Resource for Source: Assembly

home *** CD-ROM | disk | FTP | other *** search

/ Resource for Source: Assembly / assembly resource for source.iso / assem02 / chasm4.arc / CHMOD.ASM < prev next >

Wrap

Assembly Source File | 1984-05-03 | 11.1 KB | 314 lines

;================================================ ; CHMOD Version 1.1 5/3/84 ; ; by David Whitman ; ; Utility to examine and modify the read/write ; mode of a file under DOS 2.0. ; ; Syntax: ; ; CHMOD [d:][path] [filespec] [/N] [/R] [/S] [/H] ; ; If no file is specified, a help message is printed, ; summarizing the CHMOD command syntax. ; ; The attribute byte of the specified file is set ; according to the selected options: ; ; /N - normal file ; /R - read only ; /S - system file ; /H - hidden file ; ; Multiple options may be selected. /N will cancel ; options preceding it in the command line. ; ; If no options are selected, a report on the current ; mode of the specified file is sent to the standard output. ; ; On exit, ERRORLEVEL is set to reflect the current file ; mode, and/or the success of the change, as follows: ; ; normal file --> 0 ; read only file --> 1 ; hidden file --> 2 ; system file --> 4 ; failed operation --> 8 ; ; Requires DOS 2.0, will abort under earlier versions. ; ; This source file is in CHASM assembler syntax. ;====================================================== ;========== ; EQUATES ;========== @chmod equ 43H ;change file mode @dosver equ 30H ;get DOS version number @exit equ 4CH ;set ERRORLEVEL and exit @prnstr equ 09H ;print string normal equ 00H readonly equ 01H hidden equ 02H system equ 04H failure equ 08H true equ 0FFH ;boolean values false equ 00H cr equ 0DH ;carriage return lf equ 0AH ;line feed beep equ 07H ;bell param_area equ [81H] ;unformatted parameter area param_count equ [80H] ;number of characters in above ;=========================================================== chmod proc near call chkdos ;test for proper DOS call parsefile ;parse path/filename call options ;parse options, set flags call doit ;perform specified action call cleanup ;final processing, exit mov al, opflag ;set errorlevel with current attributes mov ah, @exit ;and exit int 21H endp ;================================================= ; SUBROUTINE CHKDOS ; Checks for proper DOS, exits if not 2.0 or above ;================================================= chkdos proc near mov ah, @dosver ;get dos version number int 21H ;with dos call cmp al, 2 ;2.0 or over? jae a1 ;yes, skip mov ah, @prnstr ;no, bitch mov dx, offset(baddos) ;point to message int 21H ;and print it pop ax ;reset stack int 20H ;and exit a1 ret baddos db beep, cr, lf, 'This program requires DOS 2.0!' cr, lf, '$' endp ;=================================================== ; SUBROUTINE PARSEFILE ; Scans the parameter area for a path/filename. ; Sets PATHPTR to point to the name, and terminates ; it with a 0, to make an ASCIIZ string. ; ; If no name is found, ERRORLEVEL is set to 8, ; and control is passed back to DOS. ;=================================================== parsefile proc near xor ch,ch ;cx <== # of parameter characters mov cl, param_count ; " mov di, offset(param_area) mov al, ' ' ;search for first non-blank rep scasb jcxz berror ;nothing? bitch dec di ;back up to character found inc cx ; " cmpb [di], '/' ;are we into the options? jne b1 ;no, skip berror mov ah, @prnstr ;yes, print help message mov dx, offset(nofile) int 21H pop ax ;reset stack mov ah, @exit ;set error level and exit mov al, failure int 21H b1 mov pathptr, di ;otherwise point to pathname repne ;now search for next blank scasb jcxz b2 ;reached end of data? dec di ;nope, back up to last non-blank inc cx ; " b2 movb [di], 00H ;ASCIIZ string terminator ret pathptr db 00H, 00H ;pointer to path/filename nofile db cr, lf db 'CHMOD version 1.1' cr lf db cr lf db 'Syntax: CHMOD [d:][path] [filespec] [/N] [/R] [/S] [/H]' db cr lf cr lf db 'The attribute byte of the specified file is set' cr lf db 'according to the selected options:' cr lf db cr lf db ' /N - normal file' cr lf db ' /R - read only' cr lf db ' /S - system file' cr lf db ' /H - hidden file' cr lf db cr lf db 'Multiple options may be selected.' cr lf db cr lf db 'If no options are selected, a report on the current mode' cr lf db 'of the specified file is sent to STDOUT and ERRORLEVEL'cr lf db 'is set to the value of the file attribute byte. ' cr lf cr lf db '$' endp ;===================================================== ; SUBROUTINE OPTIONS ; Scans the command line for options, and builds ; the new attribute byte in OPFLAG. ; ; If options are found, OPFOUND is set true, otherwise ; it remains false. ;====================================================== options proc near ;cx still has number of chars. left, ;di points to current position. c1 mov al, '/' ;options marked with '/' repnz ;scan for options scasb jcxz cexit ;reached end mov al, [di] ;get option character and al, 0DFH ;guarantees upper case cmp al, 'N' ;normal file? jne c2 ;no, skip movb opflag, normal ;yes, clear all bits movb opfound, true ;set found flag jmps c1 ;and loop c2 cmp al, 'R' ;read only? jne c3 ;no, skip orb opflag, readonly ;yes, set option flag movb opfound, true ;set found flag jmps c1 ;and loop c3 cmp al, 'S' ;system? jne c4 ;no, skip orb opflag, system ;yes, set option flag movb opfound, true ;set found flag jmps c1 ;and loop c4 cmp al, 'H' ;hidden? jne c1 ;no, just loop orb opflag, hidden ;yes, set option flag movb opfound, true ;set found flag jmps c1 ;and loop cexit ret opflag db 00H ;options selected - new attribute byte opfound db 00H ;if non-zero, an option was decoded endp ;======================================================== ; SUBROUTINE DOIT ; Does the actual work. Either sets new file attribute, ; or reads the existing attribute. ;======================================================== doit proc near mov dx, pathptr ;point DX at ASCIIZ path/filename cmpb opfound, false ;any options? je d1 ;no, skip xor ch,ch ;CX <== new attribute byte mov cl, opflag mov al, 01H ;enable attribute setting jmps d2 d1 mov al, 00H ;enable attribute read d2 mov ah, @chmod ;change file mode dos call int 21H jc derr ;carry flag means error and cl, 07H ;mask off high bits mov opflag, cl ;save attribute byte jmps dexit ;and exit gracefully derr cmp al, 02H ;file not found error jne d3 mov dx, offset(fnferror) mov ah, @prnstr int 21H jmps dabort d3 cmp al, 03H ;path not found error jne d4 mov dx, offset(pnferror) mov ah, @prnstr int 21h jmps dabort d4 cmp al, 05H ;access denied error jne dabort mov dx, offset(aderror) mov ah, @prnstr int 21H dabort pop ax ;reset stack mov al, failure ;set errorlevel mov ah, @exit ;and abort to dos int 21H dexit ret ;normal return fnferror db cr, lf, 'File not found.' cr, lf, '$' pnferror db cr, lf, 'Path not found.' cr, lf, '$' aderror db cr, lf, 'Access denied.' cr, lf, '$' endp ;================================================== ; SUBROUTINE CLEANUP ; If no options were specified, a report of current ; attributes is printed. ;================================================== cleanup proc near cmpb opfound, true ;were options specified? je eexit ;yes, exit mov ah, @prnstr ;print report header mov dx, offset(header) int 21H testb opflag, readonly ;read only? jz e1 mov dx, offset(roattrib) ;print attribute message int 21H e1 testb opflag, system ;system? jz e2 mov dx, offset(sattrib) ;print attribute message int 21H e2 testb opflag, hidden ;hidden? jz e3 mov dx, offset(hattrib) ;print attribute message int 21H e3 cmpb opflag, normal ;normal? jne eexit mov dx, offset(nattrib) ;print attribute message int 21H eexit ret header db cr, lf, 'Current Attributes:' cr, lf, cr, lf, '$' roattrib db ' Read only' cr, lf, '$' sattrib db ' System' cr, lf, '$' hattrib db ' Hidden' cr, lf, '$' nattrib db ' Normal' cr, lf, '$' endp