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

use core::fmt;
use crate::nn::ro;

pub type Callback = extern "Rust" fn(&NroInfo);

/// An error representing the NRO hook plugin not successfully being linked against
#[derive(Debug, Clone, Copy)]
pub struct NroHookPluginMissing;

#[allow(improper_ctypes)]
extern "C" {
    fn add_nro_load_hook(callback: Callback);
    fn add_nro_unload_hook(callback: Callback);
}

/// A function to allow adding a hook for immediately after an NRO has been loaded.
///
/// **Note:** Requires the NRO hook plugin. Will return an error otherwise.
pub fn add_hook(callback: Callback) -> Result<(), NroHookPluginMissing> {
    if (add_nro_load_hook as *const ()).is_null() {
        Err(NroHookPluginMissing)
    } else {
        unsafe {
            add_nro_load_hook(callback);
        }
        Ok(())
    }

}

pub fn add_unload_hook(callback: Callback) -> Result<(), NroHookPluginMissing> {
    if (add_nro_unload_hook as *const ()).is_null() {
        Err(NroHookPluginMissing)
    } else {
        unsafe {
            add_nro_unload_hook(callback);
        }
        Ok(())
    }
}

/// A struct to hold information related to the NRO being loaded
#[repr(C)]
#[non_exhaustive]
pub struct NroInfo<'a> {
    pub name: &'a str,
    pub module: &'a mut ro::Module
}

impl<'a> NroInfo<'a> {
    /// A function only to be used by nro_hook in order to construct NroInfos. Since fields may be
    /// added, this API is subject to change.
    #[cfg(feature = "nro_internal")]
    pub fn new(name: &'a str, module: &'a mut ro::Module) -> Self {
        Self { name, module }
    }
}

impl fmt::Display for NroHookPluginMissing {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "The NRO hook plugin could not be found and is required to add NRO hooks. Make sure hook_nro.nro is installed.")
    }
}