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child process is not created using clone()


I have observed one issue with NetBSD-3.1.
The problem description is mentioned below.

Not able to create a child process using clone()  if the executable
build by linking with pthread library.


$ cat sample_clone.c

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.h>
#include <signal.h>

#define ALIGNMENT 0x08

int pid;

fun(void *arg)
  printf("\n In child \n");

int  main()
  char *ch_stck = NULL,*ch_stck2;
  int status;

  if ((ch_stck = (char *)malloc(10000)) == NULL)
    printf("malloc() fail\n");

  printf("child stack allocated = %x\n",ch_stck);

  ch_stck2 = (void *)((unsigned long)(ch_stck + 10000) & ~(ALIGNMENT -1));

  printf("child stack = %x\n",ch_stck2);

  if ((pid = clone(&fun,ch_stck2,SIGCHLD,NULL)) == -1)
    printf("clone() fail\n");

  if ((wait(&status)) == -1)
    printf("wait() fail\n");

  return 0;

How to reproduce:
# gcc sample_clone.c -o sample_clone -lpthread

# ./sample_clone
child stack allocated = 804c000
child stack = 804e710

No child statements printed here.

But the above issue is not observed for static build.

# gcc -static sample_clone.c -o sample_clone -lpthread

# ./sample_clone
child stack allocated = 8058000
child stack = 8058000

 In child <===== Here child statements printed.

Please let me know, is this the issue in the NetBSD library ?

Waiting for the reply.

Thank You,
Amol Pise

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