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use io::{BufRead, Seek, SeekFrom};
/// reads .a files
use std::{fmt, io, mem};
#[derive(Debug)]
pub enum Error {
IO(io::Error),
NotAnArchive,
BadNumber,
BadUtf8,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
use Error::*;
match self {
IO(i) if i.kind() == io::ErrorKind::UnexpectedEof => write!(f, "unexpected EOF"),
IO(e) => write!(f, "IO error: {e}"),
NotAnArchive => write!(f, "Not an archive file."),
BadNumber => write!(f, "Bad number in archive file (file corrupt?)"),
BadUtf8 => write!(f, "Bad UTF-8 in file name."),
}
}
}
impl From<Error> for String {
fn from(e: Error) -> Self {
format!("{e}")
}
}
impl From<io::Error> for Error {
fn from(e: io::Error) -> Self {
Self::IO(e)
}
}
type Result<T> = std::result::Result<T, Error>;
struct FileMetadata {
name: String,
offset: u64,
size: u64,
}
pub struct Archive<T: BufRead + Seek> {
archive: T,
files: Vec<FileMetadata>,
}
impl<T: BufRead + Seek> Archive<T> {
pub fn new(mut archive: T) -> Result<Self> {
use Error::*;
fn parse_decimal(decimal: &[u8]) -> Result<u64> {
let s = std::str::from_utf8(decimal).map_err(|_| Error::BadNumber)?;
s.trim_end().parse().map_err(|_| Error::BadNumber)
}
fn parse_name(bytes: &[u8]) -> Result<&str> {
let s = std::str::from_utf8(bytes).map_err(|_| Error::BadUtf8)?;
Ok(&s[..=s.rfind(|c| c != ' ').unwrap_or(0)])
}
let mut signature = [0; 8];
archive.read_exact(&mut signature)?;
if &signature != b"!<arch>\n" {
return Err(NotAnArchive);
}
#[repr(C)]
#[derive(Debug)]
struct RawMetadata {
name: [u8; 16],
_timestamp: [u8; 12],
_owner_id: [u8; 6],
_group_id: [u8; 6],
_mode: [u8; 8],
size: [u8; 10],
_end_char: [u8; 2],
}
struct Metadata {
name: [u8; 16],
offset: u64,
size: u64,
}
let mut metadata = vec![];
loop {
let mut buf = [0; mem::size_of::<RawMetadata>()];
let size = archive.read(&mut buf)?;
if size < buf.len() {
break;
}
let raw: RawMetadata = unsafe { mem::transmute(buf) };
let parsed = Metadata {
name: raw.name,
offset: archive.stream_position()?,
size: parse_decimal(&raw.size)?,
};
// this can't panic, since size is 10 digits max.
let size: i64 = parsed.size.try_into().unwrap();
let offset = archive.seek(SeekFrom::Current(size))?;
if offset % 2 == 1 {
// metadata is aligned to 2 bytes
archive.seek(SeekFrom::Current(1))?;
}
metadata.push(parsed);
}
let mut long_filenames;
// see https://github.com/rust-lang/rust-clippy/issues/9274
#[allow(clippy::read_zero_byte_vec)]
{
long_filenames = vec![];
// in GNU archives, long filenames are stored in the "//" file.
for f in metadata.iter() {
if parse_name(&f.name)? == "//" {
// we found it!
archive.seek(SeekFrom::Start(f.offset))?;
long_filenames = vec![0; f.size as usize];
archive.read_exact(&mut long_filenames)?;
break;
}
}
}
let mut files = vec![];
for f in metadata.iter() {
let name = parse_name(&f.name)?;
if name == "/" || name == "//" {
continue;
}
let slice = if let Some('/') = name.chars().next() {
// a long filename
let offset_str = name[1..].trim_end();
let offset: usize = offset_str.parse().map_err(|_| BadNumber)?;
let len = long_filenames[offset..]
.iter()
.position(|&x| x == b'/')
.unwrap_or(0);
let bytes = &long_filenames[offset..offset + len];
std::str::from_utf8(bytes).map_err(|_| BadUtf8)?
} else if let Some('/') = name.chars().last() {
// filename is ended with / in GNU archives
&name[..name.len() - 1]
} else {
name
};
let filename = String::from(slice);
files.push(FileMetadata {
name: filename,
offset: f.offset,
size: f.size,
});
}
Ok(Self { archive, files })
}
/// Get number of files in archive.
pub fn file_count(&self) -> usize {
self.files.len()
}
/// Get name of file.
pub fn file_name(&self, index: usize) -> &str {
&self.files[index].name
}
/// Get all file data into memory.
///
/// I tried making a "sub-file" type but it was a mess.
pub fn file_data(&mut self, index: usize) -> Result<Vec<u8>> {
self.archive
.seek(SeekFrom::Start(self.files[index].offset))?;
let mut data = vec![0; self.files[index].size as usize];
self.archive.read_exact(&mut data)?;
Ok(data)
}
}
/// example usage. prints out the contents of the archive file. (panics on error.)
pub fn _list(path: &str) {
let f = std::fs::File::open(path).unwrap();
let mut ar = Archive::new(io::BufReader::new(f)).unwrap();
for i in 0..ar.file_count() {
use io::Write;
println!("\x1b[1m---{}---\x1b[0m", ar.file_name(i));
let bytes = ar.file_data(i).unwrap();
std::io::stdout().write_all(&bytes).unwrap();
println!("\n");
}
}
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