Redis Module execution resulting in heap error in turn SIGSEGV

[Bhuvan L]

Here is the toy module I  was trying,  intent of the module(joinedGet) was to get the hmset return value into a String separated by #.

But I am getting heap errors and in turn sig segv. I am using RC03 redis build with provided jemalloc allocator.

Requesting to suggest if any issues with my Allocation and free strategy below. 

/* helper routine to joinResponses

*/

//responseLens is currently unused. 

char* joinResponses(char *responses[], size_t* responseLens, size_t n, size_t totalLen, size_t* joinStrLen)

{

char* str;                           

  *joinStrLen = totalLen + n - 1;

  str = (char*) RedisModule_Alloc(*joinStrLen);  

  str[0] = '\0';                      

  // Append n - 1  responses  with a separator #

  size_t i;

  for( i = 0 ; i < n - 1 ; i++) {

    strcat(str, responses[i]);

    //optimize since we know the response length.

    length = strlen(str);

     str[length] = '#';            

     str[length+1] = '\0';          

    }

    // Append the last String

    strcat(str, responses[i]);

  return str;

}

/* implementation of joinedGet Command

*/

int joinedGet_RedisCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {

//Enable Auto memory

    RedisModule_AutoMemory(ctx);

    

    if (argc != 2) 

        return RedisModule_WrongArity(ctx);

    

    RedisModuleCallReply *reply = RedisModule_Call(ctx,"HGETALL", "s", argv[1]);

    if (RedisModule_CallReplyType(reply) == REDISMODULE_REPLY_ARRAY) {

    size_t replyLen = RedisModule_CallReplyLength(reply);

    if( replyLen > 1) {

    size_t idx;

    size_t totalLen = 0;

    char **response = (char**) RedisModule_Alloc( sizeof(char*) * replyLen);

size_t *responseLens = (size_t *) RedisModule_Alloc(sizeof(size_t) * replyLen);

for(idx = 0; idx < replyLen; idx++) {

RedisModuleCallReply* subreply = RedisModule_CallReplyArrayElement(reply,idx);

RedisModuleString *mystr = RedisModule_CreateStringFromCallReply(subreply);

size_t len;

char *ptr = RedisModule_StringPtrLen(mystr,&len);

totalLen += len;

responseLens[idx] = len;

response[idx] = ptr;

}

size_t joinStrLen;

char *joinStr = joinResponses(response, responseLens, replyLen,  totalLen,  &joinStrLen);

//ok to still free despite AutoMemory

RedisModule_Free(response);

RedisModule_Free(responseLens);

RedisModule_ReplyWithArray(ctx,2);

RedisModule_ReplyWithLongLong(ctx, joinStrLen);

RedisModule_ReplyWithStringBuffer(ctx, joinStr, joinStrLen);

        } else {  

RedisModule_ReplyWithCallReply(ctx,reply);

}

}

    return REDISMODULE_OK;

}