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From: "Hirokazu Yamamoto" <ocean-city AT m2 DOT ccsnet DOT ne DOT jp>
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Subject: Re: crash if fork(2) from another thread
Date: Mon, 29 Sep 2008 23:42:32 +0900
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>Your test case worked fine for me with Cygwin 1.7.x.  I don't have a
>copy of 1.5.x handy to test.

> >> I don't see any reason why this shouldn't be allowed.  You should
> >> be able to do anything you want in a child process.
> >I do not think that is true. As per
> ><http://www.opengroup.org/onlinepubs/009695399/functions/fork.html>,
> >RATIONALE, the penultimate paragraph, it is basically undefined
behaviour.
>
> I wrote the current version of cygwin's fork.

I also confirmed previous code worked fine with Cygwin 1.7.
But attached code hangs on Cygwin 1.7. (Actually this is what
test_3_join_in_forked_from_thread is doing)

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#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <assert.h>

void *thread_func_2(void* args)
{
    puts("thread_func_2"); /* hang up here */
}

void *thread_func_1(void* args)
{
    int ret;
    pid_t pid;

    puts("thread_func_1");

    pid = fork();

    assert(pid != (pid_t)-1);

    if (pid != 0) /* parent process */
    {
        int status;

        printf("parent process (child pid = %d)\n", pid);

        waitpid(pid, &status, 0);

        puts("parent process end");
    }
    else /* child process */
    {
        pthread_t thread;

        puts("child process");

        ret = pthread_create(&thread, NULL, thread_func_2, NULL);
        assert(ret == 0);

        ret = pthread_join(thread, NULL);
        assert(ret == 0);

        puts("child process end");
    }

    return args;
}

int main()
{
    int ret;
    pthread_t thread;

    ret = pthread_create(&thread, NULL, thread_func_1, NULL);
    assert(ret == 0);

    ret = pthread_join(thread, NULL);
    assert(ret == 0);
}


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