kernel: add sigsuspend

apps/test-sigsuspend.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <signal.h>
+#include <errno.h>
+#include <string.h>
+
+void handler(int sig) {
+	fprintf(stderr, "received %d\n", sig);
+}
+
+int main(int argc, char * argv[]) {
+	signal(SIGINT, handler);
+	signal(SIGWINCH, handler);
+
+	sigset_t mask;
+	sigemptyset(&mask);
+
+	while (1) {
+		int result = sigsuspend(&mask);
+		fprintf(stderr, "result = %d, errno = %s\n", result, strerror(errno));
+	}
+
+	return 0;
+}
+

base/usr/include/signal.h

@@ -24,5 +24,6 @@ extern int sigdelset(sigset_t * set, int signum);
 extern int sigismember(sigset_t * set, int signum);
 extern int sigprocmask(int how, const sigset_t * restrict set, sigset_t * restrict oset);
 extern int sigpending(sigset_t * set);
+extern int sigsuspend(const sigset_t * restrict set);
 
 _End_C_Header

base/usr/include/syscall_nums.h

@@ -76,3 +76,4 @@
 #define SYS_SIGACTION 73
 #define SYS_SIGPENDING 74
 #define SYS_SIGPROCMASK 75
+#define SYS_SIGSUSPEND 76

kernel/sys/syscall.c

@@ -1008,6 +1008,11 @@ long sys_sigprocmask(int how, sigset_t *restrict set, sigset_t * restrict oset)
 	return 0;
 }
 
+long sys_sigsuspend_cur(void) {
+	switch_task(0);
+	return -EINTR;
+}
+
 long sys_fswait(int c, int fds[]) {
 	PTR_VALIDATE(fds);
 	if (!fds) return -EFAULT;
@@ -1218,6 +1223,7 @@ static long (*syscalls[])() = {
 	[SYS_SIGACTION]    = sys_sigaction,
 	[SYS_SIGPENDING]   = sys_sigpending,
 	[SYS_SIGPROCMASK]  = sys_sigprocmask,
+	[SYS_SIGSUSPEND]   = sys_sigsuspend_cur,
 
 	[SYS_SOCKET]       = net_socket,
 	[SYS_SETSOCKOPT]   = net_setsockopt,

libc/signal/sigprocmask.c

@@ -1,3 +1,4 @@
+#include <signal.h>
 #include <sys/signal.h>
 #include <syscall.h>
 #include <syscall_nums.h>

libc/signal/sigsuspend.c

@@ -0,0 +1,17 @@
+#include <signal.h>
+#include <sys/signal.h>
+#include <syscall.h>
+#include <syscall_nums.h>
+#include <errno.h>
+
+DEFN_SYSCALL0(sigsuspend_cur, SYS_SIGSUSPEND);
+
+int sigsuspend(const sigset_t * restrict set) {
+	sigset_t old;
+	sigprocmask(SIG_SETMASK, set, &old);
+	int ret = syscall_sigsuspend_cur();
+	if (ret < 0) { errno = -ret; ret = -1; }
+	sigprocmask(SIG_SETMASK, &old, NULL);
+	return ret;
+}
+