xref: /freebsd/share/man/man9/memcpy.9 (revision 7f55dbe6ae89c356db1bc4fb2c42d9d007ae5da1)

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.Dd July 1, 2026
.Dt MEMCPY 9
.Os
.Sh NAME
.Nm memcpy ,
.Nm memcpy_data
.Nd copy bytes in memory
.Sh SYNOPSIS
.In sys/systm.h
.Ft void *
.Fn memcpy "void *dst" "const void *src" "size_t len"
.Ft void *
.Fn memcpy_data "void *dst" "const void *src" "size_t len"
.Sh DESCRIPTION
The
.Fn memcpy
function copies
.Fa len
bytes from object
.Fa src
to object
.Fa dst
in a manner that preserves the provenance of pointers in the copied object
.Pq see Xr memory_model 7 for further information .
If
.Fa src
and
.Fa dst
overlap, the results are not defined.
The
.Fn memcpy_data
function does the same except that it does not preserve the provenance
of pointers in the copied object.
On CHERI targets, the validity tag of any copied capability is
explicitly cleared.
.Sh RETURN VALUES
The
.Fn memcpy
and
.Fn memcpy_data
functions return the original value of
.Fa dst .
.Sh SEE ALSO
.Xr bcopy 9 ,
.Xr memmove 9 ,
.Xr memmove_data 9
.Sh STANDARDS
The
.Fn memcpy
function
conforms to
.St -isoC .
.Sh HISTORY
The
.Fn memcpy
function first appeared in
.At V
and was reimplemented for
.Bx 4.3 Tahoe .
The
.Fn memcpy_data
function first appeared in
.Fx 16.0 .