Think of an I/O array as a Vec<u8>
which lives outside the program. You can
index into it and copy data in and out. You can append to it or shrink it from
the back.
In I/O terms, an I/O array is an abstraction of a "file". It supports doing I/O
at arbitrary offsets, appending, and truncating. You can read from it in a
streaming fashion using [ReadAt::read_via_stream_at
].
TODO: Writing to an array in a streaming fashion is not yet supported.
This crate defines [ReadAt
], [WriteAt
], and [EditAt
] traits which define
interfaces to random-access or seekable devices, such as normal files, block
devices, disk partitions, and memory buffers.
It also defines [ArrayReader
], [ArrayWriter
], and [ArrayEditor
] types which
implement the above traits and and can be constructed from any file-like type.
On Posix-ish platforms, with support for WASI in development, these types just
contain a single file descriptor (and implement [AsRawFd
]), plus any
resources needed to safely hold the file descriptor live. On Windows, they
contain a single file handle (and implement [AsRawHandle
]).