Hi,
The following program behaves incorrectly when traced:
$ uname -a
Linux dependo 2.4.2-2 #1 Sun Apr 8 19:37:14 EDT 2001 i686 unknown
$ cc -v
Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/2.96/specs
gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-81)
$ strace -V
strace -- version 4.2
$ cat t.c
main()
{
switch (fork())
{
case -1:
write(2, "fork\n", 5);
break;
case 0:
usleep(1000000);
break;
default:
if (usleep(5000000) == -1)
write(2, "wrong\n", 6);
break;
}
exit(0);
}
$ cc t.c
$ time ./a.out
real 0m5.011s
user 0m0.000s
sys 0m0.000s
$ time strace -o /dev/null ./a.out
wrong
real 0m1.025s
user 0m0.010s
sys 0m0.010s
$
The problem appears to be that, when traced, the child process' exit()
interrupts the parent's usleep() with a SIGCHLD, the latter returning EINTR.
It also fails in the same way under Linux 2.2.16 and 2.2.19.
What am I missing?
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This archive was generated by hypermail 2b29 : Wed Aug 15 2001 - 21:00:45 EST