pub unsafe trait WriteBuf {
// Required methods
fn as_slice(&self) -> &[u8] ⓘ;
fn capacity(&self) -> usize;
fn as_mut_ptr(&mut self) -> *mut u8;
unsafe fn filled_until(&mut self, n: usize);
// Provided method
unsafe fn write_from<F>(&mut self, f: F) -> Result<usize, usize>
where F: FnOnce(*mut c_void, usize) -> Result<usize, usize> { ... }
}Expand description
Describe a resizeable bytes container like Vec<u8>.
Represents a contiguous segment of memory, a prefix of which is initialized.
It allows starting from an uninitializes chunk of memory and writing to it.
The main implementors are:
Vec<u8>and similar structures. These can start empty with a non-zero capacity, and they will be resized to cover the data written. Any existing data will be overwritten.[u8]and[u8; N]. These must start already-initialized, and will not be resized. It will be up to the caller to only use the part that was written.std::io::Cursor<T: WriteBuf>. This will ignore data before the cursor’s position, and append data after that.
Required Methods§
sourcefn as_slice(&self) -> &[u8] ⓘ
fn as_slice(&self) -> &[u8] ⓘ
Returns the valid data part of this container. Should only cover initialized data.
sourcefn capacity(&self) -> usize
fn capacity(&self) -> usize
Returns the full capacity of this container. May include uninitialized data.
sourcefn as_mut_ptr(&mut self) -> *mut u8
fn as_mut_ptr(&mut self) -> *mut u8
Returns a pointer to the start of the data.
sourceunsafe fn filled_until(&mut self, n: usize)
unsafe fn filled_until(&mut self, n: usize)
Indicates that the first n bytes of the container have been written.
Safety: this should only be called if the n first bytes of this buffer have actually been
initialized.
Provided Methods§
sourceunsafe fn write_from<F>(&mut self, f: F) -> Result<usize, usize>where
F: FnOnce(*mut c_void, usize) -> Result<usize, usize>,
unsafe fn write_from<F>(&mut self, f: F) -> Result<usize, usize>where F: FnOnce(*mut c_void, usize) -> Result<usize, usize>,
Call the given closure using the pointer and capacity from self.
Assumes the given function returns a parseable code, which if valid, represents how many
bytes were written to self.
The given closure must treat its first argument as pointing to potentially uninitialized memory, and should not read from it.
In addition, it must have written at least n bytes contiguously from this pointer, where
n is the returned value.