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

/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */
use super::list::{list_for_injection, ResourceEntry};
use crate::names::{elf_section_name, macho_section_name, macho_segment_name, pe_resource_name};
use anyhow::Context;
use postject_sys::postjector::{
    postjector_inject, PostjectorBuffer, POSTJECTOR_INJECT_ALREADY_EXISTS, POSTJECTOR_INJECT_ERROR,
    POSTJECTOR_INJECT_SUCCESS, POSTJECTOR_INJECT_UNKNOWN_EXECUTABLE_FORMAT,
    postjector_owned_buffer_data,
    postjector_owned_buffer_free, PostjectorOwnedBuffer,
};
use std::num::NonZeroUsize;
use std::ops::Deref;
use std::{mem::size_of, num::NonZeroU16};

fn adhoc_sign(executable_buffer: &[u8]) -> Result<Vec<u8>, apple_codesign::AppleCodesignError> {
    use apple_codesign::{MachOSigner, SettingsScope, SigningSettings};
    let signer = MachOSigner::new(executable_buffer)?;
    let mut signed = Vec::<u8>::with_capacity(executable_buffer.len());
    let mut settings = SigningSettings::default();
    settings.set_binary_identifier(SettingsScope::Main, "-");
    signer.write_signed_binary(&settings, &mut signed)?;
    Ok(signed)
}

struct OwnedPostInjectorBuffer(PostjectorOwnedBuffer);
impl OwnedPostInjectorBuffer {
    pub unsafe fn new(raw: PostjectorOwnedBuffer) -> Option<Self> {
        if raw.is_null() {
            None
        } else {
            Some(Self(raw))
        }
    }
}
impl Drop for OwnedPostInjectorBuffer {
    fn drop(&mut self) {
        unsafe { postjector_owned_buffer_free(self.0) }
    }
}
impl Deref for OwnedPostInjectorBuffer {
    type Target = [u8];

    fn deref(&self) -> &Self::Target {
        unsafe {
            let data = postjector_owned_buffer_data(self.0);
            std::slice::from_raw_parts(data.head, data.size)
        }
    }
}

/// Injects resource data into an executable.
/// 
/// # Example
/// ```rust
/// # use editres::injector::inject;
/// # let _ = || -> anyhow::Result<()> {
/// let mut executable_buffer = std::fs::read("a.out")?;
/// inject(&mut executable_buffer, "my_res", b"res_content")?;
/// std::fs::write("a.out", &executable_buffer)?;
/// # Ok(())
/// # };
/// ```
pub fn inject(
    executable_buffer: &mut Vec<u8>,
    resource_name: &str,
    resource_data: &[u8],
) -> anyhow::Result<()> {
    let resources =
        list_for_injection(&executable_buffer).context("Invalid sentiel format in executable")?;
    let resource_vec = resources
        .iter()
        .map(|(name, entry)| (*name, entry))
        .collect::<Vec<(&str, &ResourceEntry)>>();
    let resource_position = resource_vec
        .iter()
        .position(|(name, _)| *name == resource_name)
        .context("Resource not found")?;
    let (_, ResourceEntry::None { id_positions }) = resource_vec[resource_position] else {
        anyhow::bail!("Resource {} already exists", resource_name);
    };

    let resource_id = NonZeroUsize::new(resource_position + 1).unwrap();
    let resource_id =
        NonZeroU16::try_from(resource_id).context("Resource count exceeds the limit")?;

    let id_bytes = resource_id.get().to_be_bytes();

    let id_positions = id_positions.clone();
    drop(resources);
    for id_position in id_positions {
        let id_slice = &mut executable_buffer[id_position..(id_position + size_of::<u16>())];
        id_slice.copy_from_slice(&id_bytes);
    }
    unsafe {
        let inject_result = postjector_inject(
            PostjectorBuffer {
                head: executable_buffer.as_mut_ptr(),
                size: executable_buffer.len(),
            },
            PostjectorBuffer {
                head: resource_data.as_ptr() as *mut u8,
                size: resource_data.len(),
            },
            elf_section_name(resource_id).as_ptr(),
            macho_segment_name(resource_id).as_ptr(),
            macho_section_name(resource_id).as_ptr(),
            pe_resource_name(resource_id).as_ptr(),
            0,
        );
        if inject_result.type_ == POSTJECTOR_INJECT_ALREADY_EXISTS {
            anyhow::bail!("Resource {resource_name} has already been set before");
        } else if inject_result.type_ == POSTJECTOR_INJECT_ERROR {
            if let Some(error) = OwnedPostInjectorBuffer::new(inject_result.data) {
                anyhow::bail!("Inject failed: {}", String::from_utf8_lossy(&error));
            } else {
                anyhow::bail!("Inject failed");
            }
        } else if inject_result.type_ == POSTJECTOR_INJECT_UNKNOWN_EXECUTABLE_FORMAT {
            anyhow::bail!("Invalid executable format");
        } else if inject_result.type_ == POSTJECTOR_INJECT_SUCCESS {
            let output = OwnedPostInjectorBuffer::new(inject_result.data).unwrap();
            if inject_result.is_macho != 0 {
                *executable_buffer = adhoc_sign(&output)?;
            } else {
                executable_buffer.clear();
                executable_buffer.extend_from_slice(&output);
            }
            Ok(())
        } else {
            panic!("Unexpcted injection error {}", inject_result.type_)
        }
    }
}