blob: ec4fd0053764820ea2b76c190e5d10f4774a739b [file] [log] [blame]
// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google LLC. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//! Kernel-agnostic logic for the Rust Protobuf runtime that should not be
//! exposed to through the `protobuf` path but must be public for use by
//! generated code.
use std::slice;
/// Used to protect internal-only items from being used accidentally.
pub struct Private;
/// Represents an ABI-stable version of `NonNull<[u8]>`/`string_view` (a
/// borrowed slice of bytes) for FFI use only.
///
/// Has semantics similar to `std::string_view` in C++ and `&[u8]` in Rust,
/// but is not ABI-compatible with either.
///
/// If `len` is 0, then `ptr` can be null or dangling. C++ considers a dangling
/// 0-len `std::string_view` to be invalid, and Rust considers a `&[u8]` with a
/// null data pointer to be invalid.
#[repr(C)]
#[derive(Copy, Clone)]
pub struct PtrAndLen {
/// Pointer to the first byte.
/// Borrows the memory.
pub ptr: *const u8,
/// Length of the `[u8]` pointed to by `ptr`.
pub len: usize,
}
impl PtrAndLen {
/// Unsafely dereference this slice.
///
/// # Safety
/// - `ptr` must be valid for `len` bytes. It can be null or dangling if
/// `self.len == 0`.
pub unsafe fn as_ref<'a>(self) -> &'a [u8] {
if self.ptr.is_null() {
assert_eq!(self.len, 0, "Non-empty slice with null data pointer");
&[]
} else {
slice::from_raw_parts(self.ptr, self.len)
}
}
}