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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
//!  Decoding of DDS images
//!
//!  DDS (DirectDraw Surface) is a container format for storing DXT (S3TC) compressed images.
//!
//!  # Related Links
//!  * <https://docs.microsoft.com/en-us/windows/win32/direct3ddds/dx-graphics-dds-pguide> - Description of the DDS format.

use std::{error, fmt};
use std::io::Read;

use byteorder::{LittleEndian, ReadBytesExt};

use crate::color::ColorType;
use crate::dxt::{DxtDecoder, DxtReader, DXTVariant};
use crate::error::{
    DecodingError, ImageError, ImageFormatHint, ImageResult, UnsupportedError, UnsupportedErrorKind,
};
use crate::image::{ImageDecoder, ImageFormat};

/// Errors that can occur during decoding and parsing a DDS image
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
enum DecoderError {
    /// Wrong DDS channel width
    PixelFormatSizeInvalid(u32),
    /// Wrong DDS header size
    HeaderSizeInvalid(u32),
    /// Wrong DDS header flags
    HeaderFlagsInvalid(u32),

    /// DDS "DDS " signature invalid or missing
    DdsSignatureInvalid,
}

impl fmt::Display for DecoderError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            DecoderError::PixelFormatSizeInvalid(s) =>
                f.write_fmt(format_args!("Invalid DDS PixelFormat size: {}", s)),
            DecoderError::HeaderSizeInvalid(s) =>
                f.write_fmt(format_args!("Invalid DDS header size: {}", s)),
            DecoderError::HeaderFlagsInvalid(fs) =>
                f.write_fmt(format_args!("Invalid DDS header flags: {:#010X}", fs)),
            DecoderError::DdsSignatureInvalid =>
                f.write_str("DDS signature not found"),
        }
    }
}

impl From<DecoderError> for ImageError {
    fn from(e: DecoderError) -> ImageError {
        ImageError::Decoding(DecodingError::new(ImageFormat::Dds.into(), e))
    }
}

impl error::Error for DecoderError {}

/// Header used by DDS image files
#[derive(Debug)]
struct Header {
    flags: u32,
    height: u32,
    width: u32,
    pitch_or_linear_size: u32,
    depth: u32,
    mipmap_count: u32,
    pixel_format: PixelFormat,
    caps: u32,
    caps2: u32,
}

/// DDS pixel format
#[derive(Debug)]
struct PixelFormat {
    flags: u32,
    fourcc: [u8; 4],
    rgb_bit_count: u32,
    r_bit_mask: u32,
    g_bit_mask: u32,
    b_bit_mask: u32,
    a_bit_mask: u32,
}

impl PixelFormat {
    fn from_reader(r: &mut dyn Read) -> ImageResult<Self> {
        let size = r.read_u32::<LittleEndian>()?;
        if size != 32 {
            return Err(DecoderError::PixelFormatSizeInvalid(size).into());
        }

        Ok(Self {
            flags: r.read_u32::<LittleEndian>()?,
            fourcc: {
                let mut v = [0; 4];
                r.read_exact(&mut v)?;
                v
            },
            rgb_bit_count: r.read_u32::<LittleEndian>()?,
            r_bit_mask: r.read_u32::<LittleEndian>()?,
            g_bit_mask: r.read_u32::<LittleEndian>()?,
            b_bit_mask: r.read_u32::<LittleEndian>()?,
            a_bit_mask: r.read_u32::<LittleEndian>()?,
        })
    }
}

impl Header {
    fn from_reader(r: &mut dyn Read) -> ImageResult<Self> {
        let size = r.read_u32::<LittleEndian>()?;
        if size != 124 {
            return Err(DecoderError::HeaderSizeInvalid(size).into());
        }

        const REQUIRED_FLAGS: u32 = 0x1 | 0x2 | 0x4 | 0x1000;
        const VALID_FLAGS: u32 = 0x1 | 0x2 | 0x4 | 0x8 | 0x1000 | 0x20000 | 0x80000 | 0x800000;
        let flags = r.read_u32::<LittleEndian>()?;
        if flags & (REQUIRED_FLAGS | !VALID_FLAGS) != REQUIRED_FLAGS {
            return Err(DecoderError::HeaderFlagsInvalid(flags).into());
        }

        let height = r.read_u32::<LittleEndian>()?;
        let width = r.read_u32::<LittleEndian>()?;
        let pitch_or_linear_size = r.read_u32::<LittleEndian>()?;
        let depth = r.read_u32::<LittleEndian>()?;
        let mipmap_count = r.read_u32::<LittleEndian>()?;
        // Skip `dwReserved1`
        {
            let mut skipped = [0; 4 * 11];
            r.read_exact(&mut skipped)?;
        }
        let pixel_format = PixelFormat::from_reader(r)?;
        let caps = r.read_u32::<LittleEndian>()?;
        let caps2 = r.read_u32::<LittleEndian>()?;
        // Skip `dwCaps3`, `dwCaps4`, `dwReserved2` (unused)
        {
            let mut skipped = [0; 4 + 4 + 4];
            r.read_exact(&mut skipped)?;
        }

        Ok(Self {
            flags,
            height,
            width,
            pitch_or_linear_size,
            depth,
            mipmap_count,
            pixel_format,
            caps,
            caps2,
        })
    }
}


/// The representation of a DDS decoder
pub struct DdsDecoder<R: Read> {
    inner: DxtDecoder<R>,
}

impl<R: Read> DdsDecoder<R> {
    /// Create a new decoder that decodes from the stream `r`
    pub fn new(mut r: R) -> ImageResult<Self> {
        let mut magic = [0; 4];
        r.read_exact(&mut magic)?;
        if magic != b"DDS "[..] {
            return Err(DecoderError::DdsSignatureInvalid.into());
        }

        let header = Header::from_reader(&mut r)?;

        if header.pixel_format.flags & 0x4 != 0 {
            let variant = match &header.pixel_format.fourcc {
                b"DXT1" => DXTVariant::DXT1,
                b"DXT3" => DXTVariant::DXT3,
                b"DXT5" => DXTVariant::DXT5,
                fourcc => {
                    return Err(ImageError::Unsupported(
                        UnsupportedError::from_format_and_kind(
                            ImageFormat::Dds.into(),
                            UnsupportedErrorKind::GenericFeature(format!("DDS FourCC {:?}", fourcc)),
                        ),
                    ))
                }
            };

            if crate::utils::check_dimension_overflow(
                header.width,
                header.height,
                variant.color_type().bytes_per_pixel(),
            ) {
                return Err(ImageError::Unsupported(
                    UnsupportedError::from_format_and_kind(
                        ImageFormat::Dds.into(),
                        UnsupportedErrorKind::GenericFeature(format!(
                            "Image dimensions ({}x{}) are too large",
                            header.width, header.height
                        )),
                    ),
                ));
            }

            let inner = DxtDecoder::new(r, header.width, header.height, variant)?;
            Ok(Self { inner })
        } else {
            // For now, supports only DXT variants
            Err(ImageError::Unsupported(
                UnsupportedError::from_format_and_kind(
                    ImageFormat::Dds.into(),
                    UnsupportedErrorKind::Format(ImageFormatHint::Name("DDS".to_string())),
                ),
            ))
        }
    }
}

impl<'a, R: 'a + Read> ImageDecoder<'a> for DdsDecoder<R> {
    type Reader = DxtReader<R>;

    fn dimensions(&self) -> (u32, u32) {
        self.inner.dimensions()
    }

    fn color_type(&self) -> ColorType {
        self.inner.color_type()
    }

    fn scanline_bytes(&self) -> u64 {
        self.inner.scanline_bytes()
    }

    fn into_reader(self) -> ImageResult<Self::Reader> {
        self.inner.into_reader()
    }

    fn read_image(self, buf: &mut [u8]) -> ImageResult<()> {
        self.inner.read_image(buf)
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn dimension_overflow() {
        // A DXT1 header set to 0xFFFF_FFFC width and height (the highest u32%4 == 0)
        let header = vec![
            0x44, 0x44, 0x53, 0x20, 0x7C, 0x0, 0x0, 0x0, 0x7, 0x10, 0x8, 0x0, 0xFC, 0xFF, 0xFF, 0xFF, 0xFC,
            0xFF, 0xFF, 0xFF, 0x0, 0xC0, 0x12, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x49, 0x4D,
            0x41, 0x47, 0x45, 0x4D, 0x41, 0x47, 0x49, 0x43, 0x4B, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
            0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
            0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x20, 0x0, 0x0, 0x0, 0x4, 0x0, 0x0, 0x0, 0x44,
            0x58, 0x54, 0x31, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
            0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
            0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
        ];

        assert!(DdsDecoder::new(&header[..]).is_err());
    }
}