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When using zlib the stream object is now allocated on the heap.
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The zlib library internal state stores a pointer back to the stream, this requires the stream to have a stable memory location and never change.

This commit introduces a stream wrapper which heap allocates when using zlib but not when using miniz.
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@Lukazoid
Lukazoid committed Mar 29, 2017
1 parent fb85b41 commit 6cd3249
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Showing 2 changed files with 80 additions and 25 deletions.
54 changes: 54 additions & 0 deletions src/ffi.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ pub use self::imp::*;
mod imp {
extern crate libz_sys as z;
use std::mem;
use std::ops::{Deref, DerefMut};
use libc::{c_int, size_t, c_ulong, c_uint, c_char};

pub use self::z::*;
Expand Down Expand Up @@ -57,11 +58,64 @@ mod imp {
ZLIB_VERSION.as_ptr() as *const c_char,
mem::size_of::<mz_stream>() as c_int)
}

pub struct StreamWrapper{
inner: Box<mz_stream>,
}

impl Default for StreamWrapper {
fn default() -> StreamWrapper {
StreamWrapper {
inner: Box::new(unsafe{ mem::zeroed() })
}
}
}

impl Deref for StreamWrapper {
type Target = mz_stream;

fn deref(&self) -> &Self::Target {
& *self.inner
}
}

impl DerefMut for StreamWrapper {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut *self.inner
}
}
}

#[cfg(not(feature = "zlib"))]
mod imp {
extern crate miniz_sys;
use std::ops::{Deref, DerefMut};

pub use self::miniz_sys::*;

pub struct StreamWrapper {
inner: mz_stream,
}

impl Default for StreamWrapper {
fn default() -> StreamWrapper {
StreamWrapper {
inner : unsafe{ mem::zeroed() }
}
}
}

impl Deref for StreamWrapper {
type Target = mz_stream;

fn deref(&self) -> &Self::Target {
&self.inner
}
}

impl DerefMut for StreamWrapper {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.inner
}
}
}
51 changes: 26 additions & 25 deletions src/mem.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ use std::error::Error;
use std::fmt;
use std::io;
use std::marker;
use std::mem;
use std::slice;

use libc::{c_int, c_uint};
Expand Down Expand Up @@ -37,7 +36,7 @@ pub struct Decompress {
}

struct Stream<D: Direction> {
raw: ffi::mz_stream,
stream_wrapper: ffi::StreamWrapper,
total_in: u64,
total_out: u64,
_marker: marker::PhantomData<D>,
Expand Down Expand Up @@ -147,8 +146,8 @@ impl Compress {
/// output data should have a zlib header or not.
pub fn new(level: Compression, zlib_header: bool) -> Compress {
unsafe {
let mut state: ffi::mz_stream = mem::zeroed();
let ret = ffi::mz_deflateInit2(&mut state,
let mut state = ffi::StreamWrapper::default();
let ret = ffi::mz_deflateInit2(&mut *state,
level as c_int,
ffi::MZ_DEFLATED,
if zlib_header {
Expand All @@ -161,7 +160,7 @@ impl Compress {
debug_assert_eq!(ret, 0);
Compress {
inner: Stream {
raw: state,
stream_wrapper: state,
total_in: 0,
total_out: 0,
_marker: marker::PhantomData,
Expand All @@ -186,7 +185,7 @@ impl Compress {
///
/// This is equivalent to dropping this object and then creating a new one.
pub fn reset(&mut self) {
let rc = unsafe { ffi::mz_deflateReset(&mut self.inner.raw) };
let rc = unsafe { ffi::mz_deflateReset(&mut *self.inner.stream_wrapper) };
assert_eq!(rc, ffi::MZ_OK);

self.inner.total_in = 0;
Expand All @@ -205,18 +204,19 @@ impl Compress {
output: &mut [u8],
flush: Flush)
-> Status {
self.inner.raw.next_in = input.as_ptr() as *mut _;
self.inner.raw.avail_in = input.len() as c_uint;
self.inner.raw.next_out = output.as_mut_ptr();
self.inner.raw.avail_out = output.len() as c_uint;
let raw = &mut *self.inner.stream_wrapper;
raw.next_in = input.as_ptr() as *mut _;
raw.avail_in = input.len() as c_uint;
raw.next_out = output.as_mut_ptr();
raw.avail_out = output.len() as c_uint;

let rc = unsafe { ffi::mz_deflate(&mut self.inner.raw, flush as c_int) };
let rc = unsafe { ffi::mz_deflate(raw, flush as c_int) };

// Unfortunately the total counters provided by zlib might be only
// 32 bits wide and overflow while processing large amounts of data.
self.inner.total_in += (self.inner.raw.next_in as usize -
self.inner.total_in += (raw.next_in as usize -
input.as_ptr() as usize) as u64;
self.inner.total_out += (self.inner.raw.next_out as usize -
self.inner.total_out += (raw.next_out as usize -
output.as_ptr() as usize) as u64;

match rc {
Expand Down Expand Up @@ -263,8 +263,8 @@ impl Decompress {
/// to have a zlib header or not.
pub fn new(zlib_header: bool) -> Decompress {
unsafe {
let mut state: ffi::mz_stream = mem::zeroed();
let ret = ffi::mz_inflateInit2(&mut state,
let mut state = ffi::StreamWrapper::default();
let ret = ffi::mz_inflateInit2(&mut *state,
if zlib_header {
ffi::MZ_DEFAULT_WINDOW_BITS
} else {
Expand All @@ -273,7 +273,7 @@ impl Decompress {
debug_assert_eq!(ret, 0);
Decompress {
inner: Stream {
raw: state,
stream_wrapper: state,
total_in: 0,
total_out: 0,
_marker: marker::PhantomData,
Expand Down Expand Up @@ -313,18 +313,19 @@ impl Decompress {
output: &mut [u8],
flush: Flush)
-> Result<Status, DataError> {
self.inner.raw.next_in = input.as_ptr() as *mut u8;
self.inner.raw.avail_in = input.len() as c_uint;
self.inner.raw.next_out = output.as_mut_ptr();
self.inner.raw.avail_out = output.len() as c_uint;
let raw = &mut *self.inner.stream_wrapper;
raw.next_in = input.as_ptr() as *mut u8;
raw.avail_in = input.len() as c_uint;
raw.next_out = output.as_mut_ptr();
raw.avail_out = output.len() as c_uint;

let rc = unsafe { ffi::mz_inflate(&mut self.inner.raw, flush as c_int) };
let rc = unsafe { ffi::mz_inflate(raw, flush as c_int) };

// Unfortunately the total counters provided by zlib might be only
// 32 bits wide and overflow while processing large amounts of data.
self.inner.total_in += (self.inner.raw.next_in as usize -
self.inner.total_in += (raw.next_in as usize -
input.as_ptr() as usize) as u64;
self.inner.total_out += (self.inner.raw.next_out as usize -
self.inner.total_out += (raw.next_out as usize -
output.as_ptr() as usize) as u64;

match rc {
Expand Down Expand Up @@ -385,7 +386,7 @@ impl Decompress {
-ffi::MZ_DEFAULT_WINDOW_BITS
};
unsafe {
ffi::inflateReset2(&mut self.inner.raw, bits);
ffi::inflateReset2(&mut *self.inner.stream_wrapper, bits);
}
self.inner.total_out = 0;
self.inner.total_in = 0;
Expand Down Expand Up @@ -427,7 +428,7 @@ impl Direction for DirDecompress {
impl<D: Direction> Drop for Stream<D> {
fn drop(&mut self) {
unsafe {
let _ = D::destroy(&mut self.raw);
let _ = D::destroy(&mut *self.stream_wrapper);
}
}
}
Expand Down

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