Fix assertion failure in nix-env

  $ nix-env -f ~/Dev/nixops/ -iA foo
  nix-env: src/libexpr/eval.hh:57: void nix::Bindings::push_back(const nix::Attr&): Assertion `size_ < capacity' failed.
  Aborted

2 files changed, 8 insertions, 4 deletions

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index ed648fba8d77..f7415fb78dfd 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -39,10 +39,10 @@ public:
     typedef uint32_t size_t;
 
 private:
-    size_t size_, capacity;
+    size_t size_, capacity_;
     Attr attrs[0];
 
-    Bindings(uint32_t capacity) : size_(0), capacity(capacity) { }
+    Bindings(size_t capacity) : size_(0), capacity_(capacity) { }
     Bindings(const Bindings & bindings) = delete;
 
 public:
@@ -54,7 +54,7 @@ public:
 
     void push_back(const Attr & attr)
     {
-        assert(size_ < capacity);
+        assert(size_ < capacity_);
         attrs[size_++] = attr;
     }
 
@@ -76,6 +76,8 @@ public:
 
     void sort();
 
+    size_t capacity() { return capacity_; }
+
     friend class EvalState;
 };
 
diff --git a/src/nix-env/nix-env.cc b/src/nix-env/nix-env.cc
index f5e8ee08c42f..f3c8d3ba8953 100644
--- a/src/nix-env/nix-env.cc
+++ b/src/nix-env/nix-env.cc
@@ -132,6 +132,8 @@ static void getAllExprs(EvalState & state,
             Value & vArg(*state.allocValue());
             state.getBuiltin("import", vFun);
             mkString(vArg, path2);
+            if (v.attrs->size() == v.attrs->capacity())
+                throw Error(format("too many Nix expressions in directory ‘%1%’") % path);
             mkApp(*state.allocAttr(v, state.symbols.create(attrName)), vFun, vArg);
         }
         else if (S_ISDIR(st.st_mode))
@@ -160,7 +162,7 @@ static void loadSourceExpr(EvalState & state, const Path & path, Value & v)
        ~/.nix-defexpr directory that includes some system-wide
        directory). */
     if (S_ISDIR(st.st_mode)) {
-        state.mkAttrs(v, 16);
+        state.mkAttrs(v, 1024);
         state.mkList(*state.allocAttr(v, state.symbols.create("_combineChannels")), 0);
         StringSet attrs;
         getAllExprs(state, path, attrs, v);