logo
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
//! Functions for interacting directly with mruby structs from [`sys`].
//!
//! These functions are unsafe. Use them carefully.

use std::borrow::Cow;
use std::error;
use std::fmt;
use std::mem;
use std::ptr::{self, NonNull};

use spinoso_exception::Fatal;

use crate::core::{ClassRegistry, TryConvertMut};
use crate::error::{Error, RubyException};
use crate::state::State;
use crate::sys;
use crate::Artichoke;

/// Extract an [`Artichoke`] interpreter from the user data pointer on a
/// [`sys::mrb_state`].
///
/// Calling this function will move the [`State`] out of the [`sys::mrb_state`]
/// into the [`Artichoke`] interpreter.
///
/// # Safety
///
/// This function assumes that the user data pointer was created with
/// [`Box::into_raw`] and that the pointer is to a non-free'd
/// [`Box`]`<`[`State`]`>`.
pub unsafe fn from_user_data(mrb: *mut sys::mrb_state) -> Result<Artichoke, InterpreterExtractError> {
    let mut mrb = if let Some(mrb) = NonNull::new(mrb) {
        mrb
    } else {
        emit_fatal_warning!("ffi: Attempted to extract Artichoke from null `mrb_state`");
        return Err(InterpreterExtractError::new());
    };

    let ud = mem::replace(&mut mrb.as_mut().ud, ptr::null_mut());
    let state = if let Some(state) = NonNull::new(ud) {
        state.cast::<State>()
    } else {
        let alloc_ud = mem::replace(&mut mrb.as_mut().allocf_ud, ptr::null_mut());
        if let Some(state) = NonNull::new(alloc_ud) {
            state.cast::<State>()
        } else {
            emit_fatal_warning!("ffi: Attempted to extract Artichoke from null `mrb_state->ud` pointer");
            return Err(InterpreterExtractError::new());
        }
    };

    let state = Box::from_raw(state.as_ptr());
    Ok(Artichoke::new(mrb, state))
}

/// Failed to extract Artichoke interpreter at an FFI boundary.
#[derive(Default, Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
pub struct InterpreterExtractError {
    _private: (),
}

impl InterpreterExtractError {
    /// Constructs a new, default `InterpreterExtractError`.
    #[must_use]
    pub const fn new() -> Self {
        Self { _private: () }
    }
}

impl fmt::Display for InterpreterExtractError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("Failed to extract Artichoke Ruby interpreter from mrb_state userdata")
    }
}

impl error::Error for InterpreterExtractError {}

impl RubyException for InterpreterExtractError {
    fn message(&self) -> Cow<'_, [u8]> {
        Cow::Borrowed(b"Failed to extract Artichoke Ruby interpreter from mrb_state")
    }

    fn name(&self) -> Cow<'_, str> {
        "fatal".into()
    }

    fn vm_backtrace(&self, interp: &mut Artichoke) -> Option<Vec<Vec<u8>>> {
        let _ = interp;
        None
    }

    fn as_mrb_value(&self, interp: &mut Artichoke) -> Option<sys::mrb_value> {
        let message = interp.try_convert_mut(self.message()).ok()?;
        let value = interp.new_instance::<Fatal>(&[message]).ok().flatten()?;
        Some(value.inner())
    }
}

impl From<InterpreterExtractError> for Error {
    fn from(exception: InterpreterExtractError) -> Self {
        let err: Box<dyn RubyException> = Box::new(exception);
        Self::from(err)
    }
}

#[cfg(test)]
mod tests {
    use std::ptr::{self, NonNull};

    use crate::ffi;
    use crate::test::prelude::*;

    #[test]
    fn from_user_data_null_pointer() {
        let err = unsafe { ffi::from_user_data(ptr::null_mut()) };
        assert_eq!(err.err(), Some(InterpreterExtractError::new()));
    }

    #[test]
    fn from_user_data_null_user_data() {
        let mut interp = crate::interpreter().unwrap();
        let mrb = interp.mrb.as_ptr();
        let err = unsafe {
            // fake null user data
            (*mrb).ud = ptr::null_mut();
            ffi::from_user_data(mrb)
        };
        assert_eq!(err.err(), Some(InterpreterExtractError::new()));
        interp.mrb = NonNull::new(mrb).unwrap();
        interp.close();
    }

    #[test]
    fn from_user_data() {
        let interp = crate::interpreter().unwrap();
        let res = unsafe {
            let mrb = Artichoke::into_raw(interp);
            ffi::from_user_data(mrb)
        };
        assert!(res.is_ok());
        res.unwrap().close();
    }
}