Minor code review for parse_phrase_operator().

tglsfdc · tglsfdc · commit 00c5e511b940 · 2017-06-26T10:31:10.000-04:00
Fix its header comment, which described the old behavior of the <N> phrase distance operator; we missed updating that in commit 028350f. Also, reset errno before strtol() call, to defend against the possibility that it was already ERANGE at entry. (The lack of complaints says that it generally isn't, but this is at least a latent bug.) Very minor stylistic improvements as well. Victor Drobny noted the obsolete comment, I noted the errno issue. Back-patch to 9.6 where this code was added, just in case the errno issue is a live bug in some cases. Discussion: https://postgr.es/m/2b5382fdff9b1f79d5eb2c99c4d2cbe2@postgrespro.ru
diff --git a/src/backend/utils/adt/tsquery.c b/src/backend/utils/adt/tsquery.c
@@ -113,7 +113,7 @@ get_modifiers(char *buf, int16 *weight, bool *prefix)
  * Parse phrase operator. The operator
  * may take the following forms:
  *
- *		a <X> b (distance is no greater than X)
+ *		a <N> b (distance is exactly N lexemes)
  *		a <-> b (default distance = 1)
  *
  * The buffer should begin with '<' char
@@ -129,10 +129,9 @@ parse_phrase_operator(char *buf, int16 *distance)
 		PHRASE_ERR,
 		PHRASE_FINISH
 	}			state = PHRASE_OPEN;
-
 	char	   *ptr = buf;
 	char	   *endptr;
-	long		l = 1;
+	long		l = 1;			/* default distance */
 
 	while (*ptr)
 	{
@@ -151,16 +150,17 @@ parse_phrase_operator(char *buf, int16 *distance)
 					ptr++;
 					break;
 				}
-				else if (!t_isdigit(ptr))
+				if (!t_isdigit(ptr))
 				{
 					state = PHRASE_ERR;
 					break;
 				}
 
+				errno = 0;
 				l = strtol(ptr, &endptr, 10);
 				if (ptr == endptr)
 					state = PHRASE_ERR;
-				else if (errno == ERANGE || l > MAXENTRYPOS)
+				else if (errno == ERANGE || l < 0 || l > MAXENTRYPOS)
 					ereport(ERROR,
 							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 							 errmsg("distance in phrase operator should not be greater than %d",
