Re: [tarantool-patches] Re: [PATCH v1 1/1] xlog: fix out of static memory on metadata load

[Vladimir Davydov <vdavydov.dev@gmail.com>]

On Fri, Aug 17, 2018 at 03:39:50PM +0300, Kirill Shcherbatov wrote:
> > Too much of code duplication. Please add a helper for key matching.
> Hi! ok.
> 
> ===========================================
> 
>  src/box/xlog.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/src/box/xlog.c b/src/box/xlog.c
> index 5ed11fc..c870d9d 100644
> --- a/src/box/xlog.c
> +++ b/src/box/xlog.c
> @@ -183,6 +183,13 @@ parse_vclock(const char *val, const char *val_end, struct vclock *vclock)
>  	return 0;
>  }
>  
> +static inline bool
> +xlog_meta_key_cmp(const char *key, uint32_t key_len, const char *str,
> +		  uint32_t str_len)

What's the point of passing str_len when you can compute it right in
this function with strlen?

Also, please pass key_end instead of key_len to make function calls more
compact.

Also, if the function returns bool (which is OK), you shouldn't check
its return value against 0. And you'd better call it xlog_meta_key_match
or xlog_meta_key_equal and make it return true on match and false
otherwise.

Please fix.

> +{
> +	return key_len != str_len || memcmp(key, str, key_len);
> +}
> +
>  /**
>   * Parse xlog meta from buffer, update buffer read
>   * position in case of success
> @@ -261,8 +268,11 @@ xlog_meta_parse(struct xlog_meta *meta, const char **data,
>  		assert(val <= val_end);
>  		pos = eol + 1;
>  
> -		if (memcmp(key, INSTANCE_UUID_KEY, key_end - key) == 0 ||
> -		    memcmp(key, INSTANCE_UUID_KEY_V12, key_end - key) == 0) {
> +		size_t len = key_end - key;
> +		if (xlog_meta_key_cmp(key, len, INSTANCE_UUID_KEY,
> +				      strlen(INSTANCE_UUID_KEY)) == 0 ||
> +		    xlog_meta_key_cmp(key, len, INSTANCE_UUID_KEY_V12,
> +					  strlen(INSTANCE_UUID_KEY_V12)) == 0) {
>  			/*
>  			 * Instance: <uuid>
>  			 */
> @@ -277,19 +287,22 @@ xlog_meta_parse(struct xlog_meta *meta, const char **data,
>  				diag_set(XlogError, "can't parse instance UUID");
>  				return -1;
>  			}
> -		} else if (memcmp(key, VCLOCK_KEY, key_end - key) == 0){
> +		} else if (xlog_meta_key_cmp(key, len, VCLOCK_KEY,
> +					     strlen(VCLOCK_KEY)) == 0) {
>  			/*
>  			 * VClock: <vclock>
>  			 */
>  			if (parse_vclock(val, val_end, &meta->vclock) != 0)
>  				return -1;
> -		} else if (memcmp(key, PREV_VCLOCK_KEY, key_end - key) == 0) {
> +		} else if (xlog_meta_key_cmp(key, len, PREV_VCLOCK_KEY,
> +					     strlen(PREV_VCLOCK_KEY)) == 0) {
>  			/*
>  			 * PrevVClock: <vclock>
>  			 */
>  			if (parse_vclock(val, val_end, &meta->prev_vclock) != 0)
>  				return -1;
> -		} else if (memcmp(key, VERSION_KEY, key_end - key) == 0) {
> +		} else if (xlog_meta_key_cmp(key, len, VERSION_KEY,
> +					     strlen(VERSION_KEY)) == 0) {
>  			/* Ignore Version: for now */
>  		} else {
>  			/*