The Tor Browser: xpcom/analysis/flow.js@6474c204b198 (annotated)

xpcom/analysis/flow.js@6474c204b198 (annotated)

xpcom/analysis/flow.js

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 require({ version: '1.8' });
 require({ after_gcc_pass: 'cfg' });
 include('treehydra.js');
 include('util.js');
 include('gcc_util.js');
 include('gcc_print.js');
 include('unstable/adts.js');
 include('unstable/analysis.js');
 include('unstable/esp.js');
 /* This implements the control flows-through analysis in bug 432917 */
 var Zero_NonZero = {}
 include('unstable/zero_nonzero.js', Zero_NonZero);
 MapFactory.use_injective = true;
 // Print a trace for each function analyzed
 let TRACE_FUNCTIONS = 0;
 // Trace operation of the ESP analysis, use 2 or 3 for more detail
 let TRACE_ESP = 0;
 // Print time-taken stats
 let TRACE_PERF = 0;
 function process_tree(fndecl) {
   // At this point we have a function we want to analyze
   if (TRACE_FUNCTIONS) {
     print('* function ' + decl_name(fndecl));
     print('    ' + loc_string(location_of(fndecl)));
   }
   if (TRACE_PERF) timer_start(fstring);
   let cfg = function_decl_cfg(fndecl);
   try {
     let trace = TRACE_ESP;
     let a = new FlowCheck(cfg, trace);
     a.run();
   } catch (e if e == "skip") {
     return
   }
   print("checked " + decl_name(fndecl))
   if (cfg.x_exit_block_ptr.stateIn.substates)
     for each (let substate in cfg.x_exit_block_ptr.stateIn.substates.getValues()) {
       for each (let v in substate.getVariables()) {
         let var_state= substate.get (v)
         let blame = substate.getBlame(v)
         if (var_state != ESP.TOP && typeof var_state == 'string')
           error(decl_name(fndecl) + ": Control did not flow through " +var_state, location_of(blame))
       }
     }
   if (TRACE_PERF) timer_stop(fstring);
 }
 let track_return_loc = 0;
 const FLOW_THROUGH = "MUST_FLOW_THROUGH"
 function FlowCheck(cfg, trace) {
   let found = create_decl_set(); // ones we already found
   for (let bb in cfg_bb_iterator(cfg)) {
     for (let isn in bb_isn_iterator(bb)) {
       switch (isn.tree_code()) {
       case GIMPLE_CALL: {
         let fn = gimple_call_fndecl(isn)
         if (!fn || decl_name(fn) != FLOW_THROUGH)
           continue;
         this.must_flow_fn = fn
         break
       }
       case GIMPLE_RETURN:
         let ret_expr = return_expr(isn);
         if (track_return_loc && ret_expr) {
           TREE_CHECK(ret_expr, VAR_DECL, RESULT_DECL);
           this.rval = ret_expr;
         }
         break;
       }
     }
   }
   if (!this.must_flow_fn)
     throw "skip"
   let psvar_list = [new ESP.PropVarSpec(this.must_flow_fn, true)]
   if (this.rval)
     psvar_list.push(new ESP.PropVarSpec(this.rval))
   this.zeroNonzero = new Zero_NonZero.Zero_NonZero()
   ESP.Analysis.call(this, cfg, psvar_list, Zero_NonZero.meet, trace);
 }
 FlowCheck.prototype = new ESP.Analysis;
 function char_star_arg2string(tree) {
   return TREE_STRING_POINTER(tree.tree_check(ADDR_EXPR).operands()[0].tree_check(ARRAY_REF).operands()[0])
 }
 // State transition function. Mostly, we delegate everything to
 // another function as either an assignment or a call.
 FlowCheck.prototype.flowState = function(isn, state) {
   switch (TREE_CODE(isn)) {
   case GIMPLE_CALL: {
     let fn = gimple_call_fndecl(isn)
     if (fn == this.must_flow_fn)
       state.assignValue(fn, char_star_arg2string(gimple_call_arg(isn, 0)), isn)
     break
   }
   case GIMPLE_LABEL: {
     let label = decl_name(gimple_op(isn, 0))
     for ([value, blame] in state.yieldPreconditions(this.must_flow_fn)) {
       if (label != value) continue
       // reached the goto label we wanted =D
       state.assignValue(this.must_flow_fn, ESP.TOP, isn)
     }
     break
   }
   case GIMPLE_RETURN:
     for ([value, blame] in state.yieldPreconditions(this.must_flow_fn)) {
       if (typeof value != 'string') continue
       let loc;
       if (this.rval)
         for ([value, blame] in state.yieldPreconditions(this.rval)) {
           loc = value
           break
         }
       error("return without going through label "+ value, loc);
       return
     }
     break
   case GIMPLE_ASSIGN:
     if (track_return_loc && gimple_op(isn, 0) == this.rval) {
       state.assignValue(this.rval, location_of(isn), isn)
       break
     }
   default:
     this.zeroNonzero.flowState(isn, state)
   }
 }
 // State transition function to apply branch filters. This is kind
 // of boilerplate--we're just handling some stuff that GCC generates.
 FlowCheck.prototype.flowStateCond = function(isn, truth, state) {
   this.zeroNonzero.flowStateCond (isn, truth, state)
 }