Bug#742965: libc0.1: openpty()/forkpty() fail on kfreebsd >=9.0

[Adam Borowski <kilobyte@angband.pl>]

Package: libc0.1
Version: 2.18-4
Severity: normal


If a process has a handler for SIGCHLD, openpty() fails on kfreebsd with 9.x
kernels.  It worked ok on 8.x, and works on "real" (ie, no glibc) FreeBSD.

A reduced test case attached; when commenting out the sigaction line,
openpty() starts working again.


-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: kfreebsd-amd64 (x86_64)

Kernel: kFreeBSD 9.2-1-amd64
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libc0.1 depends on:
ii  libgcc1  1:4.8.2-16

libc0.1 recommends no packages.

Versions of packages libc0.1 suggests:
ii  debconf [debconf-2.0]  1.5.52
pn  glibc-doc              <none>
ii  locales                2.18-4

-- debconf information:
  glibc/upgrade: true
  glibc/disable-screensaver:
  glibc/restart-services:
  glibc/restart-failed:
  libraries/restart-without-asking: false

// Link with -lutil
#include <stdio.h>
#include <pty.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

static void sigchild(int dummy)
{
    while (waitpid(-1,0,WNOHANG)>0);
}

int main()
{
    int master, slave;

    struct sigaction act;
    sigemptyset(&act.sa_mask);
    act.sa_flags=SA_RESTART;
    act.sa_handler=sigchild;
    sigaction(SIGCHLD,&act,0);
    
    if (openpty(&master, &slave, 0, 0, 0))
    {
        printf("Failed: %s\n", strerror(errno));
        return 1;
    }
    printf("Ok!\n");
    return 0;
}