An Edit filter that can never be reaped no longer holds the Edit's answer: at the limit the command's group is killed and reaped off the answer's path, the stdin writer owning its input, so a filter writing its own ctl with > or >> answers EIO at 10 s instead of hanging; a running Edit keeps its own copies of the names it reports, and the panes it changes refuse Del, delete, rmdir, Undo, Redo, Get and Zerox (busy, EBUSY); e and r say unreadable files in Get's words; the reference says both sides of a filter's own ctl write need <>

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

1 files changed, 34 insertions, 1 deletions

diff --git a/test/selfmount.py b/test/selfmount.py
index 5aa9749a..61d32523 100644
--- a/test/selfmount.py
+++ b/test/selfmount.py
@@ -372,8 +372,41 @@ def run(binary):
             check(codes == ['124', '0'] and client.read(f'/pane/{edited}/body') == b'aPPle\npear\napple\npear\n',
                   f'an interrupted Edit changes nothing, and the next runs ({codes!r}, {client.read(f"/pane/{edited}/body")!r})')
             client.write('/exec', b'Msg still here\n')
-            text = ''.join(cell[0] for cell in client.screen()['cells'])
+            # The terminal is read as it is waited on: a frame the editor
+            # cannot write out (its pty full) is a frame /screen does not have.
+            deadline = time.monotonic() + 8
+            while 'still here' not in (text := ''.join(cell[0] for cell in client.screen()['cells'])) and time.monotonic() < deadline:
+                drain()
+                time.sleep(.1)
             check('still here' in text, 'the editor answers after all of that')
+            # A filter that writes its own pane's ctl through the mount. Both
+            # sides with `<>` run at once; a `>` or `>>` open on either side
+            # waits in the kernel for the other write, and the command is
+            # stopped at its 10 s limit: the Edit's write is answered then,
+            # never held by a command it cannot kill.
+            loop_pane = env_pane  # the screen has no room for another
+            client.write(f'/pane/{loop_pane}/body', b'x\n', truncate=True)
+            inner = Path(f'/tmp/{name}.inner')
+            timed = Path(f'/tmp/{name}.timed')
+            for outer_open, inner_open, quick in [('3<>', '1<>', True), ('>', '>', False), ('>>', '>', False),
+                                                  ('3<>', '>>', False), ('>', '>>', False)]:
+                # `clean`, which says nothing: a stopped filter's write still
+                # lands once the Edit's is answered.
+                inner.write_text(f'echo clean {inner_open} "$PARDES_MOUNT/pane/$winid/ctl"\n')
+                edit = f'Edit 1 > sh {inner}'
+                write = (f"exec 3<>{mount}/pane/{loop_pane}/ctl; echo '{edit}' >&3; rc=$?; exec 3>&-"
+                         if outer_open == '3<>' else f"echo '{edit}' {outer_open} {mount}/pane/{loop_pane}/ctl; rc=$?")
+                ran = run((f"s=$(date +%s%N); {write}; e=$(date +%s%N); "
+                           f"echo $rc $(( (e - s) / 1000000 )) > {timed}\n").encode())
+                rc_ms = timed.read_text().split() if timed.exists() else ['?', '-1']
+                timed.unlink(missing_ok=True)
+                ms = int(rc_ms[1])
+                ok = ms >= 0 and (ms < 2000 if quick else ms < 13000)
+                check(ran == '0' and ok, f'outer {outer_open}, filter {inner_open} on its own ctl: answered in {ms} ms (rc {rc_ms[0]})')
+            inner.unlink(missing_ok=True)
+            client.write('/exec', b'Msg after the stopped filters\n')
+            check('msg ' in client.read('/log').decode().split('after the stopped filters')[0][-40:],
+                  'and the editor answers after them')
     finally:
         os.kill(pid, signal.SIGTERM)
         time.sleep(.2)