cargo-binstall/src/helpers/extracter.rs

use std::fs::File;
use std::io::{BufRead, Read};
use std::path::Path;

use flate2::bufread::GzDecoder;
use log::debug;
use tar::{Archive, Entries};
use xz2::bufread::XzDecoder;
use zip::read::ZipArchive;
use zstd::stream::Decoder as ZstdDecoder;

use crate::{BinstallError, TarBasedFmt};

/// Visitor must iterate over all entries.
/// Entires can be in arbitary order.
pub trait TarEntriesVisitor {
    fn visit<R: Read>(&mut self, entries: Entries<'_, R>) -> Result<(), BinstallError>;
}

impl<V: TarEntriesVisitor> TarEntriesVisitor for &mut V {
    fn visit<R: Read>(&mut self, entries: Entries<'_, R>) -> Result<(), BinstallError> {
        (*self).visit(entries)
    }
}

#[derive(Debug)]
pub(super) enum Op<'a, V: TarEntriesVisitor> {
    UnpackToPath(&'a Path),
    Visit(V),
}

///  * `f` - If Some, then this function will pass
///    the entries of the `dat` to it and let it decides
///    what to do with the tar.
fn untar<R: Read, V: TarEntriesVisitor>(
    mut tar: Archive<R>,
    op: Op<'_, V>,
) -> Result<(), BinstallError> {
    match op {
        Op::Visit(mut visitor) => {
            debug!("Untaring with callback");

            visitor.visit(tar.entries()?)?;
        }
        Op::UnpackToPath(path) => {
            debug!("Untaring entire tar");
            tar.unpack(path)?;
        }
    }

    debug!("Untaring completed");

    Ok(())
}

pub(super) fn create_tar_decoder(
    dat: impl BufRead + 'static,
    fmt: TarBasedFmt,
) -> Result<Archive<Box<dyn Read>>, BinstallError> {
    use TarBasedFmt::*;

    let r: Box<dyn Read> = match fmt {
        Tar => Box::new(dat),
        Tgz => Box::new(GzDecoder::new(dat)),
        Txz => Box::new(XzDecoder::new(dat)),
        Tzstd => {
            // The error can only come from raw::Decoder::with_dictionary
            // as of zstd 0.10.2 and 0.11.2, which is specified
            // as &[] by ZstdDecoder::new, thus ZstdDecoder::new
            // should not return any error.
            Box::new(ZstdDecoder::with_buffer(dat)?)
        }
    };

    Ok(Archive::new(r))
}

/// Extract files from the specified source onto the specified path.
///
///  * `fmt` - must not be `PkgFmt::Bin` or `PkgFmt::Zip`.
///  * `filter` - If Some, then it will pass the path of the file to it
///    and only extract ones which filter returns `true`.
///    Note that this is a best-effort and it only works when `fmt`
///    is not `PkgFmt::Bin` or `PkgFmt::Zip`.
pub(super) fn extract_compressed_from_readable<V: TarEntriesVisitor, R: BufRead + 'static>(
    dat: R,
    fmt: TarBasedFmt,
    op: Op<'_, V>,
) -> Result<(), BinstallError> {
    let msg = if let Op::UnpackToPath(path) = op {
        format!("destination: {path:#?}")
    } else {
        "process in-memory".to_string()
    };

    debug!("Extracting from {fmt} archive: {msg}");

    let tar = create_tar_decoder(dat, fmt)?;
    untar(tar, op)
}

pub(super) fn unzip(dat: File, dst: &Path) -> Result<(), BinstallError> {
    debug!("Decompressing from zip archive to `{dst:?}`");

    let mut zip = ZipArchive::new(dat)?;
    zip.extract(dst)?;

    Ok(())
}