pkgar 0.1.13

Redox Package Archive
Documentation 
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use std::{
    convert::TryFrom,
    fs::{File, OpenOptions},
    io::{BufReader, Read, Seek, SeekFrom},
    path::{Path, PathBuf},
};
use sodiumoxide::crypto::sign::PublicKey;
use pkgar_core::{Entry, Header, HEADER_SIZE, PackageSrc};

use crate::{Error, ResultExt};
use crate::ext::EntryExt;

#[derive(Debug)]
pub struct PackageHead {
    head_path: PathBuf,
    root_path: PathBuf,
    pub(crate) src: BufReader<File>,
    header: Header,
}

impl PackageHead {
    pub fn new(
        head_path: impl AsRef<Path>,
        root_path: impl AsRef<Path>,
        public_key: &PublicKey
    ) -> Result<PackageHead, Error> {
        let zeroes = [0; HEADER_SIZE];
        let head_path = head_path.as_ref().to_path_buf();
        let root_path = root_path.as_ref().to_path_buf();

        let file = OpenOptions::new()
            .read(true)
            .open(&head_path)
            .chain_err(|| &head_path )?;

        let mut new = PackageHead {
            head_path,
            root_path,
            src: BufReader::new(file),

            // Need a blank header to construct the PackageHead, since we need to
            //   use a method of PackageSrc in order to get the actual header...
            header: unsafe { *Header::new_unchecked(&zeroes)? },
        };

        new.header = new.read_header(public_key)?;
        Ok(new)
    }
}

impl PackageSrc for PackageHead {
    type Err = Error;

    fn header(&self) -> Header {
        self.header
    }

    fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Result<usize, Self::Err> {
        self.src.seek(SeekFrom::Start(offset))?;
        self.src.read_exact(buf)?;
        Ok(buf.len())
    }

    /// Read from this src at a given entry's data with a given offset within that entry
    fn read_entry(&mut self, entry: Entry, offset: usize, buf: &mut [u8]) -> Result<usize, Self::Err> {
        if offset as u64 > entry.size {
            return Ok(0);
        }

        let mut end = usize::try_from(entry.size - offset as u64)
            .map_err(pkgar_core::Error::TryFromInt)?;

        if end > buf.len() {
            end = buf.len();
        }

        let relative_path = entry.check_path()
            .chain_err(|| &self.head_path)?;
        let entry_path = self.root_path.join(relative_path);
        let mut entry_file = OpenOptions::new()
            .read(true)
            .open(&entry_path)
            .chain_err(|| &entry_path)?;

        entry_file.seek(SeekFrom::Start(offset as u64))
            .chain_err(|| &entry_path)?;

        entry_file.read(&mut buf[..end])
            .chain_err(|| &entry_path)
    }
}