pub trait VmIo: Send + Sync {
// Required methods
fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>;
fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>;
// Provided methods
fn read_val<T: Pod>(&self, offset: usize) -> Result<T> { ... }
fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()> { ... }
fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()> { ... }
fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()> { ... }
fn write_vals<'a, T: Pod + 'a, I: Iterator<Item = &'a T>>(
&self,
offset: usize,
iter: I,
align: usize,
) -> Result<usize> { ... }
}Expand description
A trait that enables reading/writing data from/to a VM object,
e.g., VmSpace, FrameVec, and Frame.
§Concurrency
The methods may be executed by multiple concurrent reader and writer threads. In this case, if the results of concurrent reads or writes desire predictability or atomicity, the users should add extra mechanism for such properties.
Required Methods§
sourcefn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>
fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>
Reads a specified number of bytes at a specified offset into a given buffer.
§No short reads
On success, the output buf must be filled with the requested data
completely. If, for any reason, the requested data is only partially
available, then the method shall return an error.
sourcefn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>
fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>
Writes a specified number of bytes from a given buffer at a specified offset.
§No short writes
On success, the input buf must be written to the VM object entirely.
If, for any reason, the input data can only be written partially,
then the method shall return an error.
Provided Methods§
sourcefn read_val<T: Pod>(&self, offset: usize) -> Result<T>
fn read_val<T: Pod>(&self, offset: usize) -> Result<T>
Reads a value of a specified type at a specified offset.
sourcefn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>
fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>
sourcefn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>
fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>
Writes a value of a specified type at a specified offset.
sourcefn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>
fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>
sourcefn write_vals<'a, T: Pod + 'a, I: Iterator<Item = &'a T>>(
&self,
offset: usize,
iter: I,
align: usize,
) -> Result<usize>
fn write_vals<'a, T: Pod + 'a, I: Iterator<Item = &'a T>>( &self, offset: usize, iter: I, align: usize, ) -> Result<usize>
Writes a sequence of values given by an iterator (iter) from the specified offset (offset).
The write process stops until the VM object does not have enough remaining space
or the iterator returns None. If any value is written, the function returns Ok(nr_written),
where nr_written is the number of the written values.
The offset of every value written by this method is aligned to the align-byte boundary.
Naturally, when align equals to 0 or 1, then the argument takes no effect:
the values will be written in the most compact way.
§Example
Initializes an VM object with the same value can be done easily with write_values.
use core::iter::self;
let _nr_values = vm_obj.write_vals(0, iter::repeat(0_u32), 0).unwrap();§Panics
This method panics if align is greater than two,
but not a power of two, in release mode.