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Commitafcc877

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Fix ancient bug in parsing of BRE-mode regular expressions.
brenext(), when parsing a '*' quantifier, forgot to return any "value"for the token; per the equivalent case in next(), it should returnvalue 1 to indicate that greedy rather than non-greedy behavior iswanted. The result is that the compiled regexp could behave like 'x*?'rather than the intended 'x*', if we were unlucky enough to havea zero in v->nextvalue at this point. That seems to happen with somereliability if we have '.*' at the beginning of a BRE-mode regexp,although that depends on the initial contents of a stack-allocatedstruct, so it's not guaranteed to fail.Found by Alexander Lakhin using valgrind testing. This bug seemsto be aboriginal in Spencer's code, so back-patch all the way.Discussion:https://postgr.es/m/16814-6c5e3edd2bdf0d50@postgresql.org
1 parent15b824d commitafcc877

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3 files changed

+11
-1
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3 files changed

+11
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‎src/backend/regex/regc_lex.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -994,7 +994,7 @@ brenext(struct vars *v,
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caseCHR('*'):
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if (LASTTYPE(EMPTY)||LASTTYPE('(')||LASTTYPE('^'))
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RETV(PLAIN,c);
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RET('*');
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RETV('*',1);
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break;
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caseCHR('['):
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if (HAVE(6)&&*(v->now+0)==CHR('[')&&

‎src/test/modules/test_regex/expected/test_regex.out

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -614,6 +614,14 @@ ERROR: invalid regular expression: quantifier operand invalid
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-- expectError7.15 -a*+BADRPT
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select * from test_regex('a*+', '', '-');
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ERROR: invalid regular expression: quantifier operand invalid
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-- test for ancient brenext() bug; not currently in Tcl
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select * from test_regex('.*b', 'aaabbb', 'b');
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test_regex
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------------
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{0}
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{aaabbb}
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(2 rows)
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-- doing 8 "braces"
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-- expectMatch8.1 NQ"a{0,1}"""""
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select * from test_regex('a{0,1}', '', 'NQ');

‎src/test/modules/test_regex/sql/test_regex.sql

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -214,6 +214,8 @@ select * from test_regex('a?*', '', '-');
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select*from test_regex('a+*','','-');
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-- expectError7.15 -a*+BADRPT
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select*from test_regex('a*+','','-');
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-- test for ancient brenext() bug; not currently in Tcl
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select*from test_regex('.*b','aaabbb','b');
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-- doing 8 "braces"
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