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.\" @(#)strcpy.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd February 28, 2009 36.Dt STRCPY 3 37.Os 38.Sh NAME 39.Nm stpcpy, stpncpy, strcpy , strncpy 40.Nd copy strings 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In string.h 45.Ft char * 46.Fn stpcpy "char * restrict dst" "const char * restrict src" 47.Ft char * 48.Fn stpncpy "char * restrict dst" "const char * restrict src" "size_t len" 49.Ft char * 50.Fn strcpy "char * restrict dst" "const char * restrict src" 51.Ft char * 52.Fn strncpy "char * restrict dst" "const char * restrict src" "size_t len" 53.Sh DESCRIPTION 54The 55.Fn stpcpy 56and 57.Fn strcpy 58functions 59copy the string 60.Fa src 61to 62.Fa dst 63(including the terminating 64.Ql \e0 65character.) 66If 67.Fa src 68and 69.Fa dst 70overlap, the results are undefined. 71.Pp 72The 73.Fn stpncpy 74and 75.Fn strncpy 76functions copy at most 77.Fa len 78characters from 79.Fa src 80into 81.Fa dst . 82If 83.Fa src 84is less than 85.Fa len 86characters long, 87the remainder of 88.Fa dst 89is filled with 90.Ql \e0 91characters. 92Otherwise, 93.Fa dst 94is 95.Em not 96terminated. 97If 98.Fa src 99and 100.Fa dst 101overlap, the results are undefined. 102.Sh RETURN VALUES 103The 104.Fn strcpy 105and 106.Fn strncpy 107functions 108return 109.Fa dst . 110The 111.Fn stpcpy 112and 113.Fn stpncpy 114functions return a pointer to the terminating 115.Ql \e0 116character of 117.Fa dst . 118If 119.Fn stpncpy 120does not terminate 121.Fa dst 122with a 123.Dv NUL 124character, it instead returns a pointer to 125.Li dst[n] 126(which does not necessarily refer to a valid memory location.) 127.Sh EXAMPLES 128The following sets 129.Va chararray 130to 131.Dq Li abc\e0\e0\e0 : 132.Bd -literal -offset indent 133char chararray[6]; 134 135(void)strncpy(chararray, "abc", sizeof(chararray)); 136.Ed 137.Pp 138The following sets 139.Va chararray 140to 141.Dq Li abcdef : 142.Bd -literal -offset indent 143char chararray[6]; 144 145(void)strncpy(chararray, "abcdefgh", sizeof(chararray)); 146.Ed 147.Pp 148Note that it does 149.Em not 150.Tn NUL 151terminate 152.Va chararray 153because the length of the source string is greater than or equal 154to the length argument. 155.Pp 156The following copies as many characters from 157.Va input 158to 159.Va buf 160as will fit and 161.Tn NUL 162terminates the result. 163Because 164.Fn strncpy 165does 166.Em not 167guarantee to 168.Tn NUL 169terminate the string itself, this must be done explicitly. 170.Bd -literal -offset indent 171char buf[1024]; 172 173(void)strncpy(buf, input, sizeof(buf) - 1); 174buf[sizeof(buf) - 1] = '\e0'; 175.Ed 176.Pp 177This could be better achieved using 178.Xr strlcpy 3 , 179as shown in the following example: 180.Pp 181.Dl "(void)strlcpy(buf, input, sizeof(buf));" 182.Pp 183Note that because 184.Xr strlcpy 3 185is not defined in any standards, it should 186only be used when portability is not a concern. 187.Sh SEE ALSO 188.Xr bcopy 3 , 189.Xr memccpy 3 , 190.Xr memcpy 3 , 191.Xr memmove 3 , 192.Xr strlcpy 3 , 193.Xr wcscpy 3 194.Sh STANDARDS 195The 196.Fn strcpy 197and 198.Fn strncpy 199functions 200conform to 201.St -isoC . 202The 203.Fn stpcpy 204and 205.Fn stpncpy 206functions conform to 207.St -p1003.1-2008 . 208.Sh HISTORY 209The 210.Fn stpcpy 211function first appeared in 212.Fx 4.4 , 213and 214.Fn stpncpy 215was added in 216.Fx 8.0 . 217.Sh SECURITY CONSIDERATIONS 218The 219.Fn strcpy 220function is easily misused in a manner which enables malicious users 221to arbitrarily change a running program's functionality through a 222buffer overflow attack. 223