Mount dials its peer at once and fails if none answers; a peer out of reach is said as `dial failed: <reason>`

Mount took any well-formed dial and nothing was found out until the
first look through it, which then said `look: look: dial`. Mount now
probes the peer (version, attach, its root) with the turn out, and fails
its write, mounting nothing, when none answers; the dial errors read as
words, `no answer`, `timed out`, `hung up`, and a look through a peer
gone since names its path: `look: /n/peer/f: dial failed: no answer`.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index b8f73c6f..7c68210a 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -1712,6 +1712,22 @@ test "size sets the screen of a session no frontend is attached to, and only of
     try testing.expectEqual(@as(u16, 40), p.screen_h);
 }
 
+test "Mount dials its peer and fails, mounting nothing, when none answers; a look through a peer gone says dial failed" {
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    const root_ctl = @intFromEnum(tree.TopFile.ctl);
+    const dead = "/tmp/pardes-test-no-such-peer.sock";
+    const refused = wr(p, root_ctl, "Mount dead " ++ dead ++ "\n");
+    try testing.expectEqual(E.IO, refused.errno());
+    try testing.expectEqualStrings("Mount dead " ++ dead ++ ": dial failed: no answer \"Mount dead " ++ dead ++ "\"", refused.reply.ename);
+    try testing.expectEqual(@as(usize, 0), p.fs.mounts.items.len);
+    // Mounted when it answered, gone since: a look through it says so.
+    try p.fs.mounts.append(p.gpa, .{ .name = try p.gpa.dupe(u8, "gone"), .dial = try p.gpa.dupe(u8, dead) });
+    const looked = wr(p, @intFromEnum(tree.TopFile.look), "/n/gone/f.txt\n");
+    try testing.expect(looked.errno() != 0);
+    try testing.expect(th.logHas(p, "look: /n/gone/f.txt: dial failed: no answer"));
+}
+
 test "size is monotonic: growing is never refused, and a size once taken is taken again" {
     const p = try Pardes.init(testing.allocator, .{ .tty_only = true, .cols = 160, .rows = 60 });
     defer p.deinit();