Force duplication of libgit objects when it is convenient

implausible · srajko · commit edbb2c8b8d92 · 2016-03-23T16:20:45.000-07:00
the structs git_tree_entry, git_oid, and git_signature all represent structs which are owned by some other object. In order to simplify our memory model, we should always duplicate these 3 structs when we pull them out of libgit2. This detaches these types of structs from their owning object, such that when we delete a commit, none of the oids or signatures that we retrieved from that commit would cause bad memory access.
diff --git a/generate/input/descriptor.json b/generate/input/descriptor.json
@@ -1275,6 +1275,9 @@
       "ignore": true
     },
     "oid": {
+      "dupFunction": "git_oid_cpy",
+      "freeFunctionName": "free",
+      "selfDuplicating": true,
       "shouldAlloc": true,
       "functions": {
         "git_oid_cpy": {
@@ -1879,6 +1882,8 @@
       }
     },
 	  "signature": {
+      "dupFunction": "git_signature_dup",
+      "selfDuplicating": true,
 	    "functions": {
         "git_signature_default": {
           "isAsync": false
@@ -2218,9 +2223,6 @@
     "tree": {
       "selfFreeing": true,
       "functions": {
-        "git_tree_entry_free": {
-          "ignore": true
-        },
         "git_tree_entry_byindex": {
           "jsFunctionName": "_entryByIndex"
         },
@@ -2253,6 +2255,11 @@
         }
       }
     },
+    "tree_entry": {
+      "dupFunction": "git_tree_entry_dup",
+      "freeFunctionName": "git_tree_entry_free",
+      "selfDuplicating": true
+    },
     "writestream": {
       "cType": "git_writestream",
       "needsForwardDeclaration": false
diff --git a/generate/scripts/helpers.js b/generate/scripts/helpers.js
@@ -181,6 +181,10 @@ var Helpers = {
     typeDef.dependencies = [];
     typeDef.selfFreeing = Boolean(typeDefOverrides.selfFreeing);
 
+    if (typeDefOverrides.freeFunctionName) {
+      typeDef.freeFunctionName = typeDefOverrides.freeFunctionName;
+    }
+
     typeDef.fields = typeDef.fields || [];
     typeDef.fields.forEach(function (field, index, allFields) {
       var fieldOverrides = typeDefOverrides.fields || {};
diff --git a/generate/templates/templates/class_content.cc b/generate/templates/templates/class_content.cc
@@ -25,8 +25,17 @@ using namespace node;
 
 {% if cType %}
   {{ cppClassName }}::{{ cppClassName }}({{ cType }} *raw, bool selfFreeing) {
+    {% if selfDuplicating %}
+      {% if shouldAlloc %}
+    this->raw = ({{ cType }} *)malloc(sizeof({{ cType }}));
+    {{ dupFunction }}(this->raw, raw);
+      {% else %}
+    {{ dupFunction }}(&this->raw, raw);
+      {% endif %}
+    {% else %}
     this->raw = raw;
     this->selfFreeing = selfFreeing;
+    {%endif%}
 
     if (selfFreeing) {
       SelfFreeingInstanceCount++;
@@ -37,7 +46,10 @@ using namespace node;
   }
 
   {{ cppClassName }}::~{{ cppClassName }}() {
-    {% if freeFunctionName %}
+    {% if selfDuplicating %}
+      {{ freeFunctionName }}(this->raw);
+      this->raw = NULL;
+    {% elsif freeFunctionName %}
       if (this->selfFreeing) {
         {{ freeFunctionName }}(this->raw);
         SelfFreeingInstanceCount--;
