image/io/
mod.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
//! Input and output of images.

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

pub(crate) mod free_functions;
mod reader;

pub use self::reader::Reader;

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

#[allow(clippy::derivable_impls)]
impl Default for LimitSupport {
    fn default() -> LimitSupport {
        LimitSupport {
            _non_exhaustive: (),
        }
    }
}

/// 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, however as
/// some of the underlying decoders do not support not support such limits one cannot
/// rely on these limits being supported. For stric 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 `image::error::LimitErrorKind::Unsupported`.
///
/// Currently the only strict limits supported are the `max_image_width` and `max_image_height`
/// limits, however 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)]
#[allow(clippy::manual_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 default is 512MiB.
    pub max_alloc: Option<u64>,
    _non_exhaustive: (),
}

impl Default for Limits {
    fn default() -> Limits {
        Limits {
            max_image_width: None,
            max_image_height: None,
            max_alloc: Some(512 * 1024 * 1024),
            _non_exhaustive: (),
        }
    }
}

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

    /// 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.
    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.
    pub fn reserve_buffer(
        &mut self,
        width: u32,
        height: u32,
        color_type: ColorType,
    ) -> ImageResult<()> {
        self.check_dimensions(width, height)?;
        let in_memory_size = (width as u64)
            .saturating_mul(height as u64)
            .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.
    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.
            }
        }
    }
}