Continue the pthreads torture.

src/libthread/ucontext.c

@@ -0,0 +1,41 @@
+#include "threadimpl.h"
+
+void
+_threadinitstack(Thread *t, void (*f)(void*), void *arg)
+{
+	sigset_t zero;
+
+	/* do a reasonable initialization */
+	memset(&t->sched.uc, 0, sizeof t->sched.uc);
+	sigemptyset(&zero);
+	sigprocmask(SIG_BLOCK, &zero, &t->sched.uc.uc_sigmask);
+
+	/* call getcontext, because on Linux makecontext neglects floating point */
+	getcontext(&t->sched.uc);
+
+	/* call makecontext to do the real work. */
+	t->sched.uc.uc_stack.ss_sp = t->stk;
+	t->sched.uc.uc_stack.ss_size = t->stksize;
+	makecontext(&t->sched.uc, (void(*)())f, 1, arg);
+}
+
+void
+_threadinswitch(int enter)
+{
+	USED(enter);
+}
+
+void
+_threadstacklimit(void *bottom, void *top)
+{
+	USED(bottom);
+	USED(top);
+}
+
+void
+_swaplabel(Label *old, Label *new)
+{
+	if(swapcontext(&old->uc, &new->uc) < 0)
+		sysfatal("swapcontext: %r");
+}
+