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Diffstat (limited to 'src/libs/3rdparty/winpty/misc/Notes.txt')
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diff --git a/src/libs/3rdparty/winpty/misc/Notes.txt b/src/libs/3rdparty/winpty/misc/Notes.txt new file mode 100644 index 0000000000..410e184198 --- /dev/null +++ b/src/libs/3rdparty/winpty/misc/Notes.txt @@ -0,0 +1,219 @@ +Test programs +------------- + +Cygwin + emacs + vim + mc (Midnight Commander) + lynx + links + less + more + wget + +Capturing the console output +---------------------------- + +Initial idea: + +In the agent, keep track of the remote terminal state for N lines of +(window+history). Also keep track of the terminal size. Regularly poll for +changes to the console screen buffer, then use some number of edits to bring +the remote terminal into sync with the console. + +This idea seems to have trouble when a Unix terminal is resized. When the +server receives a resize notification, it can have a hard time figuring out +what the terminal did. Race conditions might also be a problem. + +The behavior of the terminal can be tricky: + + - When the window is expanded by one line, does the terminal add a blank line + to the bottom or move a line from the history into the top? + + - When the window is shrunk by one line, does the terminal delete the topmost + or the bottommost line? Can it delete the line with the cursor? + +Some popular behaviors for expanding: + - [all] If there are no history lines, then add a line at the bottom. + - [konsole] Always add a line at the bottom. + - [putty,xterm,rxvt] Pull in a history line from the top. + - [g-t] I can't tell. It seems to add a blank line, until the program writes + to stdout or until I click the scroll bar, then the output "snaps" back down, + pulling lines out of the history. I thought I saw different behavior + between Ubuntu 10.10 and 11.10, so maybe GNOME 3 changed something. Avoid + using "bash" to test this behavior because "bash" apparently always writes + the prompt after terminal resize. + +Some popular behaviors for shrinking: + - [konsole,putty,xterm,rxvt] If the line at the bottom is blank, then delete + it. Otherwise, move the topmost line into history. + - [g-t] If the line at the bottom has not been touched, then delete it. + Otherwise, move the topmost line into history. + +(TODO: I need to test my theories about the terminal behavior better still. +It's interesting to see how g-t handles clear differently than every other +terminal.) + +There is an ANSI escape sequence (DSR) that sends the current cursor location +to the terminal's input. One idea I had was to use this code to figure out how +the terminal had handled a resize. I currently think this idea won't work due +to race conditions. + +Newer idea: + +Keep track of the last N lines that have been sent to the remote terminal. +Poll for changes to console output. When the output changes, send just the +changed content to the terminal. In particular: + - Don't send a cursor position (CUP) code. Instead, if the line that's 3 + steps up from the latest line changes, send a relative cursor up (CUU) + code. It's OK to send an absolute column number code (CHA). + - At least in general, don't try to send complete screenshots of the current + console window. + +The idea is that sending just the changes should have good behavior for streams +of output, even when those streams modify the output (e.g. an archiver, or +maybe a downloader/packager/wget). I need to think about whether this works +for full-screen programs (e.g. emacs, less, lynx, the above list of programs). + +I noticed that console programs don't typically modify the window or buffer +coordinates. edit.com is an exception. + +I tested the pager in native Python (more?), and I verified that ENTER and SPACE +both paid no attention to the location of the console window within the screen +buffer. This makes sense -- why would they care? The Cygwin less, on the other +hand, does care. If I scroll the window up, then Cygwin less will write to a +position within the window. I didn't really expect this behavior, but it +doesn't seem to be a problem. + +Setting up a TestNetServer service +---------------------------------- + +First run the deploy.sh script to copy files into deploy. Make sure +TestNetServer.exe will run in a bare environment (no MinGW or Qt in the path). + +Install the Windows Server 2003 Resource Kit. It will have two programs in it, +instsrv and srvany. + +Run: + + InstSrv TestNetServer <path-to-srvany>\srvany.exe + +This creates a service named "TestNetServer" that uses the Microsoft service +wrapper. To configure the new service to run TestNetServer, set a registry +value: + + [HKLM\SYSTEM\CurrentControlSet\Services\TestNetServer\Parameters] + Application=<full-path>\TestNetServer.exe + +Also see http://www.iopus.com/guides/srvany.htm. + +To remove the service, run: + + InstSrv TestNetServer REMOVE + +TODO +---- + +Agent: When resizing the console, consider whether to add lines to the top +or bottom. I remember thinking the current behavior was wrong for some +application, but I forgot which one. + +Make the font as small as possible. The console window dimensions are limited by +the screen size, so making the font small reduces an unnecessary limitation on the +PseudoConsole size. There's a documented Vista/Win7 API for this +(SetCurrentConsoleFontEx), and apparently WinXP has an undocumented API +(SetConsoleFont): + http://blogs.microsoft.co.il/blogs/pavely/archive/2009/07/23/changing-console-fonts.aspx + +Make the agent work with DOS programs like edit and qbasic. + - Detect that the terminal program has resized the window/buffer and enter a + simple just-scrape-and-dont-resize mode. Track the client window size and + send the intersection of the console and the agent's client. + - I also need to generate keyboard scan codes. + - Solve the NTVDM.EXE console shutdown problem, probably by ignoring NTVDM.EXE + when it appears on the GetConsoleProcessList list. + +Rename the agent? Is the term "proxy" more accurate? + +Optimize the polling. e.g. Use a longer poll interval when the console is idle. +Do a minimal poll that checks whether the sync marker or window has moved. + +Increase the console buffer size to ~9000 lines. Beware making it so big that +reading the sync column exhausts the 32KB conhost<->agent heap. + +Reduce the memory overhead of the agent. The agent's m_bufferData array can +be small (a few hundred lines?) relative to the console buffer size. + +Try to handle console background color better. + Unix terminal emulators have a user-configurable foreground and background +color, and for best results, the agent really needs to avoid changing the colors, +especially the background color. It's undesirable/ugly to SSH into a machine +and see the command prompt change the colors. It's especially ugly that the +terminal retains its original colors and only drawn cells get the new colors. +(e.g. Resizing the window to the right uses the local terminal colors rather +than the remote colors.) It's especially ugly in gnome-terminal, which draws +user-configurable black as black, but VT100 black as dark-gray. + If there were a way to query the terminal emulator's colors, then I could +match the console's colors to the terminal and everything would just work. As +far as I know, that's not possible. + I thought of a kludge that might work. Instead of translating console white +and black to VT/100 white and black, I would translate them to "reset" and +"invert". I'd translate other colors normally. This approach should produce +ideal results for command-line work and tolerable results for full-screen +programs without configuration. Configuring the agent for black-on-white or +white-on-black would produce ideal results in all situations. + This kludge only really applies to the SSH application. For a Win32 Konsole +application, it should be easy to get the colors right all the time. + +Try using the screen reader API: + - To eliminate polling. + - To detect when a line wraps. When a line wraps, it'd be nice not to send a + CRLF to the terminal emulator so copy-and-paste works better. + - To detect hard tabs with Cygwin. + +Implement VT100/ANSI escape sequence recognition for input. Decide where this +functionality belongs. PseudoConsole.dll? Disambiguating ESC from an escape +sequence might be tricky. For the SSH server, I was thinking that when a small +SSH payload ended with an ESC character, I could assume the character was really +an ESC keypress, on the assumption that if it were an escape sequence, the +payload would probably contain the whole sequence. I'm not sure this works, +especially if there's a lot of other traffic multiplexed on the SSH socket. + +Support Unicode. + - Some DOS programs draw using line/box characters. Can these characters be + translated to the Unicode equivalents? + +Create automated tests. + +Experiment with the Terminator emulator, an emulator that doesn't wrap lines. +How many columns does it report having? What column does it report the cursor +in as it's writing past the right end of the window? Will Terminator be a +problem if I implement line wrapping detection in the agent? + +BUG: After the unix-adapter/pconsole.exe program exits, the blinking cursor is +replaced with a hidden cursor. + +Fix assert() in the agent. If it fails, the failure message needs to be +reported somewhere. Pop up a dialog box? Maybe switch the active desktop, +then show a dialog box? + +TODO: There's already a pconsole project on GitHub. Maybe rename this project +to something else? winpty? + +TODO: Can the DebugServer system be replaced with OutputDebugString? How +do we decide whose processes' output to collect? + +TODO: Three executables: + build/winpty-agent.exe + build/winpty.dll + build/console.exe + +BUG: Run the pconsole.exe inside another console. As I type dir, I see this: + D:\rprichard\pconsole> + D:\rprichard\pconsole>d + D:\rprichard\pconsole>di + D:\rprichard\pconsole>dir + In the output of "dir", every other line is blank. + There was a bug in Terminal::sendLine that was causing this to happen + frequently. Now that I fixed it, this bug should only manifest on lines + whose last column is not a space (i.e. a full line). |