From 03e0bc1171c864b9add64f0ef5351126faa4e3f5 Mon Sep 17 00:00:00 2001 From: Andrew Gierth Date: Wed, 12 Sep 2018 19:31:06 +0100 Subject: [PATCH] Repair bug in regexp split performance improvements. Commit c8ea87e4b introduced a temporary conversion buffer for substrings extracted during regexp splits. Unfortunately the code that sized it was failing to ignore the effects of ignored degenerate regexp matches, so for regexp_split_* calls it could under-size the buffer in such cases. Fix, and add some regression test cases (though those will only catch the bug if run in a multibyte encoding). Backpatch to 9.3 as the faulty code was. Thanks to the PostGIS project, Regina Obe and Paul Ramsey for the report (via IRC) and assistance in analysis. Patch by me. --- src/backend/utils/adt/regexp.c | 16 ++++++++++------ src/test/regress/expected/strings.out | 18 ++++++++++++++++++ src/test/regress/sql/strings.sql | 3 +++ 3 files changed, 31 insertions(+), 6 deletions(-) diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c index e3a852769f..7463c0dd2f 100644 --- a/src/backend/utils/adt/regexp.c +++ b/src/backend/utils/adt/regexp.c @@ -936,6 +936,7 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags, int array_len; int array_idx; int prev_match_end; + int prev_valid_match_end; int start_search; int maxlen = 0; /* largest fetch length in characters */ @@ -991,6 +992,7 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags, /* search for the pattern, perhaps repeatedly */ prev_match_end = 0; + prev_valid_match_end = 0; start_search = 0; while (RE_wchar_execute(cpattern, wide_str, wide_len, start_search, pmatch_len, pmatch)) @@ -1043,13 +1045,15 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags, matchctx->nmatches++; /* - * check length of unmatched portion between end of previous match - * and start of current one + * check length of unmatched portion between end of previous valid + * (nondegenerate, or degenerate but not ignored) match and start + * of current one */ if (fetching_unmatched && pmatch[0].rm_so >= 0 && - (pmatch[0].rm_so - prev_match_end) > maxlen) - maxlen = (pmatch[0].rm_so - prev_match_end); + (pmatch[0].rm_so - prev_valid_match_end) > maxlen) + maxlen = (pmatch[0].rm_so - prev_valid_match_end); + prev_valid_match_end = pmatch[0].rm_eo; } prev_match_end = pmatch[0].rm_eo; @@ -1075,8 +1079,8 @@ setup_regexp_matches(text *orig_str, text *pattern, text *flags, * input string */ if (fetching_unmatched && - (wide_len - prev_match_end) > maxlen) - maxlen = (wide_len - prev_match_end); + (wide_len - prev_valid_match_end) > maxlen) + maxlen = (wide_len - prev_valid_match_end); /* * Keep a note of the end position of the string for the benefit of diff --git a/src/test/regress/expected/strings.out b/src/test/regress/expected/strings.out index 19708c32fd..8e7470d1cb 100644 --- a/src/test/regress/expected/strings.out +++ b/src/test/regress/expected/strings.out @@ -674,6 +674,24 @@ SELECT regexp_split_to_array('123456','.'); {"","","","","","",""} (1 row) +SELECT regexp_split_to_array('123456',''); + regexp_split_to_array +----------------------- + {1,2,3,4,5,6} +(1 row) + +SELECT regexp_split_to_array('123456','(?:)'); + regexp_split_to_array +----------------------- + {1,2,3,4,5,6} +(1 row) + +SELECT regexp_split_to_array('1',''); + regexp_split_to_array +----------------------- + {1} +(1 row) + -- errors SELECT foo, length(foo) FROM regexp_split_to_table('thE QUick bROWn FOx jUMPs ovEr The lazy dOG', 'e', 'zippy') AS foo; ERROR: invalid regexp option: "z" diff --git a/src/test/regress/sql/strings.sql b/src/test/regress/sql/strings.sql index f9cfaeb44a..5e39458bd2 100644 --- a/src/test/regress/sql/strings.sql +++ b/src/test/regress/sql/strings.sql @@ -188,6 +188,9 @@ SELECT regexp_split_to_array('the quick brown fox jumps over the lazy dog', 'nom SELECT regexp_split_to_array('123456','1'); SELECT regexp_split_to_array('123456','6'); SELECT regexp_split_to_array('123456','.'); +SELECT regexp_split_to_array('123456',''); +SELECT regexp_split_to_array('123456','(?:)'); +SELECT regexp_split_to_array('1',''); -- errors SELECT foo, length(foo) FROM regexp_split_to_table('thE QUick bROWn FOx jUMPs ovEr The lazy dOG', 'e', 'zippy') AS foo; SELECT regexp_split_to_array('thE QUick bROWn FOx jUMPs ovEr The lazy dOG', 'e', 'iz');