From d34695b63e65f16f285df07f9aa13ad145dbc42e Mon Sep 17 00:00:00 2001
From: martijn <martijn@openbsd.org>
Date: Fri, 7 May 2021 14:31:27 +0000
Subject: [PATCH] Fix the \x escape sequence to be limited to max 2 characters,
 instead of consuming as long as there are isxdigit(3) characters available.

While here document it and mark it as an extension.

OK millert@
---
 usr.bin/printf/printf.1 | 12 +++++++++---
 usr.bin/printf/printf.c | 12 ++++--------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/usr.bin/printf/printf.1 b/usr.bin/printf/printf.1
index 73ea4645a60..37e2697810f 100644
--- a/usr.bin/printf/printf.1
+++ b/usr.bin/printf/printf.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: printf.1,v 1.34 2020/01/16 16:46:47 schwarze Exp $
+.\"	$OpenBSD: printf.1,v 1.35 2021/05/07 14:31:27 martijn Exp $
 .\"
 .\" Copyright (c) 1989, 1990 The Regents of the University of California.
 .\" All rights reserved.
@@ -32,7 +32,7 @@
 .\"
 .\"	from: @(#)printf.1	5.11 (Berkeley) 7/24/91
 .\"
-.Dd $Mdocdate: January 16 2020 $
+.Dd $Mdocdate: May 7 2021 $
 .Dt PRINTF 1
 .Os
 .Sh NAME
@@ -103,6 +103,11 @@ Write a backslash character.
 Write an 8-bit character whose ASCII value is
 the 1-, 2-, or 3-digit octal number
 .Ar num .
+.It Cm \ex Ns Ar num
+Write an 8-bit character whose ASCII value is
+the 1- or 2-digit hexadecimal
+number
+.Ar num .
 .El
 .Pp
 Each format specification is introduced by the percent
@@ -383,7 +388,8 @@ and always operates as if
 were set.
 .Pp
 The escape sequences
-.Cm \ee
+.Cm \ee ,
+.Cm \ex
 and
 .Cm \e' ,
 as well as omitting the leading digit
diff --git a/usr.bin/printf/printf.c b/usr.bin/printf/printf.c
index 30feac0559a..ecbf4ba5927 100644
--- a/usr.bin/printf/printf.c
+++ b/usr.bin/printf/printf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: printf.c,v 1.26 2016/11/18 15:53:16 schwarze Exp $	*/
+/*	$OpenBSD: printf.c,v 1.27 2021/05/07 14:31:27 martijn Exp $	*/
 
 /*
  * Copyright (c) 1989 The Regents of the University of California.
@@ -275,7 +275,7 @@ static int
 print_escape(const char *str)
 {
 	const char *start = str;
-	int value;
+	int value = 0;
 	int c;
 
 	str++;
@@ -283,7 +283,7 @@ print_escape(const char *str)
 	switch (*str) {
 	case '0': case '1': case '2': case '3':
 	case '4': case '5': case '6': case '7':
-		for (c = 3, value = 0; c-- && isodigit(*str); str++) {
+		for (c = 3; c-- && isodigit(*str); str++) {
 			value <<= 3;
 			value += octtobin(*str);
 		}
@@ -293,14 +293,10 @@ print_escape(const char *str)
 
 	case 'x':
 		str++;
-		for (value = 0; isxdigit((unsigned char)*str); str++) {
+		for (c = 2; c-- && isxdigit((unsigned char)*str); str++) {
 			value <<= 4;
 			value += hextobin(*str);
 		}
-		if (value > UCHAR_MAX) {
-			warnx ("escape sequence out of range for character");
-			rval = 1;
-		}
 		putchar (value);
 		return str - start - 1;
 		/* NOTREACHED */
-- 
2.20.1