[PATCH] Bugfix for incorrect length when decr a value

[Dustin Sallings]

   This is documented in protocol.txt.

--  
Dustin Sallings (mobile)

On Oct 18, 2007, at 3:38, "Steve Chu" <stvchu at gmail.com> wrote:

> Sorry, all.
> I made a mistake, the vlen *is* 5, because 9999 with a suffix of
> blank, but that is really weird. libmemcache is  ok for this.
>
> On 10/18/07, Steve Chu <stvchu at gmail.com> wrote:
>> Anybody can have a try:
>> -----------------------------------------------
>> # telnet 127.0.0.1 11211
>> Trying 127.0.0.1...
>> Connected to 127.0.0.1 (127.0.0.1).
>> Escape character is '^]'.
>> get test
>> END
>> add test 0 0 4
>> 9999
>> STORED
>> incr test 1
>> 10000
>> get test
>> VALUE test 0 5
>> 10000
>> END
>> decr test 1
>> 9999
>> get test
>> VALUE test 0 5
>> 9999
>> END
>> --------------
>> The vlen does not shrink when *decr* from 10000 to 9999, it is  
>> still 5!!
>> This bug does not affect most dynamic language client(php .etc), but
>> for clients that
>> use this vlen, they don't work, for example, libmemcache.
>> Also it does not follow the memcache protocol.
>> Here comes the pacth:
>> ===========================================================
>> --- memcached-trunk/memcached.c 2007-10-18 15:57:28.000000000 +0800
>> +++ memcached-new/memcached.c   2007-10-18 15:54:49.000000000 +0800
>> @@ -1366,6 +1366,7 @@ char *do_add_delta(item *it, const bool
>>     char *ptr;
>>     int64_t value;
>>     int res;
>> +    item *new_it;
>>
>>     ptr = ITEM_data(it);
>>     while ((*ptr != '\0') && (*ptr < '0' && *ptr > '9')) ptr++;    //
>> BUG: can't be true
>> @@ -1384,20 +1385,17 @@ char *do_add_delta(item *it, const bool
>>     }
>>     sprintf(buf, "%llu", value);
>>     res = strlen(buf);
>> -    if (res + 2 > it->nbytes) { /* need to realloc */
>> -        item *new_it;
>> -        new_it = do_item_alloc(ITEM_key(it), it->nkey,
>> atoi(ITEM_suffix(it) + 1), it->exptime, res + 2 );
>> -        if (new_it == 0) {
>> -            return "SERVER_ERROR out of memory";
>> -        }
>> -        memcpy(ITEM_data(new_it), buf, res);
>> -        memcpy(ITEM_data(new_it) + res, "\r\n", 3);
>> -        do_item_replace(it, new_it);
>> -        do_item_remove(new_it);       /* release our reference */
>> -    } else { /* replace in-place */
>> -        memcpy(ITEM_data(it), buf, res);
>> -        memset(ITEM_data(it) + res, ' ', it->nbytes - res - 2);
>> +
>> +    /* just alloc one, not plan to new one only when res + 2 > it- 
>> >nbytes */
>> +    new_it = do_item_alloc(ITEM_key(it), it->nkey,
>> atoi(ITEM_suffix(it) + 1), it->exptime, res + 2 );
>> +
>> +    if (new_it == 0) {
>> +        return "SERVER_ERROR out of memory";
>>     }
>> +    memcpy(ITEM_data(new_it), buf, res);
>> +    memcpy(ITEM_data(new_it) + res, "\r\n", 3);
>> +    do_item_replace(it, new_it);
>> +    do_item_remove(new_it);       /* release our reference */
>>
>>     return buf;
>> }
>> ========================================================
>>
>> --
>> Steve Chu
>> http://www.sina.com
>>
>
>
> -- 
> Steve Chu
> http://stvchu.org
>
>