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.

7 files changed, 27 insertions, 13 deletions

diff --git a/adapters/ae.h b/adapters/ae.h
index 0393992..660d82e 100644
--- a/adapters/ae.h
+++ b/adapters/ae.h
@@ -96,7 +96,7 @@ static void redisAeCleanup(void *privdata) {
     redisAeEvents *e = (redisAeEvents*)privdata;
     redisAeDelRead(privdata);
     redisAeDelWrite(privdata);
-    free(e);
+    hi_free(e);
 }
 
 static int redisAeAttach(aeEventLoop *loop, redisAsyncContext *ac) {
@@ -109,6 +109,9 @@ static int redisAeAttach(aeEventLoop *loop, redisAsyncContext *ac) {
 
     /* Create container for context and r/w events */
     e = (redisAeEvents*)hi_malloc(sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
     e->context = ac;
     e->loop = loop;
     e->fd = c->fd;
diff --git a/adapters/glib.h b/adapters/glib.h
index e0a6411..ad59dd1 100644
--- a/adapters/glib.h
+++ b/adapters/glib.h
@@ -134,6 +134,9 @@ redis_source_new (redisAsyncContext *ac)
     g_return_val_if_fail(ac != NULL, NULL);
 
     source = (RedisSource *)g_source_new(&source_funcs, sizeof *source);
+    if (source == NULL)
+        return NULL;
+
     source->ac = ac;
     source->poll_fd.fd = c->fd;
     source->poll_fd.events = 0;
diff --git a/adapters/ivykis.h b/adapters/ivykis.h
index 75616ee..179f6ab 100644
--- a/adapters/ivykis.h
+++ b/adapters/ivykis.h
@@ -43,7 +43,7 @@ static void redisIvykisCleanup(void *privdata) {
     redisIvykisEvents *e = (redisIvykisEvents*)privdata;
 
     iv_fd_unregister(&e->fd);
-    free(e);
+    hi_free(e);
 }
 
 static int redisIvykisAttach(redisAsyncContext *ac) {
@@ -56,6 +56,9 @@ static int redisIvykisAttach(redisAsyncContext *ac) {
 
     /* Create container for context and r/w events */
     e = (redisIvykisEvents*)hi_malloc(sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
     e->context = ac;
 
     /* Register functions to start/stop listening for events */
diff --git a/adapters/libev.h b/adapters/libev.h
index 1520923..7057dbd 100644
--- a/adapters/libev.h
+++ b/adapters/libev.h
@@ -116,7 +116,7 @@ static void redisLibevCleanup(void *privdata) {
     redisLibevDelRead(privdata);
     redisLibevDelWrite(privdata);
     redisLibevStopTimer(privdata);
-    free(e);
+    hi_free(e);
 }
 
 static void redisLibevTimeout(EV_P_ ev_timer *timer, int revents) {
@@ -149,6 +149,9 @@ static int redisLibevAttach(EV_P_ redisAsyncContext *ac) {
 
     /* Create container for context and r/w events */
     e = (redisLibevEvents*)hi_calloc(1, sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
     e->context = ac;
 #if EV_MULTIPLICITY
     e->loop = loop;
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 */
diff --git a/adapters/libuv.h b/adapters/libuv.h
index 7aac127..c120b1b 100644
--- a/adapters/libuv.h
+++ b/adapters/libuv.h
@@ -73,7 +73,7 @@ static void redisLibuvDelWrite(void *privdata) {
 static void on_close(uv_handle_t* handle) {
   redisLibuvEvents* p = (redisLibuvEvents*)handle->data;
 
-  free(p);
+  hi_free(p);
 }
 
 
@@ -98,11 +98,9 @@ static int redisLibuvAttach(redisAsyncContext* ac, uv_loop_t* loop) {
   ac->ev.delWrite = redisLibuvDelWrite;
   ac->ev.cleanup  = redisLibuvCleanup;
 
-  redisLibuvEvents* p = (redisLibuvEvents*)malloc(sizeof(*p));
-
-  if (!p) {
-    return REDIS_ERR;
-  }
+  redisLibuvEvents* p = (redisLibuvEvents*)hi_malloc(sizeof(*p));
+  if (p == NULL)
+      return REDIS_ERR;
 
   memset(p, 0, sizeof(*p));
 
diff --git a/adapters/macosx.h b/adapters/macosx.h
index 72121f6..3c87f1b 100644
--- a/adapters/macosx.h
+++ b/adapters/macosx.h
@@ -27,7 +27,7 @@ static int freeRedisRunLoop(RedisRunLoop* redisRunLoop) {
             CFSocketInvalidate(redisRunLoop->socketRef);
             CFRelease(redisRunLoop->socketRef);
         }
-        free(redisRunLoop);
+        hi_free(redisRunLoop);
     }
     return REDIS_ERR;
 }
@@ -80,8 +80,9 @@ static int redisMacOSAttach(redisAsyncContext *redisAsyncCtx, CFRunLoopRef runLo
     /* Nothing should be attached when something is already attached */
     if( redisAsyncCtx->ev.data != NULL ) return REDIS_ERR;
 
-    RedisRunLoop* redisRunLoop = (RedisRunLoop*) calloc(1, sizeof(RedisRunLoop));
-    if( !redisRunLoop ) return REDIS_ERR;
+    RedisRunLoop* redisRunLoop = (RedisRunLoop*) hi_calloc(1, sizeof(RedisRunLoop));
+    if (redisRunLoop == NULL)
+        return REDIS_ERR;
 
     /* Setup redis stuff */
     redisRunLoop->context = redisAsyncCtx;