os: add setsockopt

- net: use os.setsockopt()

lib/std/net.zig

@@ -1323,14 +1323,12 @@ pub const StreamServer = struct {
             self.sockfd = null;
         }
 
-        // TODO proper interface with errors in std.os
-        var optval: c_int = 1;
-
         if (self.options.reuse_address) {
-            _ = os.linux.setsockopt(
+            var optval: c_int = 1;
-                server.sockfd.?,
+            try os.setsockopt(
-                os.linux.SOL_SOCKET,
+                self.sockfd.?,
-                os.linux.SO_REUSEADDR,
+                os.SOL_SOCKET,
+                os.SO_REUSEADDR,
                 @ptrCast([*]const u8, &optval),
                 @sizeOf(c_int),
             );

lib/std/os.zig

@@ -3250,3 +3250,23 @@ pub fn sched_yield() SchedYieldError!void {
         else => return error.SystemCannotYield,
     }
 }
+
+/// Set a socket's options.
+pub fn setsockopt(fd: fd_t, level: u32, optname: u32, optval: [*]const u8, optlen: socklen_t) SetSockOptError!void {
+    const rc = system.setsockopt();
+
+    switch (errno(system.setsockopt(fd, level, optname, optval, optlen))) {
+        0 => {},
+        EBADF => unreachable,
+        EINVAL => unreachable,
+        EDOM => return error.TimeoutTooBig,
+        EISCONN => return error.AlreadyConnected,
+        ENOPROTOOOPT => return error.InvalidProtocolOption,
+        ENOTSOCK => return error.NotSocket,
+
+        ENOMEM => return error.OutOfMemory,
+        ENOBUFS => return error.SystemResources,
+
+        else => |err| return std.os.unexpectedErrno(err),
+    }
+}