1 files changed, 54 insertions, 7 deletions

diff --git a/grep.c b/grep.c
index d0b9b6c..3d7cd0e 100644
--- a/grep.c
+++ b/grep.c
@@ -477,6 +477,8 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	int options = PCRE2_MULTILINE;
 	const uint8_t *character_tables = NULL;
 	int jitret;
+	int patinforet;
+	size_t jitsizearg;
 
 	assert(opt->pcre2);
 
@@ -511,6 +513,30 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 		jitret = pcre2_jit_compile(p->pcre2_pattern, PCRE2_JIT_COMPLETE);
 		if (jitret)
 			die("Couldn't JIT the PCRE2 pattern '%s', got '%d'\n", p->pattern, jitret);
+
+		/*
+		 * The pcre2_config(PCRE2_CONFIG_JIT, ...) call just
+		 * tells us whether the library itself supports JIT,
+		 * but to see whether we're going to be actually using
+		 * JIT we need to extract PCRE2_INFO_JITSIZE from the
+		 * pattern *after* we do pcre2_jit_compile() above.
+		 *
+		 * This is because if the pattern contains the
+		 * (*NO_JIT) verb (see pcre2syntax(3))
+		 * pcre2_jit_compile() will exit early with 0. If we
+		 * then proceed to call pcre2_jit_match() further down
+		 * the line instead of pcre2_match() we'll either
+		 * segfault (pre PCRE 10.31) or run into a fatal error
+		 * (post PCRE2 10.31)
+		 */
+		patinforet = pcre2_pattern_info(p->pcre2_pattern, PCRE2_INFO_JITSIZE, &jitsizearg);
+		if (patinforet)
+			BUG("pcre2_pattern_info() failed: %d", patinforet);
+		if (jitsizearg == 0) {
+			p->pcre2_jit_on = 0;
+			return;
+		}
+
 		p->pcre2_jit_stack = pcre2_jit_stack_create(1, 1024 * 1024, NULL);
 		if (!p->pcre2_jit_stack)
 			die("Couldn't allocate PCRE2 JIT stack");
@@ -1476,31 +1502,52 @@ static void show_funcname_line(struct grep_opt *opt, struct grep_source *gs,
 	}
 }
 
+static int is_empty_line(const char *bol, const char *eol);
+
 static void show_pre_context(struct grep_opt *opt, struct grep_source *gs,
 			     char *bol, char *end, unsigned lno)
 {
-	unsigned cur = lno, from = 1, funcname_lno = 0;
-	int funcname_needed = !!opt->funcname;
-
-	if (opt->funcbody && !match_funcname(opt, gs, bol, end))
-		funcname_needed = 2;
+	unsigned cur = lno, from = 1, funcname_lno = 0, orig_from;
+	int funcname_needed = !!opt->funcname, comment_needed = 0;
 
 	if (opt->pre_context < lno)
 		from = lno - opt->pre_context;
 	if (from <= opt->last_shown)
 		from = opt->last_shown + 1;
+	orig_from = from;
+	if (opt->funcbody) {
+		if (match_funcname(opt, gs, bol, end))
+			comment_needed = 1;
+		else
+			funcname_needed = 1;
+		from = opt->last_shown + 1;
+	}
 
 	/* Rewind. */
-	while (bol > gs->buf &&
-	       cur > (funcname_needed == 2 ? opt->last_shown + 1 : from)) {
+	while (bol > gs->buf && cur > from) {
+		char *next_bol = bol;
 		char *eol = --bol;
 
 		while (bol > gs->buf && bol[-1] != '\n')
 			bol--;
 		cur--;
+		if (comment_needed && (is_empty_line(bol, eol) ||
+				       match_funcname(opt, gs, bol, eol))) {
+			comment_needed = 0;
+			from = orig_from;
+			if (cur < from) {
+				cur++;
+				bol = next_bol;
+				break;
+			}
+		}
 		if (funcname_needed && match_funcname(opt, gs, bol, eol)) {
 			funcname_lno = cur;
 			funcname_needed = 0;
+			if (opt->funcbody)
+				comment_needed = 1;
+			else
+				from = orig_from;
 		}
 	}