From 14fdf163717efe7730104832b7a4b09c963c42ea Mon Sep 17 00:00:00 2001
From: Yuri Pankov <yuripv@FreeBSD.org>
Date: Sun, 26 Jul 2020 09:15:05 +0000
Subject: [PATCH] sed: treat '[' as ordinary character in 'y' command

'y' does not handle bracket expressions, treat '[' as ordinary character
and do not apply bracket expression checks (GNU sed agrees).

PR:		247931
Reviewed by:	pfg, kevans
Tested by:	antoine (exp-run), Quentin L'Hours <lhoursquentin@gmail.com>
Differential Revision:	https://reviews.freebsd.org/D25640
---
 usr.bin/sed/compile.c          | 16 ++++++++++++----
 usr.bin/sed/tests/sed2_test.sh | 17 +++++++++++++++++
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/usr.bin/sed/compile.c b/usr.bin/sed/compile.c
index 99fa2b17a92f..a7cb3cbd6a73 100644
--- a/usr.bin/sed/compile.c
+++ b/usr.bin/sed/compile.c
@@ -437,11 +437,19 @@ compile_delimited(char *p, char *d, int is_tr)
 				linenum, fname);
 	while (*p) {
 		if (*p == '[' && *p != c) {
-			if ((d = compile_ccl(&p, d)) == NULL)
-				errx(1, "%lu: %s: unbalanced brackets ([])", linenum, fname);
-			continue;
+			if (!is_tr) {
+				if ((d = compile_ccl(&p, d)) == NULL) {
+					errx(1,
+					    "%lu: %s: unbalanced brackets ([])",
+					    linenum, fname);
+				}
+				continue;
+			}
 		} else if (*p == '\\' && p[1] == '[') {
-			*d++ = *p++;
+			if (is_tr)
+				p++;
+			else
+				*d++ = *p++;
 		} else if (*p == '\\' && p[1] == c) {
 			p++;
 		} else if (*p == '\\' &&
diff --git a/usr.bin/sed/tests/sed2_test.sh b/usr.bin/sed/tests/sed2_test.sh
index efa04f212ad4..9f831e0ed673 100755
--- a/usr.bin/sed/tests/sed2_test.sh
+++ b/usr.bin/sed/tests/sed2_test.sh
@@ -134,6 +134,22 @@ commands_on_stdin_body()
 	atf_check -o 'empty' sed -f - < insert_x
 }
 
+atf_test_case bracket_y
+bracket_y_head()
+{
+	atf_set "descr" "Verify '[' is ordinary character for 'y' command"
+}
+bracket_y_body()
+{
+	atf_check -e empty -o ignore echo | sed 'y/[/x/'
+	atf_check -e empty -o ignore echo | sed 'y/[]/xy/'
+	atf_check -e empty -o ignore echo | sed 'y/[a]/xyz/'
+	atf_check -e empty -o "inline:zyx" echo '][a' | sed 'y/[a]/xyz/'
+	atf_check -e empty -o "inline:bracket\n" echo 'bra[ke]' | sed 'y/[]/ct/'
+	atf_check -e empty -o "inline:bracket\n" \
+	    echo 'bra[ke]' | sed 'y[\[][ct['
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case inplace_command_q
@@ -142,4 +158,5 @@ atf_init_test_cases()
 	atf_add_test_case escape_subst
 	atf_add_test_case commands_on_stdin
 	atf_add_test_case hex_subst
+	atf_add_test_case bracket_y
 }