From f0c56f1f95ab35dca3d7ff65f783289a6b225146 Mon Sep 17 00:00:00 2001 From: Laurenz Albe Date: Fri, 23 May 2025 11:35:32 +0200 Subject: [PATCH v2] 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 | 36 ++++++++++++++++++++++----- src/test/regress/expected/strings.out | 12 +++++++++ src/test/regress/sql/strings.sql | 3 +++ 3 files changed, 45 insertions(+), 6 deletions(-) diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c index edee1f7880b..9d6f7675c64 100644 --- a/src/backend/utils/adt/regexp.c +++ b/src/backend/utils/adt/regexp.c @@ -773,7 +773,8 @@ similar_escape_internal(text *pat_text, text *esc_text) int plen, elen; bool afterescape = false; - bool incharclass = false; + int charclass_depth = 0; /* sqare bracket nesting level */ + int charclass_start = 0; int nquotes = 0; p = VARDATA_ANY(pat_text); @@ -904,7 +905,7 @@ 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 +954,41 @@ 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_depth++; + else if (pchar == ']' && charclass_start > 2) + 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. However, 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 174f0a68331..ce230961b5c 100644 --- a/src/test/regress/expected/strings.out +++ b/src/test/regress/expected/strings.out @@ -614,6 +614,18 @@ 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. +-- ".", "_", "%", "$", "(" and "^" should be left alone in character classes +EXPLAIN (VERBOSE, COSTS OFF) +SELECT (SELECT '') SIMILAR TO '.[.[:alnum:]_]_[]%]%[^]$]$[^^]^[(](p)'; + QUERY PLAN +------------------------------------------------------------------------------------------- + Result + Output: ((InitPlan 1).col1 ~ '^(?:\.[.[:alnum:]_].[]%].*[^]$]\$[^^]\^[(](?:p))$'::text) + InitPlan 1 + -> Result + Output: ''::text +(5 rows) + -- Test backslash escapes in regexp_replace's replacement string SELECT regexp_replace('1112223333', E'(\\d{3})(\\d{3})(\\d{4})', E'(\\1) \\2-\\3'); regexp_replace diff --git a/src/test/regress/sql/strings.sql b/src/test/regress/sql/strings.sql index f7b325baadf..94b9aa48e90 100644 --- a/src/test/regress/sql/strings.sql +++ b/src/test/regress/sql/strings.sql @@ -196,6 +196,9 @@ SELECT 'abcd\efg' SIMILAR TO '_bcd\%' ESCAPE '' AS true; -- these behaviors are per spec, though: SELECT 'abcdefg' SIMILAR TO '_bcd%' ESCAPE NULL AS null; SELECT 'abcdefg' SIMILAR TO '_bcd#%' ESCAPE '##' AS error; +-- ".", "_", "%", "$", "(" and "^" should be left alone in character classes +EXPLAIN (VERBOSE, COSTS OFF) +SELECT (SELECT '') SIMILAR TO '.[.[:alnum:]_]_[]%]%[^]$]$[^^]^[(](p)'; -- Test backslash escapes in regexp_replace's replacement string SELECT regexp_replace('1112223333', E'(\\d{3})(\\d{3})(\\d{4})', E'(\\1) \\2-\\3'); -- 2.49.0