use std::ffi::CString;
use std::io::{BufRead, Error, ErrorKind, Read, Result, Write};
use std::time;
use crate::bufreader::BufReader;
use crate::{Compression, Crc};
pub static FHCRC: u8 = 1 << 1;
pub static FEXTRA: u8 = 1 << 2;
pub static FNAME: u8 = 1 << 3;
pub static FCOMMENT: u8 = 1 << 4;
pub static FRESERVED: u8 = 1 << 5 | 1 << 6 | 1 << 7;
pub mod bufread;
pub mod read;
pub mod write;
// The maximum length of the header filename and comment fields. More than
// enough for these fields in reasonable use, but prevents possible attacks.
const MAX_HEADER_BUF: usize = 65535;
/// A structure representing the header of a gzip stream.
///
/// The header can contain metadata about the file that was compressed, if
/// present.
#[derive(PartialEq, Clone, Debug, Default)]
pub struct GzHeader {
extra: Option<Vec<u8>>,
filename: Option<Vec<u8>>,
comment: Option<Vec<u8>>,
operating_system: u8,
mtime: u32,
}
impl GzHeader {
/// Returns the `filename` field of this gzip stream's header, if present.
pub fn filename(&self) -> Option<&[u8]> {
self.filename.as_ref().map(|s| &s[..])
}
/// Returns the `extra` field of this gzip stream's header, if present.
pub fn extra(&self) -> Option<&[u8]> {
self.extra.as_ref().map(|s| &s[..])
}
/// Returns the `comment` field of this gzip stream's header, if present.
pub fn comment(&self) -> Option<&[u8]> {
self.comment.as_ref().map(|s| &s[..])
}
/// Returns the `operating_system` field of this gzip stream's header.
///
/// There are predefined values for various operating systems.
/// 255 means that the value is unknown.
pub fn operating_system(&self) -> u8 {
self.operating_system
}
/// This gives the most recent modification time of the original file being compressed.
///
/// The time is in Unix format, i.e., seconds since 00:00:00 GMT, Jan. 1, 1970.
/// (Note that this may cause problems for MS-DOS and other systems that use local
/// rather than Universal time.) If the compressed data did not come from a file,
/// `mtime` is set to the time at which compression started.
/// `mtime` = 0 means no time stamp is available.
///
/// The usage of `mtime` is discouraged because of Year 2038 problem.
pub fn mtime(&self) -> u32 {
self.mtime
}
/// Returns the most recent modification time represented by a date-time type.
/// Returns `None` if the value of the underlying counter is 0,
/// indicating no time stamp is available.
///
///
/// The time is measured as seconds since 00:00:00 GMT, Jan. 1 1970.
/// See [`mtime`](#method.mtime) for more detail.
pub fn mtime_as_datetime(&self) -> Option<time::SystemTime> {
if self.mtime == 0 {
None
} else {
let duration = time::Duration::new(u64::from(self.mtime), 0);
let datetime = time::UNIX_EPOCH + duration;
Some(datetime)
}
}
}
#[derive(Debug)]
pub enum GzHeaderState {
Start(u8, [u8; 10]),
Xlen(Option<Box<Crc>>, u8, [u8; 2]),
Extra(Option<Box<Crc>>, u16),
Filename(Option<Box<Crc>>),
Comment(Option<Box<Crc>>),
Crc(Option<Box<Crc>>, u8, [u8; 2]),
Complete,
}
impl Default for GzHeaderState {
fn default() -> Self {
Self::Complete
}
}
#[derive(Debug, Default)]
pub struct GzHeaderParser {
state: GzHeaderState,
flags: u8,
header: GzHeader,
}
impl GzHeaderParser {
fn new() -> Self {
GzHeaderParser {
state: GzHeaderState::Start(0, [0; 10]),
flags: 0,
header: GzHeader::default(),
}
}
fn parse<'a, R: Read>(&mut self, r: &'a mut R) -> Result<()> {
loop {
match &mut self.state {
GzHeaderState::Start(count, buffer) => {
while (*count as usize) < buffer.len() {
*count += read_into(r, &mut buffer[*count as usize..])? as u8;
}
// Gzip identification bytes
if buffer[0] != 0x1f || buffer[1] != 0x8b {
return Err(bad_header());
}
// Gzip compression method (8 = deflate)
if buffer[2] != 8 {
return Err(bad_header());
}
self.flags = buffer[3];
// RFC1952: "must give an error indication if any reserved bit is non-zero"
if self.flags & FRESERVED != 0 {
return Err(bad_header());
}
self.header.mtime = ((buffer[4] as u32) << 0)
| ((buffer[5] as u32) << 8)
| ((buffer[6] as u32) << 16)
| ((buffer[7] as u32) << 24);
let _xfl = buffer[8];
self.header.operating_system = buffer[9];
let crc = if self.flags & FHCRC != 0 {
let mut crc = Box::new(Crc::new());
crc.update(buffer);
Some(crc)
} else {
None
};
self.state = GzHeaderState::Xlen(crc, 0, [0; 2]);
}
GzHeaderState::Xlen(crc, count, buffer) => {
if self.flags & FEXTRA != 0 {
while (*count as usize) < buffer.len() {
*count += read_into(r, &mut buffer[*count as usize..])? as u8;
}
if let Some(crc) = crc {
crc.update(buffer);
}
let xlen = parse_le_u16(&buffer);
self.header.extra = Some(vec![0; xlen as usize]);
self.state = GzHeaderState::Extra(crc.take(), 0);
} else {
self.state = GzHeaderState::Filename(crc.take());
}
}
GzHeaderState::Extra(crc, count) => {
debug_assert!(self.header.extra.is_some());
let extra = self.header.extra.as_mut().unwrap();
while (*count as usize) < extra.len() {
*count += read_into(r, &mut extra[*count as usize..])? as u16;
}
if let Some(crc) = crc {
crc.update(extra);
}
self.state = GzHeaderState::Filename(crc.take());
}
GzHeaderState::Filename(crc) => {
if self.flags & FNAME != 0 {
let filename = self.header.filename.get_or_insert_with(Vec::new);
read_to_nul(r, filename)?;
if let Some(crc) = crc {
crc.update(filename);
crc.update(b"\0");
}
}
self.state = GzHeaderState::Comment(crc.take());
}
GzHeaderState::Comment(crc) => {
if self.flags & FCOMMENT != 0 {
let comment = self.header.comment.get_or_insert_with(Vec::new);
read_to_nul(r, comment)?;
if let Some(crc) = crc {
crc.update(comment);
crc.update(b"\0");
}
}
self.state = GzHeaderState::Crc(crc.take(), 0, [0; 2]);
}
GzHeaderState::Crc(crc, count, buffer) => {
if let Some(crc) = crc {
debug_assert!(self.flags & FHCRC != 0);
while (*count as usize) < buffer.len() {
*count += read_into(r, &mut buffer[*count as usize..])? as u8;
}
let stored_crc = parse_le_u16(&buffer);
let calced_crc = crc.sum() as u16;
if stored_crc != calced_crc {
return Err(corrupt());
}
}
self.state = GzHeaderState::Complete;
}
GzHeaderState::Complete => {
return Ok(());
}
}
}
}
fn header(&self) -> Option<&GzHeader> {
match self.state {
GzHeaderState::Complete => Some(&self.header),
_ => None,
}
}
}
impl From<GzHeaderParser> for GzHeader {
fn from(parser: GzHeaderParser) -> Self {
debug_assert!(matches!(parser.state, GzHeaderState::Complete));
parser.header
}
}
// Attempt to fill the `buffer` from `r`. Return the number of bytes read.
// Return an error if EOF is read before the buffer is full. This differs
// from `read` in that Ok(0) means that more data may be available.
fn read_into<R: Read>(r: &mut R, buffer: &mut [u8]) -> Result<usize> {
debug_assert!(!buffer.is_empty());
match r.read(buffer) {
Ok(0) => Err(ErrorKind::UnexpectedEof.into()),
Ok(n) => Ok(n),
Err(ref e) if e.kind() == ErrorKind::Interrupted => Ok(0),
Err(e) => Err(e),
}
}
// Read `r` up to the first nul byte, pushing non-nul bytes to `buffer`.
fn read_to_nul<R: Read>(r: &mut R, buffer: &mut Vec<u8>) -> Result<()> {
let mut bytes = r.bytes();
loop {
match bytes.next().transpose()? {
Some(byte) if byte == 0 => {
return Ok(());
}
Some(_) if buffer.len() == MAX_HEADER_BUF => {
return Err(Error::new(
ErrorKind::InvalidInput,
"gzip header field too long",
));
}
Some(byte) => {
buffer.push(byte);
}
None => {
return Err(ErrorKind::UnexpectedEof.into());
}
}
}
}
fn parse_le_u16(buffer: &[u8; 2]) -> u16 {
(buffer[0] as u16) | ((buffer[1] as u16) << 8)
}
fn bad_header() -> Error {
Error::new(ErrorKind::InvalidInput, "invalid gzip header")
}
fn corrupt() -> Error {
Error::new(
ErrorKind::InvalidInput,
"corrupt gzip stream does not have a matching checksum",
)
}
/// A builder structure to create a new gzip Encoder.
///
/// This structure controls header configuration options such as the filename.
///
/// # Examples
///
/// ```
/// use std::io::prelude::*;
/// # use std::io;
/// use std::fs::File;
/// use flate2::GzBuilder;
/// use flate2::Compression;
///
/// // GzBuilder opens a file and writes a sample string using GzBuilder pattern
///
/// # fn sample_builder() -> Result<(), io::Error> {
/// let f = File::create("examples/hello_world.gz")?;
/// let mut gz = GzBuilder::new()
/// .filename("hello_world.txt")
/// .comment("test file, please delete")
/// .write(f, Compression::default());
/// gz.write_all(b"hello world")?;
/// gz.finish()?;
/// # Ok(())
/// # }
/// ```
#[derive(Debug)]
pub struct GzBuilder {
extra: Option<Vec<u8>>,
filename: Option<CString>,
comment: Option<CString>,
operating_system: Option<u8>,
mtime: u32,
}
impl Default for GzBuilder {
fn default() -> Self {
Self::new()
}
}
impl GzBuilder {
/// Create a new blank builder with no header by default.
pub fn new() -> GzBuilder {
GzBuilder {
extra: None,
filename: None,
comment: None,
operating_system: None,
mtime: 0,
}
}
/// Configure the `mtime` field in the gzip header.
pub fn mtime(mut self, mtime: u32) -> GzBuilder {
self.mtime = mtime;
self
}
/// Configure the `operating_system` field in the gzip header.
pub fn operating_system(mut self, os: u8) -> GzBuilder {
self.operating_system = Some(os);
self
}
/// Configure the `extra` field in the gzip header.
pub fn extra<T: Into<Vec<u8>>>(mut self, extra: T) -> GzBuilder {
self.extra = Some(extra.into());
self
}
/// Configure the `filename` field in the gzip header.
///
/// # Panics
///
/// Panics if the `filename` slice contains a zero.
pub fn filename<T: Into<Vec<u8>>>(mut self, filename: T) -> GzBuilder {
self.filename = Some(CString::new(filename.into()).unwrap());
self
}
/// Configure the `comment` field in the gzip header.
///
/// # Panics
///
/// Panics if the `comment` slice contains a zero.
pub fn comment<T: Into<Vec<u8>>>(mut self, comment: T) -> GzBuilder {
self.comment = Some(CString::new(comment.into()).unwrap());
self
}
/// Consume this builder, creating a writer encoder in the process.
///
/// The data written to the returned encoder will be compressed and then
/// written out to the supplied parameter `w`.
pub fn write<W: Write>(self, w: W, lvl: Compression) -> write::GzEncoder<W> {
write::gz_encoder(self.into_header(lvl), w, lvl)
}
/// Consume this builder, creating a reader encoder in the process.
///
/// Data read from the returned encoder will be the compressed version of
/// the data read from the given reader.
pub fn read<R: Read>(self, r: R, lvl: Compression) -> read::GzEncoder<R> {
read::gz_encoder(self.buf_read(BufReader::new(r), lvl))
}
/// Consume this builder, creating a reader encoder in the process.
///
/// Data read from the returned encoder will be the compressed version of
/// the data read from the given reader.
pub fn buf_read<R>(self, r: R, lvl: Compression) -> bufread::GzEncoder<R>
where
R: BufRead,
{
bufread::gz_encoder(self.into_header(lvl), r, lvl)
}
fn into_header(self, lvl: Compression) -> Vec<u8> {
let GzBuilder {
extra,
filename,
comment,
operating_system,
mtime,
} = self;
let mut flg = 0;
let mut header = vec![0u8; 10];
if let Some(v) = extra {
flg |= FEXTRA;
header.push((v.len() >> 0) as u8);
header.push((v.len() >> 8) as u8);
header.extend(v);
}
if let Some(filename) = filename {
flg |= FNAME;
header.extend(filename.as_bytes_with_nul().iter().copied());
}
if let Some(comment) = comment {
flg |= FCOMMENT;
header.extend(comment.as_bytes_with_nul().iter().copied());
}
header[0] = 0x1f;
header[1] = 0x8b;
header[2] = 8;
header[3] = flg;
header[4] = (mtime >> 0) as u8;
header[5] = (mtime >> 8) as u8;
header[6] = (mtime >> 16) as u8;
header[7] = (mtime >> 24) as u8;
header[8] = if lvl.0 >= Compression::best().0 {
2
} else if lvl.0 <= Compression::fast().0 {
4
} else {
0
};
// Typically this byte indicates what OS the gz stream was created on,
// but in an effort to have cross-platform reproducible streams just
// default this value to 255. I'm not sure that if we "correctly" set
// this it'd do anything anyway...
header[9] = operating_system.unwrap_or(255);
header
}
}
#[cfg(test)]
mod tests {
use std::io::prelude::*;
use super::{read, write, GzBuilder, GzHeaderParser};
use crate::{Compression, GzHeader};
use rand::{thread_rng, Rng};
#[test]
fn roundtrip() {
let mut e = write::GzEncoder::new(Vec::new(), Compression::default());
e.write_all(b"foo bar baz").unwrap();
let inner = e.finish().unwrap();
let mut d = read::GzDecoder::new(&inner[..]);
let mut s = String::new();
d.read_to_string(&mut s).unwrap();
assert_eq!(s, "foo bar baz");
}
#[test]
fn roundtrip_zero() {
let e = write::GzEncoder::new(Vec::new(), Compression::default());
let inner = e.finish().unwrap();
let mut d = read::GzDecoder::new(&inner[..]);
let mut s = String::new();
d.read_to_string(&mut s).unwrap();
assert_eq!(s, "");
}
#[test]
fn roundtrip_big() {
let mut real = Vec::new();
let mut w = write::GzEncoder::new(Vec::new(), Compression::default());
let v = crate::random_bytes().take(1024).collect::<Vec<_>>();
for _ in 0..200 {
let to_write = &v[..thread_rng().gen_range(0..v.len())];
real.extend(to_write.iter().copied());
w.write_all(to_write).unwrap();
}
let result = w.finish().unwrap();
let mut r = read::GzDecoder::new(&result[..]);
let mut v = Vec::new();
r.read_to_end(&mut v).unwrap();
assert_eq!(v, real);
}
#[test]
fn roundtrip_big2() {
let v = crate::random_bytes().take(1024 * 1024).collect::<Vec<_>>();
let mut r = read::GzDecoder::new(read::GzEncoder::new(&v[..], Compression::default()));
let mut res = Vec::new();
r.read_to_end(&mut res).unwrap();
assert_eq!(res, v);
}
// A Rust implementation of CRC that closely matches the C code in RFC1952.
// Only use this to create CRCs for tests.
struct Rfc1952Crc {
/* Table of CRCs of all 8-bit messages. */
crc_table: [u32; 256],
}
impl Rfc1952Crc {
fn new() -> Self {
let mut crc = Rfc1952Crc {
crc_table: [0; 256],
};
/* Make the table for a fast CRC. */
for n in 0usize..256 {
let mut c = n as u32;
for _k in 0..8 {
if c & 1 != 0 {
c = 0xedb88320 ^ (c >> 1);
} else {
c = c >> 1;
}
}
crc.crc_table[n] = c;
}
crc
}
/*
Update a running crc with the bytes buf and return
the updated crc. The crc should be initialized to zero. Pre- and
post-conditioning (one's complement) is performed within this
function so it shouldn't be done by the caller.
*/
fn update_crc(&self, crc: u32, buf: &[u8]) -> u32 {
let mut c = crc ^ 0xffffffff;
for b in buf {
c = self.crc_table[(c as u8 ^ *b) as usize] ^ (c >> 8);
}
c ^ 0xffffffff
}
/* Return the CRC of the bytes buf. */
fn crc(&self, buf: &[u8]) -> u32 {
self.update_crc(0, buf)
}
}
#[test]
fn roundtrip_header() {
let mut header = GzBuilder::new()
.mtime(1234)
.operating_system(57)
.filename("filename")
.comment("comment")
.into_header(Compression::fast());
// Add a CRC to the header
header[3] = header[3] ^ super::FHCRC;
let rfc1952_crc = Rfc1952Crc::new();
let crc32 = rfc1952_crc.crc(&header);
let crc16 = crc32 as u16;
header.extend(&crc16.to_le_bytes());
let mut parser = GzHeaderParser::new();
parser.parse(&mut header.as_slice()).unwrap();
let actual = parser.header().unwrap();
assert_eq!(
actual,
&GzHeader {
extra: None,
filename: Some("filename".as_bytes().to_vec()),
comment: Some("comment".as_bytes().to_vec()),
operating_system: 57,
mtime: 1234
}
)
}
#[test]
fn fields() {
let r = vec![0, 2, 4, 6];
let e = GzBuilder::new()
.filename("foo.rs")
.comment("bar")
.extra(vec![0, 1, 2, 3])
.read(&r[..], Compression::default());
let mut d = read::GzDecoder::new(e);
assert_eq!(d.header().unwrap().filename(), Some(&b"foo.rs"[..]));
assert_eq!(d.header().unwrap().comment(), Some(&b"bar"[..]));
assert_eq!(d.header().unwrap().extra(), Some(&b"\x00\x01\x02\x03"[..]));
let mut res = Vec::new();
d.read_to_end(&mut res).unwrap();
assert_eq!(res, vec![0, 2, 4, 6]);
}
#[test]
fn keep_reading_after_end() {
let mut e = write::GzEncoder::new(Vec::new(), Compression::default());
e.write_all(b"foo bar baz").unwrap();
let inner = e.finish().unwrap();
let mut d = read::GzDecoder::new(&inner[..]);
let mut s = String::new();
d.read_to_string(&mut s).unwrap();
assert_eq!(s, "foo bar baz");
d.read_to_string(&mut s).unwrap();
assert_eq!(s, "foo bar baz");
}
#[test]
fn qc_reader() {
::quickcheck::quickcheck(test as fn(_) -> _);
fn test(v: Vec<u8>) -> bool {
let r = read::GzEncoder::new(&v[..], Compression::default());
let mut r = read::GzDecoder::new(r);
let mut v2 = Vec::new();
r.read_to_end(&mut v2).unwrap();
v == v2
}
}
#[test]
fn flush_after_write() {
let mut f = write::GzEncoder::new(Vec::new(), Compression::default());
write!(f, "Hello world").unwrap();
f.flush().unwrap();
}
}
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