From 4a3a64bd519914d18e5f0a454272d99b2169c450 Mon Sep 17 00:00:00 2001
From: Jonathan Klimt <jonathan.klimt@eonerc.rwth-aachen.de>
Date: Mon, 13 Oct 2025 17:25:00 +0200
Subject: [PATCH] fs: added feature to delegate /tmp to uhyve

---
 Cargo.toml      |  1 +
 src/fs/mod.rs   | 12 +++++++-----
 src/fs/uhyve.rs | 13 +++++++++++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index f9005fcda3..e233f16b91 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -71,6 +71,7 @@ smp = []
 strace = []
 tcp = ["net", "smoltcp", "smoltcp/socket-tcp"]
 trace = ["smoltcp?/log", "smoltcp?/verbose"]
+uhyve-tmp = []
 udp = ["net", "smoltcp", "smoltcp/socket-udp"]
 vga = []
 virtio = ["dep:virtio"]
diff --git a/src/fs/mod.rs b/src/fs/mod.rs
index 9b7a9245d3..4e46851fbf 100644
--- a/src/fs/mod.rs
+++ b/src/fs/mod.rs
@@ -340,11 +340,13 @@ pub(crate) fn init() {
 	const UTC_BUILT_TIME: &str = build_time::build_time_utc!();
 
 	FILESYSTEM.set(Filesystem::new()).unwrap();
-	FILESYSTEM
-		.get()
-		.unwrap()
-		.mkdir("/tmp", AccessPermission::from_bits(0o777).unwrap())
-		.expect("Unable to create /tmp");
+	if !(crate::env::is_uhyve() && cfg!(feature = "uhyve-tmp")) {
+		FILESYSTEM
+			.get()
+			.unwrap()
+			.mkdir("/tmp", AccessPermission::from_bits(0o777).unwrap())
+			.expect("Unable to create /tmp");
+	}
 	FILESYSTEM
 		.get()
 		.unwrap()
diff --git a/src/fs/uhyve.rs b/src/fs/uhyve.rs
index dce0a4fe58..44d9674786 100644
--- a/src/fs/uhyve.rs
+++ b/src/fs/uhyve.rs
@@ -276,4 +276,17 @@ pub(crate) fn init() {
 			)
 			.expect("Mount failed. Duplicate mount_point?");
 	}
+
+	#[cfg(feature = "uhyve-tmp")]
+	{
+		info!("Mounting /tmp as uhyve filesystem");
+		fs::FILESYSTEM
+			.get()
+			.unwrap()
+			.mount(
+				"/tmp",
+				Box::new(UhyveDirectory::new(Some("/tmp".to_string()))),
+			)
+			.unwrap();
+	}
 }