1 files changed, 25 insertions, 4 deletions
diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index 852a9ec0..9aada3ee 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -48,6 +48,11 @@ pub const State = struct {
     /// follows sets it or, refused, leaves it as it was; with none, the
     /// open's release empties it (tree.zig releaseHandle).
     dot_truncated: bool = false,
+    /// The open whose writes to `sel` are being kept together (0: none) and
+    /// the text they have made so far: the next write of that open goes at
+    /// its end, as acme's wrselrange does.
+    wrsel_by: u32 = 0,
+    wrsel: Range = .{},
     /// Opens of `event`, which hold the pane scripted.
     readers: u16 = 0,
     /// One of `readers` reads `event`; a second reading open is refused.
@@ -787,12 +792,20 @@ fn writeData(p: *Pardes, req: Req, pane: *Pane) Reply {
 
 fn writeSel(p: *Pardes, req: Req, pane: *Pane) Reply {
     if (fileOf(pane) == null) return tree.failText(req.tag, E.INVAL, e_no_text);
-    const d = dotOf(pane);
+    const pf = &pane.fs;
+    // The same open's next write follows its last; any other replaces dot.
+    const going_on = req.handle != 0 and pf.wrsel_by == req.handle;
+    const d = if (going_on) State.Range{ .q0 = pf.wrsel.q1, .q1 = pf.wrsel.q1 } else dotOf(pane);
     const q0: usize = d.q0;
     const q1: usize = @max(q0, @as(usize, d.q1));
     const take = spliceBody(p, pane, q0, q1, req.data) orelse
         return Reply.fail(req.tag, E.NOMEM);
-    setDot(pane, .{ .q0 = clip(q0 + take), .q1 = clip(q0 + take) });
+    // What was written is selected, as acme's wrsel leaves it: `cat sel`
+    // reads it back.
+    const start = if (going_on) pf.wrsel.q0 else clip(q0);
+    pf.wrsel = .{ .q0 = start, .q1 = clip(q0 + take) };
+    pf.wrsel_by = req.handle;
+    setDot(pane, pf.wrsel);
     return .{ .tag = req.tag, .written = @intCast(take) };
 }
 
@@ -1265,9 +1278,17 @@ test "sel reads the selection and writing sel replaces it" {
 
     try testing.expectEqual(Status.ok, wr(p, sel, "ONE").reply.status);
     try testing.expectEqualStrings("ONE\ntwo\n", p.panes[0].?.file.?.content);
+    // What was written is selected, as acme's wrsel leaves it.
+    try testing.expectEqualStrings("ONE", rd(p, sel, 0, 100).bytes);
+    // A write of another open replaces it; one open's writes run on.
     _ = wr(p, sel, "!");
-    try testing.expectEqualStrings("ONE!\ntwo\n", p.panes[0].?.file.?.content);
-    try testing.expectEqual(@as(u64, 0), call(p, .{ .tag = 2, .op = .getattr, .node = sel }).reply.attr.size);
+    try testing.expectEqualStrings("!\ntwo\n", p.panes[0].?.file.?.content);
+    const hs = call(p, .{ .tag = 3, .op = .open, .node = sel, .omode = 1 }).reply.handle;
+    _ = call(p, .{ .tag = 4, .op = .write, .node = sel, .handle = hs, .data = "a" });
+    _ = call(p, .{ .tag = 5, .op = .write, .node = sel, .handle = hs, .data = "b" });
+    _ = call(p, .{ .tag = 6, .op = .release, .node = sel, .handle = hs, .opened = true });
+    try testing.expectEqualStrings("ab\ntwo\n", p.panes[0].?.file.?.content);
+    try testing.expectEqualStrings("ab", rd(p, sel, 0, 100).bytes);
 }
 
 test "the flag files read and write the state acme kept behind ctl verbs" {