Made connect functions return NULL on alloc failures.

Updated documentation and examples accordingly.

README.md

@@ -44,7 +44,7 @@ After trying to connect to Redis using `redisConnect` you should
 check the `err` field to see if establishing the connection was successful:
 
     redisContext *c = redisConnect("127.0.0.1", 6379);
-    if (c->err) {
+    if (c != NULL && c->err) {
         printf("Error: %s\n", c->errstr);
         // handle error
     }

async.c

@@ -142,15 +142,27 @@ static void __redisAsyncCopyError(redisAsyncContext *ac) {
 }
 
 redisAsyncContext *redisAsyncConnect(const char *ip, int port) {
-    redisContext *c = redisConnectNonBlock(ip,port);
-    redisAsyncContext *ac = redisAsyncInitialize(c);
+    redisContext *c;
+    redisAsyncContext *ac;
+
+    c = redisConnectNonBlock(ip,port);
+    if (c == NULL)
+        return NULL;
+
+    ac = redisAsyncInitialize(c);
     __redisAsyncCopyError(ac);
     return ac;
 }
 
 redisAsyncContext *redisAsyncConnectUnix(const char *path) {
-    redisContext *c = redisConnectUnixNonBlock(path);
-    redisAsyncContext *ac = redisAsyncInitialize(c);
+    redisContext *c;
+    redisAsyncContext *ac;
+
+    c = redisConnectUnixNonBlock(path);
+    if (c == NULL)
+        return NULL;
+
+    ac = redisAsyncInitialize(c);
     __redisAsyncCopyError(ac);
     return ac;
 }

example.c

@@ -11,8 +11,13 @@ int main(void) {
 
     struct timeval timeout = { 1, 500000 }; // 1.5 seconds
     c = redisConnectWithTimeout((char*)"127.0.0.1", 6379, timeout);
-    if (c->err) {
+    if (c == NULL || c->err) {
+        if (c) {
             printf("Connection error: %s\n", c->errstr);
+            redisFree(c);
+        } else {
+            printf("Connection error: can't allocate redis context\n");
+        }
         exit(1);
     }
 

hiredis.c

@@ -1014,42 +1014,72 @@ void redisFree(redisContext *c) {
  * context will be set to the return value of the error function.
  * When no set of reply functions is given, the default set will be used. */
 redisContext *redisConnect(const char *ip, int port) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags |= REDIS_BLOCK;
     redisContextConnectTcp(c,ip,port,NULL);
     return c;
 }
 
 redisContext *redisConnectWithTimeout(const char *ip, int port, struct timeval tv) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags |= REDIS_BLOCK;
     redisContextConnectTcp(c,ip,port,&tv);
     return c;
 }
 
 redisContext *redisConnectNonBlock(const char *ip, int port) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags &= ~REDIS_BLOCK;
     redisContextConnectTcp(c,ip,port,NULL);
     return c;
 }
 
 redisContext *redisConnectUnix(const char *path) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags |= REDIS_BLOCK;
     redisContextConnectUnix(c,path,NULL);
     return c;
 }
 
 redisContext *redisConnectUnixWithTimeout(const char *path, struct timeval tv) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags |= REDIS_BLOCK;
     redisContextConnectUnix(c,path,&tv);
     return c;
 }
 
 redisContext *redisConnectUnixNonBlock(const char *path) {
-    redisContext *c = redisContextInit();
+    redisContext *c;
+
+    c = redisContextInit();
+    if (c == NULL)
+        return NULL;
+
     c->flags &= ~REDIS_BLOCK;
     redisContextConnectUnix(c,path,NULL);
     return c;

test.c

@@ -88,7 +88,10 @@ static redisContext *connect(struct config config) {
         assert(NULL);
     }
 
-    if (c->err) {
+    if (c == NULL) {
+        printf("Connection error: can't allocate redis context\n");
+        exit(1);
+    } else if (c->err) {
         printf("Connection error: %s\n", c->errstr);
         exit(1);
     }