Fix another ancient bug in parsing of BRE-mode regular expressions.

tglsfdc · tglsfdc · commit b5a66e7353ba · 2021-02-18T22:38:55.000-05:00
While poking at the regex code, I happened to notice that the bug squashed in commit afcc877 had a sibling: next() failed to return a specific value associated with the '}' token for a "\{m,n\}" quantifier when parsing in basic RE mode. Again, this could result in treating the quantifier as non-greedy, which it never should be in basic mode. For that to happen, the last character before "\}" that sets "nextvalue" would have to set it to zero, or it'd have to have accidentally been zero from the start. The failure can be provoked repeatably with, for example, a bound ending in digit "0". Like the previous patch, back-patch all the way.
diff --git a/src/backend/regex/regc_lex.c b/src/backend/regex/regc_lex.c
@@ -389,7 +389,7 @@ next(struct vars *v)
 					{
 						v->now++;
 						INTOCON(L_BRE);
-						RET('}');
+						RETV('}', 1);
 					}
 					else
 						FAILW(REG_BADBR);
diff --git a/src/test/modules/test_regex/expected/test_regex.out b/src/test/modules/test_regex/expected/test_regex.out
@@ -614,14 +614,21 @@ ERROR:  invalid regular expression: quantifier operand invalid
 -- expectError	7.15 -		a*+	BADRPT
 select * from test_regex('a*+', '', '-');
 ERROR:  invalid regular expression: quantifier operand invalid
--- test for ancient brenext() bug; not currently in Tcl
+-- tests for ancient brenext() bugs; not currently in Tcl
 select * from test_regex('.*b', 'aaabbb', 'b');
  test_regex 
 ------------
  {0}
  {aaabbb}
 (2 rows)
 
+select * from test_regex('.\{1,10\}', 'abcdef', 'bQ');
+   test_regex    
+-----------------
+ {0,REG_UBOUNDS}
+ {abcdef}
+(2 rows)
+
 -- doing 8 "braces"
 -- expectMatch	8.1  NQ		"a{0,1}"	""	""
 select * from test_regex('a{0,1}', '', 'NQ');
diff --git a/src/test/modules/test_regex/sql/test_regex.sql b/src/test/modules/test_regex/sql/test_regex.sql
@@ -214,8 +214,9 @@ select * from test_regex('a?*', '', '-');
 select * from test_regex('a+*', '', '-');
 -- expectError	7.15 -		a*+	BADRPT
 select * from test_regex('a*+', '', '-');
--- test for ancient brenext() bug; not currently in Tcl
+-- tests for ancient brenext() bugs; not currently in Tcl
 select * from test_regex('.*b', 'aaabbb', 'b');
+select * from test_regex('.\{1,10\}', 'abcdef', 'bQ');
 
 -- doing 8 "braces"
 

Original file line number	Diff line number	Diff line change
`@@ -389,7 +389,7 @@ next(struct vars *v)`
`389`	`389`	`{`
`390`	`390`	`v->now++;`
`391`	`391`	`INTOCON(L_BRE);`
`392`		`- RET('}');`
	`392`	`+ RETV('}', 1);`
`393`	`393`	`}`
`394`	`394`	`else`
`395`	`395`	`FAILW(REG_BADBR);`