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#include "pthread_impl.h"
#include <semaphore.h>
static struct chain {
struct chain *next;
sem_t sem, sem2;
} *head;
static void (*callback)(void *), *context;
static int chainlen;
static sem_t chainlock, chaindone;
static pthread_rwlock_t lock = PTHREAD_RWLOCK_INITIALIZER;
static void handler(int sig, siginfo_t *si, void *ctx)
{
struct chain ch;
pthread_t self = __pthread_self();
int old_errno = errno;
if (chainlen == libc.threads_minus_1) return;
sigqueue(self->pid, SIGSYNCCALL, (union sigval){0});
/* Threads which have already decremented themselves from the
* thread count must not act. Block further receipt of signals
* and return. */
if (self->dead) {
memset(&((ucontext_t *)ctx)->uc_sigmask, -1, 8);
errno = old_errno;
return;
}
sem_init(&ch.sem, 0, 0);
sem_init(&ch.sem2, 0, 0);
while (sem_wait(&chainlock));
ch.next = head;
head = &ch;
if (++chainlen == libc.threads_minus_1) sem_post(&chaindone);
sem_post(&chainlock);
while (sem_wait(&ch.sem));
callback(context);
sem_post(&ch.sem2);
while (sem_wait(&ch.sem));
errno = old_errno;
}
void __synccall(void (*func)(void *), void *ctx)
{
pthread_t self;
struct sigaction sa;
struct chain *cur, *next;
uint64_t oldmask;
if (!libc.threads_minus_1) {
func(ctx);
return;
}
pthread_rwlock_wrlock(&lock);
__syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &oldmask, 8);
sem_init(&chaindone, 0, 0);
sem_init(&chainlock, 0, 1);
chainlen = 0;
callback = func;
context = ctx;
sa.sa_flags = SA_SIGINFO | SA_RESTART;
sa.sa_sigaction = handler;
sigfillset(&sa.sa_mask);
__libc_sigaction(SIGSYNCCALL, &sa, 0);
self = __pthread_self();
sigqueue(self->pid, SIGSYNCCALL, (union sigval){0});
while (sem_wait(&chaindone));
for (cur=head; cur; cur=cur->next) {
sem_post(&cur->sem);
while (sem_wait(&cur->sem2));
}
func(ctx);
for (cur=head; cur; cur=next) {
next = cur->next;
sem_post(&cur->sem);
}
sa.sa_flags = 0;
sa.sa_handler = SIG_IGN;
__libc_sigaction(SIGSYNCCALL, &sa, 0);
__syscall(SYS_rt_sigprocmask, SIG_SETMASK, &oldmask, 0, 8);
pthread_rwlock_unlock(&lock);
}
void __synccall_lock()
{
pthread_rwlock_rdlock(&lock);
}
void __synccall_unlock()
{
pthread_rwlock_unlock(&lock);
}
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