From a8cf529a620201b6cb0bff179f10a008ace8a904 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 27 May 2025 14:41:21 +0900 Subject: [PATCH v3] Fix SIMILAR TO regex translation for character classes The code that translates SIMILAR TO pattern matching expressions to regular expressions didn't consider that brackets can be nested, as in [[:alpha:]%], and replaced placeholders like _ and % where it shouldn't. Fix by tracking the nesting level of brackets while considering that in expressions like []] and [^]] the first closing bracket is a regular character. Author: Laurenz Albe Reviewed-by: Michael Paquier Discussion: https://postgr.es/m/16ab039d1af455652bdf4173402ddda145f2c73b.camel@cybertec.at Backpatch-through: 13 --- src/backend/utils/adt/regexp.c | 38 +++++++++-- src/test/regress/expected/strings.out | 91 +++++++++++++++++++++++++++ src/test/regress/sql/strings.sql | 20 ++++++ 3 files changed, 143 insertions(+), 6 deletions(-) diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c index edee1f7880bd..6e2864cbbda8 100644 --- a/src/backend/utils/adt/regexp.c +++ b/src/backend/utils/adt/regexp.c @@ -773,8 +773,11 @@ similar_escape_internal(text *pat_text, text *esc_text) int plen, elen; bool afterescape = false; - bool incharclass = false; int nquotes = 0; + int charclass_depth = 0; /* Nesting level of character classes, + * encompassed by square brackets */ + int charclass_start = 0; /* State of the character class start, + * for carets */ p = VARDATA_ANY(pat_text); plen = VARSIZE_ANY_EXHDR(pat_text); @@ -904,7 +907,7 @@ similar_escape_internal(text *pat_text, text *esc_text) /* fast path */ if (afterescape) { - if (pchar == '"' && !incharclass) /* escape-double-quote? */ + if (pchar == '"' && charclass_depth < 1) /* escape-double-quote? */ { /* emit appropriate part separator, per notes above */ if (nquotes == 0) @@ -953,18 +956,41 @@ similar_escape_internal(text *pat_text, text *esc_text) /* SQL escape character; do not send to output */ afterescape = true; } - else if (incharclass) + else if (charclass_depth > 0) { if (pchar == '\\') *r++ = '\\'; *r++ = pchar; - if (pchar == ']') - incharclass = false; + + /* + * Ignore a closing bracket at the start of a character class. + * Such a bracket is taken literally rather than closing the + * class. "charclass_start" is 1 right at the beginning of a + * class and 2 after an initial caret. + */ + if (pchar == ']' && charclass_start > 2) + charclass_depth--; + else if (pchar == '[') + charclass_depth++; + + /* + * If there is a caret right after the opening bracket, it negates + * the character class, but a following closing bracket should + * still be treated as a normal character. That holds only for + * the first caret, so only the values 1 and 2 mean that closing + * brackets should be taken literally. + */ + if (pchar == '^') + charclass_start++; + else + charclass_start = 3; /* definitely past the start */ } else if (pchar == '[') { + /* start of a character class */ *r++ = pchar; - incharclass = true; + charclass_depth++; + charclass_start = 1; } else if (pchar == '%') { diff --git a/src/test/regress/expected/strings.out b/src/test/regress/expected/strings.out index 174f0a68331b..601bc7d2ec25 100644 --- a/src/test/regress/expected/strings.out +++ b/src/test/regress/expected/strings.out @@ -614,6 +614,97 @@ SELECT 'abcdefg' SIMILAR TO '_bcd%' ESCAPE NULL AS null; SELECT 'abcdefg' SIMILAR TO '_bcd#%' ESCAPE '##' AS error; ERROR: invalid escape string HINT: Escape string must be empty or one character. +-- Characters that should be left alone in character classes when a +-- SIMILAR TO regexp pattern is converted to POSIX style. +-- Underscore "_" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '_[_[:alpha:]_]_'; + QUERY PLAN +--------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:.[_[:alpha:]_].)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Percentage "%" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '%[%[:alnum:]%]%'; + QUERY PLAN +----------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:.*[%[:alnum:]%].*)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Dot "." +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '.[.[:alnum:].].'; + QUERY PLAN +----------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:\.[.[:alnum:].]\.)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Dollar "$" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '$[$[:alnum:]$]$'; + QUERY PLAN +----------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:\$[$[:alnum:]$]\$)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Opening parenthesis "(" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '([([:alnum:](]('; + QUERY PLAN +------------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:(?:[([:alnum:](](?:)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Caret "^" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '^[^[:alnum:]^[^^][[^^]][\^][[\^]]\^]^'; + QUERY PLAN +--------------------------------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:\^[^[:alnum:]^[^^][[^^]][\^][[\^]]\^]\^)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Closing square bracket "]" at the beginning of character class +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '[]%][^]%][^%]%'; + QUERY PLAN +--------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:[]%][^]%][^%].*)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + +-- Closing square bracket effective after two carets at the beginning +-- of character class. +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '[^^]^'; + QUERY PLAN +------------------------------------------------------ + Result + Output: ((InitPlan 1).col1 ~ '^(?:[^^]\^)$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + -- Test backslash escapes in regexp_replace's replacement string SELECT regexp_replace('1112223333', E'(\\d{3})(\\d{3})(\\d{4})', E'(\\1) \\2-\\3'); regexp_replace diff --git a/src/test/regress/sql/strings.sql b/src/test/regress/sql/strings.sql index f7b325baadf4..34c52b23604b 100644 --- a/src/test/regress/sql/strings.sql +++ b/src/test/regress/sql/strings.sql @@ -197,6 +197,26 @@ SELECT 'abcd\efg' SIMILAR TO '_bcd\%' ESCAPE '' AS true; SELECT 'abcdefg' SIMILAR TO '_bcd%' ESCAPE NULL AS null; SELECT 'abcdefg' SIMILAR TO '_bcd#%' ESCAPE '##' AS error; +-- Characters that should be left alone in character classes when a +-- SIMILAR TO regexp pattern is converted to POSIX style. +-- Underscore "_" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '_[_[:alpha:]_]_'; +-- Percentage "%" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '%[%[:alnum:]%]%'; +-- Dot "." +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '.[.[:alnum:].].'; +-- Dollar "$" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '$[$[:alnum:]$]$'; +-- Opening parenthesis "(" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '([([:alnum:](]('; +-- Caret "^" +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '^[^[:alnum:]^[^^][[^^]][\^][[\^]]\^]^'; +-- Closing square bracket "]" at the beginning of character class +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '[]%][^]%][^%]%'; +-- Closing square bracket effective after two carets at the beginning +-- of character class. +EXPLAIN (VERBOSE, COSTS OFF) SELECT (SELECT '') SIMILAR TO '[^^]^'; + -- Test backslash escapes in regexp_replace's replacement string SELECT regexp_replace('1112223333', E'(\\d{3})(\\d{3})(\\d{4})', E'(\\1) \\2-\\3'); SELECT regexp_replace('foobarrbazz', E'(.)\\1', E'X\\&Y', 'g'); -- 2.49.0