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Assembly Source File | 1988-03-16 | 37.4 KB | 853 lines

; WILD Public Domain 1988 by Charles Lazo III, v1.0 ; WILD.ASM This program is used to run any other program (or DOS command) ; by expanding program wild card parameters given on the command ; line. E.g., WILD PROG *.* would run a program, say PROG.EXE, ; multiple times and supply it each time with a file from the ; current directory matching *.* (i.e., every file in the current ; directory would be supplied to PROG for execution). rt equ 0dh lf equ 0ah of equ offset bptr equ byte ptr wp equ word ptr code segment assume cs:code, ds:code org 2ch env_seg dw ? ; pointer to segment of our environment org 100h begin: jmp start ;------------------------------------------------------------------------------- ; The wild card specification is placed here at the bottom of our stack to avoid ; having to specially set aside space for it. It is used by the find_first ; routine to find the first file in the current directory meeting the wild card ; specification using the DOS Find First function. ;------------------------------------------------------------------------------- wild_spec db 16 dup('STACK ') ; 128 bytes for stack our_stack label word ss_save dw ? ; place to store ss:sp sp_save dw ? memory_used dw ? ; keep track of memory paragraphs used env_size dw ? ; number of bytes in the environment stored here cspc_addr label dword dw 2 dup(?); store address of comspec variable here left_blank dw ? ; stores pointer to start of wild card spec right_blank dw ? ; stores pointer to end of wild card spec copy_size dw ? ; stores size of command on command line (WILD) buffer_ptr dw 0 ; pointer to buffer for list of filenames switches db 0 ; record presence of QUERY & NOEXT here file_attr dw 0 ; store file attributes for file find cmd_line db 128 dup(0) ; save original command line here cmdl db ?,'/c',128 dup(?) ; command line for EXEC ;------------------------------------------------------------------------------- ; The parameter table to be passed to the DOS EXEC function: ;------------------------------------------------------------------------------- params dw ? ; segment of environment block stored here dw of cmdl ; offset of command line for program EXECed dw ? ; segment of command line for program EXECed dw 55h ; offset of first FCB dw ? ; segment of first FCB dw 65h ; offset of second FCB dw ? ; segment of second FCB ;*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* ; The following routines (up to the label buffer:) operate under the assumption ; that both ds and es are set to the code segment of WILD. ;*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* ;------------------------------------------------------------------------------- ; When the WILD environment variable has NOEXT in its assignment string, then ; filename extensions are ignored (not supplied) when commands are passed to ; the DOS EXEC function. This routine will remove any extension from the file- ; name in the DTA placed there by the DOS Find First and Continue File Search ; functions if NOEXT was found in the WILD environment variable. The extension ; is removed by replacing the period separating the main part from the extension ; with a null. Note that if a period is the only part of the filename, then it ; must be the dot representing the current directory so it is not removed. ;------------------------------------------------------------------------------- remove_ext? proc near ; removes any extension from filename test switches,noe ; is WILD NOEXT env variable set? jz no_remove ; no, don't remove extension xor al,al ; find null terminating filename mov cx,14 ; max number of characters in ASCIIZ+1 cld ; (for maintenance and documentation) repne scasb ; search for null sub di,9eh ; compute number of filename characters mov cx,di ; and place it in cx for next search mov al,'.' ; search for period prior to extension mov di,9eh ; offset of filename in DTA repne scasb ; search for period jcxz no_remove ; can't remove extension if not there cmp di,9fh ; if the period was the ONLY character, jz no_remove ; then it is the current directory mov bptr [di-1],0 ; set it to null to remove the extension no_remove: ret remove_ext? endp ;------------------------------------------------------------------------------- ; find_size computes the length of a filename in the DTA placed there by the DOS ; find first and continue file search functions. The length of the filename is ; returned in cx (the null character at the end of the ASCIIZ string is included ; in the count). This routine is similar to file_size, qv. ;------------------------------------------------------------------------------- find_size proc near ; find size of filename (returned in cx) call remove_ext? ; eliminate filename extension? xor al,al ; find null at end of ASCIIZ filename mov di,9eh ; offset of filename in DTA mov cx,14 ; max number of characters in ASCIIZ+1 cld ; (for maintenance and documentation) repne scasb ; search for null in ASCIIZ filename sub di,9eh ; compute number of filename characters mov cx,di ; return value in cx ret find_size endp ;------------------------------------------------------------------------------- ; In this routine we check to see if there is enough memory presently allocated ; for the filename buffer to place another filename in the buffer. First di is ; is set to the location in the buffer where the next filename will go. If not ; enough memory has been allocated to allow the placement of another filename ; in the buffer, then more memory is allocated. By using only the memory that ; is needed by the buffer (additional memory is allocated in blocks of 16 para- ; graphs or 256 bytes; an arbitrary value) the remaining memory can be used in ; the EXEC call. ;------------------------------------------------------------------------------- set_di proc near ; sets di to point to next available mov di,buffer_ptr ; location in filename buffer push cx ; save filename size or di,di ; is it zero (uninitialized)? jz init_di ; yes, point it to start of buffer mov bx,di ; use bx to find paragraphs used now add bx,0fh ; round up to next paragraph shr bx,1 ; determine paragraph count shr bx,1 shr bx,1 shr bx,1 inc bx ; reserve one more than used mov ax,memory_used ; memory paragraphs presently allocated cmp bx,ax ; is memory to be used > allocated? ja get_more ; yes, get more memory di_set: pop cx ; restore filename size ret get_more: add ax,16 ; ask for 256 more bytes (16 paragraphs) mov bx,ax ; request sent in bx mov dx,ax ; store in dx to assure request granted mov ah,4ah ; DOS memory modify function (es is ok) int 21h ; ask DOS for it cmp bx,dx ; DOS give what we wanted? mov dx,of mem_need ; address error message in case not jz got_it ; got requested memory jmp error_exit ; nope, DOS don't have it, terminate init_di: mov di,of buffer jmp short di_set ; exit with di at start of buffer got_it: mov memory_used,bx ; update memory allocated pop cx ; restore filename size ret set_di endp ;------------------------------------------------------------------------------- ; With this call we copy the filename in the DTA (placed there by DOS Find First ; and Continue File Search functions) into the filename buffer. ;------------------------------------------------------------------------------- store_filename proc near ; store filename of file find in buffer call find_size ; find size of filename in DTA (to cx) call set_di ; set di to next location in buffer mov si,9eh ; offset of filename in DTA cld ; (for maintenance and documentation) rep movsb ; move ASCIIZ filename to buffer mov buffer_ptr,di ; update buffer pointer ret store_filename endp ;------------------------------------------------------------------------------- ; This one is similar to the find_size routine in that the size of a file is ; returned in cx. While the find_size routine gets its input from the filename ; in the DTA, this one finds sizes of filenames set into the filename buffer. ; Additionally it differs in that find_size includes the terminal null in the ; count and this one does not. Also the zero flag is set if no more filenames ; exist (else reset). ;------------------------------------------------------------------------------- file_size proc near ; size of next filename in buffer to cx mov di,buffer_ptr ; get current buffer position cmp bptr [di],0 ; was the last the final filename? jz last_done ; yes, return with zero flag set mov cx,di ; save current buffer position push cx mov cx,14 ; longer than any ASCIIZ filename string mov al,0 ; search for null in ASCIIZ filename cld ; (for maintenance and documentation) repne scasb ; find the null mov buffer_ptr,di ; store new buffer position pop cx ; recover last buffer position sub di,cx ; compute size of filename in cx xchg cx,di dec cx ; discard null and reset the zero flag last_done: ret file_size endp ;------------------------------------------------------------------------------- ; A copy of the command line as given by the user (WILD's command line) is ; maintained at the location cmd_line. The variables left_blank and right_blank ; point to the first and last characters of the wild card specification within ; cmd_line when this routine is called the first time or the first and last ; characters of the previous filename when the routine is called at succeeding ; times. This blank is resized--either made larger or smaller--depending upon ; the size of the current filename that is to be copied into it. ;------------------------------------------------------------------------------- resize_blank proc near ; adjust filename blank to right size mov ax,left_blank ; first character of blank mov bx,right_blank ; last character of blank sub bx,ax ; compute length of blank inc bx mov di,right_blank ; point to last character of blank mov al,rt ; search for return character push cx ; save filename size mov cx,127 ; larger than necessary, so ok cld ; (for maintenance and documentation) repne scasb ; find the return character dec di ; point di to return character mov cx,di ; compute number to move in cx mov ax,right_blank sub cx,ax pop ax ; get filename size cmp ax,bx ; greater, less than, or equal? je rb_done ; finished if equal jb decrease ; less than, so decrease blank sub ax,bx ; compute amount filename is greater mov si,di ; point si to return character add di,ax ; di to new location of return character std ; decrement move this time rep movsb ; make room for filename mov bx,right_blank ; adjust this variable add bx,ax mov right_blank,bx mov bx,copy_size ; and this one also add bx,ax mov copy_size,bx mov bl,cmd_line ; and this one too add bl,al mov cmd_line,bl rb_done: ret decrease: sub bx,ax ; compute amount blank is greater mov si,right_blank ; point to first character after blank inc si mov di,si ; compute new location for these chars sub di,bx cld ; (for maintenance and documentation) rep movsb ; resize blank to filename size mov ax,right_blank ; adjust this variable sub ax,bx mov right_blank,ax mov ax,copy_size ; and this one also sub ax,bx mov copy_size,ax mov al,cmd_line ; and this one too sub al,bl mov cmd_line,al ret resize_blank endp ;------------------------------------------------------------------------------- ; cx contains filename size due to maintenance of this value on the stack while ; the resize_blank routine was called previous to the call to this one. The ; routine copies a filename from the filename buffer into a holding area (the ; location in cmd_line called blank) prior to it's being copied to the command ; line used by EXEC. ;------------------------------------------------------------------------------- copy_filename proc near ; copy a buffer filename to cmd_line mov si,buffer_ptr ; point si to current filename sub si,cx ; (since file_size updated buffer_ptr dec si ; we must go back for current file) mov di,left_blank ; the place in cmd_line to copy to cld ; (for maintenance and documentation) rep movsb ; filename --> cmd_line ret copy_filename endp ;------------------------------------------------------------------------------- ; This routine prepares the next command line that will be passed to EXEC by ; using the next available filename from the filename buffer. If all filenames ; have been processed, then the zero flag is set on return, else it is reset. ;------------------------------------------------------------------------------- copy_command proc near ; copy command to EXEC's command line call file_size ; find size of filename (returned in cx) jz all_done ; no more, so return with zero flag set push cx ; save filename size call resize_blank ; adjust filename blank to right size pop cx ; restore filesize for copy_filename call copy_filename ; filename from buffer --> command line mov cx,copy_size ; get size of command line copy mov al,cmd_line ; set size of EXEC's command line add al,2 ; account for increase due to "/c" mov cmdl,al ; set in size for EXEC mov si,of cmd_line+1; copy command to be executed mov di,of cmdl+3 ; to proper location for EXEC cld ; (for maintenance and documentation) rep movsb ; do the copy or al,al ; al is nonzero so zero flag is reset all_done: ret copy_command endp ;------------------------------------------------------------------------------- ; If the WILD environment variable contains the QUERY option, then this routine ; prompts the user with "(Y/N/A)?" for Yes, No, or Abort. The zero flag is set ; on return if the user replies No, it is reset if the reply is Yes, and the ; carry flag is set if Abort is the reply (carry flag reset if Y or N). These ; flag settings are preserved by the calling routine, wild_prompt, so that the ; code that calls wild_prompt can test them. This code responds as if a Yes ; response were given if QUERY is not active. ;------------------------------------------------------------------------------- wild_query? proc near ; inquire Yes, No, or Abort if QUERY set test switches,que ; is QUERY set in switches variable? jz wq_yes ; no, return to caller as if Yes mov dx,of wq_prompt ; prompt to send to standard error mov cx,wqp_size ; number of characters to send mov bx,2 ; write to file handle 2 (std error) mov ah,40h ; with DOS function 40h int 21h wq_next: mov ah,7 ; DOS keyboard input without echo int 21h or al,al ; an ASCII character? jnz wq_ascii ; yes, process the response mov ah,7 ; no, get and discard auxiliary byte int 21h jmp short wq_next ; continue input wq_ascii: and al,0dfh ; capitalize mov response,al ; and store it for (possible) output cmp al,'Y' ; a Yes response? je wq_yes ; uhuh, reset zero flag and exit cmp al,'N' ; a No response? je wq_no ; yeah, just exit (ZF is set) cmp al,'A' ; an Abort response? je wq_abort ; yep, set carry flag and exit jmp short wq_next ; none of the above; try again wq_yes: or al,al ; reset zero flag to indicate Yes wq_no: pushf ; save flags mov dx,of response ; write this mov cx,1 ; one character mov bx,2 ; to standard error mov ah,40h ; with DOS function 40h int 21h popf ; recover return flags ret wq_abort: or al,al ; reset zero flag so not taken as No stc ; set carry flag to indicate abort jmp short wq_no ; write response to screen wq_prompt db ' (Y/N/A)? ' ; prompt user with <(Yes, No, Abort)?> wqp_size equ $-wq_prompt ; size of prompt response db ? ; place to store user response to query wild_query? endp ;------------------------------------------------------------------------------- ; Here we show the user the command that will be executed next by WILD and if ; the WILD environment variable contains the QUERY option, then we will prompt ; (Y/N/A)? also. ;------------------------------------------------------------------------------- wild_prompt proc near ; output to std out the command EXECed mov dx,of wild_pmt ; display "WILD>" lead in mov cx,wildpmt_size ; size of lead in mov bx,2 ; write to file handle 2 (std error) mov ah,40h ; with DOS function 40h int 21h mov dx,of cmdl+3 ; point to command to be EXECed mov cx,copy_size ; number of bytes to send to std out dec cx ; but not the return at end of line mov bx,2 ; write to file handle 2 (std error) mov ah,40h ; with DOS function 40h int 21h call wild_query? ; send a query? pushf ; save response mov dx,of wild_rtlf ; return/linefeed to std out mov cx,2 ; just 2 characters to send mov bx,2 ; write to file handle 2 (std error) mov ah,40h ; with DOS function 40h int 21h popf ; restore response ret wild_pmt db rt,lf,'WILD>' ; lead in for WILD wildpmt_size equ $-wild_pmt wild_rtlf db rt,lf ; newline after "prompt" wild_prompt endp find_rest: call store_filename ; store filename as ASCIIZ in buffer mov ah,4fh ; DOS continue file search function int 21h or ax,ax ; return code nonzero? jnz all_found ; yes, all files have been found jmp short find_rest ; continue file find all_found: mov di,buffer_ptr ; get file buffer pointer mov bptr [di],0 ; double null indicates end of buffer mov di,of buffer ; start now at beginning of buffer mov buffer_ptr,di ; to process filenames next_file: call copy_command ; copy command with filename to EXEC's ; copy of the command line jz exit ; zero flag set indicates completion call wild_prompt ; command to screen and maybe prompt jz next_file ; user said no to this one jc exit ; user wants to abort mov ss_save,ss ; save stack to restore upon return from mov sp_save,sp ; the EXEC lds dx,cspc_addr ; ds:dx points to name of prog to EXEC mov bx,of params ; es:bx points to parameter block mov ax,4b00h ; execute program after loading it int 21h mov ss,cs:ss_save ; restore our stack mov sp,cs:sp_save mov ax,cs ; cs --> ds, es mov ds,ax mov es,ax jmp short next_file exit: mov ax,4c00h ; terminate with error code 0 int 21h buffer: ; store list of ASCIIZ filenames here prior to processing ;*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* ; The following routines will be used before the buffer is used and not again ; after the buffer begins to fill with ASCIIZ filenames from the current ; directory. Since memory is saved by overwriting them, that is why they are ; placed here. Even though this code and data will be overwritten as the file- ; name buffer begins to fill with files, the memory saved for the program's use ; includes all memory where this code and data reside. A filename buffer is ; used to store the names of files obtained from the current directory because ; after the EXEC function is used DOS somehow looses some of the information it ; needs for the performance of the Continue File Search function. ;*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* ;------------------------------------------------------------------------------- ; We use this routine to check for the presence of a space, tab or the beginning ; of the command line in order to determine the location of the start of a wild ; card specification. ;------------------------------------------------------------------------------- space_tab_left proc near ; return with Z flag set if di points to cmp bptr [di],' ' ; a space je stl_z cmp bptr [di],9 ; a tab je stl_z cmp di,of cmd_line ; or the start of the command line je stl_z or al,al ; reset Z flag stl_z: ret space_tab_left endp ;------------------------------------------------------------------------------- ; Checks for invalid filename characters following a wild card character to ; signal the end of the wild card spec. Thus the space character--although it ; is not included in my PC DOS 3.20 manual as an invalid character (oversight?) ; --is included among them. Also the period, even though it is an invalid ; filename character is not included among those checked since it is valid as a ; character in a wild card specification (same with * and ?). ;------------------------------------------------------------------------------- check_invalid proc near ; return with Z flag set if di points to mov ah,[di] ; an invalid filename character push ax ; save wild card test character cmp ah,' ' ; space or less than? jbe ci_z ; yes, return with zero flag set mov si,of inv_chars ; point to set of invalid characters cld ; (for maintenance and documentation) get_inv: lodsb ; get one of these or al,al ; end of invalid character set? jz ci_nz ; yes, return with zero flag reset cmp ah,al ; an invalid character je ci_z ; yes, return with zero flag set jmp short get_inv ; test another ci_z: pop ax ; restore wild card test character xor ah,ah ; set zero flag ret ; return (zero flag is set) ci_nz: pop ax ; restore wild card test character or al,al ; reset zero flag ret inv_chars db '"/\[]:|< >+=;,',0 ; invalid filename characters check_invalid endp ;------------------------------------------------------------------------------- ; This routine will find the wild card specification in the copy of the command ; line (cmd_line), execute the DOS find first function, place the filename ; obtained from this function into the command line copy (cmd_line), copy this ; command into the command line that will be passed to EXEC, and then return. ; The location of the wild card spec in cmd_line is referred to by the term ; "blank", since this is a "fill in the blank" operation. ;------------------------------------------------------------------------------- find_first proc near ; find first file of wild card spec mov al,rt ; search the end of command line first mov di,81h ; start at first character mov cx,127 ; maximum is fewer, but this will do cld ; (for maintenance and documentation) repne scasb ; find return character sub di,81h ; compute number of characters to search mov copy_size,di ; store here for later use mov al,'*' ; first test for presence of an asterisk search_wild: mov cx,copy_size ; install number of characters to search mov di,of cmd_line+1; command line passed by DOS (copy) cld ; (for maintenance and documentation) repne scasb ; do search jcxz not_this_wild ; this wild card not found push di ; save position of char after wild card dec di ; move to wild card back_one: dec di ; test character left call space_tab_left ; check for space, tab or beginning jnz back_one ; go back a character and look again inc di ; point to first character in blank mov left_blank,di ; store position as start of blank pop di ; points to character after wild card dec di ; undone by next instruction over_one: inc di ; test one character right call check_invalid ; check if an invalid filename character jnz over_one ; go forward a character and look again dec di ; point to last character in blank mov right_blank,di ; store position as end of blank mov si,left_blank ; address blank for copy mov cx,di ; construct size of blank in cx inc cx sub cx,si mov di,of wild_spec ; copy blank (wild spec) here cld ; (for maintenance and documentation) rep movsb ; do the copy to work space mov bptr [di],0 ; make it an ASCIIZ string mov dx,of wild_spec ; address with ds:dx for find first mov cx,file_attr ; find files with these attributes mov ah,4eh ; DOS find first function int 21h or ax,ax ; return code nonzero? jnz none_found ; yes, no files were found, return xor ax,ax ; return code is zero none_found: ret not_this_wild: cmp al,'?' ; did we search for a "?" yet? je no_wild ; yes, no other wild mov al,'?' ; no, so search for it too jmp short search_wild no_wild: mov ax,255 ; return 255 if no wild card found ret find_first endp cspc_str db 'COMSPEC=' ; COMSPEC string to find in environment cspc_size equ $-cspc_str ; size of "COMSPEC=" string notice db rt,lf,'WILD v1.0 Public Domain 1988 by Charles Lazo ' db 'III, CIS userid 72210,17',rt,lf notice_size equ $-notice bad_DOS db rt,lf,'WILD: Requires DOS version 2 or above.',rt,lf,0 mem_need db rt,lf,'WILD: Not enough memory.',rt,lf,0 no_comspec db rt,lf,"WILD: Can't find COMSPEC in environment." db rt,lf,0 none_wild db rt,lf,'WILD: No wild card characters were found.' db rt,lf,0 no_file db rt,lf,'WILD: No files were found.',rt,lf,0 ;------------------------------------------------------------------------------- ; Execution is transferred here when an error has occured. The code that has ; transferred control here will place in dx the offset of the error message that ; will be sent to standard error. This error message must be terminated by a ; null. The program then exits with error level set to 1. ;------------------------------------------------------------------------------- error_exit: mov ax,cs ; assure ds and es at cs mov ds,ax mov es,ax mov di,dx ; find the null terminating error string xor al,al ; search for null cld ; (for maintenance and documentation) mov cx,0ffffh ; largest possible repne scasb ; find the null mov cx,di ; compute number of characters to send sub cx,dx ; in cx dec cx mov bx,2 ; send them to standard error mov ah,40h ; with DOS function 40h int 21h mov ax,4c01h ; exit with error code 1 int 21h ;------------------------------------------------------------------------------- ; Execution comes here when the program begins. First the DOS version is ; checked to be sure it is 2 or greater, then all memory is released except that ; which is needed to continue operation after the filename buffer begins to fill ; with filenames from the current directory. (All code and data is retained, ; but that which lies beyond the label buffer: is overwritten by filenames as ; the filename buffer begins to fill. If more memory is needed, then it is ; allocated by the set_di routine.) The size of the environment is determined ; so that it can be used as a limit to the number of bytes to be searched for ; the two environment variables WILD and COMSPEC. Next the string "WILD=" is ; searched for in the environment and if found, then the two data variables, ; switches and file_attr (defined at the top of this file), are initialized ; based upon the settings in this string. Finally, the string "COMSPEC=" is ; searched for in the environment and if not found, the program sends a message ; to the screen and terminates with the error level set to 1. If COMSPEC is ; found its segment and offset are stored in the variable cspc_addr to be used ; later to find the program (usually COMMAND.COM) that shall be used as a shell ; to run the command given by the user. ;------------------------------------------------------------------------------- start: mov dx,of bad_DOS ; prepare wrong version message mov ah,30h ; get DOS version number int 21h cmp al,2 ; DOS ver 2 or greater? jae DOS_ok ; yes, good DOS version jmp short error_exit; else send error and exit DOS_ok: mov dx,of notice ; show notice information mov cx,notice_size ; length of notice message mov bx,2 ; send notice message to standard error mov ah,40h ; with DOS function 40h int 21h mov bx,of last ; assure all code retained mov ax,of buffer ; assure at least 256 bytes for buffer add ax,256 cmp bx,ax ; use the larger of these two jae bx_good ; bx larger is good enough mov bx,ax ; make bx good enough bx_good: add bx,0fh ; round up to next paragraph shr bx,1 ; calculate paragraphs shr bx,1 shr bx,1 shr bx,1 mov memory_used,bx ; save here for later use mov ah,4ah ; DOS modify block to reserve bx int 21h ; paragraphs for code and buffer mov dx,memory_used ; get number requested cmp bx,dx ; is number available same as requested? mov dx,of mem_need ; address memory needed error jz modify_ok ; okay, on modify memory block jmp error_exit ; error, not able to modify block modify_ok: mov sp,of our_stack ; move stack to memory owned by us mov si,80h ; offset of command line given us by DOS mov di,of cmd_line ; place to copy command line (it is cld ; overwritten by DOS find file calls) mov cx,128 ; copy 128 bytes (DOS legal limit) rep movsb mov ax,env_seg ; get segment of environment mov params,ax ; and place it in parameter table mov params+4,cs ; segment of command line mov params+8,cs ; segment of first FCB mov params+12,cs ; segment of second FCB jmp find_env_size ; determine size of environment ;------------------------------------------------------------------------------- ; This one searches the environment for the string pointed to by es:di. The ; number of characters in the string is provided in dx, bx has the number of ; bytes to be searched and ds:si points to the starting point of the search. ; If the string is found, then the carry flag is reset to indicate success and ; the offset of the string into the segment of the environment is returned in ; si. If the search fails, then the carry flag is set prior to return. ;------------------------------------------------------------------------------- search_str proc near ; search environment for string at di mov cx,bx ; set number of bytes to search next_byte: push cx ; save number of bytes to search push si ; save start positions push di mov cx,dx ; number of characters in string at di cld ; (for maintenance and documentation) repe cmpsb ; compare the two strings jcxz str_found ; found string at di in the environment pop di ; get 'em back pop si inc si ; bump pointer pop cx ; get count loop next_byte stc ; set carry; string at di not found ret str_found: pop di ; remove stacked registers pop si pop cx clc ; clear carry; string at di found ret search_str endp ;------------------------------------------------------------------------------- ; Here we search for the meaningful values that may be contained in the WILD ; environment variable. These values are QUERY, NOEXT, H, S, and D (capital- ; ization is not significant). The file WILD.DOC gives a description of the ; meaning of each. First the whole string is capitalized and then a search is ; made for QUERY and for NOEXT. The first and/or second bit of the byte ; switches is set depending upon the success of these searches. Then H(idden), ; S(ystem) and D(irectory) values are searched and if found, then corresponding ; bits are set in the file_attr variable. Also data for this and related code ; is defined at the end of this routine. ;------------------------------------------------------------------------------- wild_settings proc near ; set switches variable by WILD= string mov cs:ws_start,si ; save offset of WILD variable setting xor bx,bx ; count here the number of characters cld ; (for documentation and maintenance) ws_next: lodsb or al,al ; is it the null at end of ASCIIZ? jz ws_search ; yes, capitalization is done inc bx ; count it cmp al,'a' ; is it below an 'a'? jb ws_next ; yes, continue cmp al,'z' ; is it above a 'z'? ja ws_next ; yes, continue and bptr [si-1],0dfh; capitalize it jmp short ws_next ; continue ws_search: mov si,cs:ws_start ; get start of WILD variables mov di,of query ; search for QUERY mov dx,query_size ; size of query string call search_str ; do the search jc do_noext ; QUERY not found; look for NOEXT or cs:switches,que ; set bit 0 to indicate QUERY found do_noext: mov si,cs:ws_start ; get start of WILD variables mov di,of noext ; search for NOEXT mov dx,noext_size ; size of query string call search_str ; do the search jc do_hidden ; no NOEXT; look for hidden switch or cs:switches,noe ; set bit 1 to indicate NOEXT found do_hidden: mov si,cs:ws_start ; get start of WILD variables mov di,of hidden ; search for hidden string mov dx,hidden_size ; size of hidden string call search_str ; do the search jc do_system ; no hidden; look for system switch or cs:file_attr,hid; set bit 1 in file attribute do_system: mov si,cs:ws_start ; get start of WILD variables mov di,of system ; search for system string mov dx,system_size ; size of system string call search_str ; do the search jc do_direct ; no system; look for direct switch or cs:file_attr,sys; set bit 2 in file attribute do_direct: mov si,cs:ws_start ; get start of WILD variables mov di,of direct ; search for direct string mov dx,direct_size ; size of direct string call search_str ; do the search jc ws_done ; no direct; all done or cs:file_attr,dir; set bit 4 in file attribute ws_done: ret ws_start dw ? ; pointer to start of WILD env variables query db 'QUERY' ; string to find in WILD env variable query_size equ $-query noext db 'NOEXT' ; another string to find noext_size equ $-noext hidden db 'H' ; find this, then include hidden files hidden_size equ $-hidden system db 'S' ; find this, then include system files system_size equ $-system direct db 'D' ; find this, then directory files direct_size equ $-direct que equ 1 ; set into switches if QUERY present noe equ 2 ; set into switches if NOEXT present hid equ 2 ; set into file_attr if hidden string sys equ 4 ; set into file_attr if system string dir equ 16 ; set into file_attr if direct string wild_settings endp ;------------------------------------------------------------------------------- ; Find the size of the environment so only this number of bytes will be searched ; for environment strings. ;------------------------------------------------------------------------------- find_env_size: mov ax,env_seg ; segment of environment --> es mov es,ax xor di,di ; search begins at start of environment xor al,al ; search for nulls in environment mov cx,8000h ; environment is no larger than 32k next_word: repne scasb ; find a null scasb ; a double null here? jz found_env_end ; yes, signals end of environment block jmp short next_word ; else continue searching found_env_end: mov ax,8000h ; number of bytes in environment --> cx xchg ax,cx sub cx,ax mov env_size,cx ; store size of our environment ;------------------------------------------------------------------------------- ; Setup segment registers for environment searches. ;------------------------------------------------------------------------------- mov ax,env_seg ; segment of environment --> ds mov ds,ax push cs ; cs --> es pop es jmp short wild_env ; handle wild environment variables ;------------------------------------------------------------------------------- ; First search for the string "WILD=" in the environment and if it is found, ; then set program switches depending upon what the WILD environment variable ; is set to. ;------------------------------------------------------------------------------- wild_str db 'WILD=' ; WILD's environment variable string wild_size equ $-wild_str ; size of "WILD=" string wild_env: xor si,si ; point to start of environment mov dx,wild_size ; characters in string "WILD=" --> dx mov di,of wild_str ; address WILD environment string mov bx,cs:env_size ; number of bytes to search for string call search_str ; find WILD string (if present) jc do_cspc ; WILD string not found; do COMSPEC add si,wild_size ; point si to value of WILD variable call wild_settings ; record switch settings in environment ;------------------------------------------------------------------------------- ; Now, search for "COMSPEC=" in the environment. If it is found, then it will ; be used to provide the copy of COMMAND.COM to be used for the EXEC call(s). ; If it is not found, then we exit with an error message. ;------------------------------------------------------------------------------- do_cspc: mov bx,cs:env_size ; number of bytes to search for COMSPEC xor si,si ; point to start of environment mov dx,cspc_size ; characters in string "COMSPEC=" --> dx mov di,of cspc_str ; address COMSPEC string call search_str ; find COMSPEC string (if present) jnc comspec_found ; no carry, COMSPEC string was found mov dx,of no_comspec; tell can't find COMSPEC, then exit jmp error_exit comspec_found: add si,cspc_size ; make si point to COMSPEC value mov wp cs:cspc_addr,si ; store comspec offset mov wp cs:cspc_addr+2,ds ; store comspec segment push cs ; cs --> ds pop ds ; (now cs, ds, and es are all same) call find_first ; find the first file in the directory cmp ax,255 ; special return for no wild card found? jne wild_found ; no, check if a file was found mov dx,of none_wild ; send this message and end jmp error_exit wild_found: or ax,ax ; a file found? jnz none_here ; no, say so and end jmp find_rest ; yes, find the remainder of files none_here: mov dx,of no_file ; address no file message jmp error_exit last: ; offset of end of program. Used to assure that all code is ; retained with memory modify operation at the start of code. code ends end begin