Fix #68: Do not write empty content to file (#71)

src/input.rs

@@ -113,9 +113,11 @@ impl Replacer {
         file.set_len(replaced.len() as u64)?;
         file.set_permissions(meta.permissions())?;
 
-        let mut mmap_target = unsafe { MmapMut::map_mut(&file)? };
+        if !replaced.is_empty() {
-        mmap_target.deref_mut().write_all(&replaced)?;
+            let mut mmap_target = unsafe { MmapMut::map_mut(&file)? };
-        mmap_target.flush_async()?;
+            mmap_target.deref_mut().write_all(&replaced)?;
+            mmap_target.flush_async()?;
+        }
 
         drop(mmap_source);
         drop(source);

tests/cli.rs

@@ -24,14 +24,27 @@ fn in_place() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn in_place_with_empty_result_file() -> Result<()> {
+    let mut file = tempfile::NamedTempFile::new()?;
+    file.write(b"a7c")?;
+    let path = file.into_temp_path();
+
+    sd().args(&["a\\dc", "", path.to_str().unwrap()])
+        .assert()
+        .success();
+    assert_file(&path.to_path_buf(), "");
+
+    Ok(())
+}
+
 #[test]
 fn replace_into_stdout() -> Result<()> {
     let mut file = tempfile::NamedTempFile::new()?;
     file.write(b"abc123def")?;
 
     #[rustfmt::skip]
-    sd()
+    sd().args(&["-p", "abc\\d+", "", file.path().to_str().unwrap()])
-        .args(&["-p", "abc\\d+", "", file.path().to_str().unwrap()])
         .assert()
         .success()
         .stdout("def");