Public Access
a6a21decbd79a5c010be8124199ea9254307618d
2
Commits
| Author | SHA1 | Message | Date | |
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 jaap-jan
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cfc2e3ae0c |
Notice when a file session stops, and give the file browser the four things it was short of
The commit before this one taught a terminal to notice its machine going away.
The file browser had the same defect and three of the same symptoms, and it is
also the screen people leave soonest — so the disconnect work and four things it
was missing arrive together, because they are the same complaint: this screen
knows less about the host than the host does.
◆ THE DISCONNECT HALF, WHICH IS THE OTHER SURFACE OF THE LAST COMMIT.
IsConnected was set at connect and cleared only by the DISCONNECT button. A host
that went away therefore left this screen saying CONNECTED over a session that
was gone, and every action after it failing with the same server message and
nothing saying why they all did.
IRemoteFileStore now carries a latched TransportFailure and a ConnectionLost
event. The latch is the shell's own — read ISshShellSession.TransportFailure for
the argument, which is unchanged. The event is not, and it is the part this
surface needs: a file browser is idle between operations, so without something
raised at the moment the transport fails, nobody finds out until they click. A
bucket implements both and raises neither, which is honest rather than a gap:
S3 is request-per-operation with no connection to lose.
- THE LISTING STAYS ON SCREEN, and that is the half that makes the rest worth
having. SftpEntry is a record of what the server said rather than a handle,
so the pane can go on showing where the user was — which is what RECONNECT
is offering to put them back into. That needed a new ShowsRemoteContents on
both heads: every "is there anything here" binding read IsConnected, which
was right while the only way to stop being connected was to press a button
that empties the pane, and wrong the moment a session could be lost.
- RECONNECT re-dials through the ordinary connect path — same host key gate,
same refusals, same log entry — and then walks back to the directory the
pane was showing. The path is read off RemotePath rather than captured,
because the pane already keeps it up to date and a copy is a second thing to
get wrong. A host wanting a typed password is asked for one rather than
dialled with an empty box.
- SessionEndedBar is now one control on both surfaces, with the shell
resolving which it is drawn over: a terminal has two endings to tell apart
and a keychain entry to check, a file session has one ending and already
captured what it would dial. The phone's Files screen has its own copy,
bound to TransfersViewModel directly, because its DataContext is that rather
than the shell.
◆ PERMISSIONS: THE PERMS COLUMN STOPS BEING READ-ONLY.
It has been a true fact about a file with nothing to be done about it since it
arrived, and the commonest next act after using this screen was opening a
terminal — a whole second authenticated connection — to chmod what had just been
uploaded.
Nine checkboxes rather than a box to type 755 into, because the mode is already
drawn as -rwxr-xr-x in the column the form was opened from: a who-can-do-what
grid is the same representation the reader is holding, where an octal field asks
them to translate something they can see into something they cannot check. The
octal is printed underneath as it changes, so the two readings check each other.
The EXEC column is headed "enter" over a directory, which is what that bit means
there and the commonest misreading of a POSIX mode. The listing is re-read after
APPLY, because a umask, an ACL or a filesystem mounted without permissions can
all land somewhere other than what was asked for.
Beside it, mode and mtime carried across a transfer — which is what makes an
uploaded deploy.sh arrive executable instead of with the server's umask on it.
THE MODE IS ONLY SENT FROM A PLATFORM THAT HAS ONE. A file on Windows has no
POSIX mode; this screen already says so by leaving the local pane's PERMS column
empty rather than filling it with a plausible -rw-r--r--, and inventing 0644, or
0755 for anything called .sh, would be this client deciding a fact about
somebody's file that nothing on the machine it came from ever said. The
timestamp goes either way, because every platform has one. A store with neither
refuses in its own words and is never asked.
◆ MULTI-SELECT: A TICK IS NOT THE LIST'S SELECTION.
The two answer different questions and the split is the whole design. The
selection is "the row I am looking at", which rename, move and permissions act
on — each takes a form naming one path and is one-at-a-time by construction. The
tick is "the rows I have gathered up", which download, upload and delete take,
and it survives the highlight moving.
With nothing ticked the batch falls back to the selection, which is what keeps
the commonest use of this screen from growing a step — the usual way a
multi-select makes a tool worse. Ticks are released once a set is queued, or a
second press sends everything again.
Deleting several names every path rather than a count, because agreeing to "3
items" is agreeing to a number, and this is the one act on this screen that
nothing walks back. Each goes on its own and a refusal does not stop the rest:
the host turns down a directory that still has something in it, and in a set of
five that must not silently cancel the four it would have removed — nor hide
which ones it did not.
A drawn checkbox rather than ctrl-click, and not for taste: the phone shares
this view model and has neither ctrl nor shift, so a multi-selection has to be a
tap target there whatever the desktop does. One shape on both heads, and a state
somebody can see.
◆ RECURSIVE FOLDERS: THE TREE BECOMES FILES BEFORE THE QUEUE SEES IT.
A directory used to be counted and skipped. It is now walked, and the queue
still knows nothing about trees — which is what keeps every property it has:
each file resumable on its own, each written to a part file and renamed into
place, none able to overwrite anything already there.
The plan is collected whole and then queued, because directories have to exist
before the files that go in them and shortest-first is the only order that
guarantees a parent before its child. It also means a walk refused halfway has
queued nothing yet, so the sentence it produces describes one outcome rather
than an outcome and a queue that half happened.
Links are counted, not followed, in both directions. One pointing at an ancestor
is a walk with no end, and on the remote side there is a second reason: an lstat
listing says a name is a link and not what it leads to, so descending would be a
round trip per entry to find out. Locally that is AttributesToSkip on the one
enumeration that decides what to descend into. A 5000-file ceiling is a backstop
for the accidental drag of a home directory, and it says so rather than
truncating quietly.
The status line grew four more ways to be partly what was asked for, and states
each: gone, refused, left alone, not a file.
◆ EDITING IN PLACE: FETCH, OPEN, WATCH, PUSH BACK.
The round trip this replaces is download, find it, open it, edit, come back,
delete the old one because nothing here overwrites, upload, check the mode
survived.
DELIBERATELY NOT THROUGH THE TRANSFER QUEUE, in either direction. The queue
refuses to overwrite, which is the right rule for a file somebody dragged and
exactly the wrong one for a file they are editing, where replacing the original
is the entire intent. The write-back deletes first: OpenWriteAsync at offset
zero writes over the beginning and leaves any tail that is longer — its own
contract says so — which for a config that got shorter means a file ending in
the back half of its previous version. Deleting is the only truncation this
interface offers, and the mode goes back on afterwards because deleting took it.
A stat before every save, compared against what the server said when the copy
was taken, catches somebody else writing while the file is open — which is how a
config gets silently reverted. There is no merge and no button pretending
otherwise; the three answers offered are the three that exist. Length and
timestamp rather than a digest, because a digest is a second full read of a file
there is otherwise no reason to fetch.
Both platform halves are injected: what opens a .conf is a registry
association, a desktop entry or a Launch Services binding depending on the
desktop, and watching a file is a platform object with its own thread. The
watcher watches the directory and filters the name, because a great many editors
write a temporary file and rename it over the top — which to a watcher pointed
at an inode is the file disappearing. The phone gets neither delegate, so the
button is not live there rather than there and disappointing.
◆ TWO THINGS FOUND ON THE WAY, BOTH WORTH STATING.
The shell suite's inline `post` was not serialising the way a dispatcher does.
Routing TransfersViewModel through it exposed a check-then-add in
OnTransferChanged that two threads turn into two rows for one transfer. Harmless
in production, where the UI thread serialises — the fixture was under-specifying
what it stood in for, and now posts under a lock.
And the edit session replaced its own record with `with` on each save, which
left the watcher holding an instance that was no longer the current one: every
save after the first quietly did nothing. The stamp moves in place now, and the
test saves twice.
◆ WHAT IS VERIFIED.
901 across the five suites this touches, 19 of them new. The layout suite earned
its keep three times over: the batch deletion card's path list overflowed the
204-pixel pane at 120, at 72 and at 56 before 32 held, and the edit strip
overflowed by 131 until the whole strip — rather than the log inside it — was
bounded. Each number in those files is measured and says which failure it came
from, because the next person to add a line to either card will move them again.
What no suite covers is the platform halves of editing: Process.Start with
UseShellExecute and a live FileSystemWatcher are the operating system, and a test
waiting on one would be measuring it. The shell's own half — when a save is
written back, when it is refused, what stopping releases — is covered against a
watcher that fires on demand.
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jaap-jan
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e2733e5cbc |
Notice when a shell ends, say which way it ended, and offer the way back
A terminal whose machine rebooted stayed green for ever. Not "went stale and
recovered late" — for ever: the tab claimed CONNECTED, the elapsed timer went
on counting, and the only thing that ever corrected it was closing the
application. That is the defect this fixes, and it turned out to be two
separate failures wearing one symptom.
◆ THE HANG IS IN SSH.NET, AND KEEP-ALIVE ALONE WOULD NOT HAVE FIXED IT.
ShellStream ends a blocked read from exactly two places: its channel being
closed, and the session raising Disconnected. A shell that exits gives the
first. But Session raises Disconnected from one method only — OnDisconnectReceived,
for a server that politely says goodbye — and a socket that simply fails goes
down a different path entirely: RaiseError fires the error event, sets the
disconnecting flag and disposes the socket, without ever raising Disconnected.
So the stream was never disposed, its Monitor.Wait was never pulsed, and the
read blocked until the process ended. The transport was gone, the client knew
the transport was gone, and nothing woke the one thread that was waiting.
That is why the first attempt at a test for this sat at thirty seconds and
failed. Both halves are needed and neither is sufficient:
- Keep-alive makes the failure HAPPEN. An idle SSH session is a socket
nobody writes to, and TCP has no way to discover that the far end has gone
without writing to it — nothing was asked, so nothing could fail. Thirty
seconds, matching OpenSSH's own ServerAliveInterval examples. It is the
write that matters and not a reply: SSH_MSG_IGNORE need not be answered,
so this is traffic rather than a heartbeat with a deadline, and there is
no timeout invented here to be wrong about a slow link.
- Disposing the stream from the error handler makes it ARRIVE. Queued to the
thread pool and not done inline, which is not tidiness: this runs on
SSH.NET's message-listener thread, and closing a channel waits for the
server's close — processed by that same thread — so an inline dispose is
the listener thread waiting on itself.
SFTP gets the keep-alive too. Its operations are request/response and bounded
by ConnectionInfo.Timeout already, so it needs no equivalent wake-up.
◆ exit AND reboot ARE TOLD APART BY A LATCH, BECAUSE THE OBVIOUS WAY IS A RACE.
Wait for the read to end and then ask whether the transport is still up, and
against a real server the answer is wrong about half the time: this was the
only channel on the connection, so sshd hangs up a millisecond after closing
it. By the time anything could ask, the transport is gone either way — and a
poll would report every ordinary `exit` as a dropped connection.
So ISshShellSession.TransportFailure is set at the moment SSH.NET raises the
failure, which its own ordering puts strictly before the disconnect that wakes
the read. A read that has just returned zero consults a settled value: set if
the transport failed, still null if the remote merely closed the channel. The
pump turns that into a TerminalSessionOutcome — RemoteClosed, ConnectionLost,
ClosedLocally — carried on SessionEnded, which used to hand over a session id
and nothing else. A subscriber cannot work this out afterwards; by the time it
hears, there is no transport left to interrogate.
Deliberately no fourth value for "the remote rebooted". Nothing on the wire
distinguishes a reboot from a cable being pulled, and a name this client
cannot check would be a guess dressed as a fact.
◆ WHAT IS DRAWN, AND WHY IT IS NOT DRAWN OVER THE PANE.
The status bar says DISCONNECTED or SHELL EXITED where it used to say NOT
CONNECTED for both — a word that is honest about a tab still dialling and
useless about one whose shell has stopped. Red for the first and grey for the
second: one is a machine that stopped answering and the other is work
finished, and crying wolf on the ordinary end of every session is its own bug.
The tab strip's dot gains the same fourth state, on both heads.
Under the terminal, a strip carrying the reason and two buttons. It takes its
own Auto grid row rather than overlaying the renderer, and that is forced
rather than chosen: the WebView is a native child view composited above
everything Avalonia draws, so the alternative is collapsing the terminal — and
the scrollback is precisely what the user wants to read, because the last
thing the remote said is usually why it went. terminal.js already writes the
same sentence into the pane; this is the copy that does not scroll away.
RECONNECT reuses the tab in place, which is what the word means to somebody
who pressed it: the terminal they were working in comes back, where it was.
It dials through the vault's ordinary connect path, so every refusal — a key
that has left the keychain, an unknown host key, a group default that has
changed since — is decided in the one place that already decides them; what
this adds is which tab the attempt belongs to. The old session is closed as
part of it, because a dead shell still holds an authenticated connection this
process has stopped reading, and its pane still holds an xterm, a scrollback
and a WebGL context, of which a browser hands out about sixteen.
Two refusals it makes rather than pretending: a host reached by typing an
address has no keychain entry to redial, and one that wants a password typed
goes to the keychain with the sheet raised rather than being dialled with an
empty box. Both say so on the strip where the button was pressed, not only in
the vault's status on a screen that surface is not.
TRY AGAIN appears on a refused connection for the same reason, and it is worth
as much: the commonest refusal is a host that was not up yet.
◆ WHAT IS ACTUALLY VERIFIED.
Two tests against a real sshd in a container. `exit` is reported as the remote
closing the session — the one a polling implementation fails, and a fake shell
cannot show it because a fake has no server behind it deciding to hang up. And
a live shell losing its transport is reported as a lost connection, produced
by dialling through a plain TCP relay the test owns and then cutting it; the
container is shared by the collection, so killing sshd was never an option.
The first draft of that second test used LoopbackProxyTests' SOCKS forward and
timed out: disconnecting the carrier of a ForwardedPortDynamic does not close
the loopback socket it accepted. Recorded in the test, because it is a
property of SSH.NET's forwarder rather than of anything here, and it is not
what a dying machine looks like.
What no test reproduces is the waiting. A relay that closes sends a FIN, so
the socket reports itself at once; a machine switched off sends nothing, and
finding that out is the keep-alive's business and the OS's retransmit budget's
— neither of which a test can hurry along without a clock this code does not
own. A reboot is prompt in practice because the machine comes back and RSTs.
Beside those: three pump outcomes, three workspace announcements, and seven
shell-flow tests covering the drop, the clean exit, reuse of the tab, retry
after a refusal, and both ways a reconnect can honestly come to nothing.
Also fixed in passing: SshNetShellSession.IsOpen read ShellStream.CanRead,
which is documented as always true — the stream stays readable after disposal
so buffered output can be drained — so it had answered "yes" for every shell
that ever existed. It reads CanWrite now. And MainWindowViewModel's session-
ended handler moved from Dispatcher.UIThread.Post to the injected post
delegate, which is what makes any of the shell half testable at all; the
remark listing the three unreachable posts is one shorter.
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