From 34ad3aedb0ce4f36fd55aa916200a68a185bf1ed Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 6 Apr 2023 15:52:37 -0400 Subject: [PATCH] Fix ts_headline() edge cases for empty query and empty search text. tsquery's GETQUERY() macro is only safe to apply to a tsquery that is known non-empty; otherwise it gives a pointer to garbage. Before commit 5a617d75d, ts_headline() avoided this pitfall, but only in a very indirect, nonobvious way. (hlCover could not reach its TS_execute call, because if the query contains no lexemes then hlFirstIndex would surely return -1.) After that commit, it fell into the trap, resulting in weird errors such as "unrecognized operator" and/or valgrind complaints. In HEAD, fix this by not calling TS_execute_locations() at all for an empty query. In the back branches, add a defensive check to hlCover() --- that's not fixing any live bug, but I judge the code a bit too fragile as-is. Also, both mark_hl_fragments() and mark_hl_words() were careless about the possibility of empty search text: in the cases where no match has been found, they'd end up telling mark_fragment() to mark from word indexes 0 to 0 inclusive, even when there is no word 0. This is harmless since we over-allocated the prs->words array, but it does annoy valgrind. Fix so that the end index is -1 and thus mark_fragment() will do nothing in such cases. Bottom line is that this fixes a live bug in HEAD, but in the back branches it's only getting rid of a valgrind nitpick. Back-patch anyway. Per report from Alexander Lakhin. Discussion: https://postgr.es/m/c27f642d-020b-01ff-ae61-086af287c4fd@gmail.com --- src/backend/tsearch/wparser_def.c | 8 ++++++-- src/test/regress/expected/tsearch.out | 21 +++++++++++++++++++++ src/test/regress/sql/tsearch.sql | 6 ++++++ 3 files changed, 33 insertions(+), 2 deletions(-) diff --git a/src/backend/tsearch/wparser_def.c b/src/backend/tsearch/wparser_def.c index a3e5baf978..98029e78fb 100644 --- a/src/backend/tsearch/wparser_def.c +++ b/src/backend/tsearch/wparser_def.c @@ -2039,6 +2039,9 @@ hlCover(HeadlineParsedText *prs, TSQuery query, int max_cover, nextpmax; hlCheck ch; + if (query->size <= 0) + return false; /* empty query matches nothing */ + /* * We look for the earliest, shortest substring of prs->words that * satisfies the query. Both the pmin and pmax indices must be words @@ -2343,7 +2346,8 @@ mark_hl_fragments(HeadlineParsedText *prs, TSQuery query, bool highlightall, /* show the first min_words words if we have not marked anything */ if (num_f <= 0) { - startpos = endpos = curlen = 0; + startpos = curlen = 0; + endpos = -1; for (i = 0; i < prs->curwords && curlen < min_words; i++) { if (!NONWORDTOKEN(prs->words[i].type)) @@ -2498,7 +2502,7 @@ mark_hl_words(HeadlineParsedText *prs, TSQuery query, bool highlightall, if (bestlen < 0) { curlen = 0; - pose = 0; + pose = -1; for (i = 0; i < prs->curwords && curlen < min_words; i++) { if (!NONWORDTOKEN(prs->words[i].type)) diff --git a/src/test/regress/expected/tsearch.out b/src/test/regress/expected/tsearch.out index 45b92a6338..4e52edf610 100644 --- a/src/test/regress/expected/tsearch.out +++ b/src/test/regress/expected/tsearch.out @@ -1990,6 +1990,27 @@ to_tsquery('english','Lorem') && phraseto_tsquery('english','ullamcorper urna'), Lorem ipsum urna. Nullam nullam ullamcorper urna (1 row) +-- Edge cases with empty query +SELECT ts_headline('english', +'', ''::tsquery); +NOTICE: text-search query doesn't contain lexemes: "" +LINE 2: '', ''::tsquery); + ^ + ts_headline +------------- + +(1 row) + +SELECT ts_headline('english', +'foo bar', ''::tsquery); +NOTICE: text-search query doesn't contain lexemes: "" +LINE 2: 'foo bar', ''::tsquery); + ^ + ts_headline +------------- + foo bar +(1 row) + --Rewrite sub system CREATE TABLE test_tsquery (txtkeyword TEXT, txtsample TEXT); \set ECHO none diff --git a/src/test/regress/sql/tsearch.sql b/src/test/regress/sql/tsearch.sql index d929210998..168eb0b971 100644 --- a/src/test/regress/sql/tsearch.sql +++ b/src/test/regress/sql/tsearch.sql @@ -549,6 +549,12 @@ SELECT ts_headline('english', to_tsquery('english','Lorem') && phraseto_tsquery('english','ullamcorper urna'), 'MaxFragments=100, MaxWords=100, MinWords=1'); +-- Edge cases with empty query +SELECT ts_headline('english', +'', ''::tsquery); +SELECT ts_headline('english', +'foo bar', ''::tsquery); + --Rewrite sub system CREATE TABLE test_tsquery (txtkeyword TEXT, txtsample TEXT);