Source file: /~heha/hsn/borg.zip/RELOCS.CPP

/************************************************************************
*		  relocs.cpp						*
* This class maintains a list of relocation items from the exe file.	*
* Borg keeps a list of any items which have been or should be relocated *
* when an executable is loaded. The class includes functions to		*
* maintain the list including loading and saving to a database file,	*
* and including relocating the image in memory when the database and	*
* the file are reloaded.						*
* The main reason for doing this is that during disassembly we can gain *
* additional information by knowing that a certain location is		*
* relocated on file load. For example with an instruction like		*
* mov eax,400000h, if the location containing 400000h is a relocation	*
* item then we know that 400000h is an offset, and so we can		*
* immediately rewrite it as mov eax, offset 400000h			*
************************************************************************/

#include <windows.h>

#include "relocs.h"
#include "data.h"
#include "debug.h"
#include "dasm.h"


/************************************************************************
* constructor function							*
************************************************************************/
relocs::relocs() {
 sizeofitem=sizeof(relocitem);
}

/************************************************************************
* destructor function							*
* - currently null							*
************************************************************************/
relocs::~relocs() { }

/************************************************************************
* addreloc								*
* - adds a reloc item to the list of relocs				*
* - a reloc item consists of only a location which is in the reloc	*
*   table, and a type for the relocation				*
************************************************************************/
void relocs::addreloc(lptr loc,reloctype type) {
 relocitem *newname;
 newname=new relocitem;
 newname->addr=loc;
 newname->type=type;
 addto(newname);
#ifdef DEBUG
 DebugMessage("Added Reloc : %04lx:%04lx",loc.segm,loc.offs);
#endif
}

/************************************************************************
* isreloc								*
* - this is the function used throughout the disassembly engine to see	*
*   if somewhere was relocated. It returns true if the location is in	*
*   the table								*
************************************************************************/
bool relocs::isreloc(lptr loc) {
 relocitem checkit,*findit;
 checkit.addr=loc;
 findit=find(&checkit);
 if (findit && findit->addr==loc) return true;
 return false;
}

/************************************************************************
* the compare function for the reloc items				*
* - relocs are sorted by location					*
************************************************************************/
int relocs::compare(relocitem *i,relocitem *j) {
 if (i->addr==j->addr) return 0;
 if (i->addr>j->addr)  return 1;
 return -1;
}

/************************************************************************
* relocfile								*
* - this should be called after loading a database file. It goes	*
*   through all of the relocs and relocates the file again since when	*
*   we load a database we simply load the file image and do not work	*
*   our way through the whole file format again.			*
************************************************************************/
bool relocs::relocfile(void) {
 dsegitem *ds;
 relocitem *ri;
 resetiterator();
 ri=nextiterator();
 while (ri) { // relocate item.
  ds=dta->findseg(ri->addr);
  if (ds) {   // changed in build 14, used to return false if not found
   switch (ri->type) {
    case RELOC_NONE:	  break;
    case RELOC_SEG:
	  ((word *)(&(ds->data[ri->addr.offs-ds->addr.offs])))[0]+=options.loadaddr.segm;
	  break;
    case RELOC_OFFS16:		break;
    case RELOC_OFFS32:		break;
    case RELOC_SEGOFFS16:	break;
    case RELOC_SEGOFFS32:	break;
    default: return false;
   }
  }
  ri=nextiterator();
 }
 return true;
}

/************************************************************************
* newitem								*
* - returns a pointer to a new relocitem, only used by database load	*
************************************************************************/
relocitem *relocs::newitem(void)
{ return (new relocitem);
}

/************************************************************************
* write_item								*
* - writes a reloc item to the savefile specified			*
*   uses the current item, and moves the iterator on			*
************************************************************************/
bool relocs::write_item(savefile *sf) {
 relocitem *currdec;
 currdec=nextiterator();
 sf->Write(currdec,sizeof(relocitem));
 return sf->okay;
}

/************************************************************************
* read_item								*
* - reads a reloc item from the savefile specified			*
************************************************************************/
bool relocs::read_item(savefile *sf) {
 relocitem *currdec;
 currdec=new relocitem;
 if (!sf->Read(currdec,sizeof(relocitem))) return false;
 addto(currdec);
 return true;
}