wait4() doesn't seem to work

[korli]

wait4() located here: ​http://cgit.haiku-os.org/haiku/tree/src/libs/bsd/wait.c#n23

Test program:

/*
 * Copyright 2007, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
 * Distributed under the terms of the MIT License.
 */


#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/resource.h> 
#define _BSD_SOURCE
#include <sys/wait.h>
#include <unistd.h>


/*!
	wait() should wait only once. If any argument is given, waitpid() should return
	an error (and errno to ECHILD), since there is no child with that process group ID.
*/


int
child2()
{
	sleep(2);
	return 2;
}


//! exits before child 2
int
child1()
{
	setpgrp();
		// put us into a new process group

	pid_t child = fork();
	if (child == 0)
		return child2();

	sleep(1);
	return 1;
}


int
main(int argc, char** argv)
{
	bool waitForGroup = argc > 1;

	pid_t child = fork();
	if (child == 0)
		return child1();

	struct rusage usage;
	pid_t pid;
	do {
		int childStatus = -1;
		pid = wait4(-1, &childStatus, 0, &usage);
		printf("wait4() returned %ld (%s), child status %d\n",
			pid, strerror(errno), childStatus);
	} while (pid >= 0);

	return 0;
}

Haiku strace output

[   581] _kern_image_relocated(0xf6d) (409 us)
[   581] _kern_set_area_protection(0x2cce, 0x5) = 0x00000000 No error (11 us)
[   581] _kern_set_area_protection(0x2cd0, 0x5) = 0x00000000 No error (10 us)
[   581] _kern_set_area_protection(0x2cd2, 0x5) = 0x00000000 No error (23 us)
[   581] _kern_get_system_info(0x72d84998) = 0x00000000 No error (7 us)
[   581] _kern_get_system_info(0x72d84798) = 0x00000000 No error (4 us)
[   581] _kern_reserve_address_range([0x18033000], 0x7, 0x48000000) = 0x00000000 No error (7 us)
[   581] _kern_create_area("heap", 0xc6b980, 0x1, 0x40000, 0x0, 0x33) = 0x00002cd6 (15 us)
[   581] _kern_fork() = 0x00000247 (241 us)
[   581] _kern_wait_for_child(0xffffffff, 0x0, 0x72d84b64) = 0x00000247 (999999 us)
[   581] --- Child exited (Child exited) ---
[   581] _kern_get_team_usage_info(0x247, 0x0, 0x72d84bb8, 0x10) = 0x80001103 Operation on invalid team (2 us)
[   581] _kern_read_stat(0x1, (nil), false, 0x72d83390, 0x58) = 0x00000000 No error (4 us)
[   581] _kern_ioctl(0x1, TCGETA, 0x72d83338, 0x20) = 0x00000000 No error (5 us)
wait4() returned -1 (No error), child status 1
[   581] _kern_write(0x1, 0xffffffffffffffff, 0x180571b0, 0x2f) = 0x0000002f (1379 us)
[   581] _kern_exit_team(0x0) (9 us)

Linux output

wait4() returned 22104 (Success), child status 256
wait4() returned 4294967295 (No child processes), child status -1