid, HANDLE subproc_ready) { subproc_init (); memset (ch, 0, sizeof *ch); ch->cb = sizeof *ch; ch->type = chtype; ch->cygpid = pid; ch->shared_h = cygwin_shared_h; ch->console_h = console_shared_h; ch->subproc_ready = subproc_ready; if (chtype != PROC_EXEC || !parent_alive) ch->parent_alive = hwait_subproc; else DuplicateHandle (hMainProc, parent_alive, hMainProc, &ch->parent_alive, 0, 1, DUPLICATE_SAME_ACCESS); } /* Check the state of all of our children to see if any are stopped or * terminated. */ static int __stdcall checkstate (waitq *parent_w) { int potential_match = 0; sigproc_printf ("nchildren %d, nzombies %d", nchildren, nzombies); /* Check already dead processes first to see if they match the criteria * given in w->next. */ for (int i = 0; i < nzombies; i++) switch (stopped_or_terminated (parent_w, zombies[i])) { case -1: potential_match = -1; break; case 1: remove_zombie (i); potential_match = 1; goto out; } sigproc_printf ("checking alive children"); /* No dead terminated children matched. Check for stopped children. */ for (int i = 0; i < nchildren; i++) switch (stopped_or_terminated (parent_w, pchildren[i])) { case -1: potential_match = -1; break; case 1: potential_match = 1; goto out; } out: sigproc_printf ("returning %d", potential_match); return potential_match; } /* Get or create a process specific semaphore used in message passing. */ static HANDLE __stdcall getsem (_pinfo *p, const char *str, int init, int max) { HANDLE h; if (p != NULL) { if (!proc_can_be_signalled (p)) { set_errno (ESRCH); return NULL; } int wait = 10000; sigproc_printf ("pid %d, ppid %d, wait %d, initializing %x", p->pid, p->ppid, wait, ISSTATE (p, PID_INITIALIZING)); for (int i = 0; ISSTATE (p, PID_INITIALIZING) && i < wait; i++) Sleep (1); } SetLastError (0); if (p == NULL) { char sa_buf[1024]; DWORD winpid = GetCurrentProcessId (); h = CreateSemaphore (allow_ntsec ? sec_user (sa_buf) : &sec_none_nih, init, max, str = shared_name (str, winpid)); p = myself; } else { h = OpenSemaphore (SEMAPHORE_ALL_ACCESS, FALSE, str = shared_name (str, p->dwProcessId)); if (h == NULL) { if (GetLastError () == ERROR_FILE_NOT_FOUND && !proc_exists (p)) set_errno (ESRCH); else set_errno (EPERM); return NULL; } } if (!h) { system_printf ("can't %s %s, %E", p ? "open" : "create", str); set_errno (ESRCH); } return h; } /* Get the sync_proc_subproc muto to control access to * children, zombie arrays. * Attempt to handle case where process is exiting as we try to grab * the mutex. */ static BOOL get_proc_lock (DWORD what, DWORD val) { Static int lastwhat = -1; if (!sync_proc_subproc) return FALSE; if (sync_proc_subproc->acquire (WPSP)) { lastwhat = what; return TRUE; } if (!sync_proc_subproc) return FALSE; system_printf ("Couldn't aquire sync_proc_subproc for(%d,%d), %E, last %d", what, val, lastwhat); return TRUE; } /* Remove a child from pchildren/hchildren by swapping it with the * last child in the list. */ static void __stdcall remove_child (int ci) { sigproc_printf ("removing [%d], pid %d, handle %p, nchildren %d", ci, pchildren[ci]->pid, hchildren[ci], nchildren); if (ci < --nchildren) { pchildren[ci] = pchildren[nchildren]; hchildren[ci] = hchildren[nchildren]; } return; } /* Remove a zombie from zombies by swapping it with the last child in the list. */ static void __stdcall remove_zombie (int ci) { sigproc_printf ("removing %d, pid %d, nzombies %d", ci, zombies[ci]->pid, nzombies); if (zombies[ci]) { ForceCloseHandle1 (zombies[ci]->hProcess, childhProc); ForceCloseHandle1 (zombies[ci]->pid_handle, pid_handle); zombies[ci]->process_state = PID_NOT_IN_USE; /* a reaped child */ zombies[ci].release (); } if (ci < --nzombies) zombies[ci] = zombies[nzombies]; return; } /* Check status of child process vs. waitq member. * * parent_w is the pointer to the parent of the waitq member in question. * child is the subprocess being considered. * * Returns * 1 if stopped or terminated child matches parent_w->next criteria * -1 if a non-stopped/terminated child matches parent_w->next criteria * 0 if child does not match parent_w->next criteria */ static int __stdcall stopped_or_terminated (waitq *parent_w, _pinfo *child) { int potential_match; waitq *w = parent_w->next; sigproc_printf ("considering pid %d", child->pid); if (w->pid == -1) potential_match = 1; else if (w->pid == 0) potential_match = child->pgid == myself->pgid; else if (w->pid < 0) potential_match = child->pgid == -w->pid; else potential_match = (w->pid == child->pid); if (!potential_match) return 0; BOOL terminated; if ((terminated = child->process_state == PID_ZOMBIE) || (w->options & WUNTRACED) && child->stopsig) { parent_w->next = w->next; /* successful wait. remove from wait queue */ w->pid = child->pid; if (!terminated) { sigproc_printf ("stopped child"); w->status = (child->stopsig << 8) | 0x7f; child->stopsig = 0; } else /* Should only get here when child has been moved to the zombies array */ { DWORD status; if (!GetExitCodeProcess (child->hProcess, &status)) status = 0xffff; if (status & EXIT_SIGNAL) w->status = (status >> 8) & 0xff; /* exited due to signal */ else w->status = (status & 0xff) << 8; /* exited via "exit ()" */ add_rusage (&myself->rusage_children, &child->rusage_children); add_rusage (&myself->rusage_children, &child->rusage_self); if (w->rusage) { add_rusage ((struct rusage *) w->rusage, &child->rusage_children); add_rusage ((struct rusage *) w->rusage, &child->rusage_self); } } if (!SetEvent (w->ev)) /* wake up wait4 () immediately */ system_printf ("couldn't wake up wait event %p, %E", w->ev); return 1; } return -potential_match; } /* Process signals by waiting for a semaphore to become signaled. * Then scan an in-memory array representing queued signals. * Executes in a separate thread. * * Signals sent from this process are sent a completion signal so * that returns from kill/raise do not occur until the signal has * has been handled, as per POSIX. */ static DWORD WINAPI wait_sig (VOID *) { /* Initialization */ (void) SetThreadPriority (hwait_sig, WAIT_SIG_PRIORITY); /* sigcatch_nosync - semaphore incremented by sig_dispatch_pending and * by foreign processes to force an examination of * the sigtodo array. * sigcatch_main - ditto for local main thread. * sigcatch_nonmain - ditto for local non-main threads. * * sigcomplete_main - event used to signal main thread on signal * completion * sigcomplete_nonmain - semaphore signaled for non-main thread on signal * completion */ sigcatch_nosync = getsem (NULL, "sigcatch", 0, MAXLONG); sigcatch_nonmain = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL); sigcatch_main = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL); sigcomplete_nonmain = CreateSemaphore (&sec_none_nih, 0, MAXLONG, NULL); sigcomplete_main = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL); sigproc_printf ("sigcatch_nonmain %p", sigcatch_nonmain); /* Setting dwProcessId flags that this process is now capable of receiving * signals. Prior to this, dwProcessId was set to the windows pid of * of the original windows process which spawned us unless this was a * "toplevel" process. */ myself->dwProcessId = GetCurrentProcessId (); myself->process_state |= PID_ACTIVE; myself->process_state &= ~PID_INITIALIZING; ProtectHandle (sigcatch_nosync); ProtectHandle (sigcatch_nonmain); ProtectHandle (sigcatch_main); ProtectHandle (sigcomplete_nonmain); ProtectHandle (sigcomplete_main); /* If we've been execed, then there is still a stub left in the previous * windows process waiting to see if it's started a cygwin process or not. * Signalling subproc_ready indicates that we are a cygwin process. */ if (child_proc_info && child_proc_info->type == PROC_EXEC) { debug_printf ("subproc_ready %p", child_proc_info->subproc_ready); if (!SetEvent (child_proc_info->subproc_ready)) system_printf ("SetEvent (subproc_ready) failed, %E"); ForceCloseHandle (child_proc_info->subproc_ready); /* Initialize an "indirect" pid block so that if someone looks up this process via its Windows PID it will be redirected to the appropriate Cygwin PID shared memory block. */ static pinfo NO_COPY myself_identity; myself_identity.init (cygwin_pid (myself->dwProcessId), PID_EXECED); } SetEvent (wait_sig_inited); sigtid = GetCurrentThreadId (); /* If we got something like a SIGINT while we were initializing, the signal thread should be waiting for this event. This signals the thread that it's ok to send the signal since the wait_sig thread is now active. */ extern HANDLE console_handler_thread_waiter; SetEvent (console_handler_thread_waiter); HANDLE catchem[] = {sigcatch_main, sigcatch_nonmain, sigcatch_nosync}; sigproc_printf ("Ready. dwProcessid %d", myself->dwProcessId); for (;;) { DWORD rc = WaitForMultipleObjects (3, catchem, FALSE, sig_loop_wait); /* sigproc_terminate sets sig_loop_wait to zero to indicate that * this thread should terminate. */ if (rc == WAIT_TIMEOUT) if (!sig_loop_wait) break; // Exiting else continue; if (rc == WAIT_FAILED) { if (sig_loop_wait != 0) system_printf ("WFMO failed, %E"); break; } rc -= WAIT_OBJECT_0; int dispatched = FALSE; sigproc_printf ("awake"); /* A sigcatch semaphore has been signaled. Scan the sigtodo * array looking for any unprocessed signals. */ pending_signals = 0; int saw_sigchld = 0; int dispatched_sigchld = 0; for (int sig = -__SIGOFFSET; sig < NSIG; sig++) { while (InterlockedDecrement (myself->getsigtodo(sig)) >= 0) { if (sig == SIGCHLD) saw_sigchld = 1; if (sig > 0 && sig != SIGCONT && sig != SIGKILL && sig != SIGSTOP && (sigismember (& myself->getsigmask (), sig) || myself->process_state & PID_STOPPED)) { sigproc_printf ("sig %d blocked", sig); break; } /* Found a signal to process */ sigproc_printf ("processing signal %d", sig); switch (sig) { case __SIGFLUSH: /* just forcing the loop */ break; /* Internal signal to force a flush of strace data to disk. */ case __SIGSTRACE: // proc_strace (); // Dump cached strace.prntf stuff. break; /* Signalled from a child process that it has stopped */ case __SIGCHILDSTOPPED: sigproc_printf ("Received child stopped notification"); dispatched |= sig_handle (SIGCHLD); if (proc_subproc (PROC_CHILDSTOPPED, 0)) dispatched |= 1; break; /* A normal UNIX signal */ default: sigproc_printf ("Got signal %d", sig); int wasdispatched = sig_handle (sig); dispatched |= wasdispatched; if (sig == SIGCHLD && wasdispatched) dispatched_sigchld = 1; goto nextsig; } } /* Decremented too far. */ if (InterlockedIncrement (myself->getsigtodo(sig)) > 0) pending_signals = 1; nextsig: continue; } if (saw_sigchld && !dispatched_sigchld) proc_subproc (PROC_CLEARWAIT, 0); /* Signal completion of signal handling depending on which semaphore * woke up the WaitForMultipleObjects above. */ switch (rc) { case 0: SetEvent (sigcomplete_main); break; case 1: ReleaseSemaphore (sigcomplete_nonmain, 1, NULL); break; default: /* Signal from another process. No need to synchronize. */ break; } if (dispatched < 0) pending_signals = 1; sigproc_printf ("looping"); } sigproc_printf ("done"); return 0; } /* Wait for subprocesses to terminate. Executes in a separate thread. */ static DWORD WINAPI wait_subproc (VOID *) { sigproc_printf ("starting"); int errloop = 0; for (;;) { DWORD rc = WaitForMultipleObjects (nchildren + 1, events, FALSE, proc_loop_wait); if (rc == WAIT_TIMEOUT) if (!proc_loop_wait) break; // Exiting else continue; if (rc == WAIT_FAILED) { if (!proc_loop_wait) break; /* It's ok to get an ERROR_INVALID_HANDLE since another thread may have closed a handle in the children[] array. So, we try looping a couple of times to stabilize. FIXME - this is not foolproof. Probably, this thread should be responsible for closing the children. */ if (++errloop < 10 && GetLastError () == ERROR_INVALID_HANDLE) continue; system_printf ("wait failed. nchildren %d, wait %d, %E", nchildren, proc_loop_wait); for (int i = 0; i < nchildren + 1; i++) if ((rc = WaitForSingleObject (events[i], 0)) == WAIT_OBJECT_0 || rc == WAIT_TIMEOUT) continue; else system_printf ("event[%d] %p, %E", i, events[0]); break; } errloop = 0; rc -= WAIT_OBJECT_0; if (rc-- != 0) (void)proc_subproc (PROC_CHILDTERMINATED, rc); sigproc_printf ("looping"); } ForceCloseHandle (events[0]); events[0] = NULL; sigproc_printf ("done"); return 0; } extern "C" { /* Provide a stack frame when calling WaitFor* functions */ #undef WaitForSingleObject DWORD __stdcall WFSO (HANDLE hHandle, DWORD dwMilliseconds) { DWORD ret; sigframe thisframe (mainthread); ret = WaitForSingleObject (hHandle, dwMilliseconds); return ret; } #undef WaitForMultipleObjects DWORD __stdcall WFMO (DWORD nCount, CONST HANDLE *lpHandles, BOOL fWaitAll, DWORD dwMilliseconds) { DWORD ret; sigframe thisframe (mainthread); ret = WaitForMultipleObjects (nCount, lpHandles, fWaitAll, dwMilliseconds); return ret; } }