Implement SheepThreads on NetBSD/ppc so that sigaltstack()s are really used

This commit is contained in:
gbeauche 2005-02-20 18:06:40 +00:00
parent 10f38d4b50
commit 436522186e

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@ -0,0 +1,462 @@
/*
* sheepthreads.c - Minimal pthreads implementation (libpthread doesn't
* like sigaltstack)
*
* SheepShaver (C) 1997-2005 Christian Bauer and Marc Hellwig
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* NOTES:
* - pthread_cancel() kills the thread immediately
* - Semaphores are VERY restricted: the only supported use is to have one
* thread sem_wait() on the semaphore while other threads sem_post() it
* (i.e. to use the semaphore as a signal)
*/
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <sched.h>
#include <pthread.h>
#include <semaphore.h>
/* Thread descriptor */
struct __pthread_st {
unsigned int tid;
};
/* Thread stack size */
#define STACK_SIZE 65536
/* From asm_linux.S */
extern int atomic_add(int *var, int add);
extern int atomic_and(int *var, int and);
extern int atomic_or(int *var, int or);
extern int test_and_set(int *var, int val);
/* Linux kernel calls */
extern int __clone(int (*fn)(void *), void *, int, void *);
/* struct sem_t */
struct _sem_st {
#define SEM_MAGIC 0x09fa4012
unsigned int sem_magic;
struct {
int status;
int spinlock;
} sem_lock;
int sem_value;
pid_t sem_waiting;
};
/* Wait for "clone" children only (Linux 2.4+ specific) */
#ifndef __WCLONE
#define __WCLONE 0
#endif
/*
* Return pthread ID of self
*/
pthread_t pthread_self(void)
{
static struct __pthread_st self_st;
static pthread_t self = NULL;
if (self == NULL) {
self = &self_st;
self->tid = getpid();
}
return self;
}
/*
* Test whether two pthread IDs are equal
*/
int pthread_equal(pthread_t t1, pthread_t t2)
{
return t1 == t2;
}
/*
* Send signal to thread
*/
int pthread_kill(pthread_t thread, int sig)
{
if (kill(thread->tid, sig) == -1)
return errno;
else
return 0;
}
/*
* Create pthread
*/
struct new_thread {
void *(*fn)(void *);
void *arg;
};
static int start_thread(void *arg)
{
struct new_thread *nt = (struct new_thread *)arg;
nt->fn(nt->arg);
return 0;
}
int pthread_create(pthread_t *thread, const pthread_attr_t *attr, void *(*start_routine)(void *), void *arg)
{
struct new_thread *nt;
void *stack;
int pid;
nt = (struct new_thread *)malloc(sizeof(struct new_thread));
nt->fn = start_routine;
nt->arg = arg;
stack = malloc(STACK_SIZE);
pid = __clone(start_thread, (char *)stack + STACK_SIZE - 16, CLONE_VM | CLONE_FS | CLONE_FILES, nt);
if (pid == -1) {
free(stack);
free(nt);
return errno;
} else {
*thread = malloc(sizeof(**thread));
if (*thread == NULL)
return -1;
(*thread)->tid = pid;
return 0;
}
}
/*
* Join pthread
*/
int pthread_join(pthread_t thread, void **ret)
{
do {
if (waitpid(thread->tid, NULL, __WCLONE) >= 0);
break;
} while (errno == EINTR);
if (ret)
*ret = NULL;
return 0;
}
/*
* Cancel thread
*/
int pthread_cancel(pthread_t thread)
{
kill(thread->tid, SIGINT);
thread->tid = (unsigned int)-1;
free(thread);
return 0;
}
/*
* Test for cancellation
*/
void pthread_testcancel(void)
{
}
/*
* Spinlocks
*/
static int try_acquire_spinlock(int *lock)
{
return test_and_set(lock, 1) == 0;
}
static void acquire_spinlock(volatile int *lock)
{
do {
while (*lock) ;
} while (test_and_set((int *)lock, 1) != 0);
}
static void release_spinlock(int *lock)
{
*lock = 0;
}
/*
* Initialize mutex
*/
int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutex_attr)
{
mutex->ptm_magic = _PT_MUTEX_MAGIC;
mutex->ptm_lock = 0;
mutex->ptm_owner = NULL;
return 0;
}
/*
* Destroy mutex
*/
int pthread_mutex_destroy(pthread_mutex_t *mutex)
{
if (mutex->ptm_magic != _PT_MUTEX_MAGIC)
return EINVAL;
if (mutex->ptm_lock != 0)
return EBUSY;
mutex->ptm_magic = _PT_MUTEX_DEAD;
return 0;
}
/*
* Lock mutex
*/
int pthread_mutex_lock(pthread_mutex_t *mutex)
{
if (mutex->ptm_magic != _PT_MUTEX_MAGIC)
return EINVAL;
acquire_spinlock(&mutex->ptm_lock);
return 0;
}
/*
* Try to lock mutex
*/
int pthread_mutex_trylock(pthread_mutex_t *mutex)
{
if (mutex->ptm_magic != _PT_MUTEX_MAGIC)
return EINVAL;
if (!try_acquire_spinlock(&mutex->ptm_lock))
return EBUSY;
return 0;
}
/*
* Unlock mutex
*/
int pthread_mutex_unlock(pthread_mutex_t *mutex)
{
if (mutex->ptm_magic != _PT_MUTEX_MAGIC)
return EINVAL;
release_spinlock(&mutex->ptm_lock);
return 0;
}
/*
* Create mutex attribute
*/
int pthread_mutexattr_init(pthread_mutexattr_t *attr)
{
attr->ptma_magic = _PT_MUTEXATTR_MAGIC;
return 0;
}
/*
* Destroy mutex attribute
*/
int pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
{
if (attr->ptma_magic != _PT_MUTEXATTR_MAGIC)
return EINVAL;
return 0;
}
/*
* Init semaphore
*/
int sem_init(sem_t *psem, int pshared, unsigned int value)
{
sem_t sem = malloc(sizeof(*sem));
if (sem == NULL) {
errno = ENOSPC;
return 0;
}
*psem = sem;
sem->sem_magic = SEM_MAGIC;
sem->sem_lock.status = 0;
sem->sem_lock.spinlock = 0;
sem->sem_value = value;
sem->sem_waiting = 0;
return 0;
}
/*
* Delete remaphore
*/
int sem_destroy(sem_t *sem)
{
if (sem == NULL || *sem == NULL || (*sem)->sem_magic != SEM_MAGIC) {
errno = EINVAL;
return -1;
}
free(*sem);
return 0;
}
/*
* Wait on semaphore
*/
void null_handler(int sig)
{
}
int sem_wait(sem_t *psem)
{
sem_t sem;
if (psem == NULL || (sem = *psem) == NULL || sem->sem_magic != SEM_MAGIC) {
errno = EINVAL;
return -1;
}
acquire_spinlock(&sem->sem_lock.spinlock);
if (sem->sem_value > 0)
atomic_add(&sem->sem_value, -1);
else {
sigset_t mask;
if (!sem->sem_lock.status) {
struct sigaction sa;
sem->sem_lock.status = SIGUSR2;
sa.sa_handler = null_handler;
sa.sa_flags = SA_RESTART;
sigemptyset(&sa.sa_mask);
sigaction(sem->sem_lock.status, &sa, NULL);
}
sem->sem_waiting = getpid();
sigemptyset(&mask);
sigsuspend(&mask);
sem->sem_waiting = 0;
}
release_spinlock(&sem->sem_lock.spinlock);
return 0;
}
/*
* Post semaphore
*/
int sem_post(sem_t *psem)
{
sem_t sem;
if (psem == NULL || (sem = *psem) == NULL || sem->sem_magic != SEM_MAGIC) {
errno = EINVAL;
return -1;
}
acquire_spinlock(&sem->sem_lock.spinlock);
if (sem->sem_waiting == 0)
atomic_add(&sem->sem_value, 1);
else
kill(sem->sem_waiting, sem->sem_lock.status);
release_spinlock(&sem->sem_lock.spinlock);
return 0;
}
/*
* Simple producer/consumer test program
*/
#ifdef TEST
#include <stdio.h>
static sem_t p_sem, c_sem;
static int data = 0;
static void *producer_func(void *arg)
{
int i, n = (int)arg;
for (i = 0; i < n; i++) {
sem_wait(&p_sem);
data++;
sem_post(&c_sem);
}
return NULL;
}
static void *consumer_func(void *arg)
{
int i, n = (int)arg;
for (i = 0; i < n; i++) {
sem_wait(&c_sem);
printf("data: %d\n", data);
sem_post(&p_sem);
}
sleep(1); // for testing pthread_join()
return NULL;
}
int main(void)
{
pthread_t producer_thread, consumer_thread;
static const int N = 5;
if (sem_init(&c_sem, 0, 0) < 0)
return 1;
if (sem_init(&p_sem, 0, 1) < 0)
return 2;
if (pthread_create(&producer_thread, NULL, producer_func, (void *)N) != 0)
return 3;
if (pthread_create(&consumer_thread, NULL, consumer_func, (void *)N) != 0)
return 4;
pthread_join(producer_thread, NULL);
pthread_join(consumer_thread, NULL);
sem_destroy(&p_sem);
sem_destroy(&c_sem);
if (data != N)
return 5;
return 0;
}
#endif