2016-10-26 09:46:20 -04:00
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//
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// Copyright (c) 2016 KAMADA Ken'ichi.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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// 1. Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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// SUCH DAMAGE.
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//
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use endian::Endian;
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/// Types and values of TIFF fields (for Exif attributes).
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#[derive(Debug)]
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pub enum Value<'a> {
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2016-11-03 06:49:10 -04:00
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/// Vector of 8-bit unsigned integers.
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Byte(Vec<u8>),
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2016-10-26 09:46:20 -04:00
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/// Slice of 8-bit bytes containing 7-bit ASCII characters.
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/// The trailing null character is not included. Note that
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/// the absence of the 8th bits is not guaranteed.
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2016-10-27 07:48:38 -04:00
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Ascii(Vec<&'a [u8]>),
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2016-10-26 09:46:20 -04:00
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/// Vector of 16-bit unsigned integers.
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Short(Vec<u16>),
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/// The type is unknown to this implementation.
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/// The associated values are the type and the count, and the
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/// offset of the "Value Offset" element.
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Unknown(u16, u32, u32),
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}
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type Parser<'a> = fn(&'a [u8], usize, usize) -> Value<'a>;
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// Return the length of a single value and the parser of the type.
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pub fn get_type_info<'a, E>(typecode: u16)
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-> (usize, Parser<'a>) where E: Endian {
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match typecode {
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1 => (1, parse_byte),
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2 => (1, parse_ascii),
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3 => (2, parse_short::<E>),
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_ => (0, parse_unknown),
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}
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}
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2016-11-03 06:49:10 -04:00
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fn parse_byte<'a>(data: &'a [u8], offset: usize, count: usize)
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-> Value<'a> {
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Value::Byte(data[offset .. offset + count].to_vec())
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}
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2016-10-26 09:46:20 -04:00
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fn parse_ascii<'a>(data: &'a [u8], offset: usize, count: usize)
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-> Value<'a> {
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// Any ASCII field can contain multiple strings [TIFF6 Image File
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// Directory].
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let iter = (&data[offset .. offset + count]).split(|&b| b == b'\0');
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let mut v: Vec<&[u8]> = iter.collect();
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if v.len() >= 2 && v.last().map_or(false, |&s| s.len() == 0) {
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v.pop();
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}
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Value::Ascii(v)
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}
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fn parse_short<'a, E>(data: &'a [u8], offset: usize, count: usize)
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-> Value<'a> where E: Endian {
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let mut val = Vec::new();
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for i in 0..count {
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val.push(E::loadu16(data, offset + i * 2));
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}
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Value::Short(val)
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}
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// This is a dummy function and will never be called.
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#[allow(unused_variables)]
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fn parse_unknown<'a>(data: &'a [u8], offset: usize, count: usize)
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-> Value<'a> {
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unreachable!()
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}
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2016-10-27 07:53:07 -04:00
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#[cfg(test)]
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mod tests {
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use endian::BigEndian;
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use super::*;
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use super::parse_ascii;
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2016-11-03 06:49:10 -04:00
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#[test]
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fn byte() {
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let sets: &[(&[u8], &[u8])] = &[
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(b"x", b""),
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(b"x\xbe\xad", b"\xbe\xad"),
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];
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let (unitlen, parser) = get_type_info::<BigEndian>(1);
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for &(data, ans) in sets {
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match parser(data, 1, (data.len() - 1) / unitlen) {
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Value::Byte(v) => assert_eq!(v, ans),
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v => panic!("wrong variant {:?}", v),
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}
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}
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}
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2016-10-27 07:53:07 -04:00
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#[test]
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fn ascii() {
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let sets: &[(&[u8], Vec<&[u8]>)] = &[
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(b"x", vec![b""]), // malformed
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(b"x\0", vec![b""]),
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(b"x\0\0", vec![b"", b""]),
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(b"xA", vec![b"A"]), // malformed
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(b"xA\0", vec![b"A"]),
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(b"xA\0B", vec![b"A", b"B"]), // malformed
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(b"xA\0B\0", vec![b"A", b"B"]),
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(b"xA\0\xbe\0", vec![b"A", b"\xbe"]), // not ASCII
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];
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for &(data, ref ans) in sets {
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match parse_ascii(data, 1, data.len() - 1) {
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Value::Ascii(v) => assert_eq!(v, *ans),
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v => panic!("wrong variant {:?}", v),
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}
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}
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}
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}
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