Struct z_stream Copy item path

The current stream state

§Custom allocators

The low-level API supports passing in a custom allocator as part of the z_stream:

struct z_stream {
    // ...
    zalloc: Option<unsafe extern "C" fn(*mut c_void, c_uint, c_uint) -> *mut c_void>,
    zfree: Option<unsafe extern "C" fn(*mut c_void, *mut c_void)>,
    opaque: *mut c_void,
}

When these fields are None (or NULL in C), the initialization functions use a default allocator, based on feature flags:

• "rust-allocator" uses the rust global allocator
• "c-allocator" uses an allocator based on malloc and free

When both are configured, the "rust-allocator" is preferred. When no default allocator is configured, and custom zalloc and zfree are provided, the initialization functions will return a Z_STREAM_ERROR.

When custom zalloc and zfree functions are given, they must adhere to the following contract to be safe:

• a call zalloc(opaque, n, m) must return a pointer p to n * m bytes of memory, or NULL if out of memory
• a call zfree(opaque, p) must free that memory

The strm.opaque value is passed to as the first argument to all calls to zalloc and zfree, but is otherwise ignored by the library.