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xtask: Use ovmf-prebuilt to download OVMF files
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This allows some code and dependencies to be deleted.
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@nicholasbishop
nicholasbishop committed Nov 4, 2024
1 parent 92a7058 commit 98d1ed2
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Showing 3 changed files with 48 additions and 176 deletions.
17 changes: 8 additions & 9 deletions Cargo.lock
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6 changes: 1 addition & 5 deletions xtask/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -13,17 +13,13 @@ fs-err = "3.0.0"
heck = "0.5.0"
itertools = "0.13.0"
log.workspace = true
lzma-rs = "0.3.0"
mbrman = "0.5.1"
nix = { version = "0.29.0", default-features = false, features = ["fs"] }
os_info = { version = "3.6.0", default-features = false }
ovmf-prebuilt = "0.2.0"
proc-macro2 = { version = "1.0.46", features = ["span-locations"] }
quote = "1.0.21"
regex = "1.10.2"
serde_json = "1.0.73"
sha2 = "0.10.6"
syn = { version = "2.0.0", features = ["full"] }
tar = "0.4.38"
tempfile = "3.6.0"
ureq = "2.8.0"
walkdir = "2.4.0"
201 changes: 39 additions & 162 deletions xtask/src/qemu.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,17 +6,15 @@ use crate::tpm::Swtpm;
use crate::util::command_to_string;
use crate::{net, platform};
use anyhow::{bail, Context, Result};
use ovmf_prebuilt::{FileType, Prebuilt, Source};
use regex::bytes::Regex;
use serde_json::{json, Value};
use sha2::{Digest, Sha256};
use std::env;
use std::ffi::OsString;
use std::io::{BufRead, BufReader, Cursor, Read, Write};
use std::io::{BufRead, BufReader, Read, Write};
use std::path::{Path, PathBuf};
use std::process::{Child, Command, Stdio};
use tar::Archive;
use tempfile::TempDir;
use ureq::Agent;
#[cfg(target_os = "linux")]
use {std::fs::Permissions, std::os::unix::fs::PermissionsExt};

Expand All @@ -38,161 +36,41 @@ const ENV_VAR_OVMF_VARS: &str = "OVMF_VARS";
/// Environment variable for overriding the path of the OVMF shell file.
const ENV_VAR_OVMF_SHELL: &str = "OVMF_SHELL";

/// Download `url` and return the raw data.
fn download_url(url: &str) -> Result<Vec<u8>> {
let agent: Agent = ureq::AgentBuilder::new()
.user_agent("uefi-rs-ovmf-downloader")
.build();

// Limit the size of the download.
let max_size_in_bytes = 5 * 1024 * 1024;

// Download the file.
println!("downloading {url}");
let resp = agent.get(url).call()?;
let mut data = Vec::with_capacity(max_size_in_bytes);
resp.into_reader()
.take(max_size_in_bytes.try_into().unwrap())
.read_to_end(&mut data)?;
println!("received {} bytes", data.len());

Ok(data)
}

// Extract the tarball's files into `prebuilt_dir`.
//
// `tarball_data` is raw decompressed tar data.
fn extract_prebuilt(tarball_data: &[u8], prebuilt_dir: &Path) -> Result<()> {
let cursor = Cursor::new(tarball_data);
let mut archive = Archive::new(cursor);

// Extract each file entry.
for entry in archive.entries()? {
let mut entry = entry?;

// Skip directories.
if entry.size() == 0 {
continue;
impl From<UefiArch> for ovmf_prebuilt::Arch {
fn from(arch: UefiArch) -> Self {
match arch {
UefiArch::AArch64 => Self::Aarch64,
UefiArch::IA32 => Self::Ia32,
UefiArch::X86_64 => Self::X64,
}

let path = entry.path()?;
// Strip the leading directory, which is the release name.
let path: PathBuf = path.components().skip(1).collect();

let dir = path.parent().unwrap();
let dst_dir = prebuilt_dir.join(dir);
let dst_path = prebuilt_dir.join(path);
println!("unpacking to {}", dst_path.display());
fs_err::create_dir_all(dst_dir)?;
entry.unpack(dst_path)?;
}

Ok(())
}

/// Update the local copy of the prebuilt OVMF files. Does nothing if the local
/// copy is already up to date.
fn update_prebuilt() -> Result<PathBuf> {
let prebuilt_dir = Path::new(OVMF_PREBUILT_DIR);
let hash_path = prebuilt_dir.join("sha256");

// Check if the hash file already has the expected hash in it. If so, assume
// that we've already got the correct prebuilt downloaded and unpacked.
if let Ok(current_hash) = fs_err::read_to_string(&hash_path) {
if current_hash == OVMF_PREBUILT_HASH {
return Ok(prebuilt_dir.to_path_buf());
/// Get a user-provided path for the given OVMF file type.
///
/// This uses the command-line arg if present, otherwise it falls back to an
/// environment variable. If neither is present, returns `None`.
fn get_user_provided_path(file_type: FileType, opt: &QemuOpt) -> Option<PathBuf> {
let opt_path;
let var_name;
match file_type {
FileType::Code => {
opt_path = &opt.ovmf_code;
var_name = ENV_VAR_OVMF_CODE;
}
}

let base_url = "https://github.com/rust-osdev/ovmf-prebuilt/releases/download";
let url = format!(
"{base_url}/{release}/{release}-bin.tar.xz",
release = OVMF_PREBUILT_TAG
);

let data = download_url(&url)?;

// Validate the hash.
let actual_hash = format!("{:x}", Sha256::digest(&data));
if actual_hash != OVMF_PREBUILT_HASH {
bail!(
"file hash {actual_hash} does not match {}",
OVMF_PREBUILT_HASH
);
}

// Unpack the tarball.
println!("decompressing tarball");
let mut decompressed = Vec::new();
let mut compressed = Cursor::new(data);
lzma_rs::xz_decompress(&mut compressed, &mut decompressed)?;

// Clear out the existing prebuilt dir, if present.
let _ = fs_err::remove_dir_all(prebuilt_dir);

// Extract the files.
extract_prebuilt(&decompressed, prebuilt_dir)?;

// Rename the x64 directory to x86_64, to match `Arch::as_str`.
fs_err::rename(prebuilt_dir.join("x64"), prebuilt_dir.join("x86_64"))?;

// Write out the hash file. When we upgrade to a new release of
// ovmf-prebuilt, the hash will no longer match, triggering a fresh
// download.
fs_err::write(&hash_path, actual_hash)?;

Ok(prebuilt_dir.to_path_buf())
}

#[derive(Clone, Copy, Debug)]
enum OvmfFileType {
Code,
Vars,
Shell,
}

impl OvmfFileType {
fn as_str(&self) -> &'static str {
match self {
Self::Code => "code",
Self::Vars => "vars",
Self::Shell => "shell",
FileType::Vars => {
opt_path = &opt.ovmf_vars;
var_name = ENV_VAR_OVMF_VARS;
}
}

fn extension(&self) -> &'static str {
match self {
Self::Code | Self::Vars => "fd",
Self::Shell => "efi",
FileType::Shell => {
opt_path = &None;
var_name = ENV_VAR_OVMF_SHELL;
}
}

/// Get a user-provided path for the given OVMF file type.
///
/// This uses the command-line arg if present, otherwise it falls back to an
/// environment variable. If neither is present, returns `None`.
fn get_user_provided_path(self, opt: &QemuOpt) -> Option<PathBuf> {
let opt_path;
let var_name;
match self {
Self::Code => {
opt_path = &opt.ovmf_code;
var_name = ENV_VAR_OVMF_CODE;
}
Self::Vars => {
opt_path = &opt.ovmf_vars;
var_name = ENV_VAR_OVMF_VARS;
}
Self::Shell => {
opt_path = &None;
var_name = ENV_VAR_OVMF_SHELL;
}
}
if let Some(path) = opt_path {
Some(path.clone())
} else {
env::var_os(var_name).map(PathBuf::from)
}
if let Some(path) = opt_path {
Some(path.clone())
} else {
env::var_os(var_name).map(PathBuf::from)
}
}

Expand All @@ -210,8 +88,8 @@ impl OvmfPaths {
/// 1. Command-line arg
/// 2. Environment variable
/// 3. Prebuilt file (automatically downloaded)
fn find_ovmf_file(file_type: OvmfFileType, opt: &QemuOpt, arch: UefiArch) -> Result<PathBuf> {
if let Some(path) = file_type.get_user_provided_path(opt) {
fn find_ovmf_file(file_type: FileType, opt: &QemuOpt, arch: UefiArch) -> Result<PathBuf> {
if let Some(path) = get_user_provided_path(file_type, opt) {
// The user provided an exact path to use; verify that it
// exists.
if path.exists() {
Expand All @@ -224,22 +102,21 @@ impl OvmfPaths {
);
}
} else {
let prebuilt_dir = update_prebuilt()?;
let prebuilt = Prebuilt::fetch(Source {
tag: OVMF_PREBUILT_TAG,
sha256: OVMF_PREBUILT_HASH,
}, OVMF_PREBUILT_DIR)?;

Ok(prebuilt_dir.join(format!(
"{arch}/{}.{}",
file_type.as_str(),
file_type.extension()
)))
Ok(prebuilt.get_file(arch.into(), file_type))
}
}

/// Find path to OVMF files by the strategy documented for
/// [`Self::find_ovmf_file`].
fn find(opt: &QemuOpt, arch: UefiArch) -> Result<Self> {
let code = Self::find_ovmf_file(OvmfFileType::Code, opt, arch)?;
let vars = Self::find_ovmf_file(OvmfFileType::Vars, opt, arch)?;
let shell = Self::find_ovmf_file(OvmfFileType::Shell, opt, arch)?;
let code = Self::find_ovmf_file(FileType::Code, opt, arch)?;
let vars = Self::find_ovmf_file(FileType::Vars, opt, arch)?;
let shell = Self::find_ovmf_file(FileType::Shell, opt, arch)?;

Ok(Self { code, vars, shell })
}
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