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handle partially uninitialized streams properly
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@folkertdev
folkertdev committed Aug 16, 2024
1 parent 4078ab8 commit 3cfa75c
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Showing 2 changed files with 150 additions and 2 deletions.
76 changes: 74 additions & 2 deletions libz-rs-sys/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -393,6 +393,10 @@ pub unsafe extern "C" fn inflateEnd(strm: *mut z_stream) -> i32 {
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `zalloc`
/// - `zfree`
/// - `opaque`
#[export_name = prefix!(inflateBackInit_)]
pub unsafe extern "C" fn inflateBackInit_(
_strm: z_streamp,
Expand Down Expand Up @@ -585,6 +589,12 @@ pub unsafe extern "C" fn inflateSyncPoint(strm: *mut z_stream) -> i32 {
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `next_in`
/// - `avail_in`
/// - `zalloc`
/// - `zfree`
/// - `opaque`
#[export_name = prefix!(inflateInit_)]
pub unsafe extern "C" fn inflateInit_(
strm: z_streamp,
Expand Down Expand Up @@ -614,6 +624,12 @@ pub unsafe extern "C" fn inflateInit_(
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `next_in`
/// - `avail_in`
/// - `zalloc`
/// - `zfree`
/// - `opaque`
#[export_name = prefix!(inflateInit2_)]
pub unsafe extern "C" fn inflateInit2_(
strm: z_streamp,
Expand All @@ -628,6 +644,24 @@ pub unsafe extern "C" fn inflateInit2_(
}
}

/// Helper that implements the actual initialization logic
///
/// # Safety
///
/// The caller must guarantee that
///
/// * Either
/// - `strm` is `NULL`
/// - `strm` satisfies the requirements of `&mut *(strm as *mut MaybeUninit<z_stream>)`
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `next_in`
/// - `avail_in`
/// - `zalloc`
/// - `zfree`
/// - `opaque`
unsafe extern "C" fn inflateInit2(strm: z_streamp, windowBits: c_int) -> c_int {
if strm.is_null() {
ReturnCode::StreamError as _
Expand All @@ -636,7 +670,16 @@ unsafe extern "C" fn inflateInit2(strm: z_streamp, windowBits: c_int) -> c_int {
window_bits: windowBits,
};

let stream = &mut *strm;
let mut stream = z_stream::default();

// SAFETY: the caller guarantees these fields are initialized
unsafe {
stream.next_in = *core::ptr::addr_of!((*strm).next_in);
stream.avail_in = *core::ptr::addr_of!((*strm).avail_in);
stream.zalloc = *core::ptr::addr_of!((*strm).zalloc);
stream.zfree = *core::ptr::addr_of!((*strm).zfree);
stream.opaque = *core::ptr::addr_of!((*strm).opaque);
}

if stream.zalloc.is_none() {
stream.zalloc = DEFAULT_ZALLOC;
Expand All @@ -647,6 +690,13 @@ unsafe extern "C" fn inflateInit2(strm: z_streamp, windowBits: c_int) -> c_int {
stream.zfree = DEFAULT_ZFREE;
}

// SAFETY: the caller guarantees this pointer is writable
unsafe { core::ptr::write(strm, stream) };

// SAFETY: we have now properly initialized this memory
// the caller guarantees the safety of `&mut *`
let stream = unsafe { &mut *strm };

zlib_rs::inflate::init(stream, config) as _
}
}
Expand Down Expand Up @@ -1386,6 +1436,10 @@ pub unsafe extern "C" fn deflateCopy(dest: z_streamp, source: z_streamp) -> c_in
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `zalloc`
/// - `zfree`
/// - `opaque`
///
/// # Example
///
Expand Down Expand Up @@ -1468,6 +1522,10 @@ pub unsafe extern "C" fn deflateInit_(
/// * Either
/// - `version` is NULL
/// - `version` satisfies the requirements of [`core::ptr::read::<u8>`]
/// * If `strm` is not `NULL`, the following fields must be initialized
/// - `zalloc`
/// - `zfree`
/// - `opaque`
///
/// # Example
///
Expand Down Expand Up @@ -1529,7 +1587,14 @@ pub unsafe extern "C" fn deflateInit2_(
strategy,
};

let stream = &mut *strm;
let mut stream = z_stream::default();

// SAFETY: the caller guarantees these fields are initialized
unsafe {
stream.zalloc = *core::ptr::addr_of!((*strm).zalloc);
stream.zfree = *core::ptr::addr_of!((*strm).zfree);
stream.opaque = *core::ptr::addr_of!((*strm).opaque);
}

if stream.zalloc.is_none() {
stream.zalloc = DEFAULT_ZALLOC;
Expand All @@ -1540,6 +1605,13 @@ pub unsafe extern "C" fn deflateInit2_(
stream.zfree = DEFAULT_ZFREE;
}

// SAFETY: the caller guarantees this pointer is writable
unsafe { core::ptr::write(strm, stream) };

// SAFETY: we have now properly initialized this memory
// the caller guarantees the safety of `&mut *`
let stream = unsafe { &mut *strm };

zlib_rs::deflate::init(stream, config) as _
}
}
Expand Down
76 changes: 76 additions & 0 deletions test-libz-rs-sys/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -713,6 +713,82 @@ mod null {
assert_eq!(err, Z_OK);
}
}

#[test]
fn inflate_init_uninitialized() {
use libz_rs_sys::*;

unsafe {
let mut strm = MaybeUninit::<z_stream>::uninit();

core::ptr::write(core::ptr::addr_of_mut!((*strm.as_mut_ptr()).avail_in), 0);
core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).next_in),
core::ptr::null(),
);

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).zalloc).cast(),
zlib_rs::allocate::Allocator::C.zalloc,
);

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).zfree).cast(),
zlib_rs::allocate::Allocator::C.zfree,
);

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).opaque),
core::ptr::null_mut(),
);

let err = inflateInit_(
strm.as_mut_ptr(),
zlibVersion(),
core::mem::size_of::<z_stream>() as _,
);
assert_eq!(err, Z_OK);

let err = inflateEnd(strm.as_mut_ptr());
assert_eq!(err, Z_OK);
}
}

#[test]
#[cfg_attr(miri, ignore = "slow")]
fn deflate_init_uninitialized() {
use libz_rs_sys::*;

unsafe {
let mut strm = MaybeUninit::<z_stream>::uninit();

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).zalloc).cast(),
zlib_rs::allocate::Allocator::C.zalloc,
);

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).zfree).cast(),
zlib_rs::allocate::Allocator::C.zfree,
);

core::ptr::write(
core::ptr::addr_of_mut!((*strm.as_mut_ptr()).opaque),
core::ptr::null_mut(),
);

let err = deflateInit_(
strm.as_mut_ptr(),
6,
zlibVersion(),
core::mem::size_of::<z_stream>() as _,
);
assert_eq!(err, Z_OK);

let err = deflateEnd(strm.as_mut_ptr());
assert_eq!(err, Z_OK);
}
}
}

#[cfg(test)]
Expand Down

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