63 lines
1.1 KiB
Rust
63 lines
1.1 KiB
Rust
//! DEFLATE loader.
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use crate::durandal::err::*;
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/// Loads a GZIP file header.
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pub fn load_gzip_header(b: &[u8]) -> ResultS<usize>
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{
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const FHCRC: u8 = 1 << 1;
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const FEXTRA: u8 = 1 << 2;
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const FNAME: u8 = 1 << 3;
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const FCOMMENT: u8 = 1 << 4;
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read_data! {
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10, LE in b =>
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id = u16[0];
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cm = u8[2];
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fl = u8[3];
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}
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if id != 0x8B1F || cm != 8 {
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bail!("not gzip format");
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}
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let mut p = 10;
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if fl & FEXTRA != 0 {
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read_data!(p + 2, LE in b => xlen = u16[p] usize;);
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if p + 2 + xlen > b.len() {
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bail!("not enough data");
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}
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p += xlen;
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}
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if fl & FNAME != 0 {
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p = skip_zero_terminated_item(&b[p..])?;
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}
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if fl & FCOMMENT != 0 {
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p = skip_zero_terminated_item(&b[p..])?;
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}
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if fl & FHCRC != 0 {
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read_data!(p + 2, LE in b => _crc = u16[p];);
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p += 2;
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}
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Ok(p)
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}
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fn skip_zero_terminated_item(b: &[u8]) -> ResultS<usize>
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{
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if let Some(i) = b.iter().position(|&n| n == 0) {
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Ok(i)
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} else {
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bail!("no end of zero terminated item");
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}
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}
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// EOF
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