Written by Marcus Meissner <marcus@jet.franken.de>, additions welcome.
(Extracted from wine/documentation/debugging)
This file describes where to start debugging Wine. If at any point you get stuck and want to ask for help, please read the How to Report A Bug section of the Wine Users Guide for information on how to write useful bug reports.
These usually show up like this:
|Unexpected Windows program segfault - opcode = 8b
|Segmentation fault in Windows program 1b7:c41.
|Loading symbols from ELF file /root/wine/wine...
|....more Loading symbols from ...
|In 16 bit mode.
|Register dump:
| CS:01b7 SS:016f DS:0287 ES:0000
| IP:0c41 SP:878a BP:8796 FLAGS:0246
| AX:811e BX:0000 CX:0000 DX:0000 SI:0001 DI:ffff
|Stack dump:
|0x016f:0x878a: 0001 016f ffed 0000 0000 0287 890b 1e5b
|0x016f:0x879a: 01b7 0001 000d 1050 08b7 016f 0001 000d
|0x016f:0x87aa: 000a 0003 0004 0000 0007 0007 0190 0000
|0x016f:0x87ba:
|
|0050: sel=0287 base=40211d30 limit=0b93f (bytes) 16-bit rw-
|Backtrace:
|0 0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c)
|1 0x01b7:0x1e5b (PXSRV_FONPUTCATFONT+0x2cd)
|2 0x01a7:0x05aa
|3 0x01b7:0x0768 (PXSRV_FONINITFONTS+0x81)
|4 0x014f:0x03ed (PDOXWIN_@SQLCURCB$Q6CBTYPEULN8CBSCTYPE+0x1b1)
|5 0x013f:0x00ac
|
|0x01b7:0x0c41 (PXSRV_FONGETFACENAME+0x7c): movw %es:0x38(%bx),%dx
|
Steps to debug a crash. You may stop at any step, but please report the bug and provide as much of the information gathered to the bug report as feasible.
Get the reason for the crash. This is usually an access to an invalid selector, an access to an out of range address in a valid selector, popping a segmentregister from the stack or the like. When reporting a crash, report this whole crashdump even if it doesn't make sense to you.
(In this case it is access to an invalid selector, for %es is 0000, as seen in the register dump).
Determine the cause of the crash. Since this is usually a primary/secondary reaction to a failed or misbehaving Wine function, rerun Wine with -debugmsg +relay added to the commandline. This will generate quite a lot of output, but usually the reason is located in the last call(s). Those lines usually look like this:
|Call KERNEL.90: LSTRLEN(0227:0692 "text") ret=01e7:2ce7 ds=0227
^^^^^^^^^ ^ ^^^^^^^^^ ^^^^^^ ^^^^^^^^^ ^^^^
| | | | | |Datasegment
| | | | |Return address
| | | |textual parameter
| | |
| | |Argument(s). This one is a win16 segmented pointer.
| |Function called.
|The module, the function is called in. In this case it is KERNEL.
|Ret KERNEL.90: LSTRLEN() retval=0x0004 ret=01e7:2ce7 ds=0227
^^^^^^
|Returnvalue is 16 bit and has the value 4.
|
If you have found a misbehaving function, try to find out why it misbehaves. Find the function in the source code. Try to make sense of the arguments passed. Usually there is a WINE_DEFAULT_DEBUG_CHANNEL(<channel>); at the beginning of the file. Rerun wine with -debugmsg +xyz,+relay added to the commandline.
Occasionally there are additional debug channels defined at the begining of the file in the form. WINE_DECLARE_DEBUG_CHANNEL(<channel>); If so the offending fuction may also uses one of these alternate channels. Look through the the function for TRACE_(<channel>)(" ... /n"); and add any additional channels to the commandline.
Additional information on how to debug using the internal debugger can be found in programs/winedbg/README.
If this information isn't clear enough or if you want to know more about what's happening in the function itself, try running wine with -debugmsg +all, which dumps ALL included debug information in wine.
If even that isn't enough, add more debug output for yourself into the functions you find relevant. See The section on Debug Logging in this guide for more information. You might also try to run the program in gdb instead of using the Wine debugger. If you do that, use handle SIGSEGV nostop noprint to disable the handling of seg faults inside gdb (needed for Win16).
You can also set a breakpoint for that function. Start wine useing winedbg instead of wine. Once the debugger is is running enter break KERNEL_LSTRLEN (replace by function you want to debug, CASE IS RELEVANT) to set a breakpoint. Then use continue to start normal program-execution. Wine will stop if it reaches the breakpoint. If the program isn't yet at the crashing call of that function, use continue again until you are about to enter that function. You may now proceed with single-stepping the function until you reach the point of crash. Use the other debugger commands to print registers and the like.
Start the program with winedbg instead of wine. When the program locks up switch to the winedbg terminal and press Ctrl-C. this will stop the program and let you debug the program as you would for a crash.
Sometimes programs are reporting failure using more or less nondescript messageboxes. We can debug this using the same method as Crashes, but there is one problem... For setting up a message box the program also calls Wine producing huge chunks of debug code.
Since the failure happens usually directly before setting up the Messagebox you can start winedbg and set a breakpoint at MessageBoxA (called by win16 and win32 programs) and proceed with continue. With --debugmsg +all Wine will now stop directly before setting up the Messagebox. Proceed as explained above.
You can also run wine using wine -debugmsg +relay program.exe 2>&1 | less -i and in less search for "MessageBox".
You may also try to disassemble the offending program to check for undocumented features and/or use of them.
The best, freely available, disassembler for Win16 programs is Windows Codeback, archive name wcbxxx.zip, which usually can be found in the Cica-Mirror subdirectory on the Wine ftp sites. (See ANNOUNCE).
Disassembling win32 programs is possible using Windows Disassembler 32, archive name something like w32dsm87.zip (or similar) on ftp.winsite.com and mirrors. The shareware version does not allow saving of disassembly listings. You can also use the newer (and in the full version better) Interactive Disassembler (IDA) from the ftp sites mentioned at the end of the document. Understanding disassembled code is mostly a question of exercise.
Most code out there uses standard C function entries (for it is usually written in C). Win16 function entries usually look like that:
push bp
mov bp, sp
... function code ..
retf XXXX <--------- XXXX is number of bytes of arguments
|
This is a FAR function with no local storage. The arguments usually start at [bp+6] with increasing offsets. Note, that [bp+6] belongs to the rightmost argument, for exported win16 functions use the PASCAL calling convention. So, if we use strcmp(a,b) with a and b both 32 bit variables b would be at [bp+6] and a at [bp+10].
Most functions make also use of local storage in the stackframe:
enter 0086, 00
... function code ...
leave
retf XXXX
|
This does mostly the same as above, but also adds 0x86 bytes of stackstorage, which is accessed using [bp-xx]. Before calling a function, arguments are pushed on the stack using something like this:
push word ptr [bp-02] <- will be at [bp+8]
push di <- will be at [bp+6]
call KERNEL.LSTRLEN
|
Here first the selector and then the offset to the passed string are pushed.
Let's debug the infamous Word SHARE.EXE messagebox:
|marcus@jet $ wine winword.exe
| +---------------------------------------------+
| | ! You must leave Windows and load SHARE.EXE|
| | before starting Word. |
| +---------------------------------------------+
|
|marcus@jet $ wine winword.exe -debugmsg +relay -debug
|CallTo32(wndproc=0x40065bc0,hwnd=000001ac,msg=00000081,wp=00000000,lp=00000000)
|Win16 task 'winword': Breakpoint 1 at 0x01d7:0x001a
|CallTo16(func=0127:0070,ds=0927)
|Call WPROCS.24: TASK_RESCHEDULE() ret=00b7:1456 ds=0927
|Ret WPROCS.24: TASK_RESCHEDULE() retval=0x8672 ret=00b7:1456 ds=0927
|CallTo16(func=01d7:001a,ds=0927)
| AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=0927 BP=0000 ES=11f7
|Loading symbols: /home/marcus/wine/wine...
|Stopped on breakpoint 1 at 0x01d7:0x001a
|In 16 bit mode.
|Wine-dbg>break MessageBoxA <---- Set Breakpoint
|Breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
|Wine-dbg>c <---- Continue
|Call KERNEL.91: INITTASK() ret=0157:0022 ds=08a7
| AX=0000 BX=3cb4 CX=1f40 DX=0000 SI=0000 DI=08a7 ES=11d7 EFL=00000286
|CallTo16(func=090f:085c,ds=0dcf,0x0000,0x0000,0x0000,0x0000,0x0800,0x0000,0x0000,0x0dcf)
|... <----- Much debugoutput
|Call KERNEL.136: GETDRIVETYPE(0x0000) ret=060f:097b ds=0927
^^^^^^ Drive 0 (A:)
|Ret KERNEL.136: GETDRIVETYPE() retval=0x0002 ret=060f:097b ds=0927
^^^^^^ DRIVE_REMOVEABLE
(It is a floppy diskdrive.)
|Call KERNEL.136: GETDRIVETYPE(0x0001) ret=060f:097b ds=0927
^^^^^^ Drive 1 (B:)
|Ret KERNEL.136: GETDRIVETYPE() retval=0x0000 ret=060f:097b ds=0927
^^^^^^ DRIVE_CANNOTDETERMINE
(I don't have drive B: assigned)
|Call KERNEL.136: GETDRIVETYPE(0x0002) ret=060f:097b ds=0927
^^^^^^^ Drive 2 (C:)
|Ret KERNEL.136: GETDRIVETYPE() retval=0x0003 ret=060f:097b ds=0927
^^^^^^ DRIVE_FIXED
(specified as a harddisk)
|Call KERNEL.97: GETTEMPFILENAME(0x00c3,0x09278364"doc",0x0000,0927:8248) ret=060f:09b1 ds=0927
^^^^^^ ^^^^^ ^^^^^^^^^
| | |buffer for fname
| |temporary name ~docXXXX.tmp
|Force use of Drive C:.
|Warning: GetTempFileName returns 'C:~doc9281.tmp', which doesn't seem to be writeable.
|Please check your configuration file if this generates a failure.
|
Whoops, it even detects that something is wrong!
|Ret KERNEL.97: GETTEMPFILENAME() retval=0x9281 ret=060f:09b1 ds=0927
^^^^^^ Temporary storage ID
|Call KERNEL.74: OPENFILE(0x09278248"C:~doc9281.tmp",0927:82da,0x1012) ret=060f:09d8 ds=0927
^^^^^^^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^
|filename |OFSTRUCT |open mode:
OF_CREATE|OF_SHARE_EXCLUSIVE|OF_READWRITE
|
This fails, since my C: drive is in this case mounted readonly.
|Ret KERNEL.74: OPENFILE() retval=0xffff ret=060f:09d8 ds=0927
^^^^^^ HFILE_ERROR16, yes, it failed.
|Call USER.1: MESSAGEBOX(0x0000,0x09278376"Sie mussen Windows verlassen und SHARE.EXE laden bevor Sie Word starten.",0x00000000,0x1030) ret=060f:084f ds=0927
|
And MessageBox'ed.
|Stopped on breakpoint 2 at 0x40189100 (MessageBoxA [msgbox.c:190])
|190 { <- the sourceline
In 32 bit mode.
Wine-dbg>
|
The code seems to find a writeable harddisk and tries to create a file there. To work around this bug, you can define C: as a networkdrive, which is ignored by the code above.
Here are some useful debugging tips, added by Andreas Mohr:
If you have a program crashing at such an early loader phase that you can't use the Wine debugger normally, but Wine already executes the program's start code, then you may use a special trick. You should do a
wine --debugmsg +relay program
|
winedbg winfile.exe
|
This way, you get into winedbg. Now you can set a breakpoint on any function the program calls in the start function and just type c to bypass the eventual calls of Winfile to this function until you are finally at the place where this function gets called by the crashing start function. Now you can proceed with your debugging as usual.
If you try to run a program and it quits after showing an error messagebox, the problem can usually be identified in the return value of one of the functions executed before MessageBox(). That's why you should re-run the program with e.g.
wine --debugmsg +relay <program name> &>relmsg
|
Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
|
Call KERNEL.96: FREELIBRARY(0x0347) ret=01cf:1033 ds=01ff
CallTo16(func=033f:0072,ds=01ff,0x0000)
Ret KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1033 ds=01ff
Call KERNEL.96: FREELIBRARY(0x036f) ret=01cf:1043 ds=01ff
CallTo16(func=0367:0072,ds=01ff,0x0000)
Ret KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:1043 ds=01ff
Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
CallTo16(func=0317:0072,ds=01ff,0x0000)
Ret KERNEL.96: FREELIBRARY() retval=0x0001 ret=01cf:105c ds=01ff
Call USER.171: WINHELP(0x02ac,0x01ff05b4 "COMET.HLP",0x0002,0x00000000) ret=01cf:1070 ds=01ff
CallTo16(func=0117:0080,ds=01ff)
Call WPROCS.24: TASK_RESCHEDULE() ret=00a7:0a2d ds=002b
Ret WPROCS.24: TASK_RESCHEDULE() retval=0x0000 ret=00a7:0a2d ds=002b
Ret USER.171: WINHELP() retval=0x0001 ret=01cf:1070 ds=01ff
Call KERNEL.96: FREELIBRARY(0x01be) ret=01df:3e29 ds=01ff
Ret KERNEL.96: FREELIBRARY() retval=0x0000 ret=01df:3e29 ds=01ff
Call KERNEL.52: FREEPROCINSTANCE(0x02cf00ba) ret=01f7:1460 ds=01ff
Ret KERNEL.52: FREEPROCINSTANCE() retval=0x0001 ret=01f7:1460 ds=01ff
Call USER.1: MESSAGEBOX(0x0000,0x01ff1246 "Runtime error 219 at 0004:1056.",0x00000000,0x1010) ret=01f7:2160 ds=01ff
|
I think that the call to MessageBox() in this example is not caused by a wrong result value of some previously executed function (it's happening quite often like that), but instead the messagebox complains about a runtime error at 0x0004:0x1056.
As the segment value of the address is only 4, I think that that is only an internal program value. But the offset address reveals something quite interesting: Offset 1056 is very close to the return address of FREELIBRARY():
Call KERNEL.96: FREELIBRARY(0x031f) ret=01cf:105c ds=01ff
^^^^
|
Provided that segment 0x0004 is indeed segment 0x1cf, we now we can use IDA (available at ftp://ftp.uni-koeln.de/pc/msdos/programming/assembler/ida35bx.zip) to disassemble the part that caused the error. We just have to find the address of the call to FreeLibrary(). Some lines before that the runtime error occurred. But be careful! In some cases you don't have to disassemble the main program, but instead some DLL called by it in order to find the correct place where the runtime error occurred. That can be determined by finding the origin of the segment value (in this case 0x1cf).
If you have created a relay file of some crashing program and want to set a breakpoint at a certain location which is not yet available as the program loads the breakpoint's segment during execution, you may set a breakpoint to GetVersion16/32 as those functions are called very often.
Then do a c until you are able to set this breakpoint without error message.
Some useful programs:
Very good DOS disassembler ! It's badly needed for debugging Wine sometimes.
Traces DOS calls (Int 21h, DPMI, ...). Use it with Windows to correct file management problems etc.
Dumps the imports and exports of a PE (Portable Executable) DLL.
Dumps the imports and exports of a PE (Portable Executable) DLL (included in wine tree).
After starting your program with
wine -debug myprog.exe
|
the program loads and you get a prompt at the program starting point. Then you can set breakpoints:
b RoutineName (by outine name) OR
b *0x812575 (by address)
|
Then you hit c (continue) to run the program. It stops at the breakpoint. You can type
step (to step one line) OR
stepi (to step one machine instruction at a time;
here, it helps to know the basic 386
instruction set)
info reg (to see registers)
info stack (to see hex values in the stack)
info local (to see local variables)
list <line number> (to list source code)
x <variable name> (to examine a variable; only works if code
is not compiled with optimization)
x 0x4269978 (to examine a memory location)
? (help)
q (quit)
|
By hitting Enter, you repeat the last command.