std: turn errno into an enum

Author: daurnimator

lib/std/c.zig

@@ -21,12 +21,12 @@ pub usingnamespace switch (builtin.os) {
     else => struct {},
 };
 
-pub fn getErrno(rc: var) u16 {
-    if (rc == -1) {
-        return @intCast(u16, _errno().*);
-    } else {
-        return 0;
-    }
+pub fn getErrno(rc: var) Errno {
+    const errno = if (rc == -1)
+        _errno().*
+    else
+        0;
+    return @intToEnum(Errno, errno);
 }
 
 /// The return type is `type` to force comptime function call execution.

lib/std/event/loop.zig

@@ -817,8 +817,8 @@ pub const Loop = struct {
                 @atomicStore(i32, &self.os_data.fs_queue_item, 1, AtomicOrder.SeqCst);
                 const rc = os.linux.futex_wake(&self.os_data.fs_queue_item, os.linux.FUTEX_WAKE, 1);
                 switch (os.linux.getErrno(rc)) {
-                    0 => {},
-                    os.EINVAL => unreachable,
+                    @intToEnum(os.linux.Errno, 0) => {},
+                    .EINVAL => unreachable,
                     else => unreachable,
                 }
             },
@@ -880,7 +880,7 @@ pub const Loop = struct {
                 .linux => {
                     const rc = os.linux.futex_wait(&self.os_data.fs_queue_item, os.linux.FUTEX_WAIT, 0, null);
                     switch (os.linux.getErrno(rc)) {
-                        0, os.EINTR, os.EAGAIN => continue,
+                        @intToEnum(os.linux.Errno, 0), .EINTR, .EAGAIN => continue,
                         else => unreachable,
                     }
                 },

lib/std/fs.zig

@@ -524,11 +524,11 @@ pub const Dir = struct {
                     if (self.index >= self.end_index) {
                         const rc = os.linux.getdents64(self.dir.fd, &self.buf, self.buf.len);
                         switch (os.linux.getErrno(rc)) {
-                            0 => {},
-                            os.EBADF => unreachable,
-                            os.EFAULT => unreachable,
-                            os.ENOTDIR => unreachable,
-                            os.EINVAL => unreachable,
+                            @intToEnum(os.linux.Errno, 0) => {},
+                            .EBADF => unreachable,
+                            .EFAULT => unreachable,
+                            .ENOTDIR => unreachable,
+                            .EINVAL => unreachable,
                             else => |err| return os.unexpectedErrno(err),
                         }
                         if (rc == 0) return null;