178 lines
5.1 KiB
Rust
178 lines
5.1 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// This test deserializes an enum in-place by transmuting to a union that
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// should have the same layout, and manipulating the tag and payloads
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// independently. This verifies that `repr(some_int)` has a stable representation,
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// and that we don't miscompile these kinds of manipulations.
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use std::time::Duration;
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use std::mem;
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#[repr(C)]
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#[derive(Copy, Clone, Eq, PartialEq, Debug)]
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enum MyEnum {
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A(u32), // Single primitive value
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B { x: u8, y: i16 }, // Composite, and the offset of `y` depends on tag being internal
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C, // Empty
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D(Option<u32>), // Contains an enum
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E(Duration), // Contains a struct
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}
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#[repr(C)]
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struct MyEnumRepr {
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tag: MyEnumTag,
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payload: MyEnumPayload,
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}
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#[repr(C)]
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#[allow(non_snake_case)]
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union MyEnumPayload {
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A: MyEnumVariantA,
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B: MyEnumVariantB,
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D: MyEnumVariantD,
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E: MyEnumVariantE,
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}
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#[repr(C)] #[derive(Copy, Clone)] enum MyEnumTag { A, B, C, D, E }
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#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantA(u32);
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#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantB {x: u8, y: i16 }
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#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantD(Option<u32>);
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#[repr(C)] #[derive(Copy, Clone)] struct MyEnumVariantE(Duration);
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fn main() {
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let result: Vec<Result<MyEnum, ()>> = vec![
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Ok(MyEnum::A(17)),
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Ok(MyEnum::B { x: 206, y: 1145 }),
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Ok(MyEnum::C),
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Err(()),
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Ok(MyEnum::D(Some(407))),
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Ok(MyEnum::D(None)),
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Ok(MyEnum::E(Duration::from_secs(100))),
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Err(()),
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];
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// Binary serialized version of the above (little-endian)
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let input: Vec<u8> = vec![
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0, 17, 0, 0, 0,
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1, 206, 121, 4,
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2,
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8, /* invalid tag value */
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3, 0, 151, 1, 0, 0,
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3, 1,
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4, 100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, /* incomplete value */
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];
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let mut output = vec![];
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let mut buf = &input[..];
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unsafe {
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// This should be safe, because we don't match on it unless it's fully formed,
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// and it doesn't have a destructor.
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let mut dest: MyEnum = mem::uninitialized();
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while buf.len() > 0 {
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match parse_my_enum(&mut dest, &mut buf) {
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Ok(()) => output.push(Ok(dest)),
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Err(()) => output.push(Err(())),
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}
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}
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}
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assert_eq!(output, result);
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}
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fn parse_my_enum<'a>(dest: &'a mut MyEnum, buf: &mut &[u8]) -> Result<(), ()> {
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unsafe {
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// Should be correct to do this transmute.
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let dest: &'a mut MyEnumRepr = mem::transmute(dest);
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let tag = read_u8(buf)?;
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dest.tag = match tag {
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0 => MyEnumTag::A,
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1 => MyEnumTag::B,
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2 => MyEnumTag::C,
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3 => MyEnumTag::D,
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4 => MyEnumTag::E,
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_ => return Err(()),
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};
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match dest.tag {
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MyEnumTag::A => {
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dest.payload.A.0 = read_u32_le(buf)?;
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}
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MyEnumTag::B => {
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dest.payload.B.x = read_u8(buf)?;
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dest.payload.B.y = read_u16_le(buf)? as i16;
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}
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MyEnumTag::C => {
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/* do nothing */
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}
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MyEnumTag::D => {
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let is_some = read_u8(buf)? == 0;
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if is_some {
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dest.payload.D.0 = Some(read_u32_le(buf)?);
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} else {
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dest.payload.D.0 = None;
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}
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}
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MyEnumTag::E => {
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let secs = read_u64_le(buf)?;
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let nanos = read_u32_le(buf)?;
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dest.payload.E.0 = Duration::new(secs, nanos);
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}
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}
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Ok(())
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}
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}
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// reader helpers
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fn read_u64_le(buf: &mut &[u8]) -> Result<u64, ()> {
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if buf.len() < 8 { return Err(()) }
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let val = (buf[0] as u64) << 0
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| (buf[1] as u64) << 8
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| (buf[2] as u64) << 16
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| (buf[3] as u64) << 24
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| (buf[4] as u64) << 32
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| (buf[5] as u64) << 40
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| (buf[6] as u64) << 48
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| (buf[7] as u64) << 56;
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*buf = &buf[8..];
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Ok(val)
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}
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fn read_u32_le(buf: &mut &[u8]) -> Result<u32, ()> {
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if buf.len() < 4 { return Err(()) }
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let val = (buf[0] as u32) << 0
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| (buf[1] as u32) << 8
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| (buf[2] as u32) << 16
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| (buf[3] as u32) << 24;
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*buf = &buf[4..];
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Ok(val)
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}
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fn read_u16_le(buf: &mut &[u8]) -> Result<u16, ()> {
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if buf.len() < 2 { return Err(()) }
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let val = (buf[0] as u16) << 0
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| (buf[1] as u16) << 8;
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*buf = &buf[2..];
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Ok(val)
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}
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fn read_u8(buf: &mut &[u8]) -> Result<u8, ()> {
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if buf.len() < 1 { return Err(()) }
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let val = buf[0];
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*buf = &buf[1..];
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Ok(val)
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}
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