/*
* MakeItSegmentedNumberOne - make a (sel,offset) into a 16:16 pointer
*/
void __far * MakeItSegmentedNumberOne( USHORT seg, ULONG offset )
{
if( !IsFlatSeg( seg ) ) return( MK_FP( seg, (USHORT) offset ) );
return( MakeSegmentedPointer( offset ) );
} /* MakeItSegmentedNumberOne */
bool CausePgmToLoadThisDLL( ULONG startLinear )
{
char savecode[LOAD_THIS_DLL_SIZE];
USHORT codesize;
USHORT len;
loadstack_t far *loadstack;
void far *ptr;
USHORT dll_name_len;
USHORT size;
char this_dll[BUFF_SIZE];
bool rc;
/*
* save a chunk of the program's code, and put in LoadThisDLL instead
*/
if( DosGetModName( ThisDLLModHandle, BUFF_SIZE, this_dll ) != 0 ) {
return( FALSE );
}
codesize = (char *)EndLoadThisDLL - (char *)LoadThisDLL;
if( codesize > LOAD_THIS_DLL_SIZE ) return( FALSE );
ReadLinear( savecode, startLinear, codesize );
if( Buff.Cmd != DBG_N_Success ) return( FALSE );
WriteLinear( (byte far *)LoadThisDLL, startLinear, codesize );
/*
* set up the stack for the routine LoadThisDLL
*/
dll_name_len = ( strlen( this_dll ) + 1 ) & ~1;
size = sizeof( loadstack_t ) + dll_name_len;
loadstack = Automagic( size );
Buff.ESP -= size;
strcpy( loadstack->load_name, this_dll );
loadstack->fail_name = NULL;
loadstack->fail_len = 0;
ptr = MakeItSegmentedNumberOne( Buff.SS, Buff.ESP + offsetof( loadstack_t, load_name ) );
loadstack->mod_name[0] = FP_OFF( ptr );
loadstack->mod_name[1] = FP_SEG( ptr );
ptr = MakeItSegmentedNumberOne( Buff.SS, Buff.ESP + offsetof( loadstack_t, hmod ) );
loadstack->phmod[0] = FP_OFF( ptr );
loadstack->phmod[1] = FP_SEG( ptr );
len = WriteBuffer( (byte far *)loadstack, Buff.SS, Buff.ESP, size );
if( len != size ) return( FALSE );
/*
* set up 16:16 CS:IP, SS:SP for execution
*/
ptr = MakeSegmentedPointer( startLinear );
Buff.CS = FP_SEG( ptr );
Buff.EIP = FP_OFF( ptr );
ptr = MakeItSegmentedNumberOne( Buff.SS, Buff.ESP );
Buff.SS = FP_SEG( ptr );
Buff.ESP = FP_OFF( ptr );
/*
* execute LoadThisDLL on behalf of the program
*/
WriteRegs( &Buff );
DebugExecute( &Buff, DBG_C_Go, FALSE );
if( Buff.Cmd != DBG_N_Breakpoint ) {
rc = FALSE;
} else {
rc = TRUE;
}
WriteLinear( savecode, startLinear, codesize );
return( rc );
}