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use std::fs::File;
use std::io::{self, Read, Seek};
#[derive(Copy, Clone, Debug)]
pub enum TagType {
/// An ID3v1.0 tag
TAGv10,
/// An ID3v1.1 enhanced tag (TAG+) in addition to the v1.0 tag
TAGv11,
/// An ID3v1.2 extended tag (EXT) in addition to the v1.0 tag
TAGv12,
}
pub fn recognise(file: &mut File) -> io::Result<Option<TagType>> {
let length = file.seek(io::SeekFrom::End(0))?;
if length < 128 { return Ok(None); }
let mut buf4 = [0u8; 4];
// Check whether we have a v1.0 tag
file.seek(io::SeekFrom::End(-128))?;
file.read_exact(&mut buf4[0..3])?;
if &buf4[0..3] == b"TAG" {
// Check whether we also have a v1.1 tag
if length >= 128 + 227 {
file.seek(io::SeekFrom::End(-128 - 227))?;
file.read_exact(&mut buf4)?;
if &buf4 == b"TAG+" {
return Ok(Some(TagType::TAGv11));
}
}
// Otherwise, check whether we also have a v1.2 tag
if length >= 128 + 128 {
file.seek(io::SeekFrom::End(-128 - 128))?;
file.read_exact(&mut buf4[0..3])?;
if &buf4[0..3] == b"EXT" {
return Ok(Some(TagType::TAGv12));
}
}
// Nope, just v1.0
Ok(Some(TagType::TAGv10))
} else {
Ok(None)
}
}
pub fn remove_tag(file: &mut File, typ: TagType) -> io::Result<()> {
let tag_len = match typ {
TagType::TAGv10 => 128,
TagType::TAGv11 => 128 + 227,
TagType::TAGv12 => 128 + 128,
};
let length = file.seek(io::SeekFrom::End(0))?;
eprintln!("remove_tag: Resizing file from {} to {} bytes", length, length - tag_len);
file.set_len(length - tag_len)?;
Ok(())
}
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