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

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

> 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.

diff --git a/src/box/xlog.c b/src/box/xlog.c
index 5ed11fc..ed6c06a 100644
--- a/src/box/xlog.c
+++ b/src/box/xlog.c
@@ -183,6 +183,12 @@ parse_vclock(const char *val, const char *val_end, struct vclock *vclock)
 	return 0;
 }
 
+static inline bool
+xlog_meta_key_equal(const char *key, uint32_t key_len, const char *str)
+{
+	return key_len == strlen(str) && memcmp(key, str, key_len) == 0;
+}
+
 /**
  * Parse xlog meta from buffer, update buffer read
  * position in case of success
@@ -261,8 +267,9 @@ 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) {
+		uint32_t key_len = key_end - key;
+		if (xlog_meta_key_equal(key, key_len, INSTANCE_UUID_KEY) ||
+		    xlog_meta_key_equal(key, key_len, INSTANCE_UUID_KEY_V12)) {
 			/*
 			 * Instance: <uuid>
 			 */
@@ -277,19 +284,19 @@ 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_equal(key, key_len, VCLOCK_KEY)) {
 			/*
 			 * 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_equal(key, key_len, PREV_VCLOCK_KEY)) {
 			/*
 			 * 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_equal(key, key_len, VERSION_KEY)) {
 			/* Ignore Version: for now */
 		} else {
 			/*