Avoid second fs write

butane_core/src/migrations/fs.rs

@@ -13,8 +13,6 @@ pub trait Filesystem: Debug {
     fn list_dir(&self, path: &Path) -> std::io::Result<Vec<PathBuf>>;
     /// Opens a file for writing. Creates it if it does not exist. Truncates it otherwise.
     fn write(&self, path: &Path) -> std::io::Result<Box<dyn Write>>;
-    /// Opens a file for writing in append mode. Fails if file does not exist.
-    fn append(&self, path: &Path) -> std::io::Result<Box<dyn Write>>;
     /// Opens a file for reading.
     fn read(&self, path: &Path) -> std::io::Result<Box<dyn Read>>;
 }
@@ -34,12 +32,6 @@ impl Filesystem for OsFilesystem {
     fn write(&self, path: &Path) -> std::io::Result<Box<dyn Write>> {
         std::fs::File::create(path).map(|f| Box::new(f) as Box<dyn Write>)
     }
-    fn append(&self, path: &Path) -> std::io::Result<Box<dyn Write>> {
-        std::fs::OpenOptions::new()
-            .append(true)
-            .open(path)
-            .map(|f| Box::new(f) as Box<dyn Write>)
-    }
     fn read(&self, path: &Path) -> std::io::Result<Box<dyn Read>> {
         std::fs::File::open(path).map(|f| Box::new(f) as Box<dyn Read>)
     }

butane_core/src/migrations/fsmigrations.rs

@@ -92,16 +92,15 @@ impl FsMigration {
     fn write_contents(&self, fname: &str, contents: &[u8]) -> Result<()> {
         self.ensure_dir()?;
         let path = self.root.join(fname);
+        let mut contents: Vec<u8> = contents.into();
+        if contents[contents.len() - 1] != b'\n' {
+            contents.push(b'\n');
+        }
         self.fs
             .write(&path)?
-            .write_all(contents)
+            .write_all(&contents)
             .map_err(<std::io::Error as Into<Error>>::into)?;
-        if contents[contents.len() - 1] != b'\n' {
-            self.fs
-                .append(&path)?
-                .write(b"\n")
-                .map_err(<std::io::Error as Into<Error>>::into)?;
-        }
+
         Ok(())
     }