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use std::io::prelude::*;
use std::io;
use std::io::SeekFrom;
use byteorder::{ReadBytesExt, BigEndian};
pub fn extract_exif<R: Read + Seek>(rdr: &mut R) -> io::Result<Vec<u8>> {
loop {
if 0xFF != try!(rdr.read_u8()) {
return Err(io::Error::new(io::ErrorKind::InvalidData, "couldn't find segment marker"));
}
let seg_id = try!(rdr.read_u8());
match seg_id {
0x0 => {}
0xD8 => {}
0xE1 => {
let len = (try!(rdr.read_u16::<BigEndian>()) - 2) as usize;
const HDR_SZ: usize = 6;
let mut hdr = vec![0u8; HDR_SZ];
try!(rdr.read_exact(&mut hdr));
if &hdr == &[b'E', b'x', b'i', b'f', 0x00, 0x00] {
let mut segment = vec![0u8; len - HDR_SZ];
try!(rdr.read_exact(&mut segment));
return Ok(segment);
}
try!(rdr.seek(SeekFrom::Current((len - HDR_SZ) as i64)));
}
_ => {
let len = try!(rdr.read_u16::<BigEndian>()) - 2;
try!(rdr.seek(SeekFrom::Current(len as i64)));
}
}
}
}