Allow users to replace allocator and handle OOM everywhere. (#800)

* Adds an indirection to every allocation/deallocation to allow users to 
  plug in ones of their choosing (use custom functions, jemalloc, etc).

* Gracefully handle OOM everywhere in hiredis.  This should make it possible
  for users of the library to have more flexibility in how they handle such situations.

* Changes `redisReaderTask->elements` from an `int` to a `long long` to prevent
  a possible overflow when transferring the task elements into a `redisReply`.

* Adds a configurable `max elements` member to `redisReader` that defaults to
  2^32 - 1.  This can be set to "unlimited" by setting the value to zero.

1 files changed, 4 insertions, 1 deletions

diff --git a/adapters/libevent.h b/adapters/libevent.h
index 0674ca6..9150979 100644
--- a/adapters/libevent.h
+++ b/adapters/libevent.h
@@ -47,7 +47,7 @@ typedef struct redisLibeventEvents {
 } redisLibeventEvents;
 
 static void redisLibeventDestroy(redisLibeventEvents *e) {
-    free(e);
+    hi_free(e);
 }
 
 static void redisLibeventHandler(int fd, short event, void *arg) {
@@ -153,6 +153,9 @@ static int redisLibeventAttach(redisAsyncContext *ac, struct event_base *base) {
 
     /* Create container for context and r/w events */
     e = (redisLibeventEvents*)hi_calloc(1, sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
     e->context = ac;
 
     /* Register functions to start/stop listening for events */