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[BUG/PRB.] VFP 9.0 FIX - ALLOCATE MORE MEMORY FOR RUSHMORE QUERY OPTIMIZATION
January 2024
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CCB
1. BUG:
In vfp9 (and vfp6, vfp7, vfp8), when using large index files for Rushmore Query Optimization,
sometimes it will cause the memory access violation exception (exception code 0xC0000005),
or the error "Index file is corrupted. Please rebuild it (Error 1066)".
The bug was reported by Dave Kaat.
2. CAUSE:
When using large index files for Rushmore Query Optimization, for exapmle, RECCOUNT()=90000000.
In VFP 9.0 and earlier versions, it will allocate (90000000 + 1002)/8 = 11250128 bytes memory to save the rushmore query data,
sometimes it will cause the memory access violation exception (exception code 0xC0000005),
or the error "Index file is corrupted. Please rebuild it (Error 1066)".
In VFP Advanced, it will allocate ((90000000 + 1002) * 17/16 + 1002*16)/8 = 11955264 bytes memory to save the rushmore query data,
so there is no the bug.
There are some BUGs in the following code.
3. RESOLUTION:
We can write some code to fix the BUG.
Fun44f1e5 :: ; proc near
push ebp ;0x0044f1e5 : 55
mov ebp , dword ptr [ esp + 8 ] ;0x0044f1e6 : 8b6c2408
;
; ----------------------------------------------------------------------------
; VFP 9.0 FIX - ALLOCATE MORE MEMORY FOR RUSHMORE QUERY OPTIMIZATION
; July 2023
; ----------------------------------------------------------------------------
; CCB
;
; In vfp9, when using large index files for Rushmore Query Optimization,
; sometimes it will cause the memory access violation exception (exception code 0xC0000005),
; or the error "Index file is corrupted. Please rebuild it (Error 1066)".
; In VFP Advanced, when using large index files for Rushmore Query Optimization,
; it will allocate more memory, so there is no the bug.
;
; 2023/7/7, by ccb
;
cmp dword ptr vfpa_sys9138_data,00h
je Label44f1ea
mov eax , ebp
shr eax , 04h
add ebp , eax
add ebp , 03EA0h
Label44f1ea ::
lea eax , dword ptr [ ebp + 2 ] ;0x0044f1ea : 8d4502
cdq ;0x0044f1ed : 99
and edx , 07h ;0x0044f1ee : 83e207
add eax , edx ;0x0044f1f1 : 03c2
sar eax , 03h ;0x0044f1f3 : c1f803
add eax , 07h ;0x0044f1f6 : 83c007
shr eax , 02h ;0x0044f1f9 : c1e802
shl eax , 02h ;0x0044f1fc : c1e002
test eax , eax ;0x0044f1ff : 85c0
je Label5e6f8c ;0x0044f201 : 0f84857d1900
push edi ;0x0044f207 : 57
lea edi , dword ptr [ eax + 4 ] ;0x0044f208 : 8d7804
pushd 00h ;0x0044f20b : 6a00
call Fun42db6a ;0x0044f20d : e858e9fdff
test eax , eax ;0x0044f212 : 85c0
je Label5e6f90 ;0x0044f214 : 0f84767d1900
push esi ;0x0044f21a : 56
add edi , 0FFFFFFFCh ;0x0044f21b : 83c7fc
mov dword ptr [eax] , edi ;0x0044f21e : 8938
lea esi , dword ptr [ eax + 4 ] ;0x0044f220 : 8d7004
xor eax , eax ;0x0044f223 : 33c0
call Fun49b3b7 ;0x0044f225 : e88dc10400
test esi , esi ;0x0044f22a : 85f6
je Label44f24f ;0x0044f22c : 7421
pushd 00h ;0x0044f22e : 6a00
push esi ;0x0044f230 : 56
pushd 03h ;0x0044f231 : 6a03
call Fun53ad17 ;0x0044f233 : e8dfba0e00
mov eax , ebp ;0x0044f238 : 8bc5
sar eax , 03h ;0x0044f23a : c1f803
mov dl , byte ptr [ esi + eax ] ;0x0044f23d : 8a1406
add eax , esi ;0x0044f240 : 03c6
and ebp , 07h ;0x0044f242 : 83e507
mov cl , byte ptr [ ebp + offset Data91fbd8 ] ;0x0044f245 : 8a8dd8fb9100
or dl , cl ;0x0044f24b : 0ad1
mov byte ptr [eax] , dl ;0x0044f24d : 8810
Label44f24f ::
mov eax , esi ;0x0044f24f : 8bc6
pop esi ;0x0044f251 : 5e
pop edi ;0x0044f252 : 5f
pop ebp ;0x0044f253 : 5d
ret 04h ;0x0044f254 : c20400
4. APPLIES TO:
VFP 6.0.8167.0
VFP 6.0.8961.0 (SP5)
VFP 7.0.0.9262
VFP 7.0.0.9465 (SP1)
VFP 8.0.0.2521
VFP 8.0.0.3117 (SP1)
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
http://www.baiyujia.com/vfpdocuments/f_vfp9fix276.asp
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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