volatile_memory: add VolatileArrayRef

Allow easily access to an array stored in a VolatileMemory object, removing
the need to do multiplications and pointer offsetting.  It also generalizes
the existing methods copy_to and copy_from in VolatileSlice.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Cargo.toml

@@ -11,6 +11,7 @@ backend-mmap = []
 
 [dependencies]
 libc = ">=0.2.39"
+cast = ">=0"
 
 [dev-dependencies]
 matches = ">=0"

src/guest_memory.rs

@@ -57,6 +57,7 @@ impl From<volatile_memory::Error> for Error {
         match e {
             volatile_memory::Error::OutOfBounds { .. } => Error::InvalidBackendAddress,
             volatile_memory::Error::Overflow { .. } => Error::InvalidBackendAddress,
+            volatile_memory::Error::TooBig { .. } => Error::InvalidBackendAddress,
             volatile_memory::Error::IOError(e) => Error::IOError(e),
             volatile_memory::Error::PartialBuffer {
                 expected,

src/lib.rs

@@ -52,6 +52,6 @@ pub use mmap::{GuestMemoryMmap, GuestRegionMmap, MmapError, MmapRegion};
 
 pub mod volatile_memory;
 pub use volatile_memory::{
-    Error as VolatileMemoryError, Result as VolatileMemoryResult, VolatileMemory, VolatileRef,
-    VolatileSlice,
+    Error as VolatileMemoryError, Result as VolatileMemoryResult, VolatileArrayRef, VolatileMemory,
+    VolatileRef, VolatileSlice,
 };