---------------------------------------------------------------------------------------
                      [BUG/PRB.] VFP 9.0 FIX - ALLOCATE MORE MEMORY FOR RUSHMORE QUERY OPTIMIZATION
                               January 2024
                 ---------------------------------------------------------------------------------------
                                     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 example, 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.