From 61746b64b0e7087b17b21df6a1c7291ad25cd428 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Tue, 26 Oct 2021 17:03:07 +0200
Subject: runner: make lock() function more generic

---
 crates/runner/src/lib.rs       | 18 +++---------------
 crates/runner/src/util/unix.rs | 25 ++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 16 deletions(-)

(limited to 'crates/runner/src')

diff --git a/crates/runner/src/lib.rs b/crates/runner/src/lib.rs
index af1e2a7..d0d8317 100644
--- a/crates/runner/src/lib.rs
+++ b/crates/runner/src/lib.rs
@@ -6,12 +6,11 @@ mod tar;
 mod task;
 mod util;
 
-use std::{fs::File, os::unix::prelude::AsRawFd, path::Path};
+use std::fs::File;
 
 use capctl::prctl;
 use ipc_channel::ipc;
 use nix::{
-	fcntl,
 	sched::CloneFlags,
 	sys::{signal, stat, wait},
 	unistd::{self, Gid, Uid},
@@ -19,7 +18,6 @@ use nix::{
 use serde::{Deserialize, Serialize};
 
 use common::{error::*, types::*};
-use util::fs;
 
 use self::{
 	jobserver::Jobserver,
@@ -123,7 +121,8 @@ impl Runner {
 	///
 	/// Unsafe: Do not call in multithreaded processes
 	pub unsafe fn new(options: &Options) -> Result<Self> {
-		let lockfile = Runner::lock()?;
+		let lockfile = unix::lock(paths::LOCKFILE, true, false)
+			.context("Failed to get lock on build directory, is another instance running?")?;
 
 		let uid = unistd::geteuid();
 		let gid = unistd::getegid();
@@ -144,17 +143,6 @@ impl Runner {
 		Ok(Runner { channel: tx })
 	}
 
-	fn lock() -> Result<File> {
-		let path = Path::new(paths::LOCKFILE);
-		fs::mkdir(path.parent().unwrap())?;
-		let file = fs::create(path)?;
-
-		fcntl::flock(file.as_raw_fd(), fcntl::FlockArg::LockExclusiveNonblock)
-			.context("Failed to get lock on build directory, is another instance running?")?;
-
-		Ok(file)
-	}
-
 	pub fn spawn(&self, task: &Task) -> ipc::IpcReceiver<Result<TaskOutput>> {
 		let (reply_tx, reply_rx) = ipc::channel().expect("IPC channel creation failed");
 
diff --git a/crates/runner/src/util/unix.rs b/crates/runner/src/util/unix.rs
index 48db764..710138c 100644
--- a/crates/runner/src/util/unix.rs
+++ b/crates/runner/src/util/unix.rs
@@ -1,4 +1,4 @@
-use std::os::unix::prelude::*;
+use std::{fs::File, os::unix::prelude::*, path::Path};
 
 use nix::{
 	fcntl::{self, FcntlArg, FdFlag, OFlag},
@@ -8,6 +8,8 @@ use nix::{
 
 use common::error::*;
 
+use super::fs;
+
 pub fn set_blocking(fd: RawFd, blocking: bool) -> Result<()> {
 	let flags = unsafe {
 		OFlag::from_bits_unchecked(fcntl::fcntl(fd, FcntlArg::F_GETFL).context("fcntl(F_GETFL)")?)
@@ -59,3 +61,24 @@ pub fn nproc() -> Result<usize> {
 
 	Ok(count)
 }
+
+pub fn lock<P: AsRef<Path>>(path: P, exclusive: bool, blocking: bool) -> Result<File> {
+	use fcntl::FlockArg::*;
+
+	if let Some(parent) = path.as_ref().parent() {
+		fs::mkdir(parent)?;
+	}
+
+	let arg = match (exclusive, blocking) {
+		(true, true) => LockExclusive,
+		(true, false) => LockExclusiveNonblock,
+		(false, true) => LockShared,
+		(false, false) => LockSharedNonblock,
+	};
+
+	let file = fs::create(path.as_ref())?;
+	fcntl::flock(file.as_raw_fd(), arg)
+		.with_context(|| format!("flock failed on {:?}", path.as_ref()))?;
+
+	Ok(file)
+}
-- 
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