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[BUG/PRB.] VFP 9.0 FIX - EDITBOX CONTROL ENTER AN INFINITE LOOP
January 2024
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CCB
1. BUG:
In the EditBox Control (and the VFP text editor, for example, the MODIFY COMMAND window),
if there are some non-printable characters (for example, CHR(0)), sometimes VFP will enter an infinite loop.
The bug occurs in vfp9, it does not occur in vfp6, vfp7 and vfp8.
The bug only occurs in DBCS (Double-Byte Character Sets) environments.
2. CAUSE:
There are some BUGs in the following code.
3. RESOLUTION:
We can write some code to fix the BUG.
Label613809 ::
mov eax , dword ptr [ ebp + 12 ] ;0x00613809 : 8b450c
xor edx , edx ;0x0061380c : 33d2
cmp dword ptr [ ebp - 8 ] , edx ;0x0061380e : 3955f8
mov edi , eax ;0x00613811 : 8bf8
mov dword ptr [ ebp - 24 ] , eax ;0x00613813 : 8945e8
jle Label61387e ;0x00613816 : 7e66
Label613818 ::
mov cl , byte ptr [eax] ;0x00613818 : 8a08
movzx esi , cl ;0x0061381a : 0fb6f1
test byte ptr [ 2 * esi + offset Data937360 ] , 040h ;0x0061381d : f604756073930040
mov dword ptr [ ebp - 24 ] , eax ;0x00613825 : 8945e8
je Label613834 ;0x00613828 : 740a
cmp cl , 0Dh ;0x0061382a : 80f90d
je Label613834 ;0x0061382d : 7405
cmp cl , 0Ah ;0x0061382f : 80f90a
jne Label61383d ;0x00613832 : 7509
Label613834 ::
test byte ptr [ esi + offset Data937120 ] , 01h ;0x00613834 : f6862071930001
je Label61386f ;0x0061383b : 7432
Label61383d ::
cmp edx , dword ptr [ ebp - 8 ] ;0x0061383d : 3b55f8
mov edi , eax ;0x00613840 : 8bf8
jnl Label61386f ;0x00613842 : 7d2b
Label613844 ::
mov cl , byte ptr [eax] ;0x00613844 : 8a08
movzx edx , cl ;0x00613846 : 0fb6d1
test byte ptr [ 2 * edx + offset Data937360 ] , 040h ;0x00613849 : f604556073930040
je Label61386f ;0x00613851 : 741c
cmp cl , 0Dh ;0x00613853 : 80f90d
je Label61386f ;0x00613856 : 7417
cmp cl , 0Ah ;0x00613858 : 80f90a
je Label61386f ;0x0061385b : 7412
mov dword ptr [ ebp - 24 ] , eax ;0x0061385d : 8945e8
call Fun418cec ;0x00613860 : e88754e0ff
mov ecx , eax ;0x00613865 : 8bc8
sub ecx , dword ptr [ ebp + 12 ] ;0x00613867 : 2b4d0c
cmp ecx , dword ptr [ ebp - 8 ] ;0x0061386a : 3b4df8
jl Label613844 ;0x0061386d : 7cd5
Label61386f ::
;
; --------------------------------------------------------------
; VFP 9.0 FIX - EDITBOX CONTROL ENTER AN INFINITE LOOP
; March 2017
; --------------------------------------------------------------
; CCB
;
; In the EditBox Control (and the VFP text editor, for example, the MODIFY COMMAND window),
; if there are some non-printable characters (for example, CHR(0)), sometimes VFP will enter an infinite loop.
;
; 2017/3/22, by ccb
;
cmp byte ptr [eax],00h
jne Label613873
inc eax
jmp Label613874
Label613873 ::
call Fun418cec ;0x0061386f : e87854e0ff
Label613874 ::
mov edx , eax ;0x00613874 : 8bd0
sub edx , dword ptr [ ebp + 12 ] ;0x00613876 : 2b550c
cmp edx , dword ptr [ ebp - 8 ] ;0x00613879 : 3b55f8
jl Label613818 ;0x0061387c : 7c9a
Label61387e ::
sub edi , dword ptr [ ebp + 12 ] ;0x0061387e : 2b7d0c
mov esi , edi ;0x00613881 : 8bf7
cmp esi , dword ptr [ ebp - 8 ] ;0x00613883 : 3b75f8
je Label61388c ;0x00613886 : 7404
test esi , esi ;0x00613888 : 85f6
jne Label6138ac ;0x0061388a : 7520
Label61388c ::
mov edi , dword ptr [ ebp + 12 ] ;0x0061388c : 8b7d0c
mov esi , dword ptr [ ebp - 24 ] ;0x0061388f : 8b75e8
mov eax , edi ;0x00613892 : 8bc7
sub esi , edi ;0x00613894 : 2bf7
call Fun418cec ;0x00613896 : e85154e0ff
sub eax , edi ;0x0061389b : 2bc7
cmp eax , esi ;0x0061389d : 3bc6
jle Label6138ac ;0x0061389f : 7e0b
mov eax , edi ;0x006138a1 : 8bc7
call Fun418cec ;0x006138a3 : e84454e0ff
mov esi , eax ;0x006138a8 : 8bf0
sub esi , edi ;0x006138aa : 2bf7
Label6138ac ::
mov edi , dword ptr [ ebp - 8 ] ;0x006138ac : 8b7df8
jmp Label4e69f6 ;0x006138af : e94231edff
4. APPLIES TO:
VFP 9.0.0.2412
VFP 9.0.0.3504 (SP1)
VFP 9.0.0.4611 (SP2)
VFP 9.0.0.5015 (SP2)
VFP 9.0.0.5411 (SP2)
VFP 9.0.0.5721 (SP2)
VFP 9.0.0.5815 (SP2)
VFP 9.0.0.6303 (SP2)
VFP 9.0.0.6602 (SP2)
VFP 9.0.0.7423 (SP2)
The bug has been fixed in VFP Advanced.
5. REFERENCE WEBSITES:
1, baiyujia.com:
http://www.baiyujia.com
2, csdn.net:
http://bbs.csdn.net/topics/100089631
3, tech-archive.net:
http://www.tech-archive.net/Archive/Fox/microsoft.public.fox.programmer.exchange/2005-12/msg00493.html
4, microsoft.com:
https://blogs.msdn.microsoft.com/calvin_hsia/2006/11/15/heres-an-infinite-loop-that-will-hang-your-machine/
5, sunyear.com.tw:
http://vfp.sunyear.com.tw/viewtopic.php?t=4835
6. OTHER:
For reference only, there is no guarantees.
Any questions or suggestions, please send me an email at ccb2000@163.com.
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