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.Dd July 1, 2026 33.Dt MEMCPY 9 34.Os 35.Sh NAME 36.Nm memcpy , 37.Nm memcpy_data 38.Nd copy bytes in memory 39.Sh SYNOPSIS 40.In sys/systm.h 41.Ft void * 42.Fn memcpy "void *dst" "const void *src" "size_t len" 43.Ft void * 44.Fn memcpy_data "void *dst" "const void *src" "size_t len" 45.Sh DESCRIPTION 46The 47.Fn memcpy 48function copies 49.Fa len 50bytes from object 51.Fa src 52to object 53.Fa dst 54in a manner that preserves the provenance of pointers in the copied object 55.Pq see Xr memory_model 7 for further information . 56If 57.Fa src 58and 59.Fa dst 60overlap, the results are not defined. 61The 62.Fn memcpy_data 63function does the same except that it does not preserve the provenance 64of pointers in the copied object. 65On CHERI targets, the validity tag of any copied capability is 66explicitly cleared. 67.Sh RETURN VALUES 68The 69.Fn memcpy 70and 71.Fn memcpy_data 72functions return the original value of 73.Fa dst . 74.Sh SEE ALSO 75.Xr bcopy 9 , 76.Xr memmove 9 , 77.Xr memmove_data 9 78.Sh STANDARDS 79The 80.Fn memcpy 81function 82conforms to 83.St -isoC . 84.Sh HISTORY 85The 86.Fn memcpy 87function first appeared in 88.At V 89and was reimplemented for 90.Bx 4.3 Tahoe . 91The 92.Fn memcpy_data 93function first appeared in 94.Fx 16.0 . 95