# HG changeset patch
# User jbe
# Date 1452219033 -3600
# Node ID 7d43be9afa565d1a781251188070b689fc42e7dd
# Parent  02a53308f008011387a26f20da8e0986457f3e86
Improved memory cleanup in case of out-of-memory errors (PQnotifies and PQunescapeBytea)

diff -r 02a53308f008 -r 7d43be9afa56 libraries/mondelefant/mondelefant_native.c
--- a/libraries/mondelefant/mondelefant_native.c	Thu Jan 07 17:44:32 2016 +0100
+++ b/libraries/mondelefant/mondelefant_native.c	Fri Jan 08 03:10:33 2016 +0100
@@ -471,13 +471,24 @@
         lua_setfield(L, 2, "message");
         return 1;
       }
+      // avoid cumulating memory leaks in case of previous out-of-memory errors:
+      if (conn->todo_PQfreemem) {
+        PQfreemem(conn->todo_PQfreemem);
+        conn->todo_PQfreemem = NULL;
+      }
       notify = PQnotifies(conn->pgconn);
       if (notify) {
+        // ensure call of PQfreemem in case of out-of-memory errors:
+        conn->todo_PQfreemem = notify;
+        // do Lua operations:
         lua_pushnil(L);
         lua_pushstring(L, notify->relname);
         lua_pushstring(L, notify->extra);
         lua_pushinteger(L, notify->be_pid);
+        // free memory allocated by PQnotifies:
         PQfreemem(notify);
+        // avoid double call of PQfreemem later:
+        conn->todo_PQfreemem = NULL;
         return 4;
       }
     }
@@ -628,7 +639,7 @@
       return luaL_error(L, "Could not allocate memory for binary quoting.");
     }
   }
-  // ensure call of PQfreemem in case of repeated out-of-memory errors:
+  // ensure call of PQfreemem in case of out-of-memory errors:
   conn->todo_PQfreemem = output;
   // create Lua string enclosed by single quotes:
   luaL_buffinit(L, &buf);
@@ -947,7 +958,7 @@
         pgstatus = PQresultStatus(res);
         rows = PQntuples(res);
         cols = PQnfields(res);
-        // ensure call of PQclear in case of repeated Lua errors:
+        // ensure call of PQclear in case of Lua errors:
         conn->todo_PQclear = res;
       }
     }
@@ -1170,6 +1181,12 @@
           } else if (binary[col]) {
             size_t binlen;
             char *binval;
+            // avoid cumulating memory leaks in case of previous out-of-memory errors:
+            if (conn->todo_PQfreemem) {
+              PQfreemem(conn->todo_PQfreemem);
+              conn->todo_PQfreemem = NULL;
+            }
+            // Unescape binary data:
             binval = (char *)PQunescapeBytea(
               (unsigned char *)PQgetvalue(res, row, col), &binlen
             );
@@ -1178,8 +1195,14 @@
                 "Could not allocate memory for binary unescaping."
               );
             }
+            // ensure call of PQfreemem in case of out-of-memory error:
+            conn->todo_PQfreemem = binval;
+            // create Lua string:
             lua_pushlstring(L, binval, binlen);
+            // free memory allocated by PQunescapeBytea:
             PQfreemem(binval);
+            // avoid double call of PQfreemem later:
+            conn->todo_PQfreemem = NULL;
           } else {
             lua_pushstring(L, PQgetvalue(res, row, col));
           }
@@ -1194,6 +1217,12 @@
         } else if (binary[col]) {
           size_t binlen;
           char *binval;
+          // avoid cumulating memory leaks in case of previous out-of-memory errors:
+          if (conn->todo_PQfreemem) {
+            PQfreemem(conn->todo_PQfreemem);
+            conn->todo_PQfreemem = NULL;
+          }
+          // Unescape binary data:
           binval = (char *)PQunescapeBytea(
             (unsigned char *)PQgetvalue(res, 0, col), &binlen
           );
@@ -1202,8 +1231,14 @@
               "Could not allocate memory for binary unescaping."
             );
           }
+          // ensure call of PQfreemem in case of out-of-memory error:
+          conn->todo_PQfreemem = binval;
+          // create Lua string:
           lua_pushlstring(L, binval, binlen);
+          // free memory allocated by PQunescapeBytea:
           PQfreemem(binval);
+          // avoid double call of PQfreemem later:
+          conn->todo_PQfreemem = NULL;
         } else {
           lua_pushstring(L, PQgetvalue(res, 0, col));
         }