Enum FileContent 

#[non_exhaustive]
pub enum FileContent {
    Owned(Vec<u8>),
    Range(FileRange),
}

A regular file’s contents: either bytes in memory, or a range of a file on the host read at the moment it is placed.

The two coexist in one entry list, deliberately. A source that maps an on-host archive yields handles; a caller that computes an entry’s bytes — rewriting one file of a tree it is otherwise passing through — supplies them owned, in the same Vec<SourceEntry>.

Why this is not just Vec<u8>

A format’s peak memory is otherwise the sum of every file it writes, because every file’s bytes are built before the first block is placed. A handle defers the bytes until the file is written, so the peak becomes the largest single file rather than the total.

The len is known without reading, which is what lets the model check a file against the large_file feature — and name the offending path — before any bytes are read.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Owned(Vec<u8>)

Bytes held in memory.

Range(FileRange)

A range of a file on the host, read when the content is placed.

Implementations

impl FileContent

pub fn len(&self) -> u64

The file’s length in bytes, without reading it.

pub fn is_empty(&self) -> bool

Whether the file is empty.

pub fn read(&self) -> Result<Cow<'_, [u8]>>

The file’s bytes, reading them from the host if they are not already in memory.

Bytes already held are borrowed, not copied: reading an Owned entry costs nothing, so a caller that reads every entry in turn never holds two copies of one file. Only a Range allocates, and only for as long as the caller keeps what it returned.

Errors

std::io::Error if the backing file cannot be read — including the case where it is shorter than the range claims, which means the file changed after the source that named it was built. An owned entry cannot fail.

Trait Implementations

impl Clone for FileContent

fn clone(&self) -> FileContent

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FileContent

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<&[u8]> for FileContent

fn from(bytes: &[u8]) -> Self

Converts to this type from the input type.

impl<const N: usize> From<&[u8; N]> for FileContent

fn from(bytes: &[u8; N]) -> Self

Converts to this type from the input type.

impl From<&str> for FileContent

fn from(text: &str) -> Self

Converts to this type from the input type.

impl From<FileRange> for FileContent

fn from(range: FileRange) -> Self

Converts to this type from the input type.

impl From<String> for FileContent

fn from(text: String) -> Self

Converts to this type from the input type.

impl From<Vec<u8>> for FileContent

fn from(bytes: Vec<u8>) -> Self

Converts to this type from the input type.

impl PartialEq for FileContent

fn eq(&self, other: &FileContent) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for FileContent

impl StructuralPartialEq for FileContent