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

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.Dd July 1, 2026
.Dt BCOPY 9
.Os
.Sh NAME
.Nm bcopy
.Nd copy bytes in object
.Sh SYNOPSIS
.In sys/systm.h
.Ft void
.Fn bcopy "const void *src" "void *dst" "size_t len"
.Sh DESCRIPTION
The
.Fn bcopy
function copies
.Fa len
bytes from object
.Fa src
to object
.Fa dst
preserving the provenance of pointers in the copied object
.Pq see Xr memory_model 7 for further information .
The two objects may overlap.
If
.Fa len
is zero, no bytes are copied.
.Pp
The
.Fn bcopy
function is deprecated and
.Fn memcpy
or
.Fn memmove
should be used as appropriate in new code.
.Sh SEE ALSO
.Xr memcpy 9 ,
.Xr memmove 9
.Sh HISTORY
A
.Fn bcopy
function appeared in
.Bx 4.2 .
.Pp
.St -p1003.1-2008
removes the specification of
.Fn bcopy
and it is marked as LEGACY in
.St -p1003.1-2004 .
New programs should use
.Xr memmove 3 .
If the input and output buffer do not overlap, then
.Xr memcpy 3
is more efficient.
Note that
.Fn bcopy
takes
.Ar src
and
.Ar dst
in the opposite order from
.Fn memmove
and
.Fn memcpy .
In practice,
.In sys/systm.h
defines
.Fn bcopy
as a macro that calls
.Fn memmove
since
.Fx 12.0 .