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grep: disable lookahead on error 

regexec(3) can fail.  E.g. on macOS it fails if it is used with an UTF-8
locale to match a valid regex against a buffer containing invalid UTF-8
characters.

git grep has two ways to search for matches in a file: Either it splits
its contents into lines and matches them separately, or it matches the
whole content and figures out line boundaries later.  The latter is done
by look_ahead() and it's quicker in the common case where most files
don't contain a match.

Fall back to line-by-line matching if look_ahead() encounters an
regexec(3) error by propagating errors out of patmatch() and bailing out
of look_ahead() if there is one.  This way we at least can find matches
in lines that contain only valid characters.  That matches the behavior
of grep(1) on macOS.

pcre2match() dies if pcre2_jit_match() or pcre2_match() fail, but since
we use the flag PCRE2_MATCH_INVALID_UTF it handles invalid UTF-8
characters gracefully.  So implement the fall-back only for regexec(3)
and leave the PCRE2 matching unchanged.

Reported-by: David Gstir <david@sigma-star.at>
Signed-off-by: René Scharfe <l.s.r@web.de>
Tested-by: David Gstir <david@sigma-star.at>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
maint
René Scharfe 2024-10-20 13:02:32 +02:00 committed by Taylor Blau
parent 34b6ce9b30
commit ce025ae4f6
2 changed files with 29 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
grep.c
View File

@ -906,15 +906,17 @@ static int patmatch(struct grep_pat *p,
const char *line, const char *eol,
regmatch_t *match, int eflags)
{
int hit;

if (p->pcre2_pattern)
hit = !pcre2match(p, line, eol, match, eflags);
else
hit = !regexec_buf(&p->regexp, line, eol - line, 1, match,
eflags);
return !pcre2match(p, line, eol, match, eflags);

return hit;
switch (regexec_buf(&p->regexp, line, eol - line, 1, match, eflags)) {
case 0:
return 1;
case REG_NOMATCH:
return 0;
default:
return -1;
}
}

static void strip_timestamp(const char *bol, const char **eol_p)
@ -952,6 +954,8 @@ static int headerless_match_one_pattern(struct grep_pat *p,

again:
hit = patmatch(p, bol, eol, pmatch, eflags);
if (hit < 0)
hit = 0;

if (hit && p->word_regexp) {
if ((pmatch[0].rm_so < 0) ||
@ -1461,6 +1465,8 @@ static int look_ahead(struct grep_opt *opt,
regmatch_t m;

hit = patmatch(p, bol, bol + *left_p, &m, 0);
if (hit < 0)
return -1;
if (!hit || m.rm_so < 0 || m.rm_eo < 0)
continue;
if (earliest < 0 || m.rm_so < earliest)
@ -1655,9 +1661,13 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
if (try_lookahead
&& !(last_hit
&& (show_function ||
lno <= last_hit + opt->post_context))
&& look_ahead(opt, &left, &lno, &bol))
lno <= last_hit + opt->post_context))) {
hit = look_ahead(opt, &left, &lno, &bol);
if (hit < 0)
try_lookahead = 0;
else if (hit)
break;
}
eol = end_of_line(bol, &left);

if ((ctx == GREP_CONTEXT_HEAD) && (eol == bol))

9
t/t7810-grep.sh
View File

@ -87,6 +87,7 @@ test_expect_success setup '
# Still a no-op.
function dummy() {}
EOF
printf "\200\nASCII\n" >invalid-utf8 &&
if test_have_prereq FUNNYNAMES
then
echo unusual >"\"unusual\" pathname" &&
@ -534,6 +535,14 @@ do
test_cmp expected actual
'

test_expect_success "grep $L searches past invalid lines on UTF-8 locale" '
LC_ALL=en_US.UTF-8 git grep A. invalid-utf8 >actual &&
cat >expected <<-EOF &&
invalid-utf8:ASCII
EOF
test_cmp expected actual
'

test_expect_success FUNNYNAMES "grep $L should quote unusual pathnames" '
cat >expected <<-EOF &&
${HC}"\"unusual\" pathname":unusual