From 89a89f785a43c951a30764a4e69e3e922bca98b3 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 24 Feb 2021 11:15:35 +0100
Subject: [PATCH] Create a fat filesystem image

---
 Cargo.lock             | 131 +++++++++++++++++++++++++++++++++++++++++
 disk_image/Cargo.toml  |   1 +
 disk_image/src/main.rs |  33 +++++++++++
 3 files changed, 165 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index ea5a63c8..79923916 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,136 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "autocfg"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
+
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
+
+[[package]]
+name = "byteorder"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae44d1a3d5a19df61dd0c8beb138458ac2a53a7ac09eba97d55592540004306b"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "chrono"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "670ad68c9088c2a963aaa298cb369688cf3f9465ce5e2d4ca10e6e0098a1ce73"
+dependencies = [
+ "libc",
+ "num-integer",
+ "num-traits",
+ "time",
+ "winapi",
+]
+
+[[package]]
+name = "disk_image"
+version = "0.1.0"
+dependencies = [
+ "fatfs",
+]
+
+[[package]]
+name = "fatfs"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e18f80a87439240dac45d927fd8f8081b6f1e34c03e97271189fa8a8c2e96c8f"
+dependencies = [
+ "bitflags",
+ "byteorder",
+ "chrono",
+ "log",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.86"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7282d924be3275cec7f6756ff4121987bc6481325397dde6ba3e7802b1a8b1c"
+
+[[package]]
+name = "log"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2cc698a63b549a70bc047073d2949cce27cd1c7b0a4a862d08a8031bc2801db"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "time"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db9e6914ab8b1ae1c260a4ae7a49b6c5611b40328a735b21862567685e73255"
+dependencies = [
+ "libc",
+ "wasi",
+ "winapi",
+]
+
 [[package]]
 name = "uefi_app"
 version = "0.1.0"
+
+[[package]]
+name = "wasi"
+version = "0.10.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/disk_image/Cargo.toml b/disk_image/Cargo.toml
index fb8be2c6..c1380d61 100644
--- a/disk_image/Cargo.toml
+++ b/disk_image/Cargo.toml
@@ -7,3 +7,4 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+fatfs = "0.3.5"
diff --git a/disk_image/src/main.rs b/disk_image/src/main.rs
index e7a11a96..ae4097cd 100644
--- a/disk_image/src/main.rs
+++ b/disk_image/src/main.rs
@@ -1,3 +1,36 @@
+use std::{fs, io, path::Path};
+
 fn main() {
     println!("Hello, world!");
 }
+
+fn create_fat_filesystem(fat_path: &Path, efi_file: &Path) {
+    // retrieve size of `.efi` file and round it up
+    let efi_size = fs::metadata(&efi_file).unwrap().len();
+    let mb = 1024 * 1024; // size of a megabyte
+                          // round it to next megabyte
+    let efi_size_rounded = ((efi_size - 1) / mb + 1) * mb;
+
+    // create new filesystem image file at the given path and set its length
+    let fat_file = fs::OpenOptions::new()
+        .read(true)
+        .write(true)
+        .create(true)
+        .truncate(true)
+        .open(&fat_path)
+        .unwrap();
+    fat_file.set_len(efi_size_rounded).unwrap();
+
+    // create new FAT file system and open it
+    let format_options = fatfs::FormatVolumeOptions::new();
+    fatfs::format_volume(&fat_file, format_options).unwrap();
+    let filesystem = fatfs::FileSystem::new(&fat_file, fatfs::FsOptions::new()).unwrap();
+
+    // copy EFI file to FAT filesystem
+    let root_dir = filesystem.root_dir();
+    root_dir.create_dir("efi").unwrap();
+    root_dir.create_dir("efi/boot").unwrap();
+    let mut bootx64 = root_dir.create_file("efi/boot/bootx64.efi").unwrap();
+    bootx64.truncate().unwrap();
+    io::copy(&mut fs::File::open(&efi_file).unwrap(), &mut bootx64).unwrap();
+}