****************************************************************** * * * VERIFY, LOCK and UNLOCK Command Handlers * * * *----------------------------------------------------------------* * * * The LOCK command protects a file from being accidentally * * deleted or overwritten. This protection is removed by the * * UNLOCK command. The VERIFY command checks that the data * * associated with a particular file is encoded on the disk * * correctly. * * All three commands require a file name and can be issued * * with the optional volume, drive and slot parameters. Their * * execution patterns are also very similar. After loading the * * accumulator with the appropriate opcode, part of the common * * file manager command handler code is called to: * * 1) close the file if it is already open. * * 2) reassign a DOS buffer to the file to be * * verified, locked or unlocked. * * 3) call the file manager to do the function. * * 4) close the file. * * The lock/unlock FUNCTIONS have almost identical function * * handlers. After setting LOKUNLOK ($B39E) to lock ($80) or * * unlock ($00) the file, the COMNOPEN routine ($AB28) is called * * to search the directory sector for the file description entry * * corresponding to the named file. Failure to find the wanted * * file results in a file-not-found error message. If the named * * file is located, its file type code is read from the * * description entry. After the hi bit of the code is dropped, * * it is merged with the LOKUNLOK mask ($B39E) and stored back * * in the file description entry. The file is then locked or * * unlocked depending on whether the hi bit of the file type code * * is set or clear. (For example, an Applesoft file has a file * * type code of $82 or $02 if it is locked or unlocked. Once the * * description entry is updated, the modified directory sector is * * written back to the disk. * * The verify FUNTION handler work much differently. It * * opens the file and then read the sectors one at a time into * * the data sector buffer. As each sector is read, a checksum is * * calculated by RWTS. If the calculated checksum agrees with * * the checksum read off the disk, the data are verified. * * Failure to verify results in an I/O error messge. * * * * Although the VERIFY command can be used by itself, it is * * also called by the INIT, SAVE and BSAVE commands. * * Unfortunately, the VERIFY command is probably the least * * understood of all the DOS commands. Because RWTS * * automatically check the integrity of the data whenever some- * * thing is read from the disk, it seems that DOS is wasting * * valuable memory space by supporting the verify command and * * function handlers. However, when it is used by the INIT, SAVE * * or BSAVE cmds, the VERIFY routine saves time by checking the * * file right after it is written. In otherwords, you don't have * * to LOAD or BLOAD the file just to make sure that all went * * well. Because the VERIFY command can be used on any type of * * file, you don't have to write special driver programs to * * "read" special file types or text files just to be be sure * * that they were written to the disk correctly. (This later * * attribute can (under the right conditions) be used as a quick * * check to see if a protection-concious author has messed around * * with the checksum bytes.) * * * ****************************************************************** * On entry - CUMLOPTN ($AA65) has been updated * to reflect parsed option words (V, D, S). * - the validity of the options issued * with the command (and their numeric * values) have been checked. * - a legal file name has been parsed and * stored in the primary file name buffer * (PRIMFNBF, $AA75). (A27D) CMDVERFY LDA #12 ;Verify opcode. (A27F) BNE LOKUNLOK ;ALWAYS. (A271) CMDLOCK LDA #7 ;Lock opcode. (A273) BNE LOKUNLOK ;ALWAYS. (A275) CMDUNLOK LDA #8 ;Unlock opcode. (A277) LOKUNLOK JSR HNDLCMD1 ;Call part of the main command handler ;routine to LOCK, UNLOCK or VERIFY ;the file. * Part of common file manager command handler code. (A2AA) HNDLCMD1 STA TEMPBYT ;Store opcode in temporary location. LDA LENPRSD ;Get L-parameter from parsed table. BNE SAVLENFM ;Was a non-zero L-parm issued with cmd? LDA LENPRSD+1 BNE SAVLENFM LDA #1 ;Length was 0 so make it 1 instead. STA LENPRSD SAVLENFM LDA LENPRSD ;Put length in FM parm list. STA RECLENFM LDA LENPRSD+1 STA RECLENFM+1 CLSLOCBF JSR CMDCLOSE ;Close file if it's already open. (A2C8) (A2EA) CMDCLOSE . . (See dis'mbly of CMDCLOSE given below.) . . - Note that execution flows thru CMDCLOSE twice if the file is already open. - The first time thru, the matching DOS filename buffer is located & then CLOSEONE is used to close the file. - Execution then jumps back to the start of CMDCLOSE. - On this second pass, a matching filename is not found because the DOS filename buffer was released on the first pass. Therefore, A5L/H is left pointing at the highest numbered (lowest in memory) FREE DOS buffer when CMCLOSE is exited via EVENTXIT and CLOSERTS. - If the file is not already open on the first entry to CMDCLOSE, only one pass is made. This single pass resembles the second pass mentioned above. . . - If necessary, the CLOSE FUNCTION updates the data sector, T/S list sector & the VTOC. It also fixes up links in the directory sectors and updates the file size if needed. . . (RTS) (A2CB) LDA A5L+1 ;Hi byte of A5L/H pointer which points at the highest ;numbered (lowest in memory) free DOS name buffer (in chain). (A2CD) BNE SAVFNPTR ;Branch if found a free buffer. (A2CF) JMP NOBUFERR ;Go issue an out-of-buffers message. ------------ ;(See dis'mbly of errors.) (A2D2) SAVFNPTR STA A3L+1 ;Reset A3L/H to point at DOS buffer that we LDA A5L ;will use for file name field buffer (chain). STA A3L (A2D8) JSR CPYPFN * NOTE: This (re)assigns a DOS buffer to the * file we want to verify, lock or unlock. The * buffer may or may not be the same one that * was just released by the CLOSE cmd above. * The highest numbered (lowest in memory) free * DOS buffer is used. (A743) CPYPFN LDY #29 ;30 bytes to copy (0 to 29). CPYPRIM LDA PRIMFNBF,Y ;Copy the name of the file wanted from STA (A3L),Y ;the primary filename buffer into the DEY ;filename field buffer (in DOS chain). BPL CPYRIM ;More chars to get. (A74D) RTS (A2DB) JSR BUFS2PRM * Get addresses of the various DOS buffers from the * chain buffer & put them in the FM parameter list. (A74E) BUFS2PRM LDY #30 ;Get addr of FM work buf, T/S list ADRINPRM LDA (A3L),Y ;buf, data sector buf & next DOS STA WRKBUFFM-30,Y ;filename buf from chain INY ;pointer buffer & put them in FM parm list. CPY #38 ;(P.S. Adr of next DOS file name buf is BNE ADRINPRM ;not used by DOS.) (A75A) RTS (A2DE) JSR CPY2PARM * Put volume, drive, & slot values plus the * address of the primary filename buffer * in the FM parameter list. (A71A) CPY2PARM LDA VOLPRSD ;From parsed table. STA VOLFM LDA DRVPRSD ;From parsed table. STA DRVFM LDA SLOTPRSD ;From parsed table. STA SLOTFM LDA ADRPFNBF ;Get the adr of the primary file STA FNAMBUFM ;name buf from the constants tbl LDA ADRPFNBF+1 ;and put it in the FM parm list. STA FNAMBUFM+1 LDA A3L ;Save adr of current DOS file name STA CURFNADR ;buf in table of DOS variables. LDA A3L+1 STA CURFNADR+1 (A742) RTS (A2E1) LDA TEMPBYT ;Get verify, lock or unlock opcode back from temporary STA OPCODEFM ;buffer & put it in the FM parameter list. (A2E7) JMP FMDRIVER ------------ * Use the file manager driver to do the * VERIFY, LOCK or UNLOCK FUNCTIONS. (A6A8) FMDRIVER JSR FILEMGR ;Call the file manager to do the function. * File manager proper. (AB06) FILEMGR TSX ;Save stk pointer so can later rtn to caller of FM. STX STKSAV (AB0A) JSR RSTRFMWA * Copy FM work buf (in DOS chain) to * FM work area (not in DOS chain). (AE6A) RSTRFMWA JSR SELWKBUF ;Point A4L/H at FM work buf. * Get addr of FM work buff from * the FM parm list & put it in * the A4L/H pointer. (AF08) SELWKBUF LDX #0 ;Offset to select ;work buffer. (AF0A) BEQ PT2FMBUF ;ALWAYS. (AF12) PT2FMBUF LDA WRKBUFFM,X STA A4L LDA WRKBUFFM+1,X STA A4L+1 (AF1C) RTS (AE6D) LDY #0 ;Zero out return code in FM parm list to STY RTNCODFM ;signal no errors as default condition. STORFMWK LDA (A4L),Y ;Copy FM work buf to FM work area. STA FMWKAREA,Y INY CPY #45 ;45 bytes to copy (0 to 44). BNE STORFMWK CLC ;WHY????? (AE7D) RTS (AB0D) LDA OPCODEFM ;Check if opcode is legal. CMP #13 ;(Must be less than 13.) BCS TOERROP ;Opcode too large so got range error. ASL ;Double val of opcode & put it in (x) TAX ;so it indexes tables of adrs. LDA FMFUNCTB+1,X ;Stick adr of appropriate function PHA ;handler on stack (hi byte first). LDA FMFUNCTB,X PHA (AB1E) RTS ;DO STACK JUMP TO FUNCTION ENTRY POINT. . . (See dis'mbly of the appropriate function.) . . RE: LOCK OR UNLOCK FUNCTION. - uses part of COMNOPEN routine. - reads in VTOC to get link to 1rst directory. - reads directory secs in & looks for file description entry with matching filename. - if matching name found, modifies the file type code with LOKUNMSK ($B39E) to denote a locked or unlocked file. - writes updated directory sector buffer to disk. . . RE: VERIFY FUNCTION. - reads in VTOC & appropriate directory, T/S list & data sectors. - The verify function simply opens & then reads a file. Actual verification occurs deep within RWTS. As the data are read in, a checksum is calculated. If the calculated checksum agrees with the checksum read off the disk, the integrity of the data is verified. Failure to verify yeilds an I/O error. . . (RTS) ============ TOERROP JMP RNGERROP ;Go handle range error. (AB1F) ------------ ;(See dis'mbly of errors.) * Return here after doing the verify, lock * or unlock functions. (Cause after @ * function is done, use stack to get back * to the original caller.) (A6AB) AFTRFUNC BCC FMDRVRTN ;(c) = 0 = no errors. LDA RTNCODFM ;Get error code from FM parameter list. CMP #$5 ;End of data error? (A6B2) BEQ TOAPPTCH ;Yes - Encountered a zeroed-out T/S link or ;a zeroed-out data pair (trk/sec vals) ;listed in the T/S list. (Not applicable ;to the lock, unlock or verify functions.) (A6B4) JMP OTHRERR ;Got an error other than an end-of-data error. ------------ ;(See dis'mbly of errors.) (A6C3) FMDRVRTN RTS (A27A) JMP CMDCLOSE ;Go back into CMDCLOSE to close the ------------ ;file that was just opened via the ;verify, lock or unlock function. * Because the file is already open, execution flows * thru the close cmd twice. The first time thru, the matching * DOS filename buffer is located & then CLOSEONE is used to * close the file via the close FUNCTION. The 2nd time thru, a * matching filename buffer is not found because the DOS * buffer was released on the first pass. Therefore, A5L/H is * left pointing at the highest numbered (lowest in memory) * FREE DOS buffer when the close command is exited via EVENTXIT * and CLOSERTS. * * (P.S. NOT ALL RAMIFICATIONS OF THE CLOSE COMMAND ARE SHOWN * BELOW.) (A2EA) CMDCLOSE LDA PRIMFNBF ;Get 1rst char from primary name buffer. CMP #" " ;Don't allow leading in name. (A2EF) BEQ CLOSEALL ;Leading = signal to close all files. ;(A close cmd was issued with no ;accompanying file name.) (A2F1) JSR GETBUFF ;Locate a DOS file buffer. * Locate buffer with same name. * If that fails, locate a free buffer. (A764) GETBUFF LDA #0 ;Default hi-byte of pointer to 0 STA A5L+1 ;(ie. assume no free buff available). (A768) JSR GETFNBF1 ;Get pointer to 1rst filename buffer in chain. (A792) GETFNBF1 LDA ADOSFNB1 ;First link to chain of DOS buffers LDX ADOSFNB1+1 ;(ie. pt 2 1rst name buf in chain). (A798) BNE SETNXPTR ;ALWAYS. (A7A4) SETNXPTR STX A3L+1 ;Put addr of 1rst filename buffer in ptr STA A3L ;(ie. highest name buffer in chain). TXA ;Get hi-byte of addr in back in (a). GETNXRTN RTS (A7A9) (A76B) JMP FNCHAR1 ;Get first byte from DOS name buf. ------------ (A76E) GETFNLNK JSR GETNXBUF * Get addr of next filename buffer in chain * from chain pointers buffer offset 37 & 36 * bytes from 1rst char of present filename * buffer. (A79A) GETNXBUF LDY #37 ;Point the pointer at the chain buffer & LDA (A3L),Y ;get addr of the next filename buffer. BEQ GETNXRTN ;If hi-byte is 0, then link zeroed out. TAX ;Save hi-byte in (x). DEY ;Pick up low-byte. LDA (A3L),Y SETNXPTR STX A3L+1 ;Stick addr of filename buffer in ptr. STA A3L TXA ;Get hi-byte back in (a). GETNXRTN RTS (A7A9) (A771) BEQ NOFNMTCH ;Link zeroed out, end of chain. FNCHAR1 JSR GETFNBY1 ;Get the 1rst char of filename from buf in chain. (A773) * Get first byte of DOS name buffer. (A7AA) GETFNBY1 LDY #0 ;Buffer is free if 1rst byte = $00. LDA (A3L),Y ;If buf occuppied, the 1rst byte = 1rst (A7AE) RTS ;char of filename which owns buffer. (A776) BNE NXFNBUF ;Take branch if buffer wasn't free. LDA A3L ;Buffer was free, there4 point the A5L/H STA A5L ;pointer at the free buffer. LDA A3L+1 STA A5L+1 (A780) BNE GETFNLNK ;ALWAYS. (A782) NXFNBUF LDY #29 ;Buffer not free there4 compare name CMPFNCHR LDA (A3L),Y ;of owner with name of file in primary CMP PRIMFNBF,Y ;name buffer. (Start with last char first.) (A789) BNE GETFNLNK ;Char doesn't match, there4 look for another ;buffer that might have same name. (A78B) DEY ;That char matched, how bout rest of name? BPL CMPFNCHR ;30 chars in name (ie. 0 to 29). CLC ;Clr carry to signal that names match. (A78F) RTS ============ (A790) NOFNMTCH SEC ;Link zeroed out. (A791) RTS ============ (A2F4) EVENTXIT BCS CLOSERTS ;EVENTUALLY exit via this route. (A2F6) JSR CLOSEONE ;Matching file name was found, so close that file. * Close a particular file. (A2FC) CLOSEONE JSR CKEXCBUF * Check if current filename buffer * belongs to an EXEC file. After all, * don't want to close buffer if we are * using it to exec (ie. would be like * burying ourselves alive). (A7AF) CKEXCBUF LDA EXECFLAG ;Check to see if EXECing. BEQ NOTEXCBF ;No sweat - not running exec file. LDA EXECBUFF ;We are EXECing, there4 chk if addr of CMP A3L ;current filename buffer same as that BNE CKEXCRTN ;for buffer belonging to EXEC. LDA EXECBUFF+1 ;Maybe - low-bytes matched, CMP A3L+1 ;so now check hi bytes of addr. BEQ CKEXCRTN ;Exec buffer = current buffer. NOTEXCBF DEX ;Not EXECing, DEX to make sure z-flag off. (A7C2) ;(P.S. (x) was orig set to large non-zero ;val on entry to GETFNBF1. There4, if now ;DEX, can be sure z-flag will be off.) CKEXCRTN RTS ;Exit with z-flag = 1 if execing. (A7C3) ; = 0 if not execing. (A2FF) BNE FREEBUFF ;Not EXECing from this particular file. LDA #0 ;Closing an exec file so shut STA EXECFLAG ;off the exec flag. FREEBUFF LDY #0 ;Free up the DOS buffer by poking a $00 in TYA ;1rst byte of filename. STA (A3L),Y (A30B) JSR BUFS2PRM * GET addresses of the DOS buffers from chain * buffer & put them in FM parameter list. (A74E) BUFS2PRM LDY #30 ;Get addresses of FM Work buffer, ADRINPRM LDA (A3L),Y ;T/S list buffer, Data sec buffer and STA WRKBUFFM-30,Y ;NEXT filename buf from the chain ptr INY ;buf & put them in the FM parameter list. CPY #38 ;(P.S. addr of NEXT filename buffer BNE ADRINPRM ;is not used by DOS.) (A75A) RTS (A30E) LDA #2 ;Stick opcode for CLOSE function STA OPCODEFM ;in the FM parameter list. (A313) JMP FMDRIVER ;Get ready to do the function. ------------ (A6A8) FMDRIVER JSR FILEMGR ;Call the file manager to do the function. (AB06) FILEMGR TSX ;Save stk ptr so we can rtn to caller. STX STKSAV (AB0A) JSR RSTRFMWA ;Copy contents of FM work buffer (in DOS ;chain) to FM work area (not in chain). (AE6A) RSTRFMWA JSR SELWKBUF ;Find FM work buffer. * Get address of FM work buffer (chain) * from the FM parameter list & stick * it in the A4L/H pointer. (AF08) SELWKBUF LDA #0 (AF0A) BEQ PT2FMBUF ;ALWAYS. (AF12) PT2FMBUF LDA WRKBUFFM,X STA A4L LDA WRKBUFFM+1,X STA A4L+1 (AF1C) RTS (AE6D) LDY #0 ;Zero-out rtn code in FM parm STY RTNCODFM ;list to signal no errors. STORFMWK LDA (A4L),Y ;Copy FM work buf (in chain) to the FM STA FMWKAREA,Y ;work area (not in DOS buffer chain). INY CPY #45 BNE STORFMWK CLC ;Why????? (AE7D) RTS (AB0D) LDA OPCODEFM ;Chk if opcode is legal. CMP #13 ;(Must be less than 13.) BCS TOERROP ;Opcode too large, got range error. ASL ;Double val of opcode & get addr of TAX ;appropriate function handler from tbl. LDA FMFUNCTB+1,X ;Put the adr on stack (hi byte first) PHA ;& then do a "stack jump" to the appropriate LDA FMFUNCTB,X ;function handler. PHA (AB1E) RTS . . (AC06) . FNCLOSE . . . (See dis'mbly of CLOSE function.) . . - if necessary, free up any sectors that were previously allocated to the file but not needed. - also updates the file size, fixes up links & updates data, VTOC, T/S list & directory sectors if necessary. . . (RTS) ============ TOERROP JMP RNGERROP ;(To $B363 - see dis'mbly of errors.) (AB1F) ------------ * Return here after doing the close function * (Cause after @ function is done, use stack * to get back to original caller.) (A6AB) AFTRFUNC BCC FMDRVRTN ;(c) = 0 = no errors. LDA RTNCODFM ;Get error code from FM parameter list. CMP #$5 ;End of data error? (A6B2) BEQ TOAPPTCH ;Yes - Encountered a zeroed-out T/S link or ;a zeroed-out data pair (trk/sec vals) ;listed in the T/S list. (Not applicable to ;the close function.) (A6B4) JMP OTHRERR ;Got an error other than an end-of-data error. ------------ ;(See dis'mbly of errors.) (A6C3) FMDRVRTN RTS (A2F9) JMP CMDCLOSE ;Go back into CMDCLOSE to point the A5L/H ------------ ;pointer at the highest numbered (lowest in ;memory) free filename buffer in chain of ;DOS buffers & then exit CMDCLOSE & CMDVERFY ;(or CMDLOCK or CMDUNLOK) via EVENTXIT & ;CLOSERTS. (A330) CLOSERTS RTS ;Exit to caller of command. ============ ;(Normally returns to AFTRCMD ($A17D) in the ;command parsing and processing routines.)