Shell refuses a name that is no executable, and bare restores the default

Shell took any word and the host quietly ran another shell at the next
spawn. It now refuses a path or name that is not executable ("Shell: x:
no executable by that name", failing a ctl write, logged err), a bare
Shell goes back to the default, and a default $SHELL that is not
executable falls back to /bin/sh. shellset's golden takes the refusal on
the message row (re-recorded by name).

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

1 files changed, 17 insertions, 0 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 0ab63fbb..76f09084 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -1389,3 +1389,20 @@ test "a setting this frontend cannot show says GUI-only, and DumpDir reads back
         try testing.expect(std.mem.indexOf(u8, rd(p, root_ctl, 0, 1 << 16).bytes, line) != null);
     }
 }
+
+test "Shell refuses a path that is no executable, and bare it goes back to the default" {
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    const root_ctl = @intFromEnum(tree.TopFile.ctl);
+    const refused = wr(p, root_ctl, "Shell /nonexistent/zzsh\n");
+    try testing.expectEqual(Status.err, refused.reply.status);
+    try testing.expect(std.mem.indexOf(u8, refused.reply.ename, "Shell: /nonexistent/zzsh: no executable by that name") != null);
+    try testing.expect(th.logHas(p, "/nonexistent/zzsh: no executable"));
+    try testing.expectEqualStrings("", p.settings.shell.requested.get());
+    try testing.expectEqual(Status.ok, wr(p, root_ctl, "Shell /bin/sh\n").reply.status);
+    try testing.expectEqualStrings("/bin/sh", p.settings.shell.requested.get());
+    try testing.expectEqual(Status.ok, wr(p, root_ctl, "Shell\n").reply.status);
+    try testing.expectEqualStrings("", p.settings.shell.requested.get());
+    var want: [300]u8 = undefined;
+    try testing.expect(std.mem.indexOf(u8, rd(p, root_ctl, 0, 8192).bytes, try std.fmt.bufPrint(&want, "Shell {s}\n", .{config.defaultShell()})) != null);
+}