static_vcruntime.rs

// Copyright 2019-2022 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

// taken from https://github.com/ChrisDenton/static_vcruntime/
// we're not using static_vcruntime directly because we want this for debug builds too

use std::{env, fs, io::Write, path::Path};

pub fn build() {
  override_msvcrt_lib();

  // Disable conflicting libraries that aren't hard coded by Rust
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:libvcruntimed.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:vcruntime.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:vcruntimed.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:libcmtd.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:msvcrt.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:msvcrtd.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:libucrt.lib");
  println!("cargo:rustc-link-arg=/NODEFAULTLIB:libucrtd.lib");
  // Set the libraries we want.
  println!("cargo:rustc-link-arg=/DEFAULTLIB:libcmt.lib");
  println!("cargo:rustc-link-arg=/DEFAULTLIB:libvcruntime.lib");
  println!("cargo:rustc-link-arg=/DEFAULTLIB:ucrt.lib");
}

/// Override the hard-coded msvcrt.lib by replacing it with a (mostly) empty object file.
fn override_msvcrt_lib() {
  // Get the right machine type for the empty library.
  let arch = std::env::var("CARGO_CFG_TARGET_ARCH");
  let machine: &[u8] = if arch.as_deref() == Ok("x86_64") {
    &[0x64, 0x86]
  } else if arch.as_deref() == Ok("x86") {
    &[0x4C, 0x01]
  } else {
    return;
  };
  let bytes: &[u8] = &[
    1, 0, 94, 3, 96, 98, 60, 0, 0, 0, 1, 0, 0, 0, 0, 0, 132, 1, 46, 100, 114, 101, 99, 116, 118,
    101, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 60, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    10, 16, 0, 46, 100, 114, 101, 99, 116, 118, 101, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 4, 0, 0, 0,
  ];

  // Write the empty "msvcrt.lib" to the output directory.
  let out_dir = env::var("OUT_DIR").unwrap();
  let path = Path::new(&out_dir).join("msvcrt.lib");
  let f = fs::OpenOptions::new()
    .write(true)
    .create_new(true)
    .open(&path);
  if let Ok(mut f) = f {
    f.write_all(machine).unwrap();
    f.write_all(bytes).unwrap();
  }
  // Add the output directory to the native library path.
  println!("cargo:rustc-link-search=native={out_dir}");
}