From 062d999e00c36692605b1ac394ffcfbb340e1771 Mon Sep 17 00:00:00 2001 From: millert <> Date: Thu, 19 Dec 2013 20:52:37 +0000 Subject: Split out strncpy and strncat from strcpy and strcat manuals. Requested by deraadt@ --- src/lib/libc/string/strncpy.3 | 153 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 153 insertions(+) create mode 100644 src/lib/libc/string/strncpy.3 (limited to 'src/lib/libc/string/strncpy.3') diff --git a/src/lib/libc/string/strncpy.3 b/src/lib/libc/string/strncpy.3 new file mode 100644 index 0000000000..dd8ddb86fc --- /dev/null +++ b/src/lib/libc/string/strncpy.3 @@ -0,0 +1,153 @@ +.\" $OpenBSD: strncpy.3,v 1.1 2013/12/19 20:52:37 millert Exp $ +.\" +.\" Copyright (c) 1990, 1991 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Chris Torek and the American National Standards Committee X3, +.\" on Information Processing Systems. +.\" +.\" 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. +.\" 3. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" 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. +.\" +.Dd $Mdocdate: December 19 2013 $ +.Dt STRNCPY 3 +.Os +.Sh NAME +.Nm strncpy +.Nd copy part of a string to another +.Sh SYNOPSIS +.In string.h +.Ft char * +.Fn strncpy "char *dst" "const char *src" "size_t len" +.Sh DESCRIPTION +The +.Fn strncpy +function copies not more than +.Fa len +characters from the string +.Fa src +to +.Fa dst . +If +.Fa src +is less than +.Fa len +characters long, +it appends +.Ql \e0 +characters for the rest of +.Fa len . +If the length of +.Fa src +is greater than or equal to +.Fa len , +.Fa dst +will +.Em not +be NUL-terminated. +.Pp +If the +.Fa src +and +.Fa dst +strings overlap, the behavior is undefined. +.Sh RETURN VALUES +The +.Fn strncpy +function returns +.Fa dst . +.Sh EXAMPLES +The following sets +.Va chararray +to +.Dq abc\e0\e0\e0 : +.Bd -literal -offset indent +(void)strncpy(chararray, "abc", 6); +.Ed +.Pp +The following sets +.Va chararray +to +.Dq abcdef +and does +.Em not +NUL terminate +.Va chararray +because the length of the source string is greater than or equal to the +length parameter. +.Fn strncpy +.Em only +NUL terminates the destination string when the length of the source +string is less than the length parameter. +.Bd -literal -offset indent +(void)strncpy(chararray, "abcdefgh", 6); +.Ed +.Pp +The following copies as many characters from +.Va input +to +.Va buf +as will fit and NUL terminates the result. +Because +.Fn strncpy +does +.Em not +guarantee to NUL terminate the string itself, it must be done by hand. +.Bd -literal -offset indent +char buf[BUFSIZ]; + +(void)strncpy(buf, input, sizeof(buf) - 1); +buf[sizeof(buf) - 1] = '\e0'; +.Ed +.Pp +Note that +.Xr strlcpy 3 +is a better choice for this kind of operation. +The equivalent using +.Xr strlcpy 3 +is simply: +.Bd -literal -offset indent +(void)strlcpy(buf, input, sizeof(buf)); +.Ed +.Sh SEE ALSO +.Xr bcopy 3 , +.Xr memccpy 3 , +.Xr memcpy 3 , +.Xr memmove 3 , +.Xr strcat 3 , +.Xr strlcpy 3 , +.Xr strncat 3 , +.Xr wcscpy 3 , +.Xr wcslcpy 3 +.Sh STANDARDS +The +.Fn strncpy +function conforms to +.St -ansiC . +.Sh HISTORY +The +.Fn strncpy +function first appeared in +.At v7 . -- cgit v1.2.3-55-g6feb