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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2023-04-06 15:52:37 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2023-04-06 15:52:37 -0400 |
| commit | a1fb4bd8562e0a7f162ff8a08c3c2ecdeb792f80 (patch) | |
| tree | 6c583557c7f51c476360e77b142da5ae551228a0 /src/backend | |
| parent | 790be6f31e6ae0484890afe77b1080b8299f6b92 (diff) | |
| download | postgresql-a1fb4bd8562e0a7f162ff8a08c3c2ecdeb792f80.tar.gz postgresql-a1fb4bd8562e0a7f162ff8a08c3c2ecdeb792f80.zip | |
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
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/tsearch/wparser_def.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/backend/tsearch/wparser_def.c b/src/backend/tsearch/wparser_def.c index 53a545863aa..7fd3a20400e 100644 --- a/src/backend/tsearch/wparser_def.c +++ b/src/backend/tsearch/wparser_def.c @@ -2046,6 +2046,9 @@ 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 @@ -2350,7 +2353,8 @@ 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)) @@ -2505,7 +2509,7 @@ 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)) |