From 81096ce9e3e3ac2036f206b0da0dd1ac1a33ca41 Mon Sep 17 00:00:00 2001
From: Alexander Weiss <alex@weissfam.de>
Date: Thu, 7 Jul 2022 09:05:22 +0200
Subject: [PATCH] chunker: Correct treatment of empty files

---
 src/chunker.rs | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/chunker.rs b/src/chunker.rs
index ead0f36..8ed9b11 100644
--- a/src/chunker.rs
+++ b/src/chunker.rs
@@ -76,7 +76,7 @@ impl<R: Read> Iterator for ChunkIter<R> {
         if size < min_size {
             self.finished = true;
             vec.truncate(size + open_buf_len);
-            return Some(Ok(vec));
+            return if vec.is_empty() { None } else { Some(Ok(vec)) };
         }
 
         self.rabin
@@ -229,3 +229,33 @@ fn qp(p: i32, g: &Polynom64) -> Polynom64 {
     // add x
     res.add(&2).modulo(g)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Cursor;
+
+    #[test]
+    fn chunk_empty() {
+        let empty: Vec<u8> = vec![];
+        let mut reader = Cursor::new(empty);
+
+        let poly = random_poly().unwrap();
+        let chunker = ChunkIter::new(&mut reader, 0, &poly);
+
+        let chunks: Vec<_> = chunker.into_iter().collect();
+        assert_eq!(0, chunks.len());
+    }
+
+    #[test]
+    fn chunk_empty_wrong_hint() {
+        let empty: Vec<u8> = vec![];
+        let mut reader = Cursor::new(empty);
+
+        let poly = random_poly().unwrap();
+        let chunker = ChunkIter::new(&mut reader, 100, &poly);
+
+        let chunks: Vec<_> = chunker.into_iter().collect();
+        assert_eq!(0, chunks.len());
+    }
+}