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newlib-cygwin/winsup/cygwin/sigproc.cc

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/* sigproc.cc: inter/intra signal and sub process handler
Copyright 1997, 1998, 1999, 2000 Cygnus Solutions.
Written by Christopher Faylor <cgf@cygnus.com>
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 <stdlib.h>
#include <time.h>
#include <sys/wait.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/cygwin.h>
#include "cygerrno.h"
#include "sync.h"
#include "sigproc.h"
#include "pinfo.h"
#include "cygheap.h"
#include "child_info.h"
#include "perthread.h"
#include <assert.h>
#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]; // All my children info
Static pinfo zombies[PSIZE]; // 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_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 (!myself->ppid_handle)
{
debug_printf ("No myself->ppid_handle");
res = FALSE;
}
else
for (int i = 0; i < 2; i++)
switch (res = WaitForSingleObject (myself->ppid_handle, 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 myself->ppid_handle(%p) failed, error %d",
myself->ppid_handle, 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)
{
return p && !(p->process_state & (PID_INITIALIZING | PID_EXITED));
}
/* 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
{
system_printf ("couldn't get proc lock. Something is wrong.");
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);
pchildren[nchildren] = vchild;
hchildren[nchildren] = vchild->hProcess;
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);
if (!DuplicateHandle (hMainProc, hMainProc, vchild->hProcess, &vchild->ppid_handle,
0, TRUE, DUPLICATE_SAME_ACCESS))
system_printf ("Couldn't duplicate my handle<%p> for pid %d, %E", hMainProc, vchild->pid);
vchild->ppid = myself->pid;
vchild->uid = myself->uid;
vchild->gid = myself->gid;
vchild->pgid = myself->pgid;
vchild->sid = myself->sid;
vchild->ctty = myself->ctty;
vchild->impersonated = myself->impersonated;
vchild->token = myself->token;
vchild->process_state |= PID_INITIALIZING | (myself->process_state & PID_USETTY);
sigproc_printf ("added pid %d to wait list, slot %d, winpid %p, handle %p",
vchild->pid, nchildren, vchild->dwProcessId,
vchild->hProcess);
nchildren++;
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:
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);
rc = 0;
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
sigproc_printf ("removing [%d], pid %d, handle %p, nchildren %d",
val, pchildren[val]->pid, hchildren[val], nchildren);
if ((int) val < --nchildren)
{
hchildren[val] = hchildren[nchildren];
pchildren[val] = pchildren[nchildren];
}
/* Don't scan the wait queue yet. Caller will send SIGCHLD to this process.
This will cause an eventual scan of waiters. */
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 if (!potential_match || !(w->next->options & WNOHANG))
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_EXITED; /* 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]->hProcess)
sigproc_printf ("%d(%d) hProcess cleared already?", pchildren[i]->pid,
pchildren[i]->dwProcessId);
else
{
ForceCloseHandle1 (pchildren[i]->hProcess, childhProc);
sigproc_printf ("%d(%d) closed 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 ();
}
nchildren = nzombies = 0;
/* Just zero sync_proc_subproc as the delete below seems to cause
problems for older gccs. */
sync_proc_subproc = NULL;
}
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);
ProtectHandle (signal_arrived);
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
/* In case of a sigsuspend */
SetEvent (signal_arrived);
/* If !hwait_sig, then the process probably hasn't even finished
* its initialization phase.
*/
if (0 && hwait_sig)
{
if (GetCurrentThreadId () != sigtid)
WaitForSingleObject (h, 10000);
ForceCloseHandle1 (h, hwait_sig);
if (GetCurrentThreadId () != sigtid)
{
ForceCloseHandle (sigcomplete_main);
ForceCloseHandle (sigcomplete_nonmain);
ForceCloseHandle (sigcatch_main);
ForceCloseHandle (sigcatch_nonmain);
ForceCloseHandle (sigcatch_nosync);
}
}
sigproc_printf ("done");
}
#if 0
/* Set this so that subsequent tests will succeed. */
if (!myself->dwProcessId)
myself->dwProcessId = GetCurrentProcessId ();
#endif
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)
{
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;
ch->pppid_handle = myself->ppid_handle;
}
/* 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 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].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_main %p", sigcatch_nonmain, sigcatch_main);
/* 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 || child_proc_info->type == PROC_SPAWN))
{
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 ();
HANDLE catchem[] = {sigcatch_main, sigcatch_nonmain, sigcatch_nosync};
sigproc_printf ("Ready. dwProcessid %d", myself->dwProcessId);
for (int i = 0; ; i++)
{
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 = -1;
int saw_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)
saw_pending_signals = 1;
nextsig:
continue;
}
/* FIXME: The dispatched stuff probably isn't needed anymore. */
if (dispatched >= 0 && pending_signals < 0 && !saw_pending_signals)
{
pending_signals = 0;
/* FIXME FIXME FIXME FIXME FIXME
This is a real kludge designed to handle runaway processes who
missed a signal and never processed a signal handler. We have
to reset signal_arrived or stuff goes crazy. */
if (i >= 20)
{
i = 0;
ResetEvent (signal_arrived);
}
}
if (nzombies && 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;
}
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++)
proc_subproc (PROC_NOTHING, 0); // Just synchronize and continue
if (errloop < 10)
continue;
system_printf ("wait failed. nchildren %d, wait %d, %E",
nchildren, proc_loop_wait);
for (int i = 0; i <= nchildren; i++)
if ((rc = WaitForSingleObject (events[i], 0)) == WAIT_OBJECT_0 ||
rc == WAIT_TIMEOUT)
continue;
else if (i == 0)
system_printf ("nchildren %d, event[%d] %p, %E", nchildren, i, events[i]);
else
{
system_printf ("nchildren %d, event[%d] %p, pchildren[%d] %p, events[0] %p, %E",
nchildren, i, events[i], i - 1, (_pinfo *) pchildren[i - 1], events[0]);
system_printf ("pid %d, dwProcessId %u, hProcess %p, progname '%s'",
pchildren[i - 1]->pid, pchildren[i - 1]->dwProcessId,
pchildren[i - 1]->hProcess, pchildren[i - 1]->progname);
}
break;
}
errloop = 0;
rc -= WAIT_OBJECT_0;
if (rc-- != 0)
{
rc = proc_subproc (PROC_CHILDTERMINATED, rc);
if (!proc_loop_wait) // Don't bother if wait_subproc is
break; // exiting
/* Send a SIGCHLD to myself. We do this here, rather than in proc_subproc
to avoid the proc_subproc lock since the signal thread will eventually
be calling proc_subproc and could unnecessarily block. */
if (rc)
sig_send (myself_nowait, SIGCHLD);
}
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;
}
}
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