bsdgrep(1): various fixes of empty pattern/exit code/-c behavior

When an empty pattern is encountered in the pattern list, I had previously
broken bsdgrep to count that as a "match all" and ignore any other patterns
in the list. This commit rectifies that mistake, among others:

- The -v flag semantics were not quite right; lines matched should have been
  counted differently based on whether the -v flag was set or not. procline
  now definitively returns whether it's matched or not, and interpreting
  that result has been kicked up a level.
- Empty patterns with the -x flag was broken similarly to empty patterns
  with the -w flag. The former is a whole-line match and should be more
  strict, only matching blank lines. No -x and no -w will will match the
  empty string at the beginning of each line.
- The exit code with -L was broken, w.r.t. modern grep. Modern grap will
  exit(0) if any file that didn't match was output, so our interpretation
  was simply backwards. The new interpretation makes sense to me.

Tests updated and added to try and catch some of this.

This misbehavior was found by autoconf while fixing ports found in PR 229925
expecting either a more sane or a more GNU-like sed.

MFC after:	1 week

contrib/netbsd-tests/usr.bin/grep/t_grep.sh

@@ -413,6 +413,60 @@ wflag_emptypat_body()
 	atf_check -o file:test4 grep -w -e "" test4
 }
 
+atf_test_case xflag_emptypat
+xflag_emptypat_body()
+{
+	printf "" > test1
+	printf "\n" > test2
+	printf "qaz" > test3
+	printf " qaz\n" > test4
+
+	# -x is whole-line, more strict than -w.
+	atf_check -s exit:1 -o empty grep -x -e "" test1
+
+	atf_check -o file:test2 grep -x -e "" test2
+
+	atf_check -s exit:1 -o empty grep -x -e "" test3
+
+	atf_check -s exit:1 -o empty grep -x -e "" test4
+
+	total=$(wc -l /COPYRIGHT | sed 's/[^0-9]//g')
+
+	# Simple checks that grep -x with an empty pattern isn't matching every
+	# line.  The exact counts aren't important, as long as they don't
+	# match the total line count and as long as they don't match each other.
+	atf_check -o save:xpositive.count grep -Fxc '' /COPYRIGHT
+	atf_check -o save:xnegative.count grep -Fvxc '' /COPYRIGHT
+
+	atf_check -o not-inline:"${total}" cat xpositive.count
+	atf_check -o not-inline:"${total}" cat xnegative.count
+
+	atf_check -o not-file:xnegative.count cat xpositive.count
+}
+
+atf_test_case xflag_emptypat_plus
+xflag_emptypat_plus_body()
+{
+	printf "foo\n\nbar\n\nbaz\n" > target
+	printf "foo\n \nbar\n \nbaz\n" > target_spacelines
+	printf "foo\nbar\nbaz\n" > matches
+	printf " \n \n" > spacelines
+
+	printf "foo\n\nbar\n\nbaz\n" > patlist1
+	printf "foo\n\nba\n\nbaz\n" > patlist2
+
+	sed -e '/bar/d' target > matches_not2
+
+	# Normal handling first
+	atf_check -o file:target grep -Fxf patlist1 target
+	atf_check -o file:matches grep -Fxf patlist1 target_spacelines
+	atf_check -o file:matches_not2 grep -Fxf patlist2 target
+
+	# -v handling
+	atf_check -s exit:1 -o empty grep -Fvxf patlist1 target
+	atf_check -o file:spacelines grep -Fxvf patlist1 target_spacelines
+}
+
 atf_test_case excessive_matches
 excessive_matches_head()
 {
@@ -551,6 +605,12 @@ grep_nomatch_flags_head()
 
 grep_nomatch_flags_body()
 {
+	grep_type
+
+	if [ $? -eq $GREP_TYPE_GNU_FREEBSD ]; then
+		atf_expect_fail "this test does not pass with GNU grep in base"
+	fi
+
 	printf "A\nB\nC\n" > test1
 
 	atf_check -o inline:"1\n" grep -c -C 1 -e "B" test1
@@ -563,7 +623,7 @@ grep_nomatch_flags_body()
 	atf_check -o inline:"test1\n" grep -l -A 1 -e "B" test1
 	atf_check -o inline:"test1\n" grep -l -C 1 -e "B" test1
 
-	atf_check -s exit:1 -o inline:"test1\n" grep -L -e "D" test1
+	atf_check -o inline:"test1\n" grep -L -e "D" test1
 
 	atf_check -o empty grep -q -e "B" test1
 	atf_check -o empty grep -q -B 1 -e "B" test1
@@ -777,6 +837,8 @@ atf_init_test_cases()
 	atf_add_test_case egrep_empty_invalid
 	atf_add_test_case zerolen
 	atf_add_test_case wflag_emptypat
+	atf_add_test_case xflag_emptypat
+	atf_add_test_case xflag_emptypat_plus
 	atf_add_test_case excessive_matches
 	atf_add_test_case wv_combo_break
 	atf_add_test_case fgrep_sanity

usr.bin/grep/grep.c

@@ -218,20 +218,9 @@ static void
 add_pattern(char *pat, size_t len)
 {
 
-	/* Do not add further pattern is we already match everything */
-	if (matchall)
-	  return;
-
 	/* Check if we can do a shortcut */
 	if (len == 0) {
 		matchall = true;
-		for (unsigned int i = 0; i < patterns; i++) {
-			free(pattern[i].pat);
-		}
-		pattern = grep_realloc(pattern, sizeof(struct pat));
-		pattern[0].pat = NULL;
-		pattern[0].len = 0;
-		patterns = 1;
 		return;
 	}
 	/* Increase size if necessary */
@@ -654,7 +643,7 @@ main(int argc, char *argv[])
 	aargv += optind;
 
 	/* Empty pattern file matches nothing */
-	if (!needpattern && (patterns == 0))
+	if (!needpattern && (patterns == 0) && !matchall)
 		exit(1);
 
 	/* Fail if we don't have any pattern */
@@ -701,11 +690,10 @@ main(int argc, char *argv[])
 
 	r_pattern = grep_calloc(patterns, sizeof(*r_pattern));
 
-	/* Don't process any patterns if we have a blank one */
 #ifdef WITH_INTERNAL_NOSPEC
-	if (!matchall && grepbehave != GREP_FIXED) {
+	if (grepbehave != GREP_FIXED) {
 #else
-	if (!matchall) {
+	{
 #endif
 		/* Check if cheating is allowed (always is for fgrep). */
 		for (i = 0; i < patterns; ++i) {
@@ -737,7 +725,12 @@ main(int argc, char *argv[])
 				matched = true;
 		}
 
-	/* Find out the correct return value according to the
-	   results and the command line option. */
+	if (Lflag)
+		matched = !matched;
+
+	/*
+	 * Calculate the correct return value according to the
+	 * results and the command line option.
+	 */
 	exit(matched ? (file_err ? (qflag ? 0 : 2) : 0) : (file_err ? 2 : 1));
 }

usr.bin/grep/util.c

@@ -210,7 +210,7 @@ procmatch_match(struct mprintc *mc, struct parsec *pc)
 		while (pc->matchidx >= MAX_MATCHES) {
 			/* Reset matchidx and try again */
 			pc->matchidx = 0;
-			if (procline(pc))
+			if (procline(pc) == !vflag)
 				printline(pc, ':');
 			else
 				break;
@@ -355,7 +355,7 @@ procfile(const char *fn)
 			return (0);
 		}
 
-		line_matched = procline(&pc);
+		line_matched = procline(&pc) == !vflag;
 		if (line_matched)
 			++lines;
 
@@ -469,17 +469,32 @@ procline(struct parsec *pc)
 
 	matchidx = pc->matchidx;
 
-	/* Special case: empty pattern with -w flag, check first character */
-	if (matchall && wflag) {
+	/*
+	 * With matchall (empty pattern), we can try to take some shortcuts.
+	 * Emtpy patterns trivially match every line except in the -w and -x
+	 * cases.  For -w (whole-word) cases, we only match if the first
+	 * character isn't a word-character.  For -x (whole-line) cases, we only
+	 * match if the line is empty.
+	 */
+	if (matchall) {
 		if (pc->ln.len == 0)
 			return (true);
-		wend = L' ';
-		if (sscanf(&pc->ln.dat[0], "%lc", &wend) != 1 || iswword(wend))
-			return (false);
-		else
+		if (wflag) {
+			wend = L' ';
+			if (sscanf(&pc->ln.dat[0], "%lc", &wend) == 1 &&
+			    !iswword(wend))
+				return (true);
+		} else if (!xflag)
 			return (true);
-	} else if (matchall)
-		return (true);
+
+		/*
+		 * If we don't have any other patterns, we really don't match.
+		 * If we do have other patterns, we must fall through and check
+		 * them.
+		 */
+		if (patterns == 0)
+			return (false);
+	}
 
 	matched = false;
 	st = pc->lnstart;
@@ -609,8 +624,6 @@ procline(struct parsec *pc)
 
 	/* Reflect the new matchidx in the context */
 	pc->matchidx = matchidx;
-	if (vflag)
-		matched = !matched;
 	return matched;
 }