Subj : why can not setstack in share library?
To   : comp.programming.threads
From : zhouxw
Date : Wed Mar 30 2005 01:22 am

Following program runs OK on Linux kernel 2.6.9 under root
/*test_merge.c*/
/* #gcc -o test_merge test_merge.c -lpthread */
#include <pthread.h>
#include <errno.h>
#include <sys/shm.h>
#define PAGE_SIZE 	4UL*1024UL*1024UL
#define ADDR 		(0x00000000UL)

void thread1(void)
{
	int i=11;
	printf("first variable of thread1 addr = %p\n", &i);
}
int main(void)
{
	pthread_attr_t attr;
	pthread_attr_init(&attr); 
	pthread_t id;
	int ret;	
	void  *addr = NULL;
	int  shmid = 0;
	
	key_t key = 600;	
	shmid = shmget(key, PAGE_SIZE,
SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W|SHM_RND);
	if(shmid != -1)
	{
		addr = shmat(shmid, (void *)ADDR , 0); 
		if (((long)addr) == -1)		
			return 1;		
	}
	ret = pthread_attr_setstack (&attr, addr , PAGE_SIZE);
	if(ret != 0 )  
		return 1;		
	ret = pthread_create(&id,&attr,(void *)thread1, NULL);
	if(ret != 0 )
		return 1;	
	pthread_join(id,NULL); 
	return (0);
}

But why if I wrapped pthread_create(3),It causeed "Segmentation fault"
:(
I display the code here:
/*my_thread.c*/
#include <pthread.h>
#include <sys/shm.h>

#define PAGE_SIZE 	4UL*1024UL*1024UL
#define ADDR 		(0x00000000UL)

int my_pthread_create(pthread_t * id, pthread_attr_t * attribute, void
* (*start_routine)(void *), void * arg)
{
	pthread_attr_t attr;
	pthread_attr_init(&attr);
	int ret;	
	int  shmid = 0;
	void  *addr = NULL;
	key_t key = 566; 
	
	shmid = shmget(key, PAGE_SIZE,
SHM_HUGETLB|IPC_CREAT|SHM_R|SHM_W|SHM_RND);
	if(shmid != -1)
	{
		addr = shmat(shmid, (void *)ADDR , 0); 
		if (((long)addr) == -1)
			return 1;
	}	
	ret = pthread_attr_setstack (&attr, addr , PAGE_SIZE);
	if(ret != 0 )		
		return 1;			
	ret=pthread_create(id,&attr,(void *)start_routine, NULL);
	if(ret != 0 )
		return 1;	
	return (0);
}

/*test.c*/
#include <stdio.h>
#include <errno.h>
#include "my_thread.h"

void thread1(void)
{
	int i=11;
	printf("first variable of thread1 addr = %p\n", &i);	
}

int main(void)
{
	pthread_t id;
	int ret;	
	ret = my_pthread_create(&id,NULL,(void *)thread1, NULL);	
	if(ret != 0 )
		printf("errno = %d\n",errno);	
	pthread_join(id,NULL); 
	return (0);
}

/*my_thread.h*/
#include <pthread.h>
#include <sys/shm.h>
extern int my_pthread_create(pthread_t * id, pthread_attr_t * attr1,
void * (*start_routine)(void *), void * arg);

/*Makefile*/
TEST:
	gcc -fpic -c -g my_thread.c my_thread.h
	gcc -shared -Wl,-soname,libmy_thread.so -o libmy_thread.so
my_thread.o
	cp ./libmy_thread.so /lib/
	cp ./libmy_thread.so /usr/lib
	gcc  test.c -o test -lmy_thread -lpthread
	
clear:
	rm -f *.o libmy_thread.so test

.