Re: DOS programs under screen
2009/4/21 Barry Kelly: Windows implements console mode as a client-server protocol between the executable (ntvdm.exe for DOS apps) and winsrv.dll (hosted in csrss.exe), but the protocol isn't easily hookable. I guess one would have to hijack the console APIs, perhaps by stepping into the application using debugging APIs and overwriting the DLL imports, but it would be pretty painful. Hi Barry, have you got any pointers to documentation or reverse engineering attempts for that console protocol? 2009/4/21 Christopher Faylor: It can be done using the same technique as Console2: http://console.sourceforge.net I don't understand how. ReadConsoleOutput() on the hidden console only gives you the cooked output in terms of character cell contents and attributes, whereas the raw output as it came from the console app would need to be sent to the pty to be displayed by the likes of screen. As far as I can see, recreating the raw output from the cooked one isn't possible in general. This article has more on this: http://homepages.tesco.net/~J.deBoynePollard/FGA/capture-console-win32.html Andy -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
On Fri, May 01, 2009 at 08:26:31PM +0100, Andy Koppe wrote: 2009/4/21 Barry Kelly: Windows implements console mode as a client-server protocol between the executable (ntvdm.exe for DOS apps) and winsrv.dll (hosted in csrss.exe), but the protocol isn't easily hookable. I guess one would have to hijack the console APIs, perhaps by stepping into the application using debugging APIs and overwriting the DLL imports, but it would be pretty painful. Hi Barry, have you got any pointers to documentation or reverse engineering attempts for that console protocol? 2009/4/21 Christopher Faylor: It can be done using the same technique as Console2: http://console.sourceforge.net I don't understand how. ReadConsoleOutput() on the hidden console only gives you the cooked output in terms of character cell contents and attributes, whereas the raw output as it came from the console app would need to be sent to the pty to be displayed by the likes of screen. If you can get the character cell contents and attributes and you can push data into the consoles input buffer then, AFAIK, that's really all you need to create a pty. You can see that Console is doing something like that because of the barely noticeable lag when you type things. Obviously it's sending things back and forth between a hidden console and displaying what it receives on the screen. (You can also see it doing this in the source code if you are so inclined) What would probably be problematic would be accommodating programs which try to manipulate console attributes since a pty program would need to maintain strict control of the hidden console. cgf -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
Andy Koppe wrote: 2009/4/21 Barry Kelly: Windows implements console mode as a client-server protocol between the executable (ntvdm.exe for DOS apps) and winsrv.dll (hosted in csrss.exe), but the protocol isn't easily hookable. I guess one would have to hijack the console APIs, perhaps by stepping into the application using debugging APIs and overwriting the DLL imports, but it would be pretty painful. Hi Barry, have you got any pointers to documentation or reverse engineering attempts for that console protocol? It is not just the console. It's a substantial fraction of the Win32 API. The NT kernel transfers the data (LPCs, local/lightweight procedure calls) across a bit like a microkernel OS design; at least that's the theory, in practice it's all pretty monolithic. You can read a little bit more about it here: http://en.wikipedia.org/wiki/Local_Procedure_Call 2009/4/21 Christopher Faylor: It can be done using the same technique as Console2: http://console.sourceforge.net I don't understand how. ReadConsoleOutput() on the hidden console only gives you the cooked output in terms of character cell contents and attributes, whereas the raw output as it came from the console app would need to be sent to the pty to be displayed by the likes of screen. As far as I can see, recreating the raw output from the cooked one isn't possible in general. You could intercept the calls to the console APIs by finding out where the imports resolve to using GetProcAddress etc. (i.e. somewhere inside where kernel32.dll is mapped to in the process), then adjusting the page permissions (VirtualProtect etc.) and rewriting the entrypoint code (save original 5 bytes of code, insert JMP your-stub-here, and at your-stub-here save the parameters, update your stuff, execute the missing code (the code you skipped - may need adjustment owing to code-relative addressing modes in e.g. Jcc instructions), then JMP back. That's all assuming you have access to the innards of the process, most likely with debugging APIs like CreateRemoteThread, DebugActiveProcess / CreateProcess w/ debug, and WaitForDebugEvent / ContinueDebugEvent debugging loop. Doing all this could be fun, but I reckon it would amount to a stack of hacks. It also requires overbearing privileges. -- Barry -- http://barrkel.blogspot.com/ -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
2009/5/1 Barry Kelly: ReadConsoleOutput() on the hidden console only gives you the cooked output in terms of character cell contents and attributes, whereas the raw output as it came from the console app would need to be sent to the pty to be displayed by the likes of screen. As far as I can see, recreating the raw output from the cooked one isn't possible in general. You could intercept the calls to the console APIs by finding out where the imports resolve to using GetProcAddress etc. (i.e. somewhere inside where kernel32.dll is mapped to in the process), then adjusting the page permissions (VirtualProtect etc.) and rewriting the entrypoint code (save original 5 bytes of code, insert JMP your-stub-here, and at your-stub-here save the parameters, update your stuff, execute the missing code (the code you skipped - may need adjustment owing to code-relative addressing modes in e.g. Jcc instructions), then JMP back. That's all assuming you have access to the innards of the process, most likely with debugging APIs like CreateRemoteThread, DebugActiveProcess / CreateProcess w/ debug, and WaitForDebugEvent / ContinueDebugEvent debugging loop. Doing all this could be fun, but I reckon it would amount to a stack of hacks. It also requires overbearing privileges. Thanks very much Barry, that's valuable info. I get the feeling this would best be attempted as a separate utility to be invoked as a wrapper around Win32 console programs. This would translate the console API calls into reads and writes on stdin and stdout. It could be used with all pty-based terminal emulators while keeping the hackery out of the Cygwin DLL. On the last point, do you really need special privileges to access the innards of your own processes? Assuming the hooking could be made to work, translating the low-level console I/O functions that reach directly into the console screen buffer would still be rather a big challenge. Perhaps the wrapper would need to be limited to high-level console I/O only. Oh, and ReadFile() and WriteFile() would need to be hooked too, to see whether they're accessing the console in question. I think I'll stick with difficulty rating Insane for this issue on the MinTTY issue tracker. Andy -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. ...and if one was possible why wouldn't the techniques that it incorporates be part of cygwin? Laziness on your part? hahahahahaha -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
On Tue, Apr 21, 2009 at 06:39:27AM -0400, Andrew Schulman wrote: I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. ...and if one was possible why wouldn't the techniques that it incorporates be part of cygwin? Laziness on your part? hahahahahaha You got me. **cgf hangs head in shame and gets back to his bon bons. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
Maybe someone knows a solution to this, but I don't. Although I maintain screen for Cygwin, I know almost nothing of the details of how terminals work. I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. It probably can't be done as long as Microsoft doesn't provide a pseudo-console interface that would allow a third-party program to fully take over the role of a console window. In the meantime, the best that can be done is the lipstick-on-a-pig approach taken by http://sourceforge.net/projects/console/, which uses Win32 interfaces for accessing a console's screen contents and paints its own version of that. Andy ps: Actually, would it be possible to invoke a process with all the Win32 console functions overwritten by custom ones? (That would of course require an awful lot of work ...) -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
Andrew Schulman wrote: In general, non-cygwin programs can't be run reliably inside of an application that uses cygwin PTYs, including xterm, rxvt, and screen. Maybe someone knows a solution to this, but I don't. Although I maintain screen for Cygwin, I know almost nothing of the details of how terminals work. I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. Windows implements console mode as a client-server protocol between the executable (ntvdm.exe for DOS apps) and winsrv.dll (hosted in csrss.exe), but the protocol isn't easily hookable. I guess one would have to hijack the console APIs, perhaps by stepping into the application using debugging APIs and overwriting the DLL imports, but it would be pretty painful. I don't know how DOS programs that use graphics modes (in fullscreen) are implemented, though these must be rare now given that Vista no longer has a full-screen mode. -- Barry -- http://barrkel.blogspot.com/ -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
On Tue, Apr 21, 2009 at 06:46:05PM +0100, Andy Koppe wrote: Andrew Schulman wrote: Maybe someone knows a solution to this, but I don't. ?Although I maintain screen for Cygwin, I know almost nothing of the details of how terminals work. ?I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. It probably can't be done as long as Microsoft doesn't provide a pseudo-console interface that would allow a third-party program to fully take over the role of a console window. In the meantime, the best that can be done is the lipstick-on-a-pig approach taken by http://sourceforge.net/projects/console/, which uses Win32 interfaces for accessing a console's screen contents and paints its own version of that. It can be done using the same technique as Console2: http://console.sourceforge.net So there is some justification in invoking the too lazy clause. I've started down the path of implementing ptys using console functions a couple of times and have always turned back due to the amount of work it would end up taking. cgf -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
James Calfee jcal...@xxx.xxx wrote on 04/20/2009 02:02:33 PM: Hi Andrew. I have change request for screen.exe under cygwin. I did not get any response from the cygwin mailing list. I guess the request is a bit too specific. Do you know where I might direct the request? In case your wondering, we are running a server program that has a DOS interface. It does not work under screen. This program is very similar to the DOS edit program which also does NOT work under screen. So, my question would be, what is required to fix screen so it will work with the DOS edit program? Thanks for your help, Jimmy Jimmy, I saw the thread on the cygwin list. I didn't answer there because I didn't have anything to add. In fact, you did get a response there from Matt Wozniski, who I thought covered it as well as I could: In general, non-cygwin programs can't be run reliably inside of an application that uses cygwin PTYs, including xterm, rxvt, and screen. Maybe someone knows a solution to this, but I don't. Although I maintain screen for Cygwin, I know almost nothing of the details of how terminals work. I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. Please note that http://cygwin.com/problems.html asks you not to send problem reports to maintainers' personal email addresses. Such reports should go to the Cygwin list, so that everyone can contribute to and benefit from the discussion. If you want to call someone's attention to a thread, you can append e.g. [ping Andrew Schulman] to the subject. But at least in my case, it's not necessary: I have my news client set to automatically flag anything that has screen in the subject. Sorry I couldn't help. Good luck, Andrew. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
On Mon, Apr 20, 2009 at 03:56:16PM -0400, Andrew Schulman wrote: James Calfee jcal...@xxx.xxx wrote on 04/20/2009 02:02:33 PM: Hi Andrew. I have change request for screen.exe under cygwin. I did not get any response from the cygwin mailing list. I guess the request is a bit too specific. Do you know where I might direct the request? In case your wondering, we are running a server program that has a DOS interface. It does not work under screen. This program is very similar to the DOS edit program which also does NOT work under screen. So, my question would be, what is required to fix screen so it will work with the DOS edit program? Thanks for your help, Jimmy Jimmy, I saw the thread on the cygwin list. I didn't answer there because I didn't have anything to add. In fact, you did get a response there from Matt Wozniski, who I thought covered it as well as I could: In general, non-cygwin programs can't be run reliably inside of an application that uses cygwin PTYs, including xterm, rxvt, and screen. Maybe someone knows a solution to this, but I don't. Although I maintain screen for Cygwin, I know almost nothing of the details of how terminals work. I could imagine some kind of a DOS-to-Unix terminal wrapper program, but I've never seen one and have no idea how it would work. ...and if one was possible why wouldn't the techniques that it incorporates be part of cygwin? cgf -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
I suppose you could always use the 'clear' command instead of cls. If you need cls specifically, you can alias it to clear. From the edit point of view, is this something you could accomplish with another command-line editor (say vim)? William Sutton On Wed, 8 Apr 2009, James Calfee wrote: We need to run a DOS program as a service. The program provides valuable information in the DOS window in an interactive ASCII color interface but does not provide any method to connect to this interface if started as a service. One solution is to run this program under screen. Unfortunately, this will not work until I can get these things resolved: * DOS cls command does not work under screen * DOS edit program does not work under screen Does anyone know how to get these things working under Cygwin's screen? Steps to produce: Open a DOS window (start, run, cmd) or open Cygwin Run something like this c:\cygwin\bin\screen cmd Or just screen cmd ... Dos text and a prompt should come up .. Type cls The command is echoed back but the console does not clear. Running 'edit' does basically the same thing too. Instead of seeing edit's blue interface, the command is echoed and the console hangs. Pressing Ctrl+C will terminate screen's session. These test do not use ANSI.sys (see absence of this device in /cygdrive/c/CONFIG.SYS).. The 'edit' program works just fine without it. Maybe screen can manage without it too. Any help is appreciated. Thanks, jc Disclaimer: This message (including attachments) is confidential and may be privileged. If you have received it by mistake please notify the sender by return e-mail and delete this message from your system. Any unauthorized use or dissemination of this message in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. RxStrategies, Inc. shall not be liable for the improper or incomplete transmission of the information contained in this communication or for any delay in its receipt or damage to your system. RxStrategies, Inc. does not guarantee that the integrity of this communication has been maintained nor that this communication is free from viruses, interceptions or interference. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/ -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
RE: DOS programs under screen
Your right, clear does work. That example is too simple though. edit is similar to the server. I'm testing with a copy of the server now. It behaves just as edit does, I see my command echoed back to me but nothing else. The session is hung and I can not see the interface. I don't actually need edit to work. I'm just trying to provide a program that can be used to test the DOS graphical interface under screen. edit re-sizes the DOS window. The server does not do this. You may know of another DOS interface that could be used to test this. -Original Message- From: William Sutton [mailto:will...@trilug.org] Sent: Wednesday, April 08, 2009 2:29 PM To: James Calfee Cc: cygwin@cygwin.com; InformationTechnology Subject: Re: DOS programs under screen I suppose you could always use the 'clear' command instead of cls. If you need cls specifically, you can alias it to clear. From the edit point of view, is this something you could accomplish with another command-line editor (say vim)? William Sutton On Wed, 8 Apr 2009, James Calfee wrote: We need to run a DOS program as a service. The program provides valuable information in the DOS window in an interactive ASCII color interface but does not provide any method to connect to this interface if started as a service. One solution is to run this program under screen. Unfortunately, this will not work until I can get these things resolved: * DOS cls command does not work under screen * DOS edit program does not work under screen Does anyone know how to get these things working under Cygwin's screen? Steps to produce: Open a DOS window (start, run, cmd) or open Cygwin Run something like this c:\cygwin\bin\screen cmd Or just screen cmd ... Dos text and a prompt should come up .. Type cls The command is echoed back but the console does not clear. Running 'edit' does basically the same thing too. Instead of seeing edit's blue interface, the command is echoed and the console hangs. Pressing Ctrl+C will terminate screen's session. These test do not use ANSI.sys (see absence of this device in /cygdrive/c/CONFIG.SYS).. The 'edit' program works just fine without it. Maybe screen can manage without it too. Any help is appreciated. Thanks, jc Disclaimer: This message (including attachments) is confidential and may be privileged. If you have received it by mistake please notify the sender by return e-mail and delete this message from your system. Any unauthorized use or dissemination of this message in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. RxStrategies, Inc. shall not be liable for the improper or incomplete transmission of the information contained in this communication or for any delay in its receipt or damage to your system. RxStrategies, Inc. does not guarantee that the integrity of this communication has been maintained nor that this communication is free from viruses, interceptions or interference. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
Re: DOS programs under screen
On Wed, Apr 8, 2009 at 5:11 PM, James Calfee jcal...@accessrxs.com wrote: Your right, clear does work. That example is too simple though. edit is similar to the server. I'm testing with a copy of the server now. It behaves just as edit does, I see my command echoed back to me but nothing else. The session is hung and I can not see the interface. I don't actually need edit to work. I'm just trying to provide a program that can be used to test the DOS graphical interface under screen. edit re-sizes the DOS window. The server does not do this. You may know of another DOS interface that could be used to test this. In general, non-cygwin programs can't be run reliably inside of an application that uses cygwin PTYs, including xterm, rxvt, and screen. Don't quote these headers. We already know them. -Original Message- From: William Sutton [mailto:x...@xxx.xxx] http://www.cygwin.com/acronyms/#PCYMTNQREAIYR Sent: Wednesday, April 08, 2009 2:29 PM To: James Calfee Cc: x...@xxx.xxx; InformationTechnology Subject: Re: DOS programs under screen [ snip http://www.cygwin.com/acronyms/#TOFU ] Disclaimer: This message (including attachments) is confidential and may be privileged... And don't do this. Such disclaimers are against unenforcible when sent to a public mailing list, and you will likely be banned from the mailing list if you continue posting them. If you need to, send emails from a private address so this doesn't happen. ~Matt -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
