editres 0.1.6

Embed data into executables after build
Documentation 
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/*
 * 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 crate::names::{elf_section_name, macho_section_name, macho_segment_name, pe_resource_name};
use std::{
    num::NonZeroU16,
    ptr::{self, null},
    slice,
};

use postject_sys::postjectee::{postjectee_find_resource, postjectee_options};

#[doc(hidden)]
pub use const_format::concatcp;

/// Declares a resource that can be injected after build.
///
/// This macro yields an expression of type `Option<&'static [u8]>`, which is
/// - `None` at first,
/// - and becomes `Some(data)` once the resource is injected into the final executable using
///   - [`injector::inject`](crate::injector::inject), or
///   - `editres` command from `editres_cli`.
///
///
/// # Example
/// ```rust
/// # use editres::resource;
/// # fn main() {
/// if let Some(res) = resource!("my_res") {
///     println!("{:?}", res);
/// } else {
///     println!("my_res hasn't be injected");
/// }
/// # }
/// ```
#[macro_export]
macro_rules! resource {
    ($name: literal) => {{
        const NAME_LEN: usize = $name.len();
        static SENTINEL: &[u8] = $crate::injectee::concatcp!(
            "\0\0",
            $name,
            '|',
            NAME_LEN,
            $crate::names::SENTINEL_SUFFIX
        )
        .as_bytes();
        unsafe { $crate::injectee::get_resource_from_sentinel(SENTINEL.as_ptr()) }
    }};
}

unsafe fn find_resource(id: NonZeroU16) -> Option<&'static [u8]> {
    let mut size = 0usize;
    let res_head = postjectee_find_resource(
        null(), // name is ignored now that we specific detailed names in options
        &mut size,
        postjectee_options {
            elf_section_name: elf_section_name(id).as_ptr(),
            macho_section_name: macho_section_name(id).as_ptr(),
            macho_segment_name: macho_segment_name(id).as_ptr(),
            pe_resource_name: pe_resource_name(id).as_ptr(),
        },
    );
    if res_head.is_null() {
        None
    } else {
        Some(slice::from_raw_parts(res_head.cast(), size))
    }
}

unsafe fn get_resource_id(sentinel_head: *const u8) -> Option<NonZeroU16> {
    let id_bytes = ptr::read_volatile::<[u8; 2]>(sentinel_head.cast());
    let id = u16::from_be_bytes(id_bytes);
    NonZeroU16::new(id)
}

#[doc(hidden)]
pub unsafe fn get_resource_from_sentinel(sentinel_head: *const u8) -> Option<&'static [u8]> {
    let id = get_resource_id(sentinel_head)?;
    Some(find_resource(id).unwrap_or_else(|| panic!("Failed to locate resource {}", id)))
}