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, 51 insertions, 36 deletions

diff --git a/hiredis.c b/hiredis.c
index 1c9e8ae..3133716 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -74,7 +74,7 @@ static redisReplyObjectFunctions defaultFunctions = {
 
 /* Create a reply object */
 static redisReply *createReplyObject(int type) {
-    redisReply *r = calloc(1,sizeof(*r));
+    redisReply *r = hi_calloc(1,sizeof(*r));
 
     if (r == NULL)
         return NULL;
@@ -101,7 +101,7 @@ void freeReplyObject(void *reply) {
         if (r->element != NULL) {
             for (j = 0; j < r->elements; j++)
                 freeReplyObject(r->element[j]);
-            free(r->element);
+            hi_free(r->element);
         }
         break;
     case REDIS_REPLY_ERROR:
@@ -109,10 +109,10 @@ void freeReplyObject(void *reply) {
     case REDIS_REPLY_STRING:
     case REDIS_REPLY_DOUBLE:
     case REDIS_REPLY_VERB:
-        free(r->str);
+        hi_free(r->str);
         break;
     }
-    free(r);
+    hi_free(r);
 }
 
 static void *createStringObject(const redisReadTask *task, char *str, size_t len) {
@@ -130,22 +130,18 @@ static void *createStringObject(const redisReadTask *task, char *str, size_t len
 
     /* Copy string value */
     if (task->type == REDIS_REPLY_VERB) {
-        buf = malloc(len-4+1); /* Skip 4 bytes of verbatim type header. */
-        if (buf == NULL) {
-            freeReplyObject(r);
-            return NULL;
-        }
+        buf = hi_malloc(len-4+1); /* Skip 4 bytes of verbatim type header. */
+        if (buf == NULL) goto oom;
+
         memcpy(r->vtype,str,3);
         r->vtype[3] = '\0';
         memcpy(buf,str+4,len-4);
         buf[len-4] = '\0';
         r->len = len - 4;
     } else {
-        buf = malloc(len+1);
-        if (buf == NULL) {
-            freeReplyObject(r);
-            return NULL;
-        }
+        buf = hi_malloc(len+1);
+        if (buf == NULL) goto oom;
+
         memcpy(buf,str,len);
         buf[len] = '\0';
         r->len = len;
@@ -161,6 +157,10 @@ static void *createStringObject(const redisReadTask *task, char *str, size_t len
         parent->element[task->idx] = r;
     }
     return r;
+
+oom:
+    freeReplyObject(r);
+    return NULL;
 }
 
 static void *createArrayObject(const redisReadTask *task, size_t elements) {
@@ -171,7 +171,7 @@ static void *createArrayObject(const redisReadTask *task, size_t elements) {
         return NULL;
 
     if (elements > 0) {
-        r->element = calloc(elements,sizeof(redisReply*));
+        r->element = hi_calloc(elements,sizeof(redisReply*));
         if (r->element == NULL) {
             freeReplyObject(r);
             return NULL;
@@ -218,7 +218,7 @@ static void *createDoubleObject(const redisReadTask *task, double value, char *s
         return NULL;
 
     r->dval = value;
-    r->str = malloc(len+1);
+    r->str = hi_malloc(len+1);
     if (r->str == NULL) {
         freeReplyObject(r);
         return NULL;
@@ -322,7 +322,7 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) {
         if (*c != '%' || c[1] == '\0') {
             if (*c == ' ') {
                 if (touched) {
-                    newargv = realloc(curargv,sizeof(char*)*(argc+1));
+                    newargv = hi_realloc(curargv,sizeof(char*)*(argc+1));
                     if (newargv == NULL) goto memory_err;
                     curargv = newargv;
                     curargv[argc++] = curarg;
@@ -471,7 +471,7 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) {
 
     /* Add the last argument if needed */
     if (touched) {
-        newargv = realloc(curargv,sizeof(char*)*(argc+1));
+        newargv = hi_realloc(curargv,sizeof(char*)*(argc+1));
         if (newargv == NULL) goto memory_err;
         curargv = newargv;
         curargv[argc++] = curarg;
@@ -487,7 +487,7 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) {
     totlen += 1+countDigits(argc)+2;
 
     /* Build the command at protocol level */
-    cmd = malloc(totlen+1);
+    cmd = hi_malloc(totlen+1);
     if (cmd == NULL) goto memory_err;
 
     pos = sprintf(cmd,"*%d\r\n",argc);
@@ -502,7 +502,7 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) {
     assert(pos == totlen);
     cmd[pos] = '\0';
 
-    free(curargv);
+    hi_free(curargv);
     *target = cmd;
     return totlen;
 
@@ -518,11 +518,11 @@ cleanup:
     if (curargv) {
         while(argc--)
             sdsfree(curargv[argc]);
-        free(curargv);
+        hi_free(curargv);
     }
 
     sdsfree(curarg);
-    free(cmd);
+    hi_free(cmd);
 
     return error_type;
 }
@@ -563,7 +563,7 @@ int redisFormatCommand(char **target, const char *format, ...) {
 int redisFormatSdsCommandArgv(sds *target, int argc, const char **argv,
                               const size_t *argvlen)
 {
-    sds cmd;
+    sds cmd, aux;
     unsigned long long totlen;
     int j;
     size_t len;
@@ -585,9 +585,13 @@ int redisFormatSdsCommandArgv(sds *target, int argc, const char **argv,
         return -1;
 
     /* We already know how much storage we need */
-    cmd = sdsMakeRoomFor(cmd, totlen);
-    if (cmd == NULL)
+    aux = sdsMakeRoomFor(cmd, totlen);
+    if (aux == NULL) {
+        sdsfree(cmd);
         return -1;
+    }
+
+    cmd = aux;
 
     /* Construct command */
     cmd = sdscatfmt(cmd, "*%i\r\n", argc);
@@ -631,7 +635,7 @@ int redisFormatCommandArgv(char **target, int argc, const char **argv, const siz
     }
 
     /* Build the command at protocol level */
-    cmd = malloc(totlen+1);
+    cmd = hi_malloc(totlen+1);
     if (cmd == NULL)
         return -1;
 
@@ -652,7 +656,7 @@ int redisFormatCommandArgv(char **target, int argc, const char **argv, const siz
 }
 
 void redisFreeCommand(char *cmd) {
-    free(cmd);
+    hi_free(cmd);
 }
 
 void __redisSetError(redisContext *c, int type, const char *str) {
@@ -678,7 +682,7 @@ redisReader *redisReaderCreate(void) {
 static redisContext *redisContextInit(const redisOptions *options) {
     redisContext *c;
 
-    c = calloc(1, sizeof(*c));
+    c = hi_calloc(1, sizeof(*c));
     if (c == NULL)
         return NULL;
 
@@ -702,16 +706,16 @@ void redisFree(redisContext *c) {
 
     sdsfree(c->obuf);
     redisReaderFree(c->reader);
-    free(c->tcp.host);
-    free(c->tcp.source_addr);
-    free(c->unix_sock.path);
-    free(c->timeout);
-    free(c->saddr);
+    hi_free(c->tcp.host);
+    hi_free(c->tcp.source_addr);
+    hi_free(c->unix_sock.path);
+    hi_free(c->timeout);
+    hi_free(c->saddr);
     if (c->funcs->free_privdata) {
         c->funcs->free_privdata(c->privdata);
     }
     memset(c, 0xff, sizeof(*c));
-    free(c);
+    hi_free(c);
 }
 
 redisFD redisFreeKeepFd(redisContext *c) {
@@ -738,6 +742,11 @@ int redisReconnect(redisContext *c) {
     c->obuf = sdsempty();
     c->reader = redisReaderCreate();
 
+    if (c->obuf == NULL || c->reader == NULL) {
+        __redisSetError(c, REDIS_ERR_OOM, "Out of memory");
+        return REDIS_ERR;
+    }
+
     if (c->connection_type == REDIS_CONN_TCP) {
         return redisContextConnectBindTcp(c, c->tcp.host, c->tcp.port,
                 c->timeout, c->tcp.source_addr);
@@ -918,6 +927,8 @@ int redisBufferWrite(redisContext *c, int *done) {
             if (nwritten == (signed)sdslen(c->obuf)) {
                 sdsfree(c->obuf);
                 c->obuf = sdsempty();
+                if (c->obuf == NULL)
+                    goto oom;
             } else {
                 sdsrange(c->obuf,nwritten,-1);
             }
@@ -925,6 +936,10 @@ int redisBufferWrite(redisContext *c, int *done) {
     }
     if (done != NULL) *done = (sdslen(c->obuf) == 0);
     return REDIS_OK;
+
+oom:
+    __redisSetError(c, REDIS_ERR_OOM, "Out of memory");
+    return REDIS_ERR;
 }
 
 /* Internal helper function to try and get a reply from the reader,
@@ -1015,11 +1030,11 @@ int redisvAppendCommand(redisContext *c, const char *format, va_list ap) {
     }
 
     if (__redisAppendCommand(c,cmd,len) != REDIS_OK) {
-        free(cmd);
+        hi_free(cmd);
         return REDIS_ERR;
     }
 
-    free(cmd);
+    hi_free(cmd);
     return REDIS_OK;
 }