musl/src/signal/siginterrupt.c

#include <stdlib.h>
#include <signal.h>

int siginterrupt(int sig, int flag)
{
	struct sigaction sa;

	sigaction(sig, NULL, &sa);
	if (flag) sa.sa_flags &= ~SA_RESTART;
	else sa.sa_flags |= SA_RESTART;

	return sigaction(sig, &sa, NULL);
}