Struct Limits 

#[non_exhaustive]
pub struct Limits { /* private fields */ }

Caps a decoder enforces while it decodes.

Every check runs per output chunk, before the chunk is written, so a stream that would pass a cap stops at the cap; a decompression bomb costs at most max_output bytes of output and the time to produce them.

Limit	Default	Cost
max_output	64 MiB	one compare per output chunk
max_ratio	off	one multiply and compare per output chunk
ratio_floor	1 MiB	(the ratio is not checked below it)
max_header (gzip)	64 KiB	one counter per header byte
max_members (gzip)	1024	one counter per member

The ratio cap is off by default: DEFLATE’s largest possible ratio is about 1032 to 1, legitimate data (zero-filled images, repeated logs) reaches hundreds to one, and the absolute cap is what bounds memory. Turn it on when you know your data, for example at 50 for JSON APIs.

Examples

use compress_lib::Limits;

let limits = Limits::new().with_max_output(1 << 20).with_max_ratio(50);
assert_eq!(limits.max_output(), 1 << 20);
assert_eq!(limits.max_ratio(), 50);

Implementations

impl Limits

pub const DEFAULT_MAX_OUTPUT: u64

The default absolute output cap: 64 MiB.

pub const DEFAULT_RATIO_FLOOR: u64

The default output size below which the ratio is not checked: 1 MiB.

pub const DEFAULT_MAX_HEADER: usize

The default cap on gzip optional header fields together: 64 KiB.

pub const DEFAULT_MAX_MEMBERS: u32 = 1024

The default cap on gzip members in one stream: 1024.

pub const fn new() -> Self

The safe defaults (see the table on Limits).

Examples

use compress_lib::Limits;

assert_eq!(Limits::new().max_output(), 64 << 20);
assert_eq!(Limits::new(), Limits::default());

pub const fn unlimited() -> Self

No output cap and no ratio cap, for trusted data such as your own files. Named so that its use stands out in review.

Examples

use compress_lib::Limits;

assert_eq!(Limits::unlimited().max_output(), u64::MAX);

pub const fn with_max_output(self, bytes: u64) -> Self

Sets the total output a decoder may produce.

Examples

let limits = compress_lib::Limits::new().with_max_output(16 << 20);
assert_eq!(limits.max_output(), 16 << 20);

pub const fn with_max_ratio(self, ratio: u32) -> Self

Sets the largest allowed ratio of output to input consumed, checked once the output passes the ratio floor. 0 turns the check off.

Examples

let limits = compress_lib::Limits::new().with_max_ratio(100);
assert_eq!(limits.max_ratio(), 100);

pub const fn with_ratio_floor(self, bytes: u64) -> Self

Sets the output size below which the ratio is not checked (small inputs legitimately have high ratios).

Examples

let limits = compress_lib::Limits::new().with_ratio_floor(64 << 10);
assert_eq!(limits.ratio_floor(), 64 << 10);

pub const fn with_max_header(self, bytes: usize) -> Self

Sets the cap on the gzip header’s optional fields (FEXTRA, FNAME, FCOMMENT) together.

Examples

let limits = compress_lib::Limits::new().with_max_header(1024);
assert_eq!(limits.max_header(), 1024);

pub const fn with_max_members(self, members: u32) -> Self

Sets the cap on members in one gzip stream.

Examples

let limits = compress_lib::Limits::new().with_max_members(1);
assert_eq!(limits.max_members(), 1);

pub const fn max_output(&self) -> u64

The total output cap.

Examples

assert_eq!(compress_lib::Limits::new().max_output(), 64 << 20);

pub const fn max_ratio(&self) -> u32

The ratio cap (0 = off).

Examples

assert_eq!(compress_lib::Limits::new().max_ratio(), 0);

pub const fn ratio_floor(&self) -> u64

The output size below which the ratio is not checked.

Examples

assert_eq!(compress_lib::Limits::new().ratio_floor(), 1 << 20);

pub const fn max_header(&self) -> usize

The gzip header field cap.

Examples

assert_eq!(compress_lib::Limits::new().max_header(), 64 << 10);

pub const fn max_members(&self) -> u32

The gzip member cap.

Examples

assert_eq!(compress_lib::Limits::new().max_members(), 1024);

Trait Implementations

impl Clone for Limits

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Limits

impl Debug for Limits

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

Formats the value using the given formatter.

impl Default for Limits

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Limits

impl Hash for Limits

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Limits

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Limits