/src/image/src/io/limits.rs

Source
use crate::{error, ColorType, ImageError, ImageResult};

/// Set of supported strict limits for a decoder.
#[derive(Clone, Debug, Default, Eq, PartialEq, Hash)]
#[allow(missing_copy_implementations)]
#[non_exhaustive]
pub struct LimitSupport {}

/// Resource limits for decoding.
///
/// Limits can be either *strict* or *non-strict*. Non-strict limits are best-effort
/// limits where the library does not guarantee that limit will not be exceeded. Do note
/// that it is still considered a bug if a non-strict limit is exceeded.
/// Some of the underlying decoders do not support such limits, so one cannot
/// rely on these limits being supported. For strict limits, the library makes a stronger
/// guarantee that the limit will not be exceeded. Exceeding a strict limit is considered
/// a critical bug. If a decoder cannot guarantee that it will uphold a strict limit, it
/// *must* fail with [`error::LimitErrorKind::Unsupported`].
///
/// The only currently supported strict limits are the `max_image_width` and `max_image_height`
/// limits, but more will be added in the future. [`LimitSupport`] will default to support
/// being false, and decoders should enable support for the limits they support in
/// [`ImageDecoder::set_limits`].
///
/// The limit check should only ever fail if a limit will be exceeded or an unsupported strict
/// limit is used.
///
/// [`LimitSupport`]: ./struct.LimitSupport.html
/// [`ImageDecoder::set_limits`]: ../trait.ImageDecoder.html#method.set_limits
#[derive(Clone, Debug, Eq, PartialEq, Hash)]
#[allow(missing_copy_implementations)]
#[non_exhaustive]
pub struct Limits {
    /// The maximum allowed image width. This limit is strict. The default is no limit.
    pub max_image_width: Option<u32>,
    /// The maximum allowed image height. This limit is strict. The default is no limit.
    pub max_image_height: Option<u32>,
    /// The maximum allowed sum of allocations allocated by the decoder at any one time excluding
    /// allocator overhead. This limit is non-strict by default and some decoders may ignore it.
    /// The bytes required to store the output image count towards this value. The default is
    /// 512MiB.
    pub max_alloc: Option<u64>,
}

/// Add some reasonable limits.
///
/// **Note**: This is not equivalent to _not_ adding limits. This may be changed in future major
/// version increases.
impl Default for Limits {
    fn default() -> Limits {
        Limits {
            max_image_width: None,
            max_image_height: None,
            max_alloc: Some(512 * 1024 * 1024),
        }
    }
}

impl Limits {
    /// Disable all limits.
    #[must_use]
    pub fn no_limits() -> Limits {
        Limits {
            max_image_width: None,
            max_image_height: None,
            max_alloc: None,
        }
    }

    /// This function checks that all currently set strict limits are supported.
    pub fn check_support(&self, _supported: &LimitSupport) -> ImageResult<()> {
        Ok(())
    }

    /// This function checks the `max_image_width` and `max_image_height` limits given
    /// the image width and height.
    pub fn check_dimensions(&self, width: u32, height: u32) -> ImageResult<()> {
        if let Some(max_width) = self.max_image_width {
            if width > max_width {
                return Err(ImageError::Limits(error::LimitError::from_kind(
                    error::LimitErrorKind::DimensionError,
                )));
            }
        }

        if let Some(max_height) = self.max_image_height {
            if height > max_height {
                return Err(ImageError::Limits(error::LimitError::from_kind(
                    error::LimitErrorKind::DimensionError,
                )));
            }
        }

        Ok(())
    }

    /// This function checks that the current limit allows for reserving the set amount
    /// of bytes, it then reduces the limit accordingly.
    pub fn reserve(&mut self, amount: u64) -> ImageResult<()> {
        if let Some(max_alloc) = self.max_alloc.as_mut() {
            if *max_alloc < amount {
                return Err(ImageError::Limits(error::LimitError::from_kind(
                    error::LimitErrorKind::InsufficientMemory,
                )));
            }

            *max_alloc -= amount;
        }

        Ok(())
    }

    /// This function acts identically to [`reserve`], but takes a `usize` for convenience.
    ///
    /// [`reserve`]: #method.reserve
    pub fn reserve_usize(&mut self, amount: usize) -> ImageResult<()> {
        match u64::try_from(amount) {
            Ok(n) => self.reserve(n),
            Err(_) if self.max_alloc.is_some() => Err(ImageError::Limits(
                error::LimitError::from_kind(error::LimitErrorKind::InsufficientMemory),
            )),
            Err(_) => {
                // Out of bounds, but we weren't asked to consider any limit.
                Ok(())
            }
        }
    }

    /// This function acts identically to [`reserve`], but accepts the width, height and color type
    /// used to create an [`ImageBuffer`] and does all the math for you.
    ///
    /// [`ImageBuffer`]: crate::ImageBuffer
    /// [`reserve`]: #method.reserve
    pub fn reserve_buffer(
        &mut self,
        width: u32,
        height: u32,
        color_type: ColorType,
    ) -> ImageResult<()> {
        self.check_dimensions(width, height)?;
        let in_memory_size = u64::from(width)
            .saturating_mul(u64::from(height))
            .saturating_mul(color_type.bytes_per_pixel().into());
        self.reserve(in_memory_size)?;
        Ok(())
    }

    /// This function increases the `max_alloc` limit with amount. Should only be used
    /// together with [`reserve`].
    ///
    /// [`reserve`]: #method.reserve
    pub fn free(&mut self, amount: u64) {
        if let Some(max_alloc) = self.max_alloc.as_mut() {
            *max_alloc = max_alloc.saturating_add(amount);
        }
    }

    /// This function acts identically to [`free`], but takes a `usize` for convenience.
    ///
    /// [`free`]: #method.free
    pub fn free_usize(&mut self, amount: usize) {
        match u64::try_from(amount) {
            Ok(n) => self.free(n),
            Err(_) if self.max_alloc.is_some() => {
                panic!("max_alloc is set, we should have exited earlier when the reserve failed");
            }
            Err(_) => {
                // Out of bounds, but we weren't asked to consider any limit.
            }
        }
    }
}

Line	Count	Source
1		use crate::{error, ColorType, ImageError, ImageResult};
2
3		/// Set of supported strict limits for a decoder.
4		#[derive(Clone, Debug, Default, Eq, PartialEq, Hash)]
5		#[allow(missing_copy_implementations)]
6		#[non_exhaustive]
7		pub struct LimitSupport {}
8
9		/// Resource limits for decoding.
10		///
11		/// Limits can be either strict or non-strict. Non-strict limits are best-effort
12		/// limits where the library does not guarantee that limit will not be exceeded. Do note
13		/// that it is still considered a bug if a non-strict limit is exceeded.
14		/// Some of the underlying decoders do not support such limits, so one cannot
15		/// rely on these limits being supported. For strict limits, the library makes a stronger
16		/// guarantee that the limit will not be exceeded. Exceeding a strict limit is considered
17		/// a critical bug. If a decoder cannot guarantee that it will uphold a strict limit, it
18		/// must fail with [`error::LimitErrorKind::Unsupported`].
19		///
20		/// The only currently supported strict limits are the `max_image_width` and `max_image_height`
21		/// limits, but more will be added in the future. [`LimitSupport`] will default to support
22		/// being false, and decoders should enable support for the limits they support in
23		/// [`ImageDecoder::set_limits`].
24		///
25		/// The limit check should only ever fail if a limit will be exceeded or an unsupported strict
26		/// limit is used.
27		///
28		/// [`LimitSupport`]: ./struct.LimitSupport.html
29		/// [`ImageDecoder::set_limits`]: ../trait.ImageDecoder.html#method.set_limits
30		#[derive(Clone, Debug, Eq, PartialEq, Hash)]
31		#[allow(missing_copy_implementations)]
32		#[non_exhaustive]
33		pub struct Limits {
34		/// The maximum allowed image width. This limit is strict. The default is no limit.
35		pub max_image_width: Option<u32>,
36		/// The maximum allowed image height. This limit is strict. The default is no limit.
37		pub max_image_height: Option<u32>,
38		/// The maximum allowed sum of allocations allocated by the decoder at any one time excluding
39		/// allocator overhead. This limit is non-strict by default and some decoders may ignore it.
40		/// The bytes required to store the output image count towards this value. The default is
41		/// 512MiB.
42		pub max_alloc: Option<u64>,
43		}
44
45		/// Add some reasonable limits.
46		///
47		/// Note: This is not equivalent to _not_ adding limits. This may be changed in future major
48		/// version increases.
49		impl Default for Limits {
50	33.6k	fn default() -> Limits {
51	33.6k	Limits {
52	33.6k	max_image_width: None,
53	33.6k	max_image_height: None,
54	33.6k	max_alloc: Some(512 * 1024 * 1024),
55	33.6k	}
56	33.6k	}
57		}
58
59		impl Limits {
60		/// Disable all limits.
61		#[must_use]
62	7.02k	pub fn no_limits() -> Limits {
63	7.02k	Limits {
64	7.02k	max_image_width: None,
65	7.02k	max_image_height: None,
66	7.02k	max_alloc: None,
67	7.02k	}
68	7.02k	}
69
70		/// This function checks that all currently set strict limits are supported.
71	34.1k	pub fn check_support(&self, _supported: &LimitSupport) -> ImageResult<()> {
72	34.1k	Ok(())
73	34.1k	}
74
75		/// This function checks the `max_image_width` and `max_image_height` limits given
76		/// the image width and height.
77	33.4k	pub fn check_dimensions(&self, width: u32, height: u32) -> ImageResult<()> {
78	33.4k	if let Some(max_width) = self.max_image_width {
79	0	if width > max_width {
80	0	return Err(ImageError::Limits(error::LimitError::from_kind(
81	0	error::LimitErrorKind::DimensionError,
82	0	)));
83	0	}
84	33.4k	}
85
86	33.4k	if let Some(max_height) = self.max_image_height {
87	0	if height > max_height {
88	0	return Err(ImageError::Limits(error::LimitError::from_kind(
89	0	error::LimitErrorKind::DimensionError,
90	0	)));
91	0	}
92	33.4k	}
93
94	33.4k	Ok(())
95	33.4k	}
96
97		/// This function checks that the current limit allows for reserving the set amount
98		/// of bytes, it then reduces the limit accordingly.
99	23.0k	pub fn reserve(&mut self, amount: u64) -> ImageResult<()> {
100	23.0k	if let Some(max_alloc) = self.max_alloc.as_mut() {
101	23.0k	if *max_alloc < amount {
102	416	return Err(ImageError::Limits(error::LimitError::from_kind(
103	416	error::LimitErrorKind::InsufficientMemory,
104	416	)));
105	22.6k	}
106
107	22.6k	*max_alloc -= amount;
108	0	}
109
110	22.6k	Ok(())
111	23.0k	}
112
113		/// This function acts identically to [`reserve`], but takes a `usize` for convenience.
114		///
115		/// [`reserve`]: #method.reserve
116	1.38k	pub fn reserve_usize(&mut self, amount: usize) -> ImageResult<()> {
117	1.38k	match u64::try_from(amount) {
118	1.38k	Ok(n) => self.reserve(n),
119	0	Err(_) if self.max_alloc.is_some() => Err(ImageError::Limits(
120	0	error::LimitError::from_kind(error::LimitErrorKind::InsufficientMemory),
121	0	)),
122		Err(_) => {
123		// Out of bounds, but we weren't asked to consider any limit.
124	0	Ok(())
125		}
126		}
127	1.38k	}
128
129		/// This function acts identically to [`reserve`], but accepts the width, height and color type
130		/// used to create an [`ImageBuffer`] and does all the math for you.
131		///
132		/// [`ImageBuffer`]: crate::ImageBuffer
133		/// [`reserve`]: #method.reserve
134	0	pub fn reserve_buffer(
135	0	&mut self,
136	0	width: u32,
137	0	height: u32,
138	0	color_type: ColorType,
139	0	) -> ImageResult<()> {
140	0	self.check_dimensions(width, height)?;
141	0	let in_memory_size = u64::from(width)
142	0	.saturating_mul(u64::from(height))
143	0	.saturating_mul(color_type.bytes_per_pixel().into());
144	0	self.reserve(in_memory_size)?;
145	0	Ok(())
146	0	}
147
148		/// This function increases the `max_alloc` limit with amount. Should only be used
149		/// together with [`reserve`].
150		///
151		/// [`reserve`]: #method.reserve
152	1.37k	pub fn free(&mut self, amount: u64) {
153	1.37k	if let Some(max_alloc) = self.max_alloc.as_mut() {
154	1.37k	*max_alloc = max_alloc.saturating_add(amount);
155	1.37k	}
156	1.37k	}
157
158		/// This function acts identically to [`free`], but takes a `usize` for convenience.
159		///
160		/// [`free`]: #method.free
161	1.37k	pub fn free_usize(&mut self, amount: usize) {
162	1.37k	match u64::try_from(amount) {
163	1.37k	Ok(n) => self.free(n),
164	0	Err(_) if self.max_alloc.is_some() => {
165	0	panic!("max_alloc is set, we should have exited earlier when the reserve failed");
166		}
167	0	Err(_) => {
168	0	// Out of bounds, but we weren't asked to consider any limit.
169	0	}
170		}
171	1.37k	}
172		}

Coverage Report

Created: 2025-10-28 08:03