/** Add edges to graph from functions that call system calls to system calls.
*
* The first 1000 vertexes (0 to 999) in the graph is reserved for system calls, which is many more than the actual system
* calls in linux. */
void
add_syscall_edges(DirectedGraph* G, std::vector<SgAsmFunction*>& all_functions)
{
// Detect all system calls and add an edge from the function to the function to the system call
for (unsigned int caller_id = 0; caller_id < all_functions.size(); ++caller_id) {
SgAsmFunction *func = all_functions[caller_id];
std::vector<SgAsmInstruction*> insns = SageInterface::querySubTree<SgAsmInstruction>(func);
for (std::vector<SgAsmInstruction*>::iterator inst_it = insns.begin(); inst_it != insns.end(); ++inst_it) {
SgAsmX86Instruction *insn = isSgAsmX86Instruction(*inst_it);
if (insn == NULL)
continue;
SgAsmBlock *block = SageInterface::getEnclosingNode<SgAsmBlock>(insn);
// On linux system calls are always interrups and all interrupts are system calls
if (insn && block && insn->get_kind()==x86_int) {
const SgAsmExpressionPtrList &opand_list = insn->get_operandList()->get_operands();
SgAsmExpression *expr = opand_list.size()==1 ? opand_list[0] : NULL;
//semantically execute the basic block to find out which sytem call was called
if (expr && expr->variantT()==V_SgAsmIntegerValueExpression &&
0x80==isSgAsmIntegerValueExpression(expr)->get_value()) {
const SgAsmStatementPtrList &stmts = block->get_statementList();
size_t int_n;
for (int_n=0; int_n<stmts.size(); int_n++) {
if (isSgAsmInstruction(stmts[int_n])==insn)
break;
}
typedef PartialSymbolicSemantics::Policy<PartialSymbolicSemantics::State,
PartialSymbolicSemantics::ValueType> Policy;
typedef X86InstructionSemantics<Policy, PartialSymbolicSemantics::ValueType> Semantics;
Policy policy;
Semantics semantics(policy);
try {
semantics.processBlock(stmts, 0, int_n);
if (policy.readRegister<32>("eax").is_known()) {
int nr = policy.readRegister<32>("eax").known_value();
boost::add_edge(caller_id, nr, *G);
}
} catch (const Semantics::Exception&) {
} catch (const Policy::Exception&) {
}
}
}
}
}
}
