From d33fb72fcb0e196848ba7f5529dd9b7494107e80 Mon Sep 17 00:00:00 2001
From: HuijingHei <hhei@redhat.com>
Date: Thu, 11 Jul 2024 18:55:59 +0800
Subject: [PATCH] filetree: add failpoint when doing exchange

Inspired by https://github.com/coreos/bootupd/pull/669#issuecomment-2220760948
---
 Cargo.lock                           | 12 ++++++++++++
 Cargo.toml                           |  1 +
 src/failpoints.rs                    | 21 +++++++++++++++++++++
 src/filetree.rs                      |  4 +++-
 src/main.rs                          |  1 +
 tests/e2e-update/e2e-update-in-vm.sh |  5 +++++
 6 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 src/failpoints.rs

diff --git a/Cargo.lock b/Cargo.lock
index e802f4a3..237fd3de 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -78,6 +78,7 @@ dependencies = [
  "chrono",
  "clap",
  "env_logger",
+ "fail",
  "fn-error-context",
  "fs2",
  "hex",
@@ -234,6 +235,17 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "fail"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe5e43d0f78a42ad591453aedb1d7ae631ce7ee445c7643691055a9ed8d3b01c"
+dependencies = [
+ "log",
+ "once_cell",
+ "rand",
+]
+
 [[package]]
 name = "fastrand"
 version = "2.0.1"
diff --git a/Cargo.toml b/Cargo.toml
index 1f7c9eac..02059c55 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ camino = "1.1.7"
 chrono = { version = "0.4.38", features = ["serde"] }
 clap = { version = "3.2", default-features = false, features = ["cargo", "derive", "std", "suggestions"] }
 env_logger = "0.10"
+fail = { version = "0.5", features = ["failpoints"] }
 fn-error-context = "0.2.1"
 fs2 = "0.4.3"
 hex = "0.4.3"
diff --git a/src/failpoints.rs b/src/failpoints.rs
new file mode 100644
index 00000000..78dce44f
--- /dev/null
+++ b/src/failpoints.rs
@@ -0,0 +1,21 @@
+//! Wrappers and utilities on top of the `fail` crate.
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// TODO: Use https://github.com/tikv/fail-rs/pull/68 once it merges
+/// copy from https://github.com/coreos/rpm-ostree/commit/aa8d7fb0ceaabfaf10252180e2ddee049d07aae3#diff-adcc419e139605fae34d17b31418dbaf515af2fe9fb766fcbdb2eaad862b3daa
+#[macro_export]
+macro_rules! try_fail_point {
+    ($name:expr) => {{
+        if let Some(e) = fail::eval($name, |msg| {
+            let msg = msg.unwrap_or_else(|| "synthetic failpoint".to_string());
+            anyhow::Error::msg(msg)
+        }) {
+            return Err(From::from(e));
+        }
+    }};
+    ($name:expr, $cond:expr) => {{
+        if $cond {
+            $crate::try_fail_point!($name);
+        }
+    }};
+}
diff --git a/src/filetree.rs b/src/filetree.rs
index 047ca384..7985e6dc 100644
--- a/src/filetree.rs
+++ b/src/filetree.rs
@@ -328,6 +328,7 @@ pub(crate) fn apply_diff(
     diff: &FileTreeDiff,
     opts: Option<&ApplyUpdateOptions>,
 ) -> Result<()> {
+    println!("{diff:?}");
     let default_opts = ApplyUpdateOptions {
         ..Default::default()
     };
@@ -382,6 +383,7 @@ pub(crate) fn apply_diff(
             .with_context(|| format!("copying {:?} to {:?}", path, path_tmp))?;
     }
 
+    println!("{updates:?}");
     // do local exchange or rename
     for (dst, tmp) in updates.iter() {
         let dst = dst.as_std_path();
@@ -395,6 +397,7 @@ pub(crate) fn apply_diff(
                 .local_rename(tmp, dst)
                 .with_context(|| format!("rename for {} and {:?}", tmp, dst))?;
         }
+        crate::try_fail_point!("exchange");
     }
     // Ensure all of the updates & changes are written persistently to disk
     if !opts.skip_sync {
@@ -705,7 +708,6 @@ mod tests {
             let b_btime_foo_new = fs::metadata(pb.join(foo))?.created()?;
             assert_eq!(b_btime_foo_new, b_btime_foo);
         }
-
         Ok(())
     }
 }
diff --git a/src/main.rs b/src/main.rs
index b075bde0..6691f26f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,6 +24,7 @@ mod component;
 mod coreos;
 #[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
 mod efi;
+mod failpoints;
 mod filesystem;
 mod filetree;
 #[cfg(any(
diff --git a/tests/e2e-update/e2e-update-in-vm.sh b/tests/e2e-update/e2e-update-in-vm.sh
index fd969cad..8b1b3028 100755
--- a/tests/e2e-update/e2e-update-in-vm.sh
+++ b/tests/e2e-update/e2e-update-in-vm.sh
@@ -67,6 +67,11 @@ tmpefimount=$(mount_tmp_efi)
 
 assert_not_has_file ${tmpefimount}/EFI/fedora/test-bootupd.efi
 
+if env FAILPOINTS='exchange=return' bootupctl update -vvv 2>err.txt; then
+    fatal "should have errored"
+fi
+assert_file_has_content_literal err.txt "error: synthetic failpoint"
+
 bootupctl update | tee out.txt
 assert_file_has_content out.txt "Previous EFI: .*"
 assert_file_has_content out.txt "Updated EFI: ${TARGET_GRUB_PKG}.*,test-bootupd-payload-1.0"