zstd-zero 0.2.1

A no-std, allocation-free streaming Zstandard decoder
Documentation 
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

use core::fmt;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
#[non_exhaustive]
pub enum DecodeError {
    DecoderPoisoned,
    InvalidMagic,
    InvalidFrameHeader,
    UnsupportedDictionary { id: u32 },
    WindowTooLarge,
    HistoryTooSmall { required: usize, provided: usize },
    BlockScratchTooSmall { required: usize, provided: usize },
    LiteralScratchTooSmall { required: usize, provided: usize },
    InvalidBlock,
    InvalidEntropyTable,
    InvalidBitstream,
    InvalidOffset,
    ChecksumMismatch { expected: u32, actual: u32 },
    ContentSizeMismatch { expected: u64, actual: u64 },
    UnexpectedEof,
    ArithmeticOverflow,
}

impl fmt::Display for DecodeError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::DecoderPoisoned => formatter.write_str("decoder is poisoned"),
            Self::InvalidMagic => formatter.write_str("invalid zstd frame magic"),
            Self::InvalidFrameHeader => formatter.write_str("invalid zstd frame header"),
            Self::UnsupportedDictionary { id } => {
                write!(formatter, "zstd dictionary {id} is not supported")
            }
            Self::WindowTooLarge => formatter.write_str("zstd window does not fit this platform"),
            Self::HistoryTooSmall { required, provided } => write!(
                formatter,
                "history buffer is too small: need {required} bytes, have {provided}"
            ),
            Self::BlockScratchTooSmall { required, provided } => write!(
                formatter,
                "block scratch is too small: need {required} bytes, have {provided}"
            ),
            Self::LiteralScratchTooSmall { required, provided } => write!(
                formatter,
                "literal scratch is too small: need {required} bytes, have {provided}"
            ),
            Self::InvalidBlock => formatter.write_str("invalid zstd block"),
            Self::InvalidEntropyTable => formatter.write_str("invalid zstd entropy table"),
            Self::InvalidBitstream => formatter.write_str("invalid zstd bitstream"),
            Self::InvalidOffset => formatter.write_str("invalid zstd match offset"),
            Self::ChecksumMismatch { expected, actual } => write!(
                formatter,
                "zstd checksum mismatch: expected {expected:08x}, got {actual:08x}"
            ),
            Self::ContentSizeMismatch { expected, actual } => write!(
                formatter,
                "zstd content-size mismatch: expected {expected}, got {actual}"
            ),
            Self::UnexpectedEof => formatter.write_str("unexpected end of zstd stream"),
            Self::ArithmeticOverflow => formatter.write_str("zstd size arithmetic overflow"),
        }
    }
}

#[cfg(test)]
mod tests {
    use std::string::ToString;

    use super::DecodeError;

    #[test]
    fn formats_every_decode_error() {
        let cases = [
            (DecodeError::DecoderPoisoned, "decoder is poisoned"),
            (DecodeError::InvalidMagic, "invalid zstd frame magic"),
            (DecodeError::InvalidFrameHeader, "invalid zstd frame header"),
            (
                DecodeError::UnsupportedDictionary { id: 42 },
                "zstd dictionary 42 is not supported",
            ),
            (
                DecodeError::WindowTooLarge,
                "zstd window does not fit this platform",
            ),
            (
                DecodeError::HistoryTooSmall {
                    required: 8,
                    provided: 3,
                },
                "history buffer is too small: need 8 bytes, have 3",
            ),
            (
                DecodeError::BlockScratchTooSmall {
                    required: 8,
                    provided: 3,
                },
                "block scratch is too small: need 8 bytes, have 3",
            ),
            (
                DecodeError::LiteralScratchTooSmall {
                    required: 8,
                    provided: 3,
                },
                "literal scratch is too small: need 8 bytes, have 3",
            ),
            (DecodeError::InvalidBlock, "invalid zstd block"),
            (
                DecodeError::InvalidEntropyTable,
                "invalid zstd entropy table",
            ),
            (DecodeError::InvalidBitstream, "invalid zstd bitstream"),
            (DecodeError::InvalidOffset, "invalid zstd match offset"),
            (
                DecodeError::ChecksumMismatch {
                    expected: 0x1234,
                    actual: 0xabcd,
                },
                "zstd checksum mismatch: expected 00001234, got 0000abcd",
            ),
            (
                DecodeError::ContentSizeMismatch {
                    expected: 12,
                    actual: 34,
                },
                "zstd content-size mismatch: expected 12, got 34",
            ),
            (DecodeError::UnexpectedEof, "unexpected end of zstd stream"),
            (
                DecodeError::ArithmeticOverflow,
                "zstd size arithmetic overflow",
            ),
        ];

        for (error, expected) in cases {
            assert_eq!(error.to_string(), expected);
        }
    }
}