----------------------------------------------------------------------------
                      [BUG/PRB.] VFP 9.0 FIX - INPUT SOME INVISIBLE CHARACTERS IN EDITOR
                                September 2024
                 ----------------------------------------------------------------------------
                                     CCB



1. BUG:

     In vfp9 (and vfp6, vfp7, vfp8), we can input the following invisible characters in Editor, the Command window and the EditBox control:
     CTRL+BACKSLASH (CTRL+\), File Separator,
     CTRL+RBRACKET (CTRL+]), Group Separator,
     CTRL+CARET (CTRL+SHIFT+6), Record Separator,
     CTRL+HYPHEN (CTRL+SHIFT+-), Unit Separator.

     The bug occurs for almost all fonts, it does not occur for a few fonts, for example, Fixedsys, System or Terminal.

     The bug also occurs in some windows applications, for example, Notepad, Firefox, Internet Explorer, Visual Studio, etc.
     The bug does not occur in some windows applications, for example, Wordpad, Word, Edge, Hiew, etc.

     There is a test program:

     *PROC testinvisiblecharacters

     SET STEP OFF
     SET ECHO OFF
     SET DEBUG OFF
     SET ESCAPE OFF
     SET TALK OFF
     SET SAFETY OFF

     _SCREEN.VISIBLE=.T.
     _SCREEN.WINDOWSTATE=2

     CLOSE DATABASES ALL
     CLOSE TABLES ALL

     ?"OK"     && ok.
     ?"CTRL+\" && there is a character CTRL+BACKSLASH between ? and "CTRL+\", we can't see it if we don't set font to Fixedsys, System or Terminal.
     ?"CTRL+]" && there is a character CTRL+RBRACKET  between ? and "CTRL+]", we can't see it if we don't set font to Fixedsys, System or Terminal.
     ?"CTRL+^" && there is a character CTRL+CARET     between ? and "CTRL+^", we can't see it if we don't set font to Fixedsys, System or Terminal.
     ?"CTRL+_" && there is a character CTRL+HYPHEN    between ? and "CTRL+_", we can't see it if we don't set font to Fixedsys, System or Terminal.
     ?"OK"     && ok.
     WAIT

     CLOSE DATABASES ALL
     CLOSE TABLES ALL

     RETURN

     * END OF PROC TESTINVISIBLECHARACTERS.

     Please refer to the picture testinvisiblecharacters_font_arial.png (set font to Arial):

     Please refer to the picture testinvisiblecharacters_font_fixedsys.png (set font to Fixedsys):

     After we compile the program file testinvisiblecharacters.prg,
     we can get the compilation error file testinvisiblecharacters.err:
     ?"CTRL+\"
     Error in line 17: Command contains unrecognized phrase/keyword.
     ?"CTRL+]"
     Error in line 18: Command contains unrecognized phrase/keyword.
     ?"CTRL+^"
     Error in line 19: Command contains unrecognized phrase/keyword.
     ?"CTRL+_"
     Error in line 20: Command contains unrecognized phrase/keyword.
     the code will not run.

     Please refer to the picture testinvisiblecharacterserr_font_arial.png (set font to Arial):

     Please refer to the picture testinvisiblecharacterserr_font_fixedsys.png (set font to Fixedsys):

     In VFP Advanced, we can't input the following invisible characters in Editor, the Command window and the EditBox control:
     CTRL+BACKSLASH (CTRL+\), File Separator,
     CTRL+RBRACKET (CTRL+]), Group Separator,
     CTRL+CARET (CTRL+SHIFT+6), Record Separator,
     CTRL+HYPHEN (CTRL+SHIFT+-), Unit Separator.
     It is helpful to solve the problem.


2. CAUSE:

     There are some BUGs in the following code.


3. RESOLUTION:

     We can write some code to fix the BUG.

     Fun415b39 :: ; proc near
             push ebx                                                        ;0x00415b39 :        53
             mov  ebx , dword ptr [ esp + 8 ]                                ;0x00415b3a :        8b5c2408
             push ebp                                                        ;0x00415b3e :        55
             mov  ebp , dword ptr [ esp + 20 ]                               ;0x00415b3f :        8b6c2414
             push esi                                                        ;0x00415b43 :        56
             mov esi , eax                                                   ;0x00415b44 :        8bf0
             push edi                                                        ;0x00415b46 :        57
             mov edx , ebx                                                   ;0x00415b47 :        8bd3
             mov ecx , esi                                                   ;0x00415b49 :        8bce
             call Fun43de2a                                                  ;0x00415b4b :        e8da820200
             mov edx , eax                                                   ;0x00415b50 :        8bd0
             xor eax , eax                                                   ;0x00415b52 :        33c0
             mov ecx , 016h                                                  ;0x00415b54 :        b916000000
             mov edi , edx                                                   ;0x00415b59 :        8bfa
             rep stosd                                                       ;0x00415b5b :        f3ab
             stosb                                                           ;0x00415b5d :        aa
             mov  ax , word ptr [ ebp + 2 ]                                  ;0x00415b5e :        668b4502
             or edi , 0FFFFFFFFh                                             ;0x00415b62 :        83cfff
             cmp ax , di                                                     ;0x00415b65 :        663bc7
             je Label483e17                                                  ;0x00415b68 :        0f84a9e20600
             movsx ecx , ax                                                  ;0x00415b6e :        0fbfc8
             mov  dword ptr [ esp + 28 ] , ecx                               ;0x00415b71 :        894c241c

     Label415b75 ::
             mov  eax , dword ptr [ esp + 28 ]                               ;0x00415b75 :        8b44241c
             mov  dword ptr [edx] , eax                                      ;0x00415b79 :        8902
             movsx ecx ,word ptr [ ebp + 0 ]                                 ;0x00415b7b :        0fbf4d00
             mov  dword ptr [ edx + 4 ] , ecx                                ;0x00415b7f :        894a04
             mov  dword ptr [ edx + 32 ] , edi                               ;0x00415b82 :        897a20
             mov  al , byte ptr [ ebp + 12 ]                                 ;0x00415b85 :        8a450c
             mov  byte ptr [ edx + 54 ] , al                                 ;0x00415b88 :        884236
             mov  cx , word ptr [ ebp + 14 ]                                 ;0x00415b8b :        668b4d0e
             mov  eax , dword ptr [ edx + 4 ]                                ;0x00415b8f :        8b4204
             or eax , 0200h                                                  ;0x00415b92 :        0d00020000
             mov  word ptr [ edx + 55 ] , cx                                 ;0x00415b97 :        66894a37
             mov  dword ptr [ edx + 40 ] , edi                               ;0x00415b9b :        897a28
             mov  word ptr [ edx + 65 ] , di                                 ;0x00415b9e :        66897a41
             mov  word ptr [ edx + 50 ] , di                                 ;0x00415ba2 :        66897a32
             mov  word ptr [ edx + 69 ] , di                                 ;0x00415ba6 :        66897a45
             mov  dword ptr [ edx + 4 ] , eax                                ;0x00415baa :        894204
             mov ecx , eax                                                   ;0x00415bad :        8bc8
             mov  ax , word ptr [ ebp + 16 ]                                 ;0x00415baf :        668b4510


     ;
     ;                 -----------------------------------------------------------------
     ;                      VFP 9.0 FIX - INPUT SOME INVISIBLE CHARACTERS IN EDITOR
     ;                                September 2024
     ;                 -----------------------------------------------------------------
     ;                                     CCB
     ;
     ; In vfp9 (and vfp6, vfp7, vfp8), we can input the following invisible characters in Editor:
     ; CTRL+BACKSLASH (CTRL+\), File Separator,
     ; CTRL+RBRACKET (CTRL+]), Group Separator,
     ; CTRL+CARET (CTRL+SHIFT+6), Record Separator,
     ; CTRL+HYPHEN (CTRL+SHIFT+-), Unit Separator.
     ; In Visual FoxPro Advanced, we can't input the following invisible characters in Editor:
     ; CTRL+BACKSLASH (CTRL+\), File Separator,
     ; CTRL+RBRACKET (CTRL+]), Group Separator,
     ; CTRL+CARET (CTRL+SHIFT+6), Record Separator,
     ; CTRL+HYPHEN (CTRL+SHIFT+-), Unit Separator.
     ;
     ; 2024/9/22, by ccb
     ;

             cmp dword ptr vfpa_sys9172_data,00h
             jne Label415bb3_invisiblecharacter4_end

     Label415bb3_invisiblecharacter1_start:
             cmp dword ptr [edx] , 0FFFFB504h
             jne Label415bb3_invisiblecharacter1_end
             mov ax , 201Ch
             mov  word ptr [ edx + 63 ] , ax
             jmp Label415b21
     Label415bb3_invisiblecharacter1_end:

     Label415bb3_invisiblecharacter3_start:
             cmp dword ptr [edx] , 0FFFFB508h
             jne Label415bb3_invisiblecharacter3_end
             mov ax , 301Eh
             mov  word ptr [ edx + 63 ] , ax
             jmp Label415b21
     Label415bb3_invisiblecharacter3_end:

     Label415bb3_invisiblecharacter4_start:
             cmp dword ptr [edx] , 0FFFFB50Fh
             jne Label415bb3_invisiblecharacter4_end
             mov ax , 301Fh
             mov  word ptr [ edx + 63 ] , ax
             jmp Label415b21
     Label415bb3_invisiblecharacter4_end:


     Label415bb3 ::
             test ax , ax                                                    ;0x00415bb3 :        6685c0
             mov  word ptr [ edx + 63 ] , ax                                 ;0x00415bb6 :        6689423f
             jne Label415b21                                                 ;0x00415bba :        0f8561ffffff

     Label415bc0 ::
             mov  ax , word ptr [ ebp + 10 ]                                 ;0x00415bc0 :        668b450a
             cmp ax , di                                                     ;0x00415bc4 :        663bc7
             jne Label5a1809                                                 ;0x00415bc7 :        0f853cbc1800

     Label415bcd ::
             mov  ax , word ptr [ ebp + 6 ]                                  ;0x00415bcd :        668b4506
             test ax , ax                                                    ;0x00415bd1 :        6685c0
             jne Label5a1824                                                 ;0x00415bd4 :        0f854abc1800
             cmp  word ptr [ ebp + 8 ] , ax                                  ;0x00415bda :        66394508
             jne Label5a1824                                                 ;0x00415bde :        0f8540bc1800

     Label415be4 ::
             mov  ax , word ptr [ ebp + 4 ]                                  ;0x00415be4 :        668b4504
             test ax , ax                                                    ;0x00415be8 :        6685c0
             jne Label41825c                                                 ;0x00415beb :        0f856b260000

     Label415bf1 ::
             movzx ebx ,word ptr [ ebp + 34 ]                                ;0x00415bf1 :        0fb75d22
             movsx eax ,word ptr [ ebp + 26 ]                                ;0x00415bf5 :        0fbf451a
             add ebx , ebp                                                   ;0x00415bf9 :        03dd
             cmp eax , 0FFFFFFFFh                                            ;0x00415bfb :        83f8ff
             je Label415c24                                                  ;0x00415bfe :        7424
             add eax , ebx                                                   ;0x00415c00 :        03c3
             mov ecx , eax                                                   ;0x00415c02 :        8bc8
             lea edi ,  dword ptr [ ecx + 1 ]                                ;0x00415c04 :        8d7901
             lea ebx ,  dword ptr [ebx]                                      ;0x00415c07 :        8d1b

     Label415c09 ::
             mov  dl , byte ptr [ecx]                                        ;0x00415c09 :        8a11
             inc ecx                                                         ;0x00415c0b :        41
             test dl , dl                                                    ;0x00415c0c :        84d2
             jne Label415c09                                                 ;0x00415c0e :        75f9
             sub ecx , edi                                                   ;0x00415c10 :        2bcf
             test ecx , ecx                                                  ;0x00415c12 :        85c9
             jle Label415c24                                                 ;0x00415c14 :        7e0e
             mov  edx , dword ptr [ esp + 20 ]                               ;0x00415c16 :        8b542414
             push ecx                                                        ;0x00415c1a :        51
             pushd 017h                                                      ;0x00415c1b :        6a17
             push edx                                                        ;0x00415c1d :        52
             push esi                                                        ;0x00415c1e :        56
             call Fun43120e                                                  ;0x00415c1f :        e8eab50100

     Label415c24 ::
             movsx eax ,word ptr [ ebp + 22 ]                                ;0x00415c24 :        0fbf4516
             cmp eax , 0FFFFFFFFh                                            ;0x00415c28 :        83f8ff
             jne Label41787a                                                 ;0x00415c2b :        0f85491c0000

     Label415c31 ::
             movsx eax ,word ptr [ ebp + 24 ]                                ;0x00415c31 :        0fbf4518
             cmp eax , 0FFFFFFFFh                                            ;0x00415c35 :        83f8ff
             je Label415c5c                                                  ;0x00415c38 :        7422
             add eax , ebx                                                   ;0x00415c3a :        03c3
             mov ecx , eax                                                   ;0x00415c3c :        8bc8
             lea edi ,  dword ptr [ ecx + 1 ]                                ;0x00415c3e :        8d7901

     Label415c41 ::
             mov  dl , byte ptr [ecx]                                        ;0x00415c41 :        8a11
             inc ecx                                                         ;0x00415c43 :        41
             test dl , dl                                                    ;0x00415c44 :        84d2
             jne Label415c41                                                 ;0x00415c46 :        75f9
             sub ecx , edi                                                   ;0x00415c48 :        2bcf
             test ecx , ecx                                                  ;0x00415c4a :        85c9
             jle Label415c5c                                                 ;0x00415c4c :        7e0e
             mov  edx , dword ptr [ esp + 20 ]                               ;0x00415c4e :        8b542414
             push ecx                                                        ;0x00415c52 :        51
             pushd 02h                                                       ;0x00415c53 :        6a02
             push edx                                                        ;0x00415c55 :        52
             push esi                                                        ;0x00415c56 :        56
             call Fun43120e                                                  ;0x00415c57 :        e8b2b50100

     Label415c5c ::
             movsx eax ,word ptr [ ebp + 18 ]                                ;0x00415c5c :        0fbf4512
             cmp eax , 0FFFFFFFFh                                            ;0x00415c60 :        83f8ff
             jne Label5a1839                                                 ;0x00415c63 :        0f85d0bb1800

     Label415c69 ::
             movsx eax ,word ptr [ ebp + 20 ]                                ;0x00415c69 :        0fbf4514
             cmp eax , 0FFFFFFFFh                                            ;0x00415c6d :        83f8ff
             jne Label5a1864                                                 ;0x00415c70 :        0f85eebb1800

     Label415c76 ::
             test  byte ptr [ ebp + 0 ] , 04h                                ;0x00415c76 :        f6450004
             jne Label415c96                                                 ;0x00415c7a :        751a
             mov  eax , dword ptr [ ebp + 28 ]                               ;0x00415c7c :        8b451c
             mov  ecx , dword ptr [ esp + 20 ]                               ;0x00415c7f :        8b4c2414
             pushd 04h                                                       ;0x00415c83 :        6a04
             pushd 03h                                                       ;0x00415c85 :        6a03
             push ecx                                                        ;0x00415c87 :        51
             mov  dword ptr [ esp + 36 ] , eax                               ;0x00415c88 :        89442424
             push esi                                                        ;0x00415c8c :        56
             lea eax ,  dword ptr [ esp + 40 ]                               ;0x00415c8d :        8d442428
             call Fun43120e                                                  ;0x00415c91 :        e878b50100

     Label415c96 ::
             mov  eax , dword ptr [esi]                                      ;0x00415c96 :        8b06
             mov  edx , dword ptr [ esp + 20 ]                               ;0x00415c98 :        8b542414
             inc edx                                                         ;0x00415c9c :        42
             mov  dword ptr [ eax + 64 ] , edx                               ;0x00415c9d :        895040
             mov  ecx , dword ptr [esi]                                      ;0x00415ca0 :        8b0e
             mov eax , edx                                                   ;0x00415ca2 :        8bc2
             mov  dword ptr [ ecx + 0ECh ] , eax                             ;0x00415ca4 :        8981ec000000
             mov  edx , dword ptr [esi]                                      ;0x00415caa :        8b16
             mov  ecx , dword ptr [ esp + 28 ]                               ;0x00415cac :        8b4c241c
             mov  dword ptr [ edx + 68 ] , eax                               ;0x00415cb0 :        894244
             mov  eax , dword ptr [esi]                                      ;0x00415cb3 :        8b06
             mov  ebp , dword ptr [ eax + 12 ]                               ;0x00415cb5 :        8b680c
             push ecx                                                        ;0x00415cb8 :        51
             lea edx ,  dword ptr [ esp + 24 ]                               ;0x00415cb9 :        8d542418
             or ebp , 080000000h                                             ;0x00415cbd :        81cd00000080
             push edx                                                        ;0x00415cc3 :        52
             mov  dword ptr [ eax + 12 ] , ebp                               ;0x00415cc4 :        89680c
             call Fun415a13                                                  ;0x00415cc7 :        e847fdffff
             test eax , eax                                                  ;0x00415ccc :        85c0
             je Label415cdf                                                  ;0x00415cce :        740f
             mov  eax , dword ptr [esi]                                      ;0x00415cd0 :        8b06
             mov  ecx , dword ptr [ eax + 8 ]                                ;0x00415cd2 :        8b4808
             cmp  ecx , dword ptr [ esp + 20 ]                               ;0x00415cd5 :        3b4c2414
             jne Label40b8ef                                                 ;0x00415cd9 :        0f85105cffff

     Label415cdf ::
             pop edi                                                         ;0x00415cdf :        5f
             pop esi                                                         ;0x00415ce0 :        5e
             pop ebp                                                         ;0x00415ce1 :        5d
             pop ebx                                                         ;0x00415ce2 :        5b
             ret 0Ch                                                         ;0x00415ce3 :        c20c00


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_vfp9fix352.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix92.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix155.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix156.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix307.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix308.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix316.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix317.asp
     http://www.baiyujia.com/vfpdocuments/f_vfp9fix318.asp

     2, ascii-code.com:
     https://www.ascii-code.com/characters/control-characters


6. OTHER:

     For reference only, there is no guarantees.

     Any questions or suggestions, please send me an email at ccb2000@163.com.