1.0.0[−][src]Function core::intrinsics::copy
pub unsafe fn copy<T>(src: *const T, dst: *mut T, count: usize)
Copies count * size_of::<T>()
bytes from src
to dst
. The source
and destination may overlap.
If the source and destination will never overlap,
copy_nonoverlapping
can be used instead.
copy
is semantically equivalent to C's memmove
, but with the argument
order swapped. Copying takes place as if the bytes were copied from src
to a temporary array and then copied from the array to dst
.
Safety
Behavior is undefined if any of the following conditions are violated:
-
src
must be valid for reads ofcount * size_of::<T>()
bytes. -
dst
must be valid for writes ofcount * size_of::<T>()
bytes. -
Both
src
anddst
must be properly aligned.
Like read
, copy
creates a bitwise copy of T
, regardless of
whether T
is Copy
. If T
is not Copy
, using both the values
in the region beginning at *src
and the region beginning at *dst
can
violate memory safety.
Note that even if the effectively copied size (count * size_of::<T>()
) is
0
, the pointers must be non-NULL and properly aligned.
Examples
Efficiently create a Rust vector from an unsafe buffer:
use std::ptr; unsafe fn from_buf_raw<T>(ptr: *const T, elts: usize) -> Vec<T> { let mut dst = Vec::with_capacity(elts); dst.set_len(elts); ptr::copy(ptr, dst.as_mut_ptr(), elts); dst }Run