[C++] Explicitly disallow $(shell) in other make constructs

5 files changed, 32 insertions, 2 deletions

diff --git a/eval.cc b/eval.cc
index 2ba4a56..3c0eae2 100644
--- a/eval.cc
+++ b/eval.cc
@@ -41,7 +41,8 @@ Evaluator::Evaluator(const Vars* vars)
       vars_(new Vars()),
       last_rule_(NULL),
       current_scope_(NULL),
-      avoid_io_(false) {
+      avoid_io_(false),
+      eval_depth_(0) {
 }
 
 Evaluator::~Evaluator() {
diff --git a/eval.h b/eval.h
index 3ebb21b..6bc21b9 100644
--- a/eval.h
+++ b/eval.h
@@ -92,6 +92,14 @@ class Evaluator {
     return used_undefined_vars_;
   }
 
+  int eval_depth() const { return eval_depth_; }
+  void IncrementEvalDepth() {
+    eval_depth_++;
+  }
+  void DecrementEvalDepth() {
+    eval_depth_--;
+  }
+
  private:
   Var* EvalRHS(Symbol lhs, Value* rhs, StringPiece orig_rhs, AssignOp op,
                bool is_override = false);
@@ -112,6 +120,10 @@ class Evaluator {
   bool is_bootstrap_;
 
   bool avoid_io_;
+  // This value tracks the nest level of make expressions. For
+  // example, $(YYY) in $(XXX $(YYY)) is evaluated with depth==2.
+  // This will be used to disallow $(shell) in other make constructs.
+  int eval_depth_;
   // Commands which should run at ninja-time (i.e., info, warning, and
   // error).
   vector<string> delayed_output_commands_;
diff --git a/expr.cc b/expr.cc
index e43d189..d0d3e38 100644
--- a/expr.cc
+++ b/expr.cc
@@ -152,7 +152,9 @@ class VarRef : public Value {
   }
 
   virtual void Eval(Evaluator* ev, string* s) const override {
+    ev->IncrementEvalDepth();
     const string&& name = name_->Eval(ev);
+    ev->DecrementEvalDepth();
     Var* v = ev->LookupVar(Intern(name));
     v->Eval(ev, s);
   }
@@ -177,11 +179,13 @@ class VarSubst : public Value {
   }
 
   virtual void Eval(Evaluator* ev, string* s) const override {
+    ev->IncrementEvalDepth();
     const string&& name = name_->Eval(ev);
     Var* v = ev->LookupVar(Intern(name));
-    const string&& value = v->Eval(ev);
     const string&& pat_str = pat_->Eval(ev);
     const string&& subst = subst_->Eval(ev);
+    ev->DecrementEvalDepth();
+    const string&& value = v->Eval(ev);
     WordWriter ww(s);
     Pattern pat(pat_str);
     for (StringPiece tok : WordScanner(value)) {
@@ -216,7 +220,9 @@ class Func : public Value {
 
   virtual void Eval(Evaluator* ev, string* s) const override {
     LOG("Invoke func %s(%s)", name(), JoinValues(args_, ",").c_str());
+    ev->IncrementEvalDepth();
     fi_->func(args_, ev, s);
+    ev->DecrementEvalDepth();
   }
 
   virtual string DebugString_() const override {
diff --git a/func.cc b/func.cc
index 33c5013..39af0e9 100644
--- a/func.cc
+++ b/func.cc
@@ -546,6 +546,11 @@ bool ShouldStoreCommandResult(StringPiece cmd) {
 void ShellFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
   string cmd = args[0]->Eval(ev);
   if (ev->avoid_io() && !HasNoIoInShellScript(cmd)) {
+    if (ev->eval_depth() > 1) {
+      ERROR("%s:%d: kati doesn't support passing results of $(shell) "
+            "to other make constructs: %s",
+            LOCF(ev->loc()), cmd.c_str());
+    }
     StripShellComment(&cmd);
     *s += "$(";
     *s += cmd;
@@ -609,12 +614,16 @@ void CallFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
                                     Intern(tmpvar_name), av[i-1].get()));
     }
   }
+
+  ev->DecrementEvalDepth();
   func->Eval(ev, s);
+  ev->IncrementEvalDepth();
 }
 
 void ForeachFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
   const string&& varname = args[0]->Eval(ev);
   const string&& list = args[1]->Eval(ev);
+  ev->DecrementEvalDepth();
   WordWriter ww(s);
   for (StringPiece tok : WordScanner(list)) {
     unique_ptr<SimpleVar> v(new SimpleVar(
@@ -623,6 +632,7 @@ void ForeachFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
     ww.MaybeAddWhitespace();
     args[2]->Eval(ev, s);
   }
+  ev->IncrementEvalDepth();
 }
 
 void OriginFunc(const vector<Value*>& args, Evaluator* ev, string* s) {
diff --git a/testcase/strip_and_shell.mk b/testcase/strip_and_shell.mk
index db1bbf2..cb550f3 100644
--- a/testcase/strip_and_shell.mk
+++ b/testcase/strip_and_shell.mk
@@ -1,3 +1,4 @@
+# TODO(c-ninja): $(shell) in another make expression is not supported.
 
 test:
 	echo $(strip $(shell pwd))