2 files changed, 30 insertions, 1 deletions
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 31265a94..aa309ad1 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -296,7 +296,7 @@ pub fn captured(p: *Pardes, req: Req, id: usize, exec: bool, text: []const u8, i
 /// The errno a builtin's failure answers with: ENOENT for what is not
 /// there (`no such`, `not found`, the words 9ns reads as ENOENT too), else
 /// EIO.
-fn failureErrno(failure: []const u8) u16 {
+pub fn failureErrno(failure: []const u8) u16 {
     if (std.mem.indexOf(u8, failure, "no such") != null or std.mem.indexOf(u8, failure, "not found") != null) return E.NOENT;
     // A pattern refused (Edit's too) is malformed input, as 9ns reads it;
     // so is a word this build has not (`invalid: acme's Put ...`).
@@ -1760,6 +1760,25 @@ test "exec Save writes the named file through the host" {
     try testing.expectEqualStrings(pane.file.?.content, p.fallback.get("/tmp/renamed.txt").?);
 }
 
+test "a refused Del written back through event fails that write, EIO, with its err" {
+    const gpa = testing.allocator;
+    const p = try withFile(gpa, "text\n");
+    defer p.deinit();
+    const serial = serialOf(p);
+    try testing.expectEqual(Status.ok, wr(p, Node.of(serial, .body), "more\n").reply.status); // unsaved
+    const event = Node.of(serial, .event);
+    const h = call(p, .{ .tag = 1, .op = .open, .node = event }).reply.handle;
+    defer _ = call(p, .{ .tag = 9, .op = .release, .node = event, .handle = h });
+    try testing.expectEqual(Status.ok, wr(p, Node.of(serial, .exec), "Del\n").reply.status);
+    const record = call(p, .{ .tag = 2, .op = .read, .node = event, .handle = h, .size = 256 }).bytes;
+    var copy: [256]u8 = undefined;
+    @memcpy(copy[0..record.len], record);
+    const back = wr(p, event, copy[0..record.len]);
+    try testing.expectEqual(E.IO, back.errno());
+    try testing.expect(std.mem.indexOf(u8, back.reply.ename, "Modified") != null);
+    try testing.expect(p.paneBySerial(serial) != null);
+}
+
 test "a pane's own look and exec go to the event reader holding it, which writes them back to act" {
     const gpa = testing.allocator;
     const p = try withFile(gpa, "Msg routed\n");
diff --git a/src/ninep/events.zig b/src/ninep/events.zig
index 4d1bbe64..1ffbaab9 100644
--- a/src/ninep/events.zig
+++ b/src/ninep/events.zig
@@ -6,6 +6,7 @@ const exec = @import("../exec.zig");
 const look = @import("../look.zig");
 const cloud9 = @import("cloud9");
 const tree = @import("tree.zig");
+const ctl = @import("ctl.zig");
 const pane_files = @import("pane.zig");
 const dump = @import("../dump.zig");
 
@@ -736,6 +737,11 @@ pub fn writeEvent(p: *Pardes, asked: Req, id: usize) Reply {
         }
         if (check.i != req.data.len) return tree.failText(req.tag, E.INVAL, tree.e_bad_event ++ ": a record is <origin><action><q0> <q1> <flag> <count> <text>, a line each");
     }
+    // What a record written back runs fails the write as a click written
+    // to exec would (a refused Del: EIO and its err), not said and lost.
+    p.fs.capturing = true;
+    p.fs.failure_len = 0;
+    defer p.fs.capturing = false;
     var run: EventReader = .{ .data = req.data };
     while (run.next()) |r| {
         const live = p.paneBySerial(serial) orelse break;
@@ -815,6 +821,10 @@ pub fn writeEvent(p: *Pardes, asked: Req, id: usize) Reply {
             else => unreachable,
         }
     }
+    if (p.fs.failure_len > 0) {
+        const failure = p.fs.failure[0..p.fs.failure_len];
+        return tree.failText(req.tag, ctl.failureErrno(failure), std.fmt.bufPrint(&p.fs.ename, "{s}", .{failure}) catch failure);
+    }
     return .{ .tag = req.tag, .written = @intCast(asked.data.len) };
 }