feat(tempfile): allow usage of custom tempdir locations

This is intended to let users optionally use custom tmpfs filesystems
or store unmapped files in directories that are not monitored by the
temporary file cleaner.

src/bin/uhyve.rs

@@ -56,6 +56,16 @@ struct Args {
 	#[clap(long)]
 	file_mapping: Vec<String>,
 
+	/// The path that should be used for temporary directories storing unmapped files.
+	///
+	/// This is useful for manually created tmpfs filesystems and for selecting
+	/// directories not managed by a temporary file cleaner, which can remove open files
+	/// manually. In most cases, mapping the guest path /root/ instead should be sufficient.
+	///
+	/// Defaults to /tmp.
+	#[clap(long)]
+	tempdir_path: Option<String>,
+
 	#[clap(flatten, next_help_heading = "Memory OPTIONS")]
 	memory_args: MemoryArgs,
 
@@ -257,6 +267,7 @@ impl From<Args> for Params {
 			#[cfg(target_os = "linux")]
 			gdb_port,
 			file_mapping,
+			tempdir_path,
 			kernel: _,
 			kernel_args,
 			output,
@@ -277,6 +288,7 @@ impl From<Args> for Params {
 			#[cfg(target_os = "macos")]
 			gdb_port: None,
 			kernel_args,
+			tempdir_path,
 			// TODO
 			output: if let Some(outp) = output {
 				Output::from_str(&outp).unwrap()

src/isolation/filemap.rs

@@ -24,15 +24,16 @@ impl UhyveFileMap {
 	/// Creates a UhyveFileMap.
 	///
 	/// * `mappings` - A list of host->guest path mappings with the format "./host_path.txt:guest.txt"
-	pub fn new(mappings: &[String]) -> UhyveFileMap {
+	/// * `tempdir_path` - Path to create temporary directory on
+	pub fn new(mappings: &[String], tempdir_path: &Option<String>) -> UhyveFileMap {
 		UhyveFileMap {
 			files: mappings
 				.iter()
 				.map(String::as_str)
 				.map(Self::split_guest_and_host_path)
 				.map(Result::unwrap)
 				.collect(),
-			tempdir: create_temp_dir(),
+			tempdir: create_temp_dir(tempdir_path),
 		}
 	}
 
@@ -193,7 +194,7 @@ mod tests {
 			path_prefix.clone() + "/this_symlink_leads_to_a_file" + ":guest_file_symlink",
 		];
 
-		let mut map = UhyveFileMap::new(&map_parameters);
+		let mut map = UhyveFileMap::new(&map_parameters, &None);
 
 		assert_eq!(
 			map.get_host_path("readme_file.md").unwrap(),
@@ -245,7 +246,7 @@ mod tests {
 			host_path_map.to_str().unwrap(),
 			guest_path_map.to_str().unwrap()
 		)];
-		let mut map = UhyveFileMap::new(&uhyvefilemap_params);
+		let mut map = UhyveFileMap::new(&uhyvefilemap_params, &None);
 
 		let mut found_host_path = map.get_host_path(target_guest_path.clone().to_str().unwrap());
 
@@ -276,7 +277,7 @@ mod tests {
 			guest_path_map.to_str().unwrap()
 		)];
 
-		map = UhyveFileMap::new(&uhyvefilemap_params);
+		map = UhyveFileMap::new(&uhyvefilemap_params, &None);
 
 		target_guest_path = PathBuf::from("/root/this_symlink_leads_to_a_file");
 		target_host_path = fixture_path.clone();
@@ -289,7 +290,7 @@ mod tests {
 
 		// Tests directory traversal with no maps
 		let empty_array: [String; 0] = [];
-		map = UhyveFileMap::new(&empty_array);
+		map = UhyveFileMap::new(&empty_array, &None);
 		found_host_path = map.get_host_path(target_guest_path.to_str().unwrap());
 		assert!(found_host_path.is_none());
 	}

src/isolation/tempdir.rs

@@ -1,15 +1,30 @@
 use std::{fs::Permissions, os::unix::fs::PermissionsExt};
 
 use tempfile::{Builder, TempDir};
+use uuid::Uuid;
 
 /// Creates a temporary directory.
-pub fn create_temp_dir() -> TempDir {
-	let dir = Builder::new()
-		.permissions(Permissions::from_mode(0o700))
-		.prefix("uhyve-")
-		.tempdir()
-		.ok()
-		.unwrap_or_else(|| panic!("The temporary directory could not be created."));
+///
+/// * `dir_path` - The location in which the temporary directory should be created.
+pub fn create_temp_dir(dir_path: &Option<String>) -> TempDir {
+	let dir: TempDir;
+	if let Some(dir_path) = dir_path {
+		dir = Builder::new()
+			.permissions(Permissions::from_mode(0o700))
+			.prefix("uhyve-")
+			.suffix(&Uuid::new_v4().to_string())
+			.tempdir_in(dir_path)
+			.ok()
+			.unwrap_or_else(|| panic!("The temporary directory could not be created."));
+	} else {
+		dir = Builder::new()
+			.permissions(Permissions::from_mode(0o700))
+			.prefix("uhyve-")
+			.suffix(&Uuid::new_v4().to_string())
+			.tempdir()
+			.ok()
+			.unwrap_or_else(|| panic!("The temporary directory could not be created."));
+	}
 
 	let dir_permissions = dir.path().metadata().unwrap().permissions();
 	assert!(!dir_permissions.readonly());

src/params.rs

@@ -38,6 +38,9 @@ pub struct Params {
 	/// Mapped paths between the guest and host OS
 	pub file_mapping: Vec<String>,
 
+	/// Path to create temporary directory on
+	pub tempdir_path: Option<String>,
+
 	/// Kernel output handling
 	pub output: Output,
 
@@ -59,6 +62,7 @@ impl Default for Params {
 			cpu_count: Default::default(),
 			gdb_port: Default::default(),
 			file_mapping: Default::default(),
+			tempdir_path: Default::default(),
 			kernel_args: Default::default(),
 			output: Default::default(),
 			stats: false,

src/vm.rs

@@ -185,7 +185,10 @@ impl<VirtBackend: VirtualizationBackend> UhyveVm<VirtBackend> {
 			"gdbstub is only supported with one CPU"
 		);
 
-		let file_mapping = Mutex::new(UhyveFileMap::new(&params.file_mapping));
+		let file_mapping = Mutex::new(UhyveFileMap::new(
+			&params.file_mapping,
+			&params.tempdir_path,
+		));
 
 		let output = match params.output {
 			params::Output::None => Output::None,