UNIX for Advanced & Expert Users

/*header defs*/
typedef struct custom_thread {
        int cr_return;
	int thread_stack_size;
	pthread_t tid;
	pthread_attr_t attr;
	void *newstack;
} CTHREAD;
extern CTHREAD *init_custom_thread(int, int (*)(void *));
extern void destroy_custom_thread(CTHREAD *);

/*from shared library*/
extern CTHREAD *init_custom_thread(int sz, int (*teststackalloc)(void *arg)) {
CTHREAD *ret;

               if ( (ret = malloc(sizeof(*ret))) == NULL) {return NULL;}
               ret->thread_stack_size = sz;
               if ( (ret->newstack = malloc(sz)) == NULL) {free(ret); return NULL;}
               if (teststackalloc!= NULL) {
                    if (teststackalloc(ret->newstack) != 0) {free(ret->newstack); free(ret); return NULL;}
               }
               pthread_attr_init(&ret->attr);
               ret->cr_return = pthread_attr_setstack(&ret->attr,ret->newstack,ret->thread_stack_size);
               return ret;
}

extern void destroy_custom_thread(CTHREAD *arg) {

                                  if (arg->newstack != NULL) {free(arg->newstack); arg->newstack = NULL;}
                                  free(arg);
                                  arg = NULL;
}

/*test program*/

#include "custom_stack.h"
#include <limits.h>

void *hello_world(void *arg) {
                             
                  printf("Hello world from thread id %d.\n",pthread_self());
                  pthread_exit(NULL);
}

void dothread_work(CTHREAD *new_id) {
               pthread_create(&new_id->tid,&new_id->attr,hello_world,NULL);
               pthread_join(new_id->tid,NULL);
               destroy_custom_thread(new_id);
}
                
int main(void) {
int i = 0; 
CTHREAD *new_id;

               new_id = init_custom_thread(PTHREAD_STACK_MIN * 2, NULL);
               if (new_id == NULL) {return 1;}
               for (i = 0 ; i < 100; i++) {dothread_work(new_id); new_id = init_custom_thread(PTHREAD_STACK_MIN * 2, NULL);}
               dothread_work(new_id);
               return 0;
}