Added file locking to the append writes using fs2.

Author: kkysen

Cargo.lock

@@ -18,6 +18,7 @@ camino = "1.0"
 # Used for parsing `rust-toolchain.toml`.
 # We don't need to edit at all, but `cargo` uses `toml-edit`, so we want to match it.
 toml_edit = "0.14"
+fs2 = "0.4"
 
 [build-dependencies]
 rustc-private-link = { path = "../rustc-private-link" }

dynamic_instrumentation/Cargo.toml

@@ -2,6 +2,7 @@ use anyhow::Context;
 use c2rust_analysis_rt::metadata::Metadata;
 use c2rust_analysis_rt::mir_loc::{self, EventMetadata, Func, MirLoc, MirLocId, TransferKind};
 use c2rust_analysis_rt::HOOK_FUNCTIONS;
+use fs2::FileExt;
 use fs_err::OpenOptions;
 use indexmap::IndexSet;
 use log::debug;
@@ -76,7 +77,10 @@ impl Instrumenter {
             .write(true)
             .open(metadata_path)
             .context("Could not open metadata file")?;
-        file.write_all(&bytes)?;
+        file.file_mut().lock_exclusive()?;
+        let e = file.write_all(&bytes);
+        file.file_mut().unlock()?;
+        e?;
         Ok(())
     }