implement forkall

[musl] / src / thread / forkall.c

diff --git a/src/thread/forkall.c b/src/thread/forkall.c
new file mode 100644 (file)
index 0000000..403818e
--- /dev/null
+++ b/src/thread/forkall.c
@@ -0,0 +1,66 @@
+#include "pthread_impl.h"
+#include <setjmp.h>
+
+struct thread {
+       struct thread *next;
+       pthread_t td;
+       jmp_buf jb;
+       void *tmp, *stack;
+};
+
+struct ctx {
+       struct thread *list;
+       pthread_t caller;
+       pid_t pid;
+       size_t cnt;
+       pthread_barrier_t barrier;
+};
+
+static void restart_thread(pthread_t self)
+{
+       struct thread *t = self->start_arg;
+       self->start_arg = t->tmp;
+       self->pid = getpid();
+       longjmp(t->jb, 1);
+}
+
+static void do_forkall(void *p)
+{
+       struct ctx *c = p, *volatile cv = c;
+       char tmpstack[2048];
+       struct thread *tp, t = {
+               .td = __pthread_self(),
+               .next = c->list,
+               .stack = tmpstack+1024
+       };
+
+       if (t.td != c->caller) {
+               c->cnt++;
+               t.tmp = t.td->start_arg;
+               t.td->start_arg = &t;
+               if (setjmp(t.jb)) {
+                       c = cv;
+                       if (c->pid) return;
+                       pthread_barrier_wait(&c->barrier);
+                       return;
+               }
+               c->list = &t;
+               __synccall_wait();
+               return;
+       }
+       c->pid = syscall(SYS_fork);
+       if (c->pid) return;
+
+       pthread_barrier_init(&c->barrier, 0, c->cnt);
+       for (tp=c->list; tp; tp=tp->next)
+               if (__uniclone(tp->stack, restart_thread, tp->td) < 0)
+                       _exit(127);
+       pthread_barrier_wait(&c->barrier);
+}
+
+pid_t forkall()
+{
+       struct ctx c = { .caller = pthread_self() };
+       __synccall(do_forkall, &c);
+       return c.pid;
+}