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use std::borrow::Cow;
use ownable::{traits as ownable_traits, IntoOwned, ToOwned};
use tracing::trace;
use winnow::{
binary::{le_u16, le_u32, le_u64, length_take},
seq,
token::literal,
PResult, Parser, Partial,
};
use crate::error::{Error, FormatError};
/// 4.3.16 End of central directory record:
#[derive(Debug, ToOwned, IntoOwned, Clone)]
pub struct EndOfCentralDirectoryRecord<'a> {
/// number of this disk
pub disk_nbr: u16,
/// number of the disk with the start of the central directory
pub dir_disk_nbr: u16,
/// total number of entries in the central directory on this disk
pub dir_records_this_disk: u16,
/// total number of entries in the central directory
pub directory_records: u16,
/// size of the central directory
pub directory_size: u32,
/// offset of start of central directory with respect to the starting disk number
pub directory_offset: u32,
/// .ZIP file comment
pub comment: Cow<'a, [u8]>,
}
impl<'a> EndOfCentralDirectoryRecord<'a> {
/// Does not include comment size & comment data
const MIN_LENGTH: usize = 20;
const SIGNATURE: &'static str = "PK\x05\x06";
/// Find the end of central directory record in a block of data
pub fn find_in_block(b: &'a [u8]) -> Option<Located<Self>> {
for i in (0..(b.len().saturating_sub(Self::MIN_LENGTH + 1))).rev() {
let mut input = Partial::new(&b[i..]);
if let Ok(directory) = Self::parser.parse_next(&mut input) {
return Some(Located {
offset: i as u64,
inner: directory,
});
}
}
None
}
/// Parser for the end of central directory record
pub fn parser(i: &mut Partial<&'a [u8]>) -> PResult<Self> {
let _ = literal(Self::SIGNATURE).parse_next(i)?;
seq! {Self {
disk_nbr: le_u16,
dir_disk_nbr: le_u16,
dir_records_this_disk: le_u16,
directory_records: le_u16,
directory_size: le_u32,
directory_offset: le_u32,
comment: length_take(le_u16).map(Cow::Borrowed),
}}
.parse_next(i)
}
}
/// 4.3.15 Zip64 end of central directory locator
#[derive(Debug)]
pub struct EndOfCentralDirectory64Locator {
/// number of the disk with the start of the zip64 end of central directory
pub dir_disk_number: u32,
/// relative offset of the zip64 end of central directory record
pub directory_offset: u64,
/// total number of disks
pub total_disks: u32,
}
impl EndOfCentralDirectory64Locator {
/// Length of the locator
pub const LENGTH: usize = 20;
const SIGNATURE: &'static str = "PK\x06\x07";
/// Parser for the zip64 end of central directory locator
pub fn parser(i: &mut Partial<&'_ [u8]>) -> PResult<Self> {
_ = literal(Self::SIGNATURE).parse_next(i)?;
seq! {Self {
dir_disk_number: le_u32,
directory_offset: le_u64,
total_disks: le_u32,
}}
.parse_next(i)
}
}
/// 4.3.14 Zip64 end of central directory record
#[derive(Debug, Clone, ToOwned, IntoOwned)]
pub struct EndOfCentralDirectory64Record {
/// size of zip64 end of central directory record
pub record_size: u64,
/// version made by
pub creator_version: u16,
/// version needed to extract
pub reader_version: u16,
/// number of this disk
pub disk_nbr: u32,
/// number of the disk with the start of the central directory
pub dir_disk_nbr: u32,
/// total number of entries in the central directory on this disk
pub dir_records_this_disk: u64,
/// total number of entries in the central directory
pub directory_records: u64,
/// size of the central directory
pub directory_size: u64,
/// offset of the start of central directory with respect to the
/// starting disk number
pub directory_offset: u64,
}
impl EndOfCentralDirectory64Record {
const SIGNATURE: &'static str = "PK\x06\x06";
/// Parser for the zip64 end of central directory record
pub fn parser(i: &mut Partial<&'_ [u8]>) -> PResult<Self> {
_ = literal(Self::SIGNATURE).parse_next(i)?;
seq! {Self {
record_size: le_u64,
creator_version: le_u16,
reader_version: le_u16,
disk_nbr: le_u32,
dir_disk_nbr: le_u32,
dir_records_this_disk: le_u64,
directory_records: le_u64,
directory_size: le_u64,
directory_offset: le_u64,
}}
.parse_next(i)
}
}
/// A zip structure and its location in the input file
#[derive(Debug, Clone)]
pub struct Located<T> {
/// Absolute by offset from the start of the file
pub offset: u64,
/// The structure itself
pub inner: T,
}
impl<T> ownable_traits::ToOwned for Located<T>
where
T: ownable_traits::ToOwned,
{
type Owned = Located<T::Owned>;
fn to_owned(&self) -> Self::Owned {
Located {
offset: self.offset,
inner: self.inner.to_owned(),
}
}
}
impl<T> ownable_traits::IntoOwned for Located<T>
where
T: ownable_traits::IntoOwned,
{
type Owned = Located<T::Owned>;
fn into_owned(self) -> Self::Owned {
Located {
offset: self.offset,
inner: self.inner.into_owned(),
}
}
}
/// Coalesces zip and zip64 "end of central directory" record info
#[derive(ToOwned, IntoOwned)]
pub struct EndOfCentralDirectory<'a> {
/// The end of central directory record
pub dir: Located<EndOfCentralDirectoryRecord<'a>>,
/// The zip64 end of central directory record
pub dir64: Option<Located<EndOfCentralDirectory64Record>>,
/// Zip files may be prepended by arbitrary data, this is how much
/// data is at the beginning of the file that isn't part of the zip
pub global_offset: i64,
}
impl<'a> EndOfCentralDirectory<'a> {
pub(crate) fn new(
size: u64,
dir: Located<EndOfCentralDirectoryRecord<'a>>,
dir64: Option<Located<EndOfCentralDirectory64Record>>,
) -> Result<Self, Error> {
let mut res = Self {
dir,
dir64,
global_offset: 0,
};
//
// Pure .zip files look like this:
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// <------directory_size----->
// [ Data 1 ][ Data 2 ][ Central directory ][ ??? ]
// ^ ^ ^
// 0 directory_offset directory_end_offset
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// But there exist some valid zip archives with padding at the beginning, like so:
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// <--global_offset-> <------directory_size----->
// [ Padding ][ Data 1 ][ Data 2 ][ Central directory ][ ??? ]
// ^ ^ ^ ^
// 0 global_offset computed_directory_offset directory_end_offset
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// (e.g. https://www.icculus.org/mojosetup/ installers are ELF binaries with a .zip file appended)
//
// `directory_end_offset` is found by scanning the file (so it accounts for padding), but
// `directory_offset` is found by reading a data structure (so it does not account for padding).
// If we just trusted `directory_offset`, we'd be reading the central directory at the wrong place:
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// <------directory_size----->
// [ Padding ][ Data 1 ][ Data 2 ][ Central directory ][ ??? ]
// ^ ^ ^
// 0 directory_offset - woops! directory_end_offset
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
let computed_directory_offset = res
.located_directory_offset()
.checked_sub(res.directory_size())
.ok_or(FormatError::DirectoryOffsetPointsOutsideFile)?;
// did we find a valid offset?
if (0..size).contains(&computed_directory_offset) {
// that's different from the recorded one?
if computed_directory_offset != res.directory_offset() {
// then assume the whole file is offset
res.global_offset =
computed_directory_offset as i64 - res.directory_offset() as i64;
res.set_directory_offset(computed_directory_offset);
}
}
// make sure directory_offset points to somewhere in our file
trace!(
"directory offset = {}, valid range = 0..{}",
res.directory_offset(),
size
);
if !(0..size).contains(&res.directory_offset()) {
return Err(FormatError::DirectoryOffsetPointsOutsideFile.into());
}
Ok(res)
}
#[inline]
pub(crate) fn located_directory_offset(&self) -> u64 {
match self.dir64.as_ref() {
Some(d64) => d64.offset,
None => self.dir.offset,
}
}
#[inline]
pub(crate) fn directory_offset(&self) -> u64 {
match self.dir64.as_ref() {
Some(d64) => d64.inner.directory_offset,
None => self.dir.inner.directory_offset as u64,
}
}
#[inline]
pub(crate) fn directory_size(&self) -> u64 {
match self.dir64.as_ref() {
Some(d64) => d64.inner.directory_size,
None => self.dir.inner.directory_size as u64,
}
}
#[inline]
pub(crate) fn set_directory_offset(&mut self, offset: u64) {
match self.dir64.as_mut() {
Some(d64) => d64.inner.directory_offset = offset,
None => self.dir.inner.directory_offset = offset as u32,
};
}
#[inline]
pub(crate) fn directory_records(&self) -> u64 {
match self.dir64.as_ref() {
Some(d64) => d64.inner.directory_records,
None => self.dir.inner.directory_records as u64,
}
}
#[inline]
pub(crate) fn comment(&self) -> &[u8] {
&self.dir.inner.comment
}
}