3 Jan
2017
3 Jan
'17
4:08 p.m.
Random832 <random832(a)fastmail.com> wrote:
On Tue, Jan 3, 2017, at 09:06, David wrote:
The text requiring the full 32-bit value is not new....
It was required in 1996 already, but then somebody introduced a bug into the
text and that was not aligned with the expected behavior.
BTW: the 24 bits are a result of coding a new wait interface into the historic
ABI by using the top 16 bits in the wait() argument value.
I should write a test program that retrieved the waitid() results from the the
SIGCHLD handler and see whether that is OK as well.
Here is the new code:
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdio.h>
/*
* Non-standard compliant platforms may need
* #include <signal.h> or something similar
* in addition to the include files above.
*/
extern void handler(int sig, siginfo_t *sip, void *context);
extern void dosig(void);
pid_t cpid;
int
main()
{
siginfo_t si;
pid_t pid;
int ret;
dosig();
if ((pid = fork()) < 0)
exit(1);
cpid = pid;
if (pid == 0) {
_exit(1234567890);
}
ret = waitid(P_PID, pid, &si, WEXITED);
printf("ret: %d si_pid: %ld si_status: %d si_code: %d\n",
ret,
(long) si.si_pid, si.si_status, si.si_code);
if (pid != si.si_pid)
printf("si_pid in struct siginfo should be %ld but is %ld\n",
(long) pid, (long) si.si_pid);
if (si.si_status != 1234567890)
printf("si_status in struct siginfo should be %d (0x%x) but is %d (0x%x)\n",
1234567890, 1234567890, si.si_status, si.si_status);
if (si.si_code != CLD_EXITED)
printf("si_code in struct siginfo should be %d (0x%x) but is %d (0x%x)\n",
CLD_EXITED, CLD_EXITED, si.si_code, si.si_code);
if (CLD_EXITED != 1)
printf("CLD_EXITED is %d on this platform\n", CLD_EXITED);
return (0);
}
/*
* Include it here to allow to verify that #include <sys/wait.h>
* makes siginfo_t available
*/
#include <signal.h>
void
handler(int sig, siginfo_t *sip, void *context)
{
printf("received SIGCHLD (%d), si_pid: %ld si_status: %d si_code: %d\n",
sig, (long) sip->si_pid, sip->si_status, sip->si_code);
if (sip->si_pid != cpid)
printf("SIGCHLD: si_pid in struct siginfo should be %ld but is %ld\n",
(long) cpid, (long) sip->si_pid);
if (sip->si_status != 1234567890)
printf("SIGCHLD: si_status in struct siginfo should be %d (0x%x) but is %d
(0x%x)\n",
1234567890, 1234567890, sip->si_status, sip->si_status);
if (sip->si_code != CLD_EXITED)
printf("SIGCHLD: si_code in struct siginfo should be %d (0x%x) but is %d
(0x%x)\n",
CLD_EXITED, CLD_EXITED, sip->si_code, sip->si_code);
}
void
dosig()
{
struct sigaction sa;
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART|SA_SIGINFO;
sigaction(SIGCHLD, &sa, NULL);
}
Jörg
--
EMail:joerg@schily.net (home) Jörg Schilling D-13353 Berlin
joerg.schilling(a)fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.org/private/ http://sourceforge.net/projects/schilytools/files/
MacOS passes this except for the si_status test.
MacOS uses a signed int
there. I???m not sure what the standard says.
The problem isn't the fact that it's signed, it's the fact that it's
only a 24-bit value (i.e. the high 8 bits are replaced with
sign-extension of bit 23). Look at the hex - expected 0x499602d2 vs
actual 0xff9602d2
However, OSX only claims compliance to Issue 6 (unistd.h _XOPEN_VERSION
600), and the text requiring that the full 32-bit value be preserved is
new to Issue 7.