; LINK : error LNK2001: unresolved external symbol _WinMainCRTStartup
; except.exe : fatal error LNK1120: 1 unresolved externals
; Written by Jeremy Gordon 2002
; except.asm Conversion of except1.asm (Goasm) to masm code
;
;
.386
.MODEL FLAT, STDCALL
OPTION CASEMAP: NONE
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc
include \masm32\include\advapi32.inc
include \masm32\include\shlwapi.inc
include \masm32\macros\macros.asm
includelib \masm32\lib\kernel32.lib
includelib \masm32\lib\user32.lib
includelib \masm32\lib\advapi32.lib
includelib \masm32\lib\shlwapi.lib
.DATA
HappyStr db "Except1,This is a very happy ending",0
Except db "Except1,There was an exception - do you want me to swallow it?",0
Except1 db "Except1",0
Except2 db "Except1 - well it's all over for now.",0
Unwind db "The system calling the handler again for more clearing up (unwinding)",0
FATALMESS DB "I thoroughly enjoyed it and I have already tidied everything up - "
DB "you know, completed records, closed file handles, "
DB "released memory, that sort of thing .."
DB "Glad this was by design - bye, bye .."
DB ".. but first, I expect the system will do an unwind ..",0
.CODE
assume fs: @data
;ASSUME fs:NOTHING ; This statement generates this
;
START:
; Lets make our final handler which would do all clearing up if the program has to close
PUSH offset FINAL_HANDLER
CALL SetUnhandledExceptionFilter
CALL PROTECTED_AREA
CALL CLEAR_UP ;here the program clears up normally
PUSH 40h ;exclamation sign + ok button only
push offset Except1
PUSH offset HappyStr
push 0
CALL MessageBoxA ;wait till ok pressed
PUSH 0 ;code meaning a succesful conclusion
CALL ExitProcess ;and finish with aplomb!
; PROGRAM END
PROTECTED_AREA:
;PUSH EBP,0,0 ; )create the
push ebp
push 0
push 0
PUSH OFFSET SAFE_PLACE ; )ERR structure
PUSH OFFSET HANDLER ; )on the
;FS PUSH [0] ; )stack
push dword ptr fs:[0] ; line 71 error A2108: use of register assumed to ERROR
;FS MOV [0],ESP ;point to structure just established on the stack
mov dword ptr fs:[0],esp ; line 74 error A2108: use of register assumed to ERROR
;*********************** and now lets cause the exception ..
XOR ECX,ECX ;set ecx to zero
DIV ECX ;divide by zero, causing exception
;*********************** because of the exception the code never gets to here
SAFE_PLACE: ;but the handler will jump to here ..
;FS POP [0] ;restore original exception handler from stack
pop dword ptr fs:[0] ; line 86 error A2108: use of register assumed to ERROR
ADD ESP,14h ;throw away remainder of ERR structure made earlier
RET
;This simple handler is called by the system when the divide by zero
;occurs.In this handler the user is given a choice of swallowing the
;exception by jumping to the safe-place, or not dealing with it at all,
;in which case the system will send the exception to the FINAL_HANDLER
HANDLER:
;save registers as required by Windows
PUSH EBX
PUSH EDI
PUSH ESI
MOV EBX,[EBP+8] ;get exception record in ebx
MOV EAX,[EBX+4] ;get flag sent by the system
TEST AL,1h ;see if its a non-continuable exception
JNE short nodeal
;JNZ >.nodeal ;yes, so not allowed by system to touch it
TEST AL,2h ;see if its the system unwinding
JNE short unwind ;yes
PUSH 24h ;question mark + YES/NO buttons
PUSH offset Except1
push offset Except
CALL MessageBoxA ;wait till button pressed
CMP EAX,6 ;see if yes clicked
JNE short nodeal ;no -line 113 orig. jnz
; go to SAFE_PLACE
MOV ESI,[EBP+10h] ;get register context record in esi
MOV EDI,[EBP+0Ch] ;get pointer to ERR structure in edi
MOV [ESI+0C4h],EDI ;insert new esp (happens to be pointer to ERR)
MOV EAX,[EDI+8] ;get address of SAFE_PLACE given in ERR structure
MOV [ESI+0B8h],EAX ;insert that as new eip in register context
MOV EAX,[EDI+14h] ;get ebp at safe place given in ERR structure
MOV [ESI+0B4h],EAX ;insert that as new ebp in register context
XOR EAX,EAX ;eax=3D0 reload context and return to system
jmp short fin
;JMP > fin
unwind:
PUSH 40h ;exclamation sign + ok button only
PUSH offset Except1
PUSH offset Unwind
PUSH 0
CALL MessageBoxA ;wait till ok pressed, then return eax=3D1
nodeal:
MOV EAX,1 ;eax=3D1 system to go to next handler
fin:
POP ESI
POP EDI
POP EBX
RET
CLEAR_UP: ;all clearing up would be done here
RET
;
FINAL_HANDLER: ;system passes EXCEPTION_POINTERS
PUSH EBX
PUSH EDI
PUSH ESI ;save registers as required by Windows
CALL CLEAR_UP
PUSH 40h ;exclamation sign + ok button only
PUSH offset Except2
PUSH offset FATALMESS
CALL MessageBoxA ;wait till ok pressed
MOV EAX,1 ;terminate process without showing system message box
POP ESI
pop EDI
pop EBX
RET
end
WinMainCRTStartup is a C compiler entry routine
maybe something Jeremy is using requires the OBJ to be linked with a C compiler
i am just spit-balling, here - lol
Using polink
Quote
polink /entry:START /subsystem:console except.obj
POLINK: error: Unresolved external symbol '_START'.
POLINK: fatal error: 1 unresolved external(s).
Using golink
Quote
golink /entry START /console except.obj kernel32.dll user32.dll
Warning!
Specified entry point (START) was not found.
Output file: except.exe
Format: win32 size: 2,048 bytes
Weird...
ohhhhh
Andy, your code ends with...
end
for EXE source files, it should always reference the entry point
end START
I already tried that.
The program compiles, but doesn't run correctly.
Andy
error:
start:
end start ; The start here is missing in your source code
i don't see the "CLEAR_UP" routine in your code
The clear up wasn't in my code.
i put a working version in the other thread
I buggered up my bldall.bat and am trying to figure out where the mistake is.