Collect task output to tar files

6 files changed, 88 insertions, 9 deletions

diff --git a/examples/foo.yml b/examples/foo.yml
index e0ded83..6f60bbb 100644
--- a/examples/foo.yml
+++ b/examples/foo.yml
@@ -5,4 +5,5 @@ tasks:
     run: |
       ls -lha
       ls -lha /proc/self/fd
-      echo foo > foo
+      mkdir foo
+      echo foobar > foo/bar
diff --git a/src/runner/runc.rs b/src/runner/runc.rs
index 62a3bf1..938bab0 100644
--- a/src/runner/runc.rs
+++ b/src/runner/runc.rs
@@ -20,7 +20,7 @@ fn runner(
 	init_error_sender: ipc::IpcSender<init::Error>,
 	channel: ipc::IpcReceiver<Request>,
 ) -> ! {
-	if let Err(error) = init::runc_unshare() {
+	if let Err(error) = init::runc_preinit() {
 		init_error_sender.send(error).expect("IPC send() failed");
 		process::exit(1);
 	}
@@ -37,7 +37,7 @@ fn runner(
 	unistd::setgid(unistd::Gid::from_raw(0)).expect("setgid()");
 	unistd::setgroups(&[]).expect("setgroups()");
 
-	init::runc_initialize().unwrap();
+	init::runc_init().unwrap();
 
 	unsafe { signal::signal(signal::Signal::SIGCHLD, signal::SigHandler::SigIgn) }.unwrap();
 
diff --git a/src/runner/runc/init.rs b/src/runner/runc/init.rs
index e574789..f686e3e 100644
--- a/src/runner/runc/init.rs
+++ b/src/runner/runc/init.rs
@@ -51,12 +51,13 @@ impl From<Error> for io::Error {
 	}
 }
 
-pub fn runc_unshare() -> Result<(), Error> {
+pub fn runc_preinit() -> Result<(), Error> {
+	DirBuilder::new().recursive(true).create("build/state")?;
 	sched::unshare(CloneFlags::CLONE_NEWUSER | CloneFlags::CLONE_NEWNS).to_io_result()?;
 	Ok(())
 }
 
-pub fn runc_initialize() -> Result<(), Error> {
+pub fn runc_init() -> Result<(), Error> {
 	prepare_buildtmp()?;
 	Ok(())
 }
diff --git a/src/runner/runc/run.rs b/src/runner/runc/run.rs
index 7e9a41c..09bd875 100644
--- a/src/runner/runc/run.rs
+++ b/src/runner/runc/run.rs
@@ -1,4 +1,9 @@
-use std::{fs::DirBuilder, io, process};
+use std::{
+	fs::{DirBuilder, File},
+	io,
+	path::{Path, PathBuf},
+	process,
+};
 
 use nix::{
 	mount::{self, MsFlags},
@@ -7,7 +12,11 @@ use nix::{
 };
 use serde::{Deserialize, Serialize};
 
-use crate::{types::*, unshare, util::ToIOResult};
+use crate::{
+	types::*,
+	unshare,
+	util::{self, ToIOResult},
+};
 
 use super::spec;
 
@@ -59,6 +68,23 @@ fn init_task() -> Result<(), Error> {
 	Ok(())
 }
 
+fn output_filename(task: TaskRef) -> PathBuf {
+	Path::new("build/state").join(format!("{}.tar", task))
+}
+
+fn collect_output(task: TaskRef, task_def: Task) -> Result<(), io::Error> {
+	// Temporarily switch to the user running Rebel to get the right
+	// owner for the tar files
+	let file = {
+		let _setegid = util::setegid(unistd::Gid::from_raw(unshare::BUILD_GID))?;
+		let _seteuid = util::seteuid(unistd::Uid::from_raw(unshare::BUILD_UID))?;
+
+		File::create(output_filename(task))?
+	};
+
+	util::tar::pack(file, "build/tmp/runc/workdir", task_def.output.iter())?.sync_all()
+}
+
 pub fn handle_task(task: TaskRef, task_def: Task) -> Result<(), Error> {
 	init_task()?;
 
@@ -89,5 +115,7 @@ pub fn handle_task(task: TaskRef, task_def: Task) -> Result<(), Error> {
 		String::from_utf8_lossy(output.stdout.as_slice()),
 	);
 
+	collect_output(task, task_def)?;
+
 	Ok(())
 }
diff --git a/src/util.rs b/src/util.rs
index f5bbfaa..d388a59 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -7,7 +7,7 @@ use std::{
 };
 
 use ipc_channel::ipc;
-use nix::sys::wait;
+use nix::{sys::wait, unistd};
 
 pub trait ToIOResult<T> {
 	fn to_io_result(self) -> Result<T>;
@@ -68,3 +68,31 @@ impl<T> CheckDisconnect for result::Result<T, ipc::IpcError> {
 		}
 	}
 }
+
+pub struct SetEUID(unistd::Uid);
+
+impl Drop for SetEUID {
+	fn drop(&mut self) {
+		unistd::seteuid(self.0).expect("failed to reset effective UID");
+	}
+}
+
+pub fn seteuid(uid: unistd::Uid) -> Result<SetEUID> {
+	let old_uid = unistd::geteuid();
+	unistd::seteuid(uid).to_io_result()?;
+	Ok(SetEUID(old_uid))
+}
+
+pub struct SetEGID(unistd::Gid);
+
+impl Drop for SetEGID {
+	fn drop(&mut self) {
+		unistd::setegid(self.0).expect("failed to reset effective GID");
+	}
+}
+
+pub fn setegid(gid: unistd::Gid) -> Result<SetEGID> {
+	let old_gid = unistd::getegid();
+	unistd::setegid(gid).to_io_result()?;
+	Ok(SetEGID(old_gid))
+}
diff --git a/src/util/tar.rs b/src/util/tar.rs
index 07ad795..885663e 100644
--- a/src/util/tar.rs
+++ b/src/util/tar.rs
@@ -1,11 +1,32 @@
 use std::{
 	ffi::CString,
 	fs::DirBuilder,
-	io::{self, Read},
+	io::{self, Read, Write},
 	os::unix::ffi::OsStrExt,
 	path::Path,
 };
 
+pub fn pack<W: Write, P: AsRef<Path>, E: AsRef<Path>, I: Iterator<Item = E>>(
+	archive: W,
+	source: P,
+	entries: I,
+) -> io::Result<W> {
+	let mut ar = tar::Builder::new(archive);
+	ar.mode(tar::HeaderMode::Deterministic);
+	ar.follow_symlinks(false);
+
+	for entry in entries {
+		let path = source.as_ref().join(entry.as_ref());
+		if path.is_dir() {
+			ar.append_dir_all(entry.as_ref(), path)?;
+		} else {
+			ar.append_path_with_name(path, entry.as_ref())?;
+		}
+	}
+
+	ar.into_inner()
+}
+
 pub fn unpack<R: Read, P: AsRef<Path>>(archive: R, dest: P) -> io::Result<()> {
 	let dest_path = dest.as_ref();