208 lines
4.7 KiB
Groff
208 lines
4.7 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" 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. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the University of
|
|
.\" California, Berkeley and its contributors.
|
|
.\" 4. 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.
|
|
.\"
|
|
.\" @(#)strcpy.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd August 9, 2001
|
|
.Dt STRCPY 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm strcpy , strncpy
|
|
.Nd copy strings
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In string.h
|
|
.Ft char *
|
|
.Fn stpcpy "char *dst" "const char *src"
|
|
.Ft char *
|
|
.Fn strcpy "char * restrict dst" "const char * restrict src"
|
|
.Ft char *
|
|
.Fn strncpy "char * restrict dst" "const char * restrict src" "size_t len"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn stpcpy
|
|
and
|
|
.Fn strcpy
|
|
functions
|
|
copy the string
|
|
.Fa src
|
|
to
|
|
.Fa dst
|
|
(including the terminating
|
|
.Ql \e0
|
|
character.)
|
|
.Pp
|
|
The
|
|
.Fn strncpy
|
|
function copies at most
|
|
.Fa len
|
|
characters from
|
|
.Fa src
|
|
into
|
|
.Fa dst .
|
|
If
|
|
.Fa src
|
|
is less than
|
|
.Fa len
|
|
characters long,
|
|
the remainder of
|
|
.Fa dst
|
|
is filled with
|
|
.Ql \e0
|
|
characters.
|
|
Otherwise,
|
|
.Fa dst
|
|
is
|
|
.Em not
|
|
terminated.
|
|
.Sh RETURN VALUES
|
|
The
|
|
.Fn strcpy
|
|
and
|
|
.Fn strncpy
|
|
functions
|
|
return
|
|
.Fa dst .
|
|
The
|
|
.Fn stpcpy
|
|
function returns a pointer to the terminating
|
|
.Ql \e0
|
|
character of
|
|
.Fa dst .
|
|
.Sh EXAMPLES
|
|
The following sets
|
|
.Va chararray
|
|
to
|
|
.Dq Li abc\e0\e0\e0 :
|
|
.Bd -literal -offset indent
|
|
char chararray[6];
|
|
|
|
(void)strncpy(chararray, "abc", sizeof(chararray));
|
|
.Ed
|
|
.Pp
|
|
The following sets
|
|
.Va chararray
|
|
to
|
|
.Dq Li abcdef :
|
|
.Bd -literal -offset indent
|
|
char chararray[6];
|
|
|
|
(void)strncpy(chararray, "abcdefgh", sizeof(chararray));
|
|
.Ed
|
|
.Pp
|
|
Note that it does
|
|
.Em not
|
|
.Tn NUL
|
|
terminate
|
|
.Va chararray
|
|
because the length of the source string is greater than or equal
|
|
to the length argument.
|
|
.Pp
|
|
The following copies as many characters from
|
|
.Va input
|
|
to
|
|
.Va buf
|
|
as will fit and
|
|
.Tn NUL
|
|
terminates the result.
|
|
Because
|
|
.Fn strncpy
|
|
does
|
|
.Em not
|
|
guarantee to
|
|
.Tn NUL
|
|
terminate the string itself, this must be done explicitly.
|
|
.Bd -literal -offset indent
|
|
char buf[1024];
|
|
|
|
(void)strncpy(buf, input, sizeof(buf) - 1);
|
|
buf[sizeof(buf) - 1] = '\e0';
|
|
.Ed
|
|
.Pp
|
|
This could be better achieved using
|
|
.Xr strlcpy 3 ,
|
|
as shown in the following example:
|
|
.Pp
|
|
.Dl "(void)strlcpy(buf, input, sizeof(buf));"
|
|
.Pp
|
|
Note that because
|
|
.Xr strlcpy 3
|
|
is not defined in any standards, it should
|
|
only be used when portability is not a concern.
|
|
.Sh SECURITY CONSIDERATIONS
|
|
The
|
|
.Fn strcpy
|
|
function is easily misused in a manner which enables malicious users
|
|
to arbitrarily change a running program's functionality through a
|
|
buffer overflow attack.
|
|
(See
|
|
the FSA
|
|
and
|
|
.Sx EXAMPLES . )
|
|
.Sh SEE ALSO
|
|
.Xr bcopy 3 ,
|
|
.Xr memccpy 3 ,
|
|
.Xr memcpy 3 ,
|
|
.Xr memmove 3 ,
|
|
.Xr strlcpy 3
|
|
.Rs
|
|
.%T "The FreeBSD Security Architecture"
|
|
.Re
|
|
(See
|
|
.Pa "/usr/share/doc/{to be decided}" . )
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn strcpy
|
|
and
|
|
.Fn strncpy
|
|
functions
|
|
conform to
|
|
.St -isoC .
|
|
The
|
|
.Fn stpcpy
|
|
function is an MS-DOS and GNUism.
|
|
The
|
|
.Fn stpcpy
|
|
function
|
|
conforms to no standard.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn stpcpy
|
|
function first appeared in
|
|
.Fx 4.4 ,
|
|
coming from 1998-vintage Linux.
|