configparser: skip space characters

Summary:
Previously, a line with all space characters is considered "illegal" and I
didn't handle it. It would actually be parsed as part of config name.

Let's skip them. So config files with spaces would behave sanely.

Reviewed By: DurhamG

Differential Revision: D8887370

fbshipit-source-id: e55d221d281fc58b2d2efbcb9196e7f68a78d719

lib/configparser/src/config.rs

@@ -265,7 +265,7 @@ impl ConfigSet {
 
         while pos < buf.len() {
             match buf[pos] {
-                b'\n' | b'\r' => pos += 1,
+                b'\n' | b'\r' | b' ' | b'\t' => pos += 1,
                 b'[' => {
                     let section_start = pos + 1;
                     match memchr(b']', &buf.as_ref()[section_start..]) {
@@ -653,6 +653,18 @@ mod tests {
         assert_eq!(sources[1].location().unwrap(), (PathBuf::new(), 52..53));
     }
 
+    #[test]
+    fn test_parse_spaces() {
+        let mut cfg = ConfigSet::new();
+        cfg.parse(
+            "[a]\n\
+             \t#\n\
+             x=1",
+            &"".into(),
+        );
+        assert_eq!(cfg.get("a", "x"), Some("1".into()));
+    }
+
     #[test]
     fn test_parse_errors() {
         let mut cfg = ConfigSet::new();