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Fix bug #12829 with aborts on MS-Windows when several child processes die.

Browse source 
nt/inc/sys/wait.h: New file, with prototype of waitpid and
 definitions of macros it needs.
 nt/inc/ms-w32.h (wait): Don't define, 'wait' is not used anymore.
 (sys_wait): Remove prototype.
 nt/config.nt (HAVE_SYS_WAIT_H): Define to 1.

 src/w32proc.c (create_child): Don't clip the PID of the child
 process to fit into an Emacs integer, as this is no longer a
 restriction.
 (waitpid): Rename from sys_wait.  Emulate a Posix 'waitpid' by
 reaping only the process specified by PID argument, if that is
 positive.  Use PID instead of dead_child to know which process to
 reap.  Wait for the child to die only if WNOHANG is not in
 OPTIONS.
 (sys_select): Don't set dead_child.
 src/sysdep.c (wait_for_termination_1): Remove the WINDOWSNT portion,
 as it is no longer needed.
 src/process.c (waitpid, WUNTRACED) [!WNOHANG]: Remove definitions,
 no longer needed.
 (record_child_status_change): Remove the setting of
 record_at_most_one_child for the !WNOHANG case.
This commit is contained in:
Eli Zaretskii 2012-11-17 18:46:45 +02:00
parent a631d0e047
commit 22bae83fa8
8 changed files with 156 additions and 66 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
nt/ChangeLog
View file

@ -1,3 +1,13 @@
2012-11-17 Eli Zaretskii <eliz@gnu.org>
* inc/sys/wait.h: New file, with prototype of waitpid and
definitions of macros it needs.
* inc/ms-w32.h (wait): Don't define, 'wait' is not used anymore.
(sys_wait): Remove prototype.
* config.nt (HAVE_SYS_WAIT_H): Define to 1.
2012-11-17 Dani Moncayo <dmoncayo@gmail.com>
* zipdist.bat (ZIP_CHECK): Remove unused label. When invoking 7z

2
nt/config.nt
View file

@ -986,7 +986,7 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#undef HAVE_SYS_VLIMIT_H
/* Define to 1 if you have <sys/wait.h> that is POSIX.1 compatible. */
#undef HAVE_SYS_WAIT_H
#define HAVE_SYS_WAIT_H 1
/* Define to 1 if you have the <term.h> header file. */
#undef HAVE_TERM_H

3
nt/inc/ms-w32.h
View file

@ -183,15 +183,12 @@ extern char *getenv ();
/* Subprocess calls that are emulated. */
#define spawnve sys_spawnve
#define wait sys_wait
#define kill sys_kill
#define signal sys_signal
/* Internal signals. */
#define emacs_raise(sig) emacs_abort()
extern int sys_wait (int *);
/* termcap.c calls that are emulated. */
#define tputs sys_tputs
#define tgetstr sys_tgetstr

33
nt/inc/sys/wait.h Normal file
View file

@ -0,0 +1,33 @@
/* A limited emulation of sys/wait.h on Posix systems.
Copyright (C) 2012 Free Software Foundation, Inc.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#ifndef INC_SYS_WAIT_H_
#define INC_SYS_WAIT_H_
#define WNOHANG 1
#define WUNTRACED 2
#define WSTOPPED 2 /* same as WUNTRACED */
#define WEXITED 4
#define WCONTINUED 8
/* The various WIF* macros are defined in src/syswait.h. */
extern pid_t waitpid (pid_t, int *, int);
#endif /* INC_SYS_WAIT_H_ */

20
src/ChangeLog
View file

@ -1,3 +1,23 @@
2012-11-17 Eli Zaretskii <eliz@gnu.org>
* w32proc.c (create_child): Don't clip the PID of the child
process to fit into an Emacs integer, as this is no longer a
restriction.
(waitpid): Rename from sys_wait. Emulate a Posix 'waitpid' by
reaping only the process specified by PID argument, if that is
positive. Use PID instead of dead_child to know which process to
reap. Wait for the child to die only if WNOHANG is not in
OPTIONS.
(sys_select): Don't set dead_child.
* sysdep.c (wait_for_termination_1): Remove the WINDOWSNT portion,
as it is no longer needed.
* process.c (waitpid, WUNTRACED) [!WNOHANG]: Remove definitions,
no longer needed.
(record_child_status_change): Remove the setting of
record_at_most_one_child for the !WNOHANG case.
2012-11-17 Paul Eggert <eggert@cs.ucla.edu>
Fix problems in ns port found by static checking.

20
src/process.c
View file

@ -130,18 +130,6 @@ extern int sys_select (int, SELECT_TYPE *, SELECT_TYPE *, SELECT_TYPE *,
EMACS_TIME *, void *);
#endif
/* This is for DOS_NT ports. FIXME: Remove this old portability cruft
by having DOS_NT ports implement waitpid instead of wait. Nowadays
POSIXish hosts all define waitpid, WNOHANG, and WUNTRACED, as these
have been standard since POSIX.1-1988. */
#ifndef WNOHANG
# undef waitpid
# define waitpid(pid, status, options) wait (status)
#endif
#ifndef WUNTRACED
# define WUNTRACED 0
#endif
/* Work around GCC 4.7.0 bug with strict overflow checking; see
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52904>.
These lines can be removed once the GCC bug is fixed. */
@ -6295,17 +6283,9 @@ record_child_status_change (pid_t pid, int w)
{
#ifdef SIGCHLD
# ifdef WNOHANG
/* On POSIXish hosts, record at most one child only if we already
know one child that has exited. */
bool record_at_most_one_child = 0 <= pid;
# else
/* On DOS_NT (the only porting target that lacks WNOHANG),
record the status of at most one child process, since the SIGCHLD
handler must return right away. If any more processes want to
signal us, we will get another signal. */
bool record_at_most_one_child = 1;
# endif
Lisp_Object tail;

7
src/sysdep.c
View file

@ -289,10 +289,6 @@ wait_for_termination_1 (pid_t pid, int interruptible)
{
while (1)
{
#ifdef WINDOWSNT
wait (0);
break;
#else /* not WINDOWSNT */
int status;
int wait_result = waitpid (pid, &status, 0);
if (wait_result < 0)
@ -306,7 +302,8 @@ wait_for_termination_1 (pid_t pid, int interruptible)
break;
}
#endif /* not WINDOWSNT */
/* Note: the MS-Windows emulation of waitpid calls QUIT
internally. */
if (interruptible)
QUIT;
}

127
src/w32proc.c
View file

@ -789,7 +789,6 @@ alarm (int seconds)
/* Child process management list. */
int child_proc_count = 0;
child_process child_procs[ MAX_CHILDREN ];
child_process *dead_child = NULL;
static DWORD WINAPI reader_thread (void *arg);
@ -1042,9 +1041,6 @@ create_child (char *exe, char *cmdline, char *env, int is_gui_app,
if (cp->pid < 0)
cp->pid = -cp->pid;
/* pid must fit in a Lisp_Int */
cp->pid = cp->pid & INTMASK;
*pPid = cp->pid;
return TRUE;
@ -1120,55 +1116,110 @@ reap_subprocess (child_process *cp)
delete_child (cp);
}
/* Wait for any of our existing child processes to die
When it does, close its handle
Return the pid and fill in the status if non-NULL. */
/* Wait for a child process specified by PID, or for any of our
existing child processes (if PID is nonpositive) to die. When it
does, close its handle. Return the pid of the process that died
and fill in STATUS if non-NULL. */
int
sys_wait (int *status)
pid_t
waitpid (pid_t pid, int *status, int options)
{
DWORD active, retval;
int nh;
int pid;
child_process *cp, *cps[MAX_CHILDREN];
HANDLE wait_hnd[MAX_CHILDREN];
DWORD timeout_ms;
int dont_wait = (options & WNOHANG) != 0;
nh = 0;
if (dead_child != NULL)
/* According to Posix:
PID = -1 means status is requested for any child process.
PID > 0 means status is requested for a single child process
whose pid is PID.
PID = 0 means status is requested for any child process whose
process group ID is equal to that of the calling process. But
since Windows has only a limited support for process groups (only
for console processes and only for the purposes of passing
Ctrl-BREAK signal to them), and since we have no documented way
of determining whether a given process belongs to our group, we
treat 0 as -1.
PID < -1 means status is requested for any child process whose
process group ID is equal to the absolute value of PID. Again,
since we don't support process groups, we treat that as -1. */
if (pid > 0)
{
/* We want to wait for a specific child */
wait_hnd[nh] = dead_child->procinfo.hProcess;
cps[nh] = dead_child;
if (!wait_hnd[nh]) emacs_abort ();
nh++;
active = 0;
goto get_result;
int our_child = 0;
/* We are requested to wait for a specific child. */
for (cp = child_procs + (child_proc_count-1); cp >= child_procs; cp--)
{
/* Some child_procs might be sockets; ignore them. Also
ignore subprocesses whose output is not yet completely
read. */
if (CHILD_ACTIVE (cp)
&& cp->procinfo.hProcess
&& cp->pid == pid)
{
our_child = 1;
break;
}
}
if (our_child)
{
if (cp->fd < 0 || (fd_info[cp->fd].flags & FILE_AT_EOF) != 0)
{
wait_hnd[nh] = cp->procinfo.hProcess;
cps[nh] = cp;
nh++;
}
else if (dont_wait)
{
/* PID specifies our subprocess, but its status is not
yet available. */
return 0;
}
}
if (nh == 0)
{
/* No such child process, or nothing to wait for, so fail. */
errno = ECHILD;
return -1;
}
}
else
{
for (cp = child_procs + (child_proc_count-1); cp >= child_procs; cp--)
/* some child_procs might be sockets; ignore them */
if (CHILD_ACTIVE (cp) && cp->procinfo.hProcess
&& (cp->fd < 0 || (fd_info[cp->fd].flags & FILE_AT_EOF) != 0))
{
wait_hnd[nh] = cp->procinfo.hProcess;
cps[nh] = cp;
nh++;
}
{
if (CHILD_ACTIVE (cp)
&& cp->procinfo.hProcess
&& (cp->fd < 0 || (fd_info[cp->fd].flags & FILE_AT_EOF) != 0))
{
wait_hnd[nh] = cp->procinfo.hProcess;
cps[nh] = cp;
nh++;
}
}
if (nh == 0)
{
/* Nothing to wait on, so fail. */
errno = ECHILD;
return -1;
}
}
if (nh == 0)
{
/* Nothing to wait on, so fail */
errno = ECHILD;
return -1;
}
if (dont_wait)
timeout_ms = 0;
else
timeout_ms = 1000; /* check for quit about once a second. */
do
{
/* Check for quit about once a second. */
QUIT;
active = WaitForMultipleObjects (nh, wait_hnd, FALSE, 1000);
active = WaitForMultipleObjects (nh, wait_hnd, FALSE, timeout_ms);
} while (active == WAIT_TIMEOUT);
if (active == WAIT_FAILED)
@ -1198,8 +1249,10 @@ sys_wait (int *status)
}
if (retval == STILL_ACTIVE)
{
/* Should never happen */
/* Should never happen. */
DebPrint (("Wait.WaitForMultipleObjects returned an active process\n"));
if (pid > 0 && dont_wait)
return 0;
errno = EINVAL;
return -1;
}
@ -1213,6 +1266,8 @@ sys_wait (int *status)
else
retval <<= 8;
if (pid > 0 && active != 0)
emacs_abort ();
cp = cps[active];
pid = cp->pid;
#ifdef FULL_DEBUG
@ -2001,9 +2056,7 @@ sys_select (int nfds, SELECT_TYPE *rfds, SELECT_TYPE *wfds, SELECT_TYPE *efds,
DebPrint (("select calling SIGCHLD handler for pid %d\n",
cp->pid));
#endif
dead_child = cp;
sig_handlers[SIGCHLD] (SIGCHLD);
dead_child = NULL;
}
}
else if (fdindex[active] == -1)