1 files changed, 20 insertions, 8 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 3c90156..7075477 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -42,6 +42,14 @@ const BUF_SIZE: usize = 1024 * 1024;
 /// An entry in a file manifest.
 #[derive(Serialize, Debug)]
 pub struct ManifestEntry {
+    #[serde(skip)]
+    is_regular: bool,
+
+    // Store the original name in a hidden field, for compute_checksum.
+    #[serde(skip)]
+    filename: PathBuf,
+
+    // We store pathname as a string so that we can handle non-UTF8 names.
     path: String,
     #[serde(with = "mode")]
     mode: u32,
@@ -60,29 +68,33 @@ impl ManifestEntry {
     /// caller. This function doesn't query the system for it.
     ///
     /// The structure can be serialized using serde.
-    pub fn new(path: &Path) -> std::io::Result<Self> {
+    pub async fn new(path: &Path) -> std::io::Result<Self> {
         let m = symlink_metadata(path)?;
-        let hash = if m.is_file() {
-            Some(file_checksum(path)?)
-        } else {
-            None
-        };
         let target = if m.file_type().is_symlink() {
             Some(read_link(path)?)
         } else {
             None
         };
         Ok(Self {
+            is_regular: m.is_file(),
+            filename: path.to_path_buf(),
             path: path.to_string_lossy().into_owned(),
             mode: m.st_mode(),
             mtime: m.st_mtime(),
             mtime_nsec: m.st_mtime_nsec(),
             nlink: m.st_nlink(),
             size: if m.is_dir() { None } else { Some(m.st_size()) },
-            sha256: hash,
+            sha256: None,
             target,
         })
     }
+
+    pub fn compute_checksum(&mut self) -> std::io::Result<()> {
+        if self.is_regular {
+            self.sha256 = Some(file_checksum(&self.filename)?);
+        }
+        Ok(())
+    }
 }
 
 fn file_checksum(path: &Path) -> std::io::Result<String> {
@@ -90,8 +102,8 @@ fn file_checksum(path: &Path) -> std::io::Result<String> {
 
     let file = File::open(path)?;
     let mut reader = BufReader::new(file);
-    let mut buf = vec![0; BUF_SIZE];
     loop {
+        let mut buf = vec![0; BUF_SIZE];
         let n = reader.read(&mut buf)?;
         if n == 0 {
             break;