Improve network usage for small text changes (#166)

sync-server/src/utils/is_binary.rs

@@ -0,0 +1,26 @@
+/// Heuristically determine if the given data is a binary or a text file's
+/// content.
+///
+/// Only text inputs can be reconciled using the crate's functions.
+#[must_use]
+pub fn is_binary(data: &[u8]) -> bool {
+    if data.contains(&0) {
+        // Even though the NUL character is valid in UTF-8, it's highly suspicious in
+        // human-readable text.
+        return true;
+    }
+
+    std::str::from_utf8(data).is_err()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_is_binary() {
+        assert!(is_binary(&[0, 159, 146, 150]));
+        assert!(is_binary(&[0, 12]));
+        assert!(!is_binary(b"hello"));
+    }
+}