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use crate::driver::FileDriver;
use crate::zip::{ZipError, ZipFileInfo, ZipResult};
use std::io::{
Error as IoError, ErrorKind as IoErrorKind, Read, Result as IoResult, Seek, SeekFrom, Write,
};
pub struct ZipFile<'d, Io> {
io: &'d mut Io,
info: &'d ZipFileInfo,
bounds: (u64, u64),
cursor: u64,
}
impl<'d, Io> FileDriver for ZipFile<'d, Io> {
type Io = Io;
type FileInfo = ZipFileInfo;
fn info(&self) -> &Self::FileInfo {
self.info
}
}
impl<'d, Io: Read + Seek> ZipFile<'d, Io> {
pub fn new(io: &'d mut Io, info: &'d ZipFileInfo) -> ZipResult<Self> {
io.seek(SeekFrom::Start(info.header_pointer))?;
let buf = {
let mut buf = [0; 30];
io.read(&mut buf)?;
buf
};
if u32::from_le_bytes(buf[..4].try_into().unwrap()) != 0x04034b50 {
return Err(ZipError::InvalidFileHeaderSignature.into());
}
let data_pointer = info.header_pointer
+ 30
+ u16::from_le_bytes(buf[26..28].try_into().unwrap()) as u64
+ u16::from_le_bytes(buf[28..30].try_into().unwrap()) as u64;
io.seek(SeekFrom::Start(data_pointer))?;
Ok(Self {
io,
info,
bounds: (data_pointer, data_pointer + info.compressed_size),
cursor: data_pointer,
})
}
}
impl<'d, Io: Read> Read for ZipFile<'d, Io> {
fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
let upper = buf.len().min((self.bounds.1 - self.cursor) as usize);
self.cursor += upper as u64;
self.io.read(&mut buf[..upper])
}
}
impl<'d, Io: Write> Write for ZipFile<'d, Io> {
fn write(&mut self, buf: &[u8]) -> IoResult<usize> {
todo!()
}
fn flush(&mut self) -> IoResult<()> {
todo!()
}
}
impl<'d, Io: Seek> Seek for ZipFile<'d, Io> {
fn seek(&mut self, pos: SeekFrom) -> IoResult<u64> {
self.cursor = match pos {
SeekFrom::Start(offset) => self.bounds.0 + offset,
SeekFrom::End(offset) => {
let cursor = self.bounds.1.saturating_add_signed(offset);
if cursor < self.bounds.0 {
return Err(IoError::new(
IoErrorKind::InvalidInput,
ZipError::NegativeFileOffset,
));
}
cursor
}
SeekFrom::Current(offset) => {
let cursor = self.cursor.saturating_add_signed(offset);
if cursor < self.bounds.0 {
return Err(IoError::new(
IoErrorKind::InvalidInput,
ZipError::NegativeFileOffset,
));
}
cursor
}
}
.min(self.bounds.1);
Ok(self.io.seek(SeekFrom::Start(self.cursor))? - self.bounds.0)
}
}
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