From f7d0343ead29cd3e44eccd1c8b7cc291b79209fe 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 d8b6921234..171fcc8a44 100644 --- a/src/backend/utils/adt/regexp.c +++ b/src/backend/utils/adt/regexp.c @@ -982,6 +982,7 @@ setup_regexp_matches(text *orig_str, text *pattern, pg_re_flags *re_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 */ @@ -1024,6 +1025,7 @@ setup_regexp_matches(text *orig_str, text *pattern, pg_re_flags *re_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)) @@ -1076,13 +1078,15 @@ setup_regexp_matches(text *orig_str, text *pattern, pg_re_flags *re_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; @@ -1108,8 +1112,8 @@ setup_regexp_matches(text *orig_str, text *pattern, pg_re_flags *re_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 cbe66c375c..189bdffdca 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 5a82237870..f2203ef1b1 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');