exif/
webp.rs

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1//
2// Copyright (c) 2020 KAMADA Ken'ichi.
3// All rights reserved.
4//
5// Redistribution and use in source and binary forms, with or without
6// modification, are permitted provided that the following conditions
7// are met:
8// 1. Redistributions of source code must retain the above copyright
9//    notice, this list of conditions and the following disclaimer.
10// 2. Redistributions in binary form must reproduce the above copyright
11//    notice, this list of conditions and the following disclaimer in the
12//    documentation and/or other materials provided with the distribution.
13//
14// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24// SUCH DAMAGE.
25//
26
27use std::io::{BufRead, ErrorKind};
28
29use crate::endian::{Endian, LittleEndian};
30use crate::error::Error;
31use crate::util::{BufReadExt as _, ReadExt as _};
32
33// Chunk identifiers for RIFF.
34const FCC_RIFF: [u8; 4] = *b"RIFF";
35const FCC_WEBP: [u8; 4] = *b"WEBP";
36const FCC_EXIF: [u8; 4] = *b"EXIF";
37
38// Get the contents of the Exif chunk from a WebP file.
39pub fn get_exif_attr<R>(reader: &mut R)
40                        -> Result<Vec<u8>, Error> where R: BufRead {
41    match get_exif_attr_sub(reader) {
42        Err(Error::Io(ref e)) if e.kind() == ErrorKind::UnexpectedEof =>
43            Err(Error::InvalidFormat("Broken WebP file")),
44        r => r,
45    }
46}
47
48fn get_exif_attr_sub<R>(reader: &mut R)
49                        -> Result<Vec<u8>, Error> where R: BufRead {
50    let mut sig = [0; 12];
51    reader.read_exact(&mut sig)?;
52    if sig[0..4] != FCC_RIFF || sig[8..12] != FCC_WEBP {
53        return Err(Error::InvalidFormat("Not a WebP file"));
54    }
55    let mut file_size = LittleEndian::loadu32(&sig, 4) as usize;
56    file_size = file_size.checked_sub(4)
57        .ok_or(Error::InvalidFormat("Invalid header file size"))?;
58
59    // Scan the series of chunks.
60    while file_size > 0 {
61        file_size = file_size.checked_sub(8)
62            .ok_or(Error::InvalidFormat("Chunk overflowing parent"))?;
63        let mut cheader = [0; 8];
64        reader.read_exact(&mut cheader)?;
65        let mut size = LittleEndian::loadu32(&cheader, 4) as usize;
66        file_size = file_size.checked_sub(size)
67            .ok_or(Error::InvalidFormat("Chunk overflowing parent"))?;
68        if cheader[0..4] == FCC_EXIF {
69            let mut payload = Vec::new();
70            reader.read_exact_len(&mut payload, size)?;
71            return Ok(payload);
72        }
73        if size % 2 != 0 && file_size > 0 {
74            file_size -= 1;
75            size = size.checked_add(1).expect("ex-file_size - size > 0");
76        }
77        reader.discard_exact(size)?;
78    }
79    Err(Error::NotFound("WebP"))
80}
81
82pub fn is_webp(buf: &[u8]) -> bool {
83    buf.len() >= 12 && buf[0..4] == FCC_RIFF && buf[8..12] == FCC_WEBP
84}
85
86#[cfg(test)]
87mod tests {
88    use super::*;
89
90    #[test]
91    fn truncated() {
92        let mut data = b"RIFF\x10\0\0\0WEBPEXIF\x04\0\0\0Exif".to_vec();
93        assert_eq!(get_exif_attr(&mut &data[..]).unwrap(), b"Exif");
94        while let Some(_) = data.pop() {
95            get_exif_attr(&mut &data[..]).unwrap_err();
96        }
97    }
98
99    #[test]
100    fn no_exif() {
101        let data = b"RIFF\x0c\0\0\0WEBPwhat\0\0\0\0";
102        assert_err_pat!(get_exif_attr(&mut &data[..]), Error::NotFound(_));
103    }
104
105    #[test]
106    fn empty() {
107        let data = b"RIFF\x16\0\0\0WEBPodd_\x01\0\0\0X\0EXIF\0\0\0\0";
108        assert_ok!(get_exif_attr(&mut &data[..]), b"");
109    }
110
111    #[test]
112    fn non_empty() {
113        let data = b"RIFF\x1a\0\0\0WEBPeven\x02\0\0\0XYEXIF\x03\0\0\0abcd";
114        assert_ok!(get_exif_attr(&mut &data[..]), b"abc");
115    }
116
117    #[test]
118    fn read_first() {
119        let data = b"RIFF\x18\0\0\0WEBPEXIF\x02\0\0\0abEXIF\x02\0\0\0cd";
120        assert_ok!(get_exif_attr(&mut &data[..]), b"ab");
121    }
122
123    #[test]
124    fn out_of_toplevel_chunk() {
125        let data = b"RIFF\x0e\0\0\0WEBPwhat\x02\0\0\0abEXIF\x02\0\0\0cd";
126        assert_err_pat!(get_exif_attr(&mut &data[..]), Error::NotFound(_));
127    }
128
129    #[test]
130    fn overflowing_parent() {
131        let mut data = b"RIFF\x10\0\0\0WEBPEXIF\x04\0\0\0Exif".to_vec();
132        assert_eq!(get_exif_attr(&mut &data[..]).unwrap(), b"Exif");
133        for x in 0x05..=0x0f {
134            data[4] = x;
135            assert_err_pat!(get_exif_attr(&mut &data[..]),
136                            Error::InvalidFormat(_));
137        }
138        data[4] = 0x04;
139        assert_err_pat!(get_exif_attr(&mut &data[..]), Error::NotFound(_));
140    }
141
142    #[test]
143    fn odd_at_last_without_padding() {
144        let data = b"RIFF\x17\0\0\0WEBPwhat\0\0\0\0EXIF\x03\0\0\0abc";
145        assert_ok!(get_exif_attr(&mut &data[..]), b"abc");
146    }
147}
exif/webp.rs

exif/
webp.rs
