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Assembly Source File | 1991-11-04 | 22.6 KB | 665 lines

;WATCH.ASM ;resident routine watches programs going resident ;and keeps a list of interrupt vector changes in an internal data structure ;============================================================================== ; to be assembled by TASM ; Copyright (c) 1986,1991 Kim Kokkonen, TurboPower Software. ; May be freely distributed but not sold except by permission. ; telephone: 719-260-6641, Compuserve 76004,2611 ;============================================================================== ; version 2.2 3/4/87 ; First release, version to be consistent with MAPMEM.PAS ; : ; long intervening history ; : ; version 3.0 9/24/91 ; add tracking for TSRs that unload themselves ; add support for TSRs loaded high ; WATCH may be loaded high ; version 3.1 11/4/91 ; rewrite again to solve problems with SWAPMM, FSP, DATAPATH, DATAMON ;============================================================================== ; ;uncomment following line to generate more publics in MAP file ;define debug cseg segment public para assume cs:cseg, ds:nothing, es:nothing, ss:nothing locals @@ org 080H cmdline label byte ;pointer to command line org 100H pentry: jmp init ;always put the following in WATCH.MAP to update MEMU.PAS public nextchange,emesg,changevectors,origvectors ;*********************************************************************** ;data structures part of COM file even nextchange dw 0 ;next position to write in changes area dosver dw ? ;DOS version number umbstat dw ? ;UMB link status firstmcb dw ? ;first MCB segment ;temporary stack used by interrupt handler newsp dw ? ;initial stack pointer newss dw ? ;segment of our temporary stack (=cseg) tmpret dw ? ;used while switching stacks ;information saved about the calling program oldsp dw ? ;stack pointer oldss dw ? ;stack segment ;for saving last 16 bytes, wiped out when opening high memory topseg dw ? ;segment at top of memory to save mcbbuf dw 8 dup (?) ;buffer to save it in ;previous interrupt handlers dos_int label dword old21 dw 2 dup (?) ;old int21 vector tsr_int label dword old27 dw 2 dup (?) ;old int27 vector ;id code for a PSP data block pspid equ 0FFFFH ;id used to indicate a PSP block ;structure of a changevectors data block pspblock struc id dw ? ;id word, always pspid psp dw ? ;psp segment len dw ? ;length of psp unu1 dw ? ;unused pspblock ends vecblock struc vec dw ? ;vector number 0..255 veco dw ? ;vector offset vecs dw ? ;vector segment unu2 dw ? ;unused vecblock ends ;*********************************************************************** ;resident data structures not part of COM file changevectors = offset emesg ;data area overwrites emesg & beyond vrecsize = 8 ;number of bytes per vector change record maxchanges = 128 ;maximum number of vector changes vsize = maxchanges*vrecsize ;size of vector change area in bytes ;vector table buffers origvectors = offset changevectors+vsize ;location of original vector table veclen = 1024 ;size of vector table in bytes newstackpos = origvectors+veclen ;location of newstack ssize = 128 ;number of bytes in temporary stack newloc = newstackpos+ssize ;location for relocated installation code ;*********************************************************************** ;int21 handler ; traps functions 31, 49, 4C, and 7761 int21h proc far ifdef debug public int21h endif assume ds:nothing pushf ;save flags sti ;allow interrupts cmp ah,31H ;terminate and stay resident call? jne @@1 call addcurrpsp ;dx = paras to keep jmp short @@4 @@1: cmp ah,49H ;deallocate block call? jne @@2 call remblock ;remove specified block if a psp jmp short @@4 @@2: cmp ah,4CH ;normal program halt? jne @@3 call checkblocks jmp short @@4 @@3: cmp ax,7761H ;"wa"tch ID call? jne @@4 call checkblocks ;assure change list up to date push bp mov bp,sp ;set up stack frame and word ptr [bp+8],0FFFEH ;clear carry flag pop bp xchg ah,al ;flip ah and al as a signature mov bx,cs ;return WATCH psp in bx popf iret ;return to caller @@4: popf jmp dos_int ;let DOS take over int21h endp ;*********************************************************************** ;int27 handler ; watches for programs going resident int27h proc far ifdef debug public int27h endif assume ds:nothing pushf sti push dx add dx,15 ;pass size of block in paras to addcurrpsp shr dx,1 shr dx,1 shr dx,1 shr dx,1 call addcurrpsp ;get current psp and add block to list pop dx popf jmp tsr_int int27h endp ;*********************************************************************** ;get current PSP in bx and add new block ;entry: dx = paragraphs to keep addcurrpsp proc near ifdef debug public addcurrpsp endif assume ds:nothing call setup ;switch stacks and save registers assume ds:cseg mov ah,51H ;get current PSP in bx pushf call dos_int call addblock ;add block at bx, length dx to changes call shutdown ;restore registers and switch stacks assume ds:nothing ret addcurrpsp endp ;*********************************************************************** ;remove PSP block, if any, specified by es remblock proc near ifdef debug public remblock endif assume ds:nothing call setup ;switch stacks and save registers assume ds:cseg mov bx,es ;save segment being deallocated in bx call matchpsp ;return offset in changevectors of segment or si,si ;any matching block? jz @@1 call rempsp ;remove psp @@1: call shutdown ;restore registers and switch stacks assume ds:nothing ret remblock endp ;*********************************************************************** ;check for new memory blocks and add if needed ;remove halting psp from change list if needed checkblocks proc near ifdef debug public checkblocks endif assume ds:nothing call setup ;switch stacks and save registers assume ds:cseg mov ah,51H ;get current psp in bx pushf call dos_int call matchpsp ;is current program in change list? or si,si jz @@0 ;jump if not call rempsp ;remove it if not @@0: mov cx,bx ;cx = psp of halting program call openhigh ;open high memory if available mov ax,firstmcb ;start with first mcb @@1: mov es,ax mov bx,es:[0001h] ;bx = psp of block mov dx,es:[0003h] ;dx = len of block inc ax cmp ax,bx ;does psp = mcb+1? jne @@2 ;jump if not cmp ax,cx ;does psp = current program? je @@2 ;jump if so push dx call matchpsp ;find matching psp in changevectors pop dx or si,si ;is there a matching psp? jnz @@2 ;jump if so push ax push cx push dx call addblock ;add this psp pop dx pop cx pop ax @@2: cmp byte ptr es:[0000h],'Z' ;end of chain je @@3 add ax,dx jmp @@1 @@3: call resthigh ;restore high memory call shutdown ;restore registers and switch stacks assume ds:nothing ret checkblocks endp ;*********************************************************************** ;setup routine for interrupt hook routines ; switches stacks, saves registers, sets ds=cs setup proc near ifdef debug public setup endif assume ds:nothing pop cs:tmpret ;save return address as we switch stacks mov oldss,ss ;save current stack mov oldsp,sp cli ;switch to our stack mov ss,newss mov sp,newsp sti push ax ;store registers push bx push cx push dx push si push di push bp push ds push es push cs ;set ds=cs pop ds assume ds:cseg push cs:tmpret ;return ret setup endp ;*********************************************************************** ;shutdown routine for interrupt hook routines ; restores registers, switches stacks shutdown proc near ifdef debug public shutdown endif pop cs:tmpret pop es ;restore registers pop ds assume ds:nothing pop bp pop di pop si pop dx pop cx pop bx pop ax cli ;restore stack mov ss,cs:oldss mov sp,cs:oldsp sti push cs:tmpret ;return ret shutdown endp ;*********************************************************************** ;add specified block to changes ; entry: bx = psp of block, dx = length of block in paras addblock proc near ifdef debug public addblock endif assume ds:cseg call addhdr ;add a psp header block call addvecs ;add blocks for each hooked vector ret addblock endp ;*********************************************************************** ;add header for a psp block ; entry: bx = psp of block, dx = length of block in paras ; exit: alters di addhdr proc near ifdef debug public addhdr endif assume ds:nothing mov di,nextchange cmp di,vsize-vrecsize ;assure room for next record ja @@1 mov word ptr cs:changevectors[di].id,pspid mov cs:changevectors[di].psp,bx mov cs:changevectors[di].len,dx add di,vrecsize mov nextchange,di @@1: ret addhdr endp ;*********************************************************************** ;add vector blocks for each hooked vector ; entry: bx = psp of block, dx = length of block in paras ; exit: alters ax,cx,dx,si,di,bp addvecs proc near ifdef debug public addvecs endif assume ds:cseg push ds add dx,bx ;now dx points to end of block mov di,nextchange ;cs:changevectors[di] -> output area xor si,si mov ds,si ;ds:si -> vectors assume ds:nothing xor cx,cx ;cx = vector counter cld ;forward @@1: lodsw ;ax = vector offset mov bp,ax ;save vector offset lodsw ;ax = vector segment cmp ax,bx ;is vector above low limit? jb @@2 cmp ax,dx ;is vector below high limit? jae @@2 cmp di,vsize-vrecsize ;room for another entry? ja @@2 mov cs:changevectors[di].vec,cx ;save entry for this vector mov cs:changevectors[di].veco,bp mov cs:changevectors[di].vecs,ax add di,vrecsize @@2: inc cx ;next vector cmp cx,0FFh jbe @@1 mov nextchange,di pop ds assume ds:cseg ret addvecs endp ;*********************************************************************** ;find changeblock matching psp ; entry: bx = psp to match ; exit: si = matching block, or 0 if none ; destroys dx matchpsp proc near ifdef debug public matchpsp endif assume ds:cseg mov si,offset changevectors mov dx,si add dx,nextchange ;dx = next unused spot in changevectors @@1: cmp si,dx ;end of table jae @@3 cmp word ptr [si].id,pspid ;psp indicator? jnz @@2 ;jump if not cmp [si].psp,bx ;matching psp? jnz @@2 ;jump if not ret ;else return with match @@2: add si,vrecsize jmp @@1 @@3: xor si,si ;no match if here ret matchpsp endp ;*********************************************************************** ;remove all blocks associated with psp at offset si ; exit: alters cx,dx,si,di,es rempsp proc near ifdef debug public rempsp endif assume ds:cseg mov di,si ;save destination add si,vrecsize ;move to next record mov dx,offset changevectors add dx,nextchange ;dx = address of next unused @@1: cmp si,dx ;end of table? jae @@2 ;jump if so cmp word ptr [si].id,pspid ;next psp indicator? je @@2 ;jump if so add si,vrecsize ;next block jmp @@1 ;and loop @@2: mov cx,dx sub cx,si shr cx,1 ;cx = words to move push cs pop es ;es = ds = cs cld rep movsw ;copy down remaining blocks sub si,di sub nextchange,si ;update nextchange ret rempsp endp ;*********************************************************************** ;open high memory for DOS 5 ;exit: changes ax,bx openhigh proc near ifdef debug public openhigh endif assume ds:cseg cmp byte ptr dosver,5 ;DOS 5? jne @@2 mov ax,5802H ;get UMB link status int 21H jnc @@1 xor al,al @@1: xor ah,ah mov umbstat,ax ;save status ;save last segment in low memory, which DOS will overwrite push cx push si push di push ds push es xor si,si mov ds,topseg ;ds:si -> region to buffer push cs pop es ;es = cs mov di,offset mcbbuf ;es:di -> our buffer mov cx,8 ;buffer 8 words cld rep movsw pop es pop ds pop di pop si pop cx mov ax,5803H mov bx,1 int 21H ;open high memory if possible @@2: ret openhigh endp ;*********************************************************************** ;restore high memory link for DOS 5 resthigh proc near ifdef debug public resthigh endif assume ds:cseg cmp byte ptr dosver,5 ;DOS 5? jne @@1 mov ax,5803H mov bx,umbstat int 21H ;restore last segment in low memory, which DOS overwrote push cx push si push di push es mov si,offset mcbbuf mov es,topseg xor di,di mov cx,8 ;buffer 8 words cld rep movsw pop es pop di pop si pop cx @@1: ret resthigh endp ;*********************************************************************** ;resident portion above, temporary portion below ;*********************************************************************** align 16 emesg db 'Cannot install WATCH more than once....',13,10,36 mesg db 'WATCH 3.1, Copyright 1991 TurboPower Software',13,10 db 'Installed successfully',13,10,36 pname db 'TSR WATCHER' plen equ $-pname ;length of string ;*********************************************************************** ;add dummy changeblocks for all psps already resident adddummypsp proc near ifdef debug public adddummypsp endif assume ds:cseg call openhigh ;open high memory if available mov ah,52H int 21H ;get DOS list of lists mov ax,es:[bx-2] ;get first MCB segment mov firstmcb,ax ;save it for use later too push ds assume ds:nothing @@1: mov ds,ax mov bx,ds:[0001h] ;bx = psp of block mov dx,ds:[0003h] ;dx = len of block inc ax cmp ax,bx ;does psp = mcb+1? jne @@2 ;jump if not cmp ax,newss ;does psp = WATCH itself? je @@2 ;jump if so call addhdr ;add a header for this block @@2: cmp byte ptr ds:[0000h],'Z' ;end of chain je @@3 add ax,dx jmp @@1 @@3: pop ds assume ds:cseg call resthigh ;restore high memory ret adddummypsp endp ;*********************************************************************** init proc near ifdef debug public init endif assume ds:cseg ;use int 21h test to check for previous installation mov ax,7761H ;special id function int 21H jc @@1 ;not installed if function fails cmp ax,6177H jnz @@1 ;not installed if id code not returned ;error exit mov dx,offset emesg ;error message mov ah,09H int 21H ;DOS print string mov ax,4C01H ;exit with error int 21H ;not already installed @@1: mov dx,offset mesg ;success message mov ah,09H int 21H ;DOS print string ;initialize location of WATCH stack mov newsp,newstackpos+ssize mov newss,cs ;stack seg is code seg ;put an id label at offset 80H to allow other programs to recognize WATCH mov cx,plen ;length of name string mov si,offset pname ;offset of name string mov di,offset cmdline ;offset of DOS command line cld ;transfer in forward direction mov al,cl stosb ;store length byte first rep movsb ;transfer characters ;get DOS version mov ax,3000h int 21H mov dosver,ax ;get top of memory segment int 12H mov cl,6 shl ax,cl dec ax mov topseg,ax ;add psp records for all blocks already resident call adddummypsp ;relocate ourselves out of the way of the resident tables push cs pop es mov di,newloc+10H push di ;will act as a return address mov si,offset @@2 mov cx,@@3-@@2 rep movsb ;move code ret ;"return" to the relocated code ;store image of original vector table (overwrites messages and non-res code) @@2: mov di,origvectors push ds xor si,si ;offset 0 mov ds,si ;source address segment 0 mov cx,200H ;512 words to store rep movsw ;copy vectors to our table pop ds ;store current int 21 and 27 vectors mov ax,3527H int 21H mov old27,bx mov old27[2],es mov ax,3521H int 21H mov old21,bx mov old21[2],es ;install new vectors mov ax,2527H mov dx,offset int27h int 21H mov ax,2521H mov dx,offset int21h int 21H ;terminate and stay resident mov dx,newloc add dx,15 mov cl,4 shr dx,cl mov ax,3100H ;return success code int 21H ;note WATCH will track itself @@3: init endp cseg ends end pentry