Commit beae3cea17

@@ -867,13 +867,13 @@ pub const app_mask: sigset_t = [2]u32{ 0xfffffffc, 0x7fffffff } ++ [_]u32{0xffff
 pub const k_sigaction = if (is_mips)
     extern struct {
         flags: usize,
-        sigaction: ?fn (i32, *siginfo_t, ?*c_void) callconv(.C) void,
+        sigaction: ?fn (i32, *const siginfo_t, ?*const c_void) callconv(.C) void,
         mask: [4]u32,
         restorer: fn () callconv(.C) void,
     }
 else
     extern struct {
-        sigaction: ?fn (i32, *siginfo_t, ?*c_void) callconv(.C) void,
+        sigaction: ?fn (i32, *const siginfo_t, ?*const c_void) callconv(.C) void,
         flags: usize,
         restorer: fn () callconv(.C) void,
         mask: [2]u32,
@@ -881,7 +881,7 @@ else
 
 /// Renamed from `sigaction` to `Sigaction` to avoid conflict with the syscall.
 pub const Sigaction = extern struct {
-    pub const sigaction_fn = fn (i32, *siginfo_t, ?*c_void) callconv(.C) void;
+    pub const sigaction_fn = fn (i32, *const siginfo_t, ?*const c_void) callconv(.C) void;
     sigaction: ?sigaction_fn,
     mask: sigset_t,
     flags: u32,

@@ -857,35 +857,42 @@ pub fn sigprocmask(flags: u32, noalias set: ?*const sigset_t, noalias oldset: ?*
     return syscall4(.rt_sigprocmask, flags, @ptrToInt(set), @ptrToInt(oldset), NSIG / 8);
 }
 
-pub fn sigaction(sig: u6, noalias act: *const Sigaction, noalias oact: ?*Sigaction) usize {
+pub fn sigaction(sig: u6, noalias act: ?*const Sigaction, noalias oact: ?*Sigaction) usize {
     assert(sig >= 1);
     assert(sig != SIGKILL);
     assert(sig != SIGSTOP);
 
-    const restorer_fn = if ((act.flags & SA_SIGINFO) != 0) restore_rt else restore;
-    var ksa = k_sigaction{
-        .sigaction = act.sigaction,
-        .flags = act.flags | SA_RESTORER,
-        .mask = undefined,
-        .restorer = @ptrCast(fn () callconv(.C) void, restorer_fn),
-    };
-    var ksa_old: k_sigaction = undefined;
-    const ksa_mask_size = @sizeOf(@TypeOf(ksa_old.mask));
-    @memcpy(@ptrCast([*]u8, &ksa.mask), @ptrCast([*]const u8, &act.mask), ksa_mask_size);
+    var ksa: k_sigaction = undefined;
+    var oldksa: k_sigaction = undefined;
+    const mask_size = @sizeOf(@TypeOf(ksa.mask));
+
+    if (act) |new| {
+        const restorer_fn = if ((new.flags & SA_SIGINFO) != 0) restore_rt else restore;
+        ksa = k_sigaction{
+            .sigaction = new.sigaction,
+            .flags = new.flags | SA_RESTORER,
+            .mask = undefined,
+            .restorer = @ptrCast(fn () callconv(.C) void, restorer_fn),
+        };
+        @memcpy(@ptrCast([*]u8, &ksa.mask), @ptrCast([*]const u8, &new.mask), mask_size);
+    }
+
+    const ksa_arg = if (act != null) @ptrToInt(&ksa) else 0;
+    const oldksa_arg = if (oact != null) @ptrToInt(&oldksa) else 0;
+
     const result = switch (builtin.arch) {
         // The sparc version of rt_sigaction needs the restorer function to be passed as an argument too.
-        .sparc, .sparcv9 => syscall5(.rt_sigaction, sig, @ptrToInt(&ksa), @ptrToInt(&ksa_old), @ptrToInt(ksa.restorer), ksa_mask_size),
-        else => syscall4(.rt_sigaction, sig, @ptrToInt(&ksa), @ptrToInt(&ksa_old), ksa_mask_size),
+        .sparc, .sparcv9 => syscall5(.rt_sigaction, sig, ksa_arg, oldksa_arg, @ptrToInt(ksa.restorer), mask_size),
+        else => syscall4(.rt_sigaction, sig, ksa_arg, oldksa_arg, mask_size),
     };
-    const err = getErrno(result);
-    if (err != 0) {
-        return result;
-    }
+    if (getErrno(result) != 0) return result;
+
     if (oact) |old| {
-        old.sigaction = ksa_old.sigaction;
-        old.flags = @truncate(u32, ksa_old.flags);
-        @memcpy(@ptrCast([*]u8, &old.mask), @ptrCast([*]const u8, &ksa_old.mask), ksa_mask_size);
+        old.sigaction = oldksa.sigaction;
+        old.flags = @truncate(u32, oldksa.flags);
+        @memcpy(@ptrCast([*]u8, &old.mask), @ptrCast([*]const u8, &oldksa.mask), mask_size);
     }
+
     return 0;
 }
 

@@ -646,3 +646,33 @@ test "shutdown socket" {
     };
     os.closeSocket(sock);
 }
+
+var signal_test_failed = true;
+
+test "sigaction" {
+    if (builtin.os.tag == .wasi or builtin.os.tag == .windows)
+        return error.SkipZigTest;
+
+    const S = struct {
+        fn handler(sig: i32, info: *const os.siginfo_t, ctx_ptr: ?*const c_void) callconv(.C) void {
+            // Check that we received the correct signal.
+            signal_test_failed = info.signo == os.SIGUSR1;
+        }
+    };
+
+    var sa = os.Sigaction{
+        .sigaction = S.handler,
+        .mask = os.empty_sigset,
+        .flags = os.SA_RESETHAND,
+    };
+    var old_sa: os.Sigaction = undefined;
+    // Install the new signal handler.
+    os.sigaction(os.SIGUSR1, &sa, null);
+    // Check that we can read it back correctly.
+    os.sigaction(os.SIGUSR1, null, &old_sa);
+    testing.expectEqual(S.handler, old_sa.sigaction.?);
+    testing.expect((old_sa.flags & os.SA_RESETHAND) != 0);
+    // Invoke the handler.
+    try os.raise(os.SIGUSR1);
+    testing.expect(signal_test_failed == false);
+}

@@ -200,7 +200,7 @@ pub usingnamespace switch (builtin.os.tag) {
         pub extern "c" fn gettimeofday(noalias tv: ?*timeval, noalias tz: ?*timezone) c_int;
         pub extern "c" fn nanosleep(rqtp: *const timespec, rmtp: ?*timespec) c_int;
         pub extern "c" fn sched_yield() c_int;
-        pub extern "c" fn sigaction(sig: c_int, noalias act: *const Sigaction, noalias oact: ?*Sigaction) c_int;
+        pub extern "c" fn sigaction(sig: c_int, noalias act: ?*const Sigaction, noalias oact: ?*Sigaction) c_int;
         pub extern "c" fn sigprocmask(how: c_int, noalias set: ?*const sigset_t, noalias oset: ?*sigset_t) c_int;
         pub extern "c" fn socket(domain: c_uint, sock_type: c_uint, protocol: c_uint) c_int;
         pub extern "c" fn stat(noalias path: [*:0]const u8, noalias buf: *libc_stat) c_int;
@@ -215,7 +215,7 @@ pub usingnamespace switch (builtin.os.tag) {
         pub extern "c" fn gettimeofday(noalias tv: ?*timeval, noalias tz: ?*timezone) c_int;
         pub extern "c" fn nanosleep(rqtp: *const timespec, rmtp: ?*timespec) c_int;
         pub extern "c" fn sched_yield() c_int;
-        pub extern "c" fn sigaction(sig: c_int, noalias act: *const Sigaction, noalias oact: ?*Sigaction) c_int;
+        pub extern "c" fn sigaction(sig: c_int, noalias act: ?*const Sigaction, noalias oact: ?*Sigaction) c_int;
         pub extern "c" fn sigprocmask(how: c_int, noalias set: ?*const sigset_t, noalias oset: ?*sigset_t) c_int;
         pub extern "c" fn stat(noalias path: [*:0]const u8, noalias buf: *libc_stat) c_int;
     },
@@ -227,7 +227,7 @@ pub usingnamespace switch (builtin.os.tag) {
         pub extern "c" fn gettimeofday(noalias tv: ?*timeval, noalias tz: ?*timezone) c_int;
         pub extern "c" fn nanosleep(rqtp: *const timespec, rmtp: ?*timespec) c_int;
         pub extern "c" fn sched_yield() c_int;
-        pub extern "c" fn sigaction(sig: c_int, noalias act: *const Sigaction, noalias oact: ?*Sigaction) c_int;
+        pub extern "c" fn sigaction(sig: c_int, noalias act: ?*const Sigaction, noalias oact: ?*Sigaction) c_int;
         pub extern "c" fn sigprocmask(how: c_int, noalias set: ?*const sigset_t, noalias oset: ?*sigset_t) c_int;
         pub extern "c" fn socket(domain: c_uint, sock_type: c_uint, protocol: c_uint) c_int;
         pub extern "c" fn stat(noalias path: [*:0]const u8, noalias buf: *libc_stat) c_int;

@@ -4592,7 +4592,7 @@ pub fn sigaltstack(ss: ?*stack_t, old_ss: ?*stack_t) SigaltstackError!void {
 }
 
 /// Examine and change a signal action.
-pub fn sigaction(sig: u6, act: *const Sigaction, oact: ?*Sigaction) void {
+pub fn sigaction(sig: u6, act: ?*const Sigaction, oact: ?*Sigaction) void {
     switch (errno(system.sigaction(sig, act, oact))) {
         0 => return,
         EFAULT => unreachable,