Leaked source code of windows server 2003
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;**************************************************************************
;* HELPER.ASM
;*
;* Assembly routines used by more than one module
;*
;**************************************************************************
INCLUDE TOOLPRIV.INC
INCLUDE WINDOWS.INC
PMODE32 = 0
PMODE = 1
SWAPPRO = 0
INCLUDE WINKERN.INC
INCLUDE NEWEXE.INC
INCLUDE TDB.INC
;** External functions
externNP Walk386VerifyLocHeap
externNP Walk286VerifyLocHeap
externFP GetCurrentTask
externFP InterruptUnRegister
externFP NotifyUnRegister
externNP SignalUnRegister
externFP TaskFirst
externFP TaskNext
;** Functions
sBegin CODE
assumes CS,CODE
.286p
; HelperVerifySeg
;
; Verifies that a selector is valid and that the segment it points
; to is safe for reading out to wcb bytes offset
; Returns 0 if too short or the length of the segment.
; Preserves all used registers except the return value, AX
cProc HelperVerifySeg, <PUBLIC,NEAR>, <dx>
parmW wSeg
parmW wcb
cBegin
;** Verify that this is a valid selector and that it is long enough
cCall HelperSegLen, <wSeg> ;Check the segment
or dx,dx ;>64K? If so, always return OK
jnz HVS_End
cmp ax,wcb ;Long enough?
ja HVS_End ;Yes, return the length
HVS_Bad:
xor ax,ax ;No. Return FALSE
HVS_End:
cEnd
; HelperHandleToSel
; Converts a handle to a selector. This routine knows how to
; handle 3.0 and 3.1 differences as well as 286 & 386 differences.
cProc HelperHandleToSel, <NEAR,PUBLIC>, <ds>
parmW h ;Handle
cBegin
mov ax,_DATA ;Get the data segment
mov ds,ax ;Point with DS
mov ax,h ;Get the handle
test wTHFlags,TH_WIN30 ;Win3.0?
jz HTS_Win31 ;No
test ax,1 ;Check the low bit
jnz HTS_End ;It's already a selector
dec ax ;Decrement for proper selector
jmp SHORT HTS_End ;Out of here
HTS_Win31:
or ax,1 ;Set the bit
HTS_End:
cEnd
; HelperVerifyLocHeap
;
; Uses the processor-specific local heap verify routine to check the
; validity of a local heap.
;
; Call:
; AX = Block handle or selector
; DS must point to TOOLHELP's DGROUP
; Return:
; Carry flag set iff NOT a local heap segment
;
; Destroys all registers except AX, ESI, EDI, DS, and ES
HelperVerifyLocHeap PROC Near
PUBLIC HelperVerifyLocHeap
test wTHFlags,TH_KERNEL_386 ;Are we using KRNL386?
jz HVL_286 ;No
jmp Walk386VerifyLocHeap ;Jump to the 386 routine
HVL_286:
jmp Walk286VerifyLocHeap ;Jump to the 286 routine
HVL_End:
ret
HelperVerifyLocHeap ENDP
; HelperGlobalType
;
; Given data about a block, gropes around trying to decipher the
; block type. Parameters are passed and returned in the GLOBALENTRY
; structure.
cProc HelperGlobalType, <PUBLIC,NEAR>, <si,di,ds>
parmD lpGlobal
localV Task,<SIZE TASKENTRY>
cBegin
lds si,lpGlobal ;Get the pointer
mov [si].ge_wData,0 ;Clear the wData field
; Zero's not a valid seg # or type #
;** Check for internal block types
mov bx,[si].ge_hOwner ;Get the owner handle
mov ax,GT_SENTINEL ;Just in case...
cmp bx,GA_SENTINAL ;Is this a sentinel?
jz HGT_JmpEnd ;Yes, get out
mov ax,GT_BURGERMASTER ;Just in case...
cmp bx,GT_BURGERMASTER ;Burgermaster?
jz HGT_JmpEnd ;Yes, get out
cmp bx,-7 ;Lowest number reserved
jb HGT_0 ;Not an internal block
mov ax,GT_INTERNAL ;Internal KERNEL block type
HGT_JmpEnd:
jmp HGT_End ;Get out
HGT_0:
;** Check for a free block
or bx,bx ;Check for 0: Free block
jnz HGT_2 ;Not zero
mov ax,GT_FREE ;Free blocks have zero owner
jmp HGT_End ;Unknown type
HGT_2:
;** Check for DGROUP and other data segments
mov ax,[si].ge_wFlags ;Get the block flags
test ax,GAH_DGROUP ;Is this a DGROUP segment
jnz @F
jmp HGT_10 ;Didn't find it so continue
@@:
;** Save the segment number of the segment
mov ax,[si].ge_hOwner ;Get the module database
push ax ;Save for later
mov bx,[si].ge_hBlock ;Get the handle
cCall HelperGetSegNumber ;Get the segment number
mov [si].ge_wData,ax ;Save the segment number
pop bx ;Get hExe back in BX
;** Try two methods: First, see if it is the hInst of the FIRST
;** instance of its module
lsl cx, bx ;Is this segment OK?
jnz HGT_5 ;No, punt and call it unknown data
cmp cx, ne_pautodata ;Long enough?
jbe HGT_5 ;No, get out
mov es,bx ;Point with ES
cmp es:[ne_magic],NEMAGIC ;Make sure we have a module database
jnz HGT_5 ;It isn't so get out
mov bx,es:[ne_pautodata] ;Point to the segment table entry
or bx,bx ;Is there a DGROUP segment?
jz HGT_5 ;No, flag as unknown data
mov ax,es:[bx].ns_handle ;Get the handle from the table
cmp ax,[si].ge_hBlock ;Does the DGROUP handle point here?
jnz HGT_3 ;No, might be multiple instance
mov ax,GT_DGROUP ;Matches, must be DGROUP
jmp HGT_End ;Get out
HGT_3:
;** It's not the first instance of this module.
;** All multiple instance things will be on the task list
;** so try to find it there.
mov bx,[si].ge_hBlock ;Get the handle
cCall HelperHandleToSel,<bx> ;Get the selector for this
mov di,ax ;Save in DI
mov ax,SIZE TASKENTRY ;Get the struct size
mov WORD PTR Task.te_dwSize[0],ax ;Put in struct
mov WORD PTR Task.te_dwSize[2],0 ;Clear high word
lea ax,Task ;Get the structure
cCall TaskFirst, <ss,ax> ;Get the first task's info
or ax,ax ;No tasks?
jz HGT_5 ;Just call it data (not DGROUP)
HGT_TaskLoop:
mov ax,Task.te_hInst ;Get this task's hInst
cCall HelperHandleToSel, <ax> ;Convert to selector
cmp ax,di ;Is this a match?
je HGT_TaskFound ;Yes, do it
lea ax,Task ;Point to the struct
cCall TaskNext, <ss,ax> ;Get the next one
or ax,ax ;End of the line?
jnz HGT_TaskLoop ;Nope, do the next one
HGT_5: mov ax,GT_DATA ;Unknown data segment
jmp HGT_End ;Get out
HGT_TaskFound:
mov ax,GT_DGROUP ;Matches, must be DGROUP
jmp HGT_End ;Get out
HGT_10:
;** Check for a task database
mov ax,[si].ge_hBlock ;Get the segment
mov bx,TDBSize ;Get the limit to verify
push ax ;Save the segment
cCall HelperVerifySeg <ax,bx> ;Make sure we can check signature
pop bx ;Retrieve the segment value
or ax,ax ;Zero return means bad
jz HGT_20 ;Not a task database
mov es,bx ;Point to the segment
cmp es:[TDB_sig],TDB_SIGNATURE ;Is this really a TDB?
jnz HGT_20 ;Nope, go on
mov ax,GT_TASK ;Set the task flag
jmp HGT_End ;Get out
HGT_20:
;** Now check for Module database
mov ax,[si].ge_hOwner ;Get the owner handle
cCall HelperHandleToSel, <ax> ;Convert to selector for compare
mov cx,ax ;Save in CX
mov ax,[si].ge_hBlock ;Does this block own itself?
cCall HelperHandleToSel, <ax> ;Convert to selector for compare
cmp ax,cx ;Do the pointers match?
jnz HGT_24 ;No, so it's not a module database
mov ax,GT_MODULE ;Set type
jmp HGT_End ;Get out
HGT_24:
;** Check for a code segment. If found, return segment number
mov ax,[si].ge_hOwner ;Get the module database
push ax ;Save the selector
cCall HelperVerifySeg <ax,2> ;Make sure this is OK to put in ES
pop bx ;Retrieve in BX
or ax,ax ;Zero means bad
jnz @F
jmp SHORT HGT_Unknown
@@: mov es,bx ;Point with ES
xor dx,dx ;Use DX to count segments
cmp es:[ne_magic],NEMAGIC ;Make sure we have a module database
jz HGT_25 ;Looks good
jmp SHORT HGT_40 ;Not code or resource, try next
HGT_25: mov cx,es:[ne_cseg] ;Get max number of segments
jcxz HGT_30 ;No segments
mov di,es:[ne_segtab] ;Point to the segment table
mov bx,[si].ge_hBlock ;Get the block we're looking for
HGT_SegLoop:
inc dx ;Bump the segment number
cmp bx,es:[di].ns_handle ;Is this the correct segment entry?
jz HGT_27 ;Yes, get out
add di,SIZE new_seg1 ;Bump to next entry
loop HGT_SegLoop ;Loop back to check next entry
jmp SHORT HGT_30 ;Now check resources
HGT_27:
mov [si].ge_wData,dx ;Save the segment count
mov ax,GT_CODE ;Flag that it's a code segment
jmp SHORT HGT_End ;Get out
;** Check to see if it's a resource. If so, return resource type #
HGT_30: mov di,es:[ne_rsrctab] ;Point to the resource table
cmp di,es:[ne_restab] ;If both point to same place, no rsrc
jz HGT_40 ;No resource table -- unknown type
add di,2 ;Skip past alignment count
HGT_TypeLoop:
mov dx,es:[di].rt_id ;DX holds current type number
or dx,dx ;Zero type means end of res table
jz HGT_40 ;Not found so get out!
mov cx,es:[di].rt_nres ;Get the number of resources
add di,SIZE RSRC_TYPEINFO ;Bump past the structure
HGT_ResLoop:
cmp bx,es:[di].rn_handle ;Is it this resource?
jz HGT_FoundRes ;Yep. This is the one
add di,SIZE RSRC_NAMEINFO ;Bump past this structure
loop HGT_ResLoop ;Loop for next resource structure
jmp HGT_TypeLoop ;Try the next type
;** Found the resource, now compute the resource type
HGT_FoundRes:
test dx,RSORDID ;If this bit set, must be ordinal type
jnz HGT_32 ;Yep. Ordinal
mov dx,GD_USERDEFINED ;Named resources are all user-def
HGT_32: and dx,NOT RSORDID ;Clear the flag bit
cmp dx,GD_MAX_RESOURCE ;If the type is too big, it's user-def
jbe HGT_34 ;Standard type
mov dx,GD_USERDEFINED ;User-defined resource type
HGT_34: mov [si].ge_wData,dx ;Save the type
mov ax,GT_RESOURCE ;Return that it's a resource
jmp SHORT HGT_End ;Get out
HGT_40:
HGT_Unknown:
mov ax,GT_UNKNOWN ;Unknown type
HGT_End:
mov [si].ge_wType,ax ;Save the type and exit
cEnd
; HelperGrabSelector
;
; Allocates a selector from DPMI.
cProc HelperGrabSelector, <NEAR,PUBLIC>
cBegin
xor ax,ax ;DPMI Function 0, allocate LDT sels
mov cx,1 ;Just 1 sel
int 31h ;Call DPMI. Selector in AX
cEnd
; HelperReleaseSelector
;
; Frees a selector to DPMI
cProc HelperReleaseSelector, <NEAR,PUBLIC>
parmW wSelector
cBegin
mov ax,1 ;DPMI function 1, free LDT sels
mov bx,wSelector ;Get the sel
int 31h ;Free it
cEnd
; HelperSetSignalProc
; Puts a signal proc in a task's TDB so that it gets called in place
; of USER's proc. Returns the old USER proc.
cProc HelperSetSignalProc, <NEAR,PUBLIC>, <si,di>
parmW hTask,
parmD lpfn
cBegin
;** Point to the TDB
mov es,hTask ;Point with ES
;** Swap the new with the old and return the old one
mov ax,WORD PTR lpfn ;Get the new signal proc
xchg ax,WORD PTR es:[TDB_USignalProc] ;Switch with the old one
mov dx,WORD PTR lpfn + 2 ;Get HIWORD
xchg dx,WORD PTR es:[TDB_USignalProc + 2] ;Switch with old one
cEnd
; HelperSignalProc
; Cleans up when a TOOLHELP-using app is terminated. This proc
; MUST chain on to USER's signal proc. Note that action is only taken
; on the death signal (BX = 0666h)
cProc HelperSignalProc, <FAR,PUBLIC>
cBegin NOGEN
;** Save all registers
sub sp,4
push bp
mov bp,sp ;Make a stack frame
pusha
push ds
push es
;** Get a pointer to the correct SIGNAL structure
mov ax,_DATA ;Get the TOOLHELP.DLL DS
mov ds,ax ;Point with DS
cCall GetCurrentTask ;Get the current task in AX
mov di,ax ;Save task in DI
mov si,npSignalHead ;Get the first struct
HSP_SigLoop:
or si,si ;End of the list?
jz HSP_Return ;Yes -- This is bad!!
cmp di,[si].si_hTask ;Task match?
je HSP_FoundIt ;Yes
mov si,[si].si_pNext ;Get the next one
jmp HSP_SigLoop ;Loop around
;** Compute the fake return address (old signal proc)
HSP_FoundIt:
mov ax,WORD PTR [si].si_lpfnOld ;Get LOWORD of old proc
mov [bp + 2],ax ;Put on stack frame
mov dx,WORD PTR [si].si_lpfnOld + 2 ;Get HIWORD of old proc
mov [bp + 4],dx ;Put on stack frame
;** See if we have the death signal. If not, don't do anything
;** but just chain on. 20h is the signal for task exit
cmp bx, 20h ;Is this the death signal?
jne HSP_Done ;No. Don't cleanup
;** Since we have a death signal, use it to clean up everything
push ax ;Save the return address
push dx
cCall InterruptUnRegister, <di> ;Unregister any interrupt callbacks
cCall NotifyUnRegister, <di> ;Unregister any notification callbacks
cCall SignalUnRegister, <di> ;Unregister any signal callbacks
;** If we have fooled with the LRU lock (we only do this on 286
;** machines), we must force it unlocked.
cmp wLRUCount, 0 ;Is it set?
je HSP_NoLRUFoolingAround ;No, don't mess with this
mov es, hMaster ;Point to GlobalInfo struct
mov ax, es:[gi_lrulock] ;Get current lock count
sub ax, wLRUCount ;Get rid of the amount we messed it up
jns @F ;Result is OK--no underflow
xor ax, ax ;We don't like negative, so zero it
@@: mov es:[gi_lrulock], ax ;Save the result
mov wLRUCount, 0 ;No more LRU count
HSP_NoLRUFoolingAround:
pop dx
pop ax
;** Make sure we have a proc to chain to
HSP_Done:
or ax,dx ;NULL pointer?
jz HSP_Return ;Yes, don't chain to this one
HSP_ChainOn:
pop es
pop ds
popa
pop bp
retf ;Jump to next signal proc
HSP_Return:
pop es
pop ds
popa
pop bp
add sp,4 ;Clear fake return address
retf 10 ;Return to signal caller
cEnd NOGEN
; HelperSegLen
; Gets the length of a segment, regardless whether it is a 286 or
; 386 segment.
; Returns the DWORD length of the segment or zero on error.
; Doesn't trash registers except DX:AX
cProc HelperSegLen, <NEAR,PUBLIC>, <si,di,cx>
parmW wSeg
cBegin
;** Make sure the segment is present
mov cx,wSeg ;Get the selector
lar ax,cx ;Get the access rights
jnz HSL_Bad ;If LAR fails, this is bad
test ax,8000h ;Is this segment present?
jz HSL_Bad ;No, call it bad
;** Do different stuff on 286 and 386/486
mov ax,__WinFlags ;Get the flags
test ax,WF_CPU286 ;286?
jnz HSL_Do286 ;Yes, do 16 bit stuff
;** Get the 32 bit length
.386p
lsl eax,ecx ;Get the limit
jnz SHORT HSL_Bad ;We have an error
mov edx,eax ;Get HIWORD in DX
shr edx,16
jmp SHORT HSL_End ;Done
.286p
;** Get the 16 bit length
HSL_Do286:
xor dx,dx ;286 never has >64K segs
lsl ax,cx ;Get the limit
jnz HSL_Bad ;Bad if LSL fails
jmp SHORT HSL_End ;Done
HSL_Bad:
xor ax,ax ;Zero return value
xor dx,dx
HSL_End:
cEnd
; HelperGetSegNumber
;
; Returns the segment number corresponding to a selector given the
; hExe.
;
; Caller: AX=hExe, BX=Handle
; Exit: AX=Seg Number or 0
cProc HelperGetSegNumber, <NEAR,PUBLIC>, <di>
cBegin
lsl cx, ax ;Is the segment OK to load?
jnz HGSN_Error ;No, don't do it
cmp cx, ne_segtab ;Long enough?
jbe HGSN_Error ;No
mov es,ax ;Point with ES
xor dx,dx ;Use DX to count segments
cmp es:[ne_magic],NEMAGIC ;Make sure we have an hExe
jnz HGSN_Error ;Nope, get out
mov cx,es:[ne_cseg] ;Get max number of segments
jcxz HGSN_Error ;No segments
mov di,es:[ne_segtab] ;Point to the segment table
HGSN_SegLoop:
inc dx ;Bump the segment number
cmp bx,es:[di].ns_handle ;Is this the correct segment entry?
je HGSN_FoundIt ;Yes, get out
add di,SIZE new_seg1 ;Bump to next entry
loop HGSN_SegLoop ;Loop back to check next entry
jmp SHORT HGSN_Error ;Not found
HGSN_FoundIt:
mov ax,dx ;Get segment number
jmp SHORT HGSN_End
HGSN_Error:
xor ax,ax ;Error return
HGSN_End:
cEnd
;** Internal helper functions
; HelperPDBtoTDB
;
; Takes a PDB handle and finds the task handle associated with it.
; Caller: AX = PDB Handle
; Return: AX = TDB handle or zero if no TDB exists for it
cProc HelperPDBtoTDB, <NEAR,PUBLIC>
cBegin
;** Point to the first TDB
mov dx,_DATA ;Get the library static segment
mov es,dx ;Point with ES
mov bx,es:[npwTDBHead] ;Get pointer to first TDB
mov dx,es:[segKernel] ;Get the KERNEL data segment
mov es,dx ;Point with ES
mov dx,es:[bx] ;Get the first TDB
;** Check this TDB's PDB to see if it matches
PT_Loop:
mov es,dx ;Get the TDB segment
cmp ax,es:[TDB_PDB] ;Compare PDB pointers
jz PT_Found ;This is it
mov dx,es:[TDB_next] ;Get the next TDB
or dx,dx ;End of the line?
jnz PT_Loop ;Nope, loop back
xor ax,ax ;Return NULL'
jmp SHORT PT_End ;Outta here
PT_Found:
mov ax,es ;Save the found value
PT_End:
cEnd
sEnd
END