totally_safe_transmute/
lib.rs

1#![forbid(unsafe_code)]
2
3pub fn totally_safe_transmute<T, U>(v: T) -> U {
4    #[repr(C)]
5    enum E<T, U> {
6        T(T),
7        #[allow(dead_code)] U(U),
8    }
9    let v = E::T(v);
10
11    #[cfg(target_os = "linux")]
12    {
13        use std::{io::{self, Write, Seek}, fs};
14
15        let mut f = fs::OpenOptions::new()
16            .write(true)
17            .open("/proc/self/mem").expect("welp");
18
19        f.seek(io::SeekFrom::Start(&v as *const _ as u64)).expect("oof");
20        f.write(&[1]).expect("darn");
21    }
22
23    #[cfg(target_os = "windows")]
24    {
25        use std::{env, process, fs};
26        let p = env::temp_dir().join("random-collision-free-name-I1G3qPvXTU4RvRML.ps1");
27        fs::write(&p, r#"
28            Param (
29                [int]$parentPid,
30                [UInt64]$tagAddress
31            )
32
33            Add-Type -TypeDefinition @"
34                using System;
35                using System.Runtime.InteropServices;
36
37                public static class Helper {
38                    const int PROCESS_VM_WRITE = 0x0020;
39                    const int PROCESS_VM_OPERATION = 0x0008;
40
41                    [DllImport("kernel32.dll")]
42                    public static extern IntPtr OpenProcess(int dwDesiredAccess,
43                        bool bInheritHandle, int dwProcessId);
44
45                    [DllImport("kernel32.dll", SetLastError = true)]
46                    public static extern bool WriteProcessMemory(IntPtr hProcess, ulong lpBaseAddress,
47                        byte[] lpBuffer, int dwSize, IntPtr lpNumberOfBytesWritten);
48                    
49                    public static void Run(int parentPid, ulong tagAddress) {
50                        IntPtr handle = OpenProcess(PROCESS_VM_WRITE | PROCESS_VM_OPERATION, false, parentPid);
51                        WriteProcessMemory(handle, tagAddress, new byte[]{1}, 1, (IntPtr) 0);
52                    }
53                }
54            "@
55
56            [Helper]::Run($parentPid, $tagAddress) 
57        "#.replace("\n            ", "\n")).unwrap();
58        let i = process::id();
59        if !process::Command::new("powershell")
60            .args(&[&p.to_str().unwrap(), &i.to_string()[..], &(&v as *const _ as u64).to_string()])
61            .spawn()
62            .unwrap()
63            .wait()
64            .unwrap()
65            .success() { panic!("install linux lol"); }
66        fs::remove_file(&p).unwrap();
67    }
68
69    if let E::U(v) = v {
70        return v;
71    }
72
73    panic!("rip");
74}
75
76#[test]
77fn main() {
78    let v: Vec<u8> = b"foo".to_vec();
79    let v: String = totally_safe_transmute(v);
80    assert_eq!(&v, "foo");
81}
totally_safe_transmute/lib.rs

totally_safe_transmute/
lib.rs
