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GP-2291 Support for unions through partial containers

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caheckman 2022-08-24 11:46:46 -04:00
parent d3efd60d54
commit cb9c12894e
21 changed files with 678 additions and 182 deletions
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51
Ghidra/Features/Decompiler/src/decompile/cpp/funcdata_varnode.cc
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@ -858,50 +858,31 @@ bool Funcdata::syncVarnodesWithSymbols(const ScopeLocal *lm,bool typesyes)
return updateoccurred;
}
/// If the Varnode is a partial Symbol with \e union data-type, the best description of the Varnode's
/// data-type is delayed until data-type propagation is started.
/// We attempt to resolve this description and also lay down any facing resolutions for the Varnode
/// If the Varnode is a partial of a Symbol with a \e union data-type component, we assign
/// a partial union data-type (TypePartialUnion) to the Varnode, so that facing resolutions
/// can be provided.
/// \param vn is the given Varnode
/// \return the best data-type or null
/// \return the partial data-type or null
Datatype *Funcdata::checkSymbolType(Varnode *vn)
{
if (vn->isTypeLock()) return vn->getType();
SymbolEntry *entry = vn->getSymbolEntry();
Symbol *sym = entry->getSymbol();
if (sym->getType()->getMetatype() != TYPE_UNION)
Datatype *curType = sym->getType();
if (curType->getSize() == vn->getSize())
return (Datatype *)0;
TypeUnion *unionType = (TypeUnion *)sym->getType();
int4 off = (int4)(vn->getOffset() - entry->getAddr().getOffset()) + entry->getOffset();
if (off == 0 && unionType->getSize() == vn->getSize())
int4 curOff = (vn->getAddr().getOffset() - entry->getAddr().getOffset()) + entry->getOffset();
// Drill down until we hit something that isn't a containing structure
while(curType != (Datatype *)0 && curType->getMetatype() == TYPE_STRUCT && curType->getSize() > vn->getSize()) {
uintb newOff;
curType = curType->getSubType(curOff, &newOff);
curOff = newOff;
}
if (curType == (Datatype *)0 || curType->getSize() <= vn->getSize() || curType->getMetatype() != TYPE_UNION)
return (Datatype *)0;
const TypeField *finalField = (const TypeField *)0;
uintb finalOff = 0;
list<PcodeOp *>::const_iterator iter;
for(iter=vn->beginDescend();iter!=vn->endDescend();++iter) {
PcodeOp *op = *iter;
const TypeField *field = unionType->resolveTruncation(off, op, op->getSlot(vn),off);
if (field != (const TypeField *)0) {
finalField = field;
finalOff = off;
}
}
if (vn->isWritten()) {
const TypeField *field = unionType->resolveTruncation(off, vn->getDef(), -1, off);
if (field != (const TypeField *)0) {
finalField = field;
finalOff = off;
}
}
if (finalField != (const TypeField *)0) { // If any use of the Varnode resolves to a specific field
// Try to truncate down to a final data-type to assign to the Varnode
Datatype *ct = finalField->type;
while(ct != (Datatype *)0 && (finalOff != 0 || ct->getSize() != vn->getSize())) {
ct = ct->getSubType(finalOff, &finalOff);
}
return ct;
}
return (Datatype *)0;
// If we hit a containing union
return glb->types->getTypePartialUnion((TypeUnion *)curType, curOff, vn->getSize());
}
/// A Varnode overlaps the given SymbolEntry. Make sure the Varnode is part of the variable