1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" from: @(#)strcpy.3 8.1 (Berkeley) 6/4/93 33.\" $NetBSD: strcpy.3,v 1.20 2009/05/02 09:37:32 wiz Exp $ 34.\" 35.Dd May 1, 2009 36.Dt STRCPY 3 37.Os 38.Sh NAME 39.Nm stpcpy , 40.Nm stpncpy , 41.Nm strcpy , 42.Nm strncpy 43.Nd copy strings 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In string.h 48.Ft char * 49.Fn stpcpy "char * restrict dst" "const char * restrict src" 50.Ft char * 51.Fn stpncpy "char * restrict dst" "const char * restrict src" "size_t len" 52.Ft char * 53.Fn strcpy "char * restrict dst" "const char * restrict src" 54.Ft char * 55.Fn strncpy "char * restrict dst" "const char * restrict src" "size_t len" 56.Sh DESCRIPTION 57The 58.Fn stpcpy 59and 60.Fn strcpy 61functions 62copy the string 63.Fa src 64to 65.Fa dst 66(including the terminating 67.Ql \e0 68character). 69.Pp 70The 71.Fn stpncpy 72and 73.Fn strncpy 74functions copy at most 75.Fa len 76characters from 77.Fa src 78into 79.Fa dst . 80If 81.Fa src 82is less than 83.Fa len 84characters long, 85the remainder of 86.Fa dst 87is filled with 88.Ql \e0 89characters. 90Otherwise, 91.Fa dst 92is 93.Em not 94terminated. 95.Sh RETURN VALUES 96The 97.Fn strcpy 98and 99.Fn strncpy 100functions 101return 102.Fa dst . 103The 104.Fn stpcpy 105and 106.Fn stpncpy 107functions return a pointer to the terminating 108.Ql \e0 109character of 110.Fa dst . 111If 112.Fn stpncpy 113does not terminate 114.Fa dst 115with a 116.Dv NUL 117character, it instead returns a pointer to 118.Li dst[len] 119(which does not necessarily refer to a valid memory location.) 120.Sh EXAMPLES 121The following sets 122.Va chararray 123to 124.Dq Li abc\e0\e0\e0 : 125.Bd -literal -offset indent 126char chararray[6]; 127 128(void)strncpy(chararray, "abc", sizeof(chararray)); 129.Ed 130.Pp 131The following sets 132.Va chararray 133to 134.Dq Li abcdef : 135.Bd -literal -offset indent 136char chararray[6]; 137 138(void)strncpy(chararray, "abcdefgh", sizeof(chararray)); 139.Ed 140.Pp 141Note that it does 142.Em not 143.Dv NUL Ns No -terminate 144.Va chararray 145because the length of the source string is greater than or equal 146to the length parameter. 147.Fn strncpy 148.Em only 149.Dv NUL Ns No -terminates 150the destination string when the length of the source 151string is less than the length parameter. 152.Pp 153The following copies as many characters from 154.Va input 155to 156.Va buf 157as will fit and 158.Dv NUL Ns No -terminates 159the result. 160Because 161.Fn strncpy 162does 163.Em not 164guarantee to 165.Dv NUL Ns No -terminate 166the string itself, this must be done explicitly. 167.Bd -literal -offset indent 168char buf[1024]; 169 170(void)strncpy(buf, input, sizeof(buf) - 1); 171buf[sizeof(buf) - 1] = '\e0'; 172.Ed 173.Pp 174This could be better and more simply achieved using 175.Xr strlcpy 3 , 176as shown in the following example: 177.Bd -literal -offset indent 178(void)strlcpy(buf, input, sizeof(buf)); 179.Ed 180.Pp 181Note that because 182.Xr strlcpy 3 183is not defined in any standards, it should 184only be used when portability is not a concern. 185.Sh SEE ALSO 186.Xr bcopy 3 , 187.Xr memccpy 3 , 188.Xr memcpy 3 , 189.Xr memmove 3 , 190.Xr strlcpy 3 , 191.Xr wcscpy 3 192.Sh STANDARDS 193The 194.Fn strcpy 195and 196.Fn strncpy 197functions 198conform to 199.St -isoC-99 . 200The 201.Fn stpcpy 202and 203.Fn stpncpy 204functions conform to 205.St -p1003.1-2008 . 206.Sh HISTORY 207The 208.Fn stpcpy 209and 210.Fn stpncpy 211functions first appeared in 212.Nx 6.0 . 213.Sh SECURITY CONSIDERATIONS 214The 215.Fn strcpy 216and 217.Fn stpcpy 218functions are easily misused in a manner which enables malicious users 219to arbitrarily change a running program's functionality through a 220buffer overflow attack. 221