Hi,
There appears to be a problem with signal handling in Cygwin, whereby
it is possible under load for signals not to be delivered to the
process they have been sent to when expected. However, they only
appear to be deferred, and are delivered on receipt of a subsequent
signal.
To test this, I used the following stand-alone program, and
passed signals to it using the "kill(1)" command:
Test program "sighand.c":
-------------------------
=====================================================
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
/* Test signal handler */
#ifdef USE_SIGACTION
struct sigaction sAction,sOld;
#endif
/* Counters and running flag */
int iInt = 0;
int iUsr1 = 0;
int iAlarm = 0;
int bRunning = 0;
/* Forward declaration of handler */
void trap(int);
main() {
#ifdef USE_SIGACTION
/* Set signal disposition using sigaction() */
printf("sighand: using sigaction()\n");
sigemptyset(&(sAction.sa_mask));
sAction.sa_handler = trap;
sAction.sa_flags = 0;
if (sigaction(SIGINT,&sAction,&sOld) == -1)
perror("sigaction(INT)");
if (sigaction(SIGUSR1,&sAction,&sOld) == -1)
perror("sigaction(USR1)");
if (sigaction(SIGALRM,&sAction,&sOld) == -1)
perror("sigaction(ALRM)");
if (sigaction(SIGTERM,&sAction,&sOld) == -1)
perror("sigaction(TERM)");
#else
/* Set signal disposition using signal() */
printf("sighand: using signal()\n");
signal(SIGINT,trap);
signal(SIGUSR1,trap);
signal(SIGALRM,trap);
signal(SIGTERM,trap);
#endif
/* Main loop - run until SIGTERM resets run flag */
bRunning = 1;
while (bRunning)
pause();
/* Report signal counts */
printf("SIGINT : %d received\n",iInt);
printf("SIGUSR1: %d received\n",iUsr1);
printf("SIGALRM: %d received\n",iAlarm);
exit(0);
}
/* Signal trap */
void trap(int iSig) {
/* Report and bump counter: SIGTERM stops run */
printf("Trapped signal %d\n",iSig);
switch (iSig) {
case SIGINT:
iInt++;
break;
case SIGUSR1:
iUsr1++;
break;
case SIGALRM:
iAlarm++;
break;
case SIGTERM:
bRunning = 0;
break;
}
/* If using signal(), we must reset! */
#ifndef USE_SIGACTION
signal(iSig,trap);
#endif
return;
}
=====================================================
Compilation:
$ gcc [-DUSE_SIGACTION] sighand.c -o sighand
Test commands issued (from another bash):
-----------------------------------------
Find the PID of sighand, then
$ for n in 1 2 3 4 5 6 7 8 9 10; do kill -USR1 <PID>; done
$ kill -INT <PID>
(kill -INT repeated until no more SIGUSR1s are reported)
$ kill <PID>
Output of signand after above test:
-----------------------------------
sighand: using sigaction()
Trapped signal 30
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 30
Trapped signal 2
Trapped signal 2
Trapped signal 15
SIGINT : 9 received
SIGUSR1: 10 received
SIGALRM: 0 received
The output is similar, whether the program is compiled with
"-DUSE_SIGACTION" or not.
Can anyone throw any light on this - is there something I'm missing, or is it
something I'll have to live with?
And before you ask, NO, I haven't the experience (yet :-) to debug the Cygwin
code and patch it!
Regards,
Gary Rowe
-----------------
Output of "cygcheck -srv" follows:
----------------------------------
Cygnus Win95/NT Configuration Diagnostics
Current System Time: Tue Mar 13 15:00:37 2001
WinNT Ver 4.0 build 1381 Service Pack 5
Path: /r7systems/bin.nt4
/usr/local/bin
/usr/bin
/bin
/cygdrive/c/WINNT/system32
/cygdrive/c/WINNT
/cygdrive/c/PROGRA~1/TCL/bin
/usr/bin
/usr/local/bin
/cygdrive/c/NetExpress/base/BIN
/cygdrive/c/MSDEV/BIN
/cygdrive/c/dos
.
/emacs-20.7/bin
/cobol/BIN
SysDir: C:\WINNT\System32
WinDir: C:\WINNT
PWD = `/home/angus/test'
USER = `angus'
MAKE_MODE = `unix'
HOME = `/home/angus'
NUMBER_OF_PROCESSORS = `1'
PROMPT = `$P$G'
LOGONSERVER = `\\GARYDESK'
OS2LIBPATH = `C:\WINNT\system32\os2\dll;'
COMSPEC = `C:\WINNT\system32\cmd.exe'
IS = `/r7systems'
LASTREL = `7.00.0'
!C: = `C:\cygwin\bin'
YCFLAGS = `-DNT4 -DISAMDLL'
SYSTEMDRIVE = `C:'
SYSREL = `NT4_SP5_CYGWIN-1.1.4'
HOSTNAME = `GARYDESK'
INCLUDE = `c:\msdev\include;c:\msdev\mfc\include;%include%'
PROCESSOR_REVISION = `0703'
MSDEVDIR = `C:\MSDEV'
CISAM = `/usr/local/cisam'
OS_LIBS = `-lcompat -lcygipc -lcygwin -lkernel32 -L/usr/local/cisam/lib -lisam'
PATHEXT = `.COM;.EXE;.BAT;.CMD'
COMPUTERNAME = `GARYDESK'
WINDIR = `C:\WINNT'
USERPROFILE = `C:\WINNT\Profiles\angus'
LS = `/r7systems/lib.nt4'
OS_CIOS = `'
PS1 = `$PWD\$ '
SYS = `/r7systems'
MS = `/r7systems/messages'
COBRTS = `CBLRTSS'
MANDIR = `/r7systems/man'
LCFLAGS = `-DNT4 -DISAMDLL'
M = `d:/bankmaster/messages'
SHL_EXT = `DLL'
MACHTYPE = `i686-pc-cygwin'
COBLIB = `/cobol/LIB'
PROCESSOR_IDENTIFIER = `x86 Family 6 Model 7 Stepping 3, GenuineIntel'
OS = `Windows_NT'
OLDPWD = `/home/angus'
BS = `/r7systems/bin.nt4'
PROCESSOR_ARCHITECTURE = `x86'
TEMP = `/cygdrive/c/TEMP'
PROCESSOR_LEVEL = `6'
SYSTEMROOT = `C:\WINNT'
CS = `/r7systems/config'
PLATFORM = `NT4'
HOMEDRIVE = `C:'
LIB = `c:\msdev\lib;c:\msdev\mfc\lib;%lib%'
SHLVL = `1'
LOGNAME = `angus'
HOMEPATH = `\'
USERDOMAIN = `GARYDESK'
MSC = `/r7systems/messages'
OS_FLAGS = `-DNT4 -DISAMDLL'
USERNAME = `Angus'
SHELL = `/bin/sh'
HOSTTYPE = `i686'
OS_DMS = `'
OSTYPE = `cygwin'
TERM = `pcansi'
_ = `/usr/bin/cygcheck.exe'
TZ = `IST-5:30'
HKEY_CURRENT_USER\Software\Cygnus Solutions
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2
(default) = `/cygdrive'
cygdrive flags = 0x00000022
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/bankmaster
(default) = `d:\bankmaster'
flags = 0x00000000
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/cobol
(default) = `d:\netexpress\base'
flags = 0x00000000
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/copylib
(default) = `d:\copylib'
flags = 0x00000000
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/download
(default) = `d:\download'
flags = 0x00000002
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/nusrc
(default) = `g:\vol1\port\tpg217'
flags = 0x00000000
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/port
(default) = `d:\r7systems.old'
flags = 0x00000002
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/r7systems
(default) = `d:\r7systems'
flags = 0x00000002
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\mounts v2\/temp
(default) = `d:\temp'
flags = 0x00000000
HKEY_CURRENT_USER\Software\Cygnus Solutions\Cygwin\Program Options
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\Installed Components
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\Installed
Components\C:/cygwin
(default) = `20000517'
bash = `0002.0004.0001'
binutils = `19990818.0002'
bison = `0000'
byacc = `0000'
bzip = `0000'
clear = `0001.0000'
crypt = `0001.0000'
cygwin = `0001.0001.0002'
dejagnu = `0000'
diff = `0TAR.00GZ'
expect = `0000'
fileutils = `0000'
findutils = `0000'
flex = `0TAR.00GZ'
gawk = `0TAR.00GZ'
gcc = `0002.0095.0002.0002'
gdb = `20000610'
gperf = `0000'
grep = `0TAR.00GZ'
groff = `0001.011a.0001'
inetutils = `0001.0003.0002.0004'
less = `0TAR.00GZ'
libpng = `0001.0000.0006.0001'
login = `0001.0003'
m = `0TAR.00GZ'
make = `0003.0079.0001'
man = `0001.005g.0002'
patch = `0000'
sed = `0003.0002.0001'
shellutils = `0000'
tar = `0TAR.00GZ'
tcltk = `20000610'
termcap = `20000618.0001'
texinfo = `0000'
textutils = `0000'
time = `0TAR.00GZ'
zlib = `0001.0001.0003.0001'
GZIP = `0TAR.00GZ'
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\mounts v2
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\mounts v2\/
(default) = `c:\cygwin'
flags = 0x0000000a
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\mounts v2\/usr/bin
(default) = `c:/cygwin/bin'
flags = 0x0000000a
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\mounts v2\/usr/lib
(default) = `c:/cygwin/lib'
flags = 0x0000000a
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\Cygwin\Program Options
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\00
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\01
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\02
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\03
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\04
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\05
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\06
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\07
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\08
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\09
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0A
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0B
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0C
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0D
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0E
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\0F
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\10
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\11
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\12
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\13
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\14
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\15
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\16
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\17
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\18
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\19
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\1A
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\1B
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\1C
HKEY_LOCAL_MACHINE\SOFTWARE\Cygnus Solutions\CYGWIN.DLL setup\b15.0\mounts\1D
c: hd FAT 2047Mb 86% CP UN
d: hd NTFS 2063Mb 63% CP CS UN PA FC
e: net FAT 2047Mb 75% CP UN
f: net NTFS 2055Mb 62% CP CS UN PA FC
g: net FAT 2047Mb 82% CP UN
h: net NTFS 2055Mb 67% CP CS UN PA FC
r: cd N/A N/A
g:\vol1\port\tpg217 /nusrc user textmode
d:\netexpress\base /cobol user textmode
d:\r7systems.old /port user binmode
c:\cygwin\bin /usr/bin system binmode
c:\cygwin\lib /usr/lib system binmode
d:\bankmaster /bankmaster user textmode
d:\r7systems /r7systems user binmode
d:\download /download user binmode
d:\copylib /copylib user textmode
c:\cygwin / system binmode
d:\temp /temp user textmode
Found: c:\cygwin\bin\bash.exe
Found: c:\cygwin\bin\cat.exe
Found: c:\cygwin\bin\cpp.exe
Found: c:\cygwin\bin\find.exe
Found: c:\dos\find.exe
Warning: c:\cygwin\bin\find.exe hides c:\dos\find.exe
Found: c:\cygwin\bin\gcc.exe
Found: c:\cygwin\bin\gdb.exe
Found: c:\cygwin\bin\ld.exe
Found: c:\cygwin\bin\ls.exe
Found: c:\cygwin\bin\make.exe
Found: c:\cygwin\bin\sh.exe
56k 2000/12/03 c:\cygwin\bin\cygbz21.0.dll - os=4.0 img=1.0 sys=4.0
"cygbz21.0.dll" v0.0 ts=2000/11/21 5:23
18k 2000/10/23 c:\cygwin\bin\cyggdbm.dll - os=4.0 img=1.0 sys=4.0
"cyggdbm.dll" v0.0 ts=2000/10/23 7:56
14k 2000/10/23 c:\cygwin\bin\cygintl.dll - os=4.0 img=1.0 sys=4.0
"cygintl.dll" v0.0 ts=2000/10/24 0:32
45k 2000/10/22 c:\cygwin\bin\cygjbig1.dll - os=4.0 img=1.0 sys=4.0
"cygjbig1.dll" v0.0 ts=2000/10/23 4:36
119k 2000/10/23 c:\cygwin\bin\cygjpeg6b.dll - os=4.0 img=1.0 sys=4.0
"cygjpeg6b.dll" v0.0 ts=2000/10/23 6:28
17k 2001/01/07 c:\cygwin\bin\cyghistory4.dll - os=4.0 img=1.0 sys=4.0
"cyghistory4.dll" v0.0 ts=2001/1/7 10:04
108k 2001/01/07 c:\cygwin\bin\cygreadline4.dll - os=4.0 img=1.0 sys=4.0
"cygreadline4.dll" v0.0 ts=2001/1/7 10:04
81k 2000/12/05 c:\cygwin\bin\cygitcl30.dll - os=4.0 img=1.0 sys=4.0
"cygitcl30.dll" v0.0 ts=2000/11/26 7:13
35k 2000/12/05 c:\cygwin\bin\cygitk30.dll - os=4.0 img=1.0 sys=4.0
"cygitk30.dll" v0.0 ts=2000/11/26 7:13
623k 2000/12/05 c:\cygwin\bin\cygtk80.dll - os=4.0 img=1.0 sys=4.0
"cygtk80.dll" v0.0 ts=2000/11/26 7:13
243k 2000/10/23 c:\cygwin\bin\cygtiff3.dll - os=4.0 img=1.0 sys=4.0
"cygtiff3.dll" v0.0 ts=2000/10/23 6:44
41k 2000/11/20 c:\cygwin\bin\cygXpm-noX4.dll - os=4.0 img=1.0 sys=4.0
"cygXpm-noX4.dll" v0.0 ts=2000/11/20 8:11
45k 2000/11/20 c:\cygwin\bin\cygXpm-X4.dll - os=4.0 img=1.0 sys=4.0
"cygXpm-X4.dll" v0.0 ts=2000/11/20 8:15
82k 2001/01/21 c:\cygwin\bin\cygform5.dll - os=4.0 img=1.0 sys=4.0
"cygform5.dll" v0.0 ts=2001/1/22 2:09
53k 2001/01/21 c:\cygwin\bin\cygmenu5.dll - os=4.0 img=1.0 sys=4.0
"cygmenu5.dll" v0.0 ts=2001/1/22 2:09
414k 2001/01/21 c:\cygwin\bin\cygncurses++5.dll - os=4.0 img=1.0 sys=4.0
"cygncurses++5.dll" v0.0 ts=2001/1/22 2:10
299k 2001/01/21 c:\cygwin\bin\cygncurses5.dll - os=4.0 img=1.0 sys=4.0
"cygncurses5.dll" v0.0 ts=2001/1/22 2:08
34k 2001/01/21 c:\cygwin\bin\cygpanel5.dll - os=4.0 img=1.0 sys=4.0
"cygpanel5.dll" v0.0 ts=2001/1/22 2:08
390k 2001/01/18 c:\cygwin\bin\cygtcl80.dll - os=4.0 img=1.0 sys=4.0
"cygtcl80.dll" v0.0 ts=2001/1/18 10:14
5k 2001/01/18 c:\cygwin\bin\cygtclpip80.dll - os=4.0 img=1.0 sys=4.0
10k 2001/01/18 c:\cygwin\bin\cygtclreg80.dll - os=4.0 img=1.0 sys=4.0
"cygtclreg80.dll" v0.0 ts=2001/1/18 10:14
163k 2001/02/03 c:\cygwin\bin\cygpng2.dll - os=4.0 img=1.0 sys=4.0
"cygpng2.dll" v0.0 ts=2001/2/4 2:51
49k 2001/02/03 c:\cygwin\bin\cygz.dll - os=4.0 img=1.0 sys=4.0
"cygz.dll" v0.0 ts=2001/2/4 2:05
615k 2001/01/31 c:\cygwin\bin\cygwin1.dll - os=4.0 img=1.0 sys=4.0
"cygwin1.dll" v0.0 ts=2001/1/31 20:38
Cygwin DLL version info:
dll major: 1001
dll minor: 8
dll epoch: 19
dll bad signal mask: 19005
dll old termios: 5
dll malloc env: 28
api major: 0
api minor: 34
shared data: 3
dll identifier: cygwin1
mount registry: 2
cygnus registry name: Cygnus Solutions
cygwin registry name: Cygwin
program options name: Program Options
cygwin mount registry name: mounts v2
cygdrive flags: cygdrive flags
cygdrive prefix: cygdrive prefix
cygdrive default prefix:
build date: Wed Jan 31 10:08:38 EST 2001
shared id: cygwin1S3
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