 @@ -1,14 +1,14 @@
-.\"	$NetBSD: ctype.3,v 1.23 2017/12/12 14:13:52 abhinav Exp $
+.\"	$NetBSD: ctype.3,v 1.24 2019/01/15 00:31:19 riastradh Exp $
 .\"
 .\" Copyright (c) 1991 Regents of the University of California.
 .\" All rights reserved.
 .\"
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
 .\" are met:
 .\" 1. Redistributions of source code must retain the above copyright
 .\"    notice, this list of conditions and the following disclaimer.
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
 @@ -20,27 +20,27 @@
 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
 .\"     @(#)ctype.3	6.5 (Berkeley) 4/19/91
 .\"
-.Dd December 8, 2017
+.Dd January 15, 2019
 .Dt CTYPE 3
 .Os
 .Sh NAME
 .Nm ctype
 .Nd character classification and mapping functions
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
 .In ctype.h
 .Fn isalpha "int c"
 .Fn isupper "int c"
 .Fn islower "int c"
 .Fn isdigit "int c"
 @@ -126,13 +126,83 @@ must first be cast to
 to ensure that the values are within the correct range.
 Casting a negative-valued
 .Vt char
 or
 .Vt signed char
 directly to
 .Vt int
 will produce a negative-valued
 .Vt int ,
 which will be outside the range of allowed values
 (unless it happens to be equal to
 .Dv EOF ,
 but even that would not give the desired result).
 .Pp
 Because the bugs may manifest as silent misbehavior or as crashes only
 when fed input outside the US-ASCII range, the
 .Nx
 implementation of the
 .Nm
 functions is designed to elicit a compiler warning for code that passes
 inputs of type
 .Vt char
 in order to flag code that may pass negative values at runtime that
 would lead to undefined behavior:
 .Bd -literal offset indent
 #include <ctype.h>
 #include <locale.h>
 #include <stdio.h>
 int
 main(int argc, char **argv)
+{
 	if (argc < 2)
 		return 1;
 	setlocale(LC_ALL, "");
 	printf("%d %d\en", *argv[1], isprint(*argv[1]));
 	printf("%d %d\en", (int)(unsigned char)*argv[1],
 	    isprint((int)(unsigned char)*argv[1]));
 	return 0;
+}
 .Ed
 .Pp
 When compiling this program, GCC reports a warning for the line that
 passes
 .Vt char .
 At runtime, you may get nonsense answers for some inputs without the
 cast -- if you're lucky and it doesn't crash or make demons come flying
 out of your nose:
 .Bd -literal -offset indent
 % gcc -Wall -o test test.c
 test.c: In function 'main':
 test.c:12:2: warning: array subscript has type 'char'
 % LANG=C ./test "`printf '\e270'`"
 -72 5
 0
 % LC_CTYPE=C ./test "`printf '\e377'`"
 -1 0
 0
 % LC_CTYPE=fr_FR.ISO8859-1 ./test "`printf '\e377'`"
 -1 0
 2
 .Ed
 .Pp
 Some implementations of libc, such as glibc as of 2018, attempt to
 avoid the worst of the undefined behavior by defining the functions to
 work for all integer inputs representable by either
 .Vt unsigned char
 or
 .Vt char ,
 and suppress the warning.
 However, this is not an excuse for avoiding conversion to
 .Vt unsigned char :
 if
 .Dv EOF
 coincides with any such value, as it does when it is -1 on platforms
 with signed
 .Dv char ,
 programs that pass
 .Vt char
 will still necessarily confuse the classification and mapping of
 .Dv EOF
 with the classification and mapping of some non-EOF inputs.