Support UTF-8-BOM when importing CSV (#2360)

The csv crate already supports it, but the meta line parsing didn't.

rslib/src/import_export/text/csv/import.rs

@@ -18,6 +18,7 @@ use crate::import_export::ImportProgress;
 use crate::import_export::NoteLog;
 use crate::io::open_file;
 use crate::prelude::*;
+use crate::text::strip_utf8_bom;
 
 impl Collection {
     pub fn import_csv(
@@ -222,7 +223,7 @@ fn remove_tags_line_from_reader(reader: &mut (impl Read + Seek)) -> Result<()> {
     let mut buf_reader = BufReader::new(reader);
     let mut first_line = String::new();
     buf_reader.read_line(&mut first_line)?;
-    let offset = if first_line.starts_with("tags:") {
+    let offset = if strip_utf8_bom(&first_line).starts_with("tags:") {
         first_line.as_bytes().len()
     } else {
         0
@@ -380,4 +381,13 @@ mod test {
         assert_field_eq!(notes[1].fields, [Some("foo"), Some("bar")]);
         assert_eq!(notes[1].notetype, NameOrId::Name(String::from("Cloze")));
     }
+
+    #[test]
+    fn should_ignore_bom() {
+        let metadata = CsvMetadata::defaults_for_testing();
+        assert_imported_fields!(metadata, "\u{feff}foo,bar\n", [[Some("foo"), Some("bar")]]);
+        assert!(import!(metadata, "\u{feff}#foo\n").is_empty());
+        assert!(import!(metadata, "\u{feff}#html:true\n").is_empty());
+        assert!(import!(metadata, "\u{feff}tags:foo\n").is_empty());
+    }
 }

rslib/src/import_export/text/csv/metadata.rs

@@ -28,6 +28,7 @@ pub use crate::pb::import_export::CsvMetadata;
 use crate::prelude::*;
 use crate::text::html_to_text_line;
 use crate::text::is_html;
+use crate::text::strip_utf8_bom;
 
 /// The maximum number of preview rows.
 const PREVIEW_LENGTH: usize = 5;
@@ -96,6 +97,7 @@ impl Collection {
     /// True if the line is a meta line, i.e. a comment, or starting with
     /// 'tags:'.
     fn parse_first_line(&mut self, line: &str, metadata: &mut CsvMetadata) -> bool {
+        let line = strip_utf8_bom(line);
         if let Some(tags) = line.strip_prefix("tags:") {
             metadata.global_tags = collect_tags(tags);
             true
@@ -739,4 +741,14 @@ mod test {
         // html is stripped
         assert_eq!(meta.preview[1].vals, ["baz", ""]);
     }
+
+    #[test]
+    fn should_parse_first_first_line_despite_bom() {
+        let mut col = open_test_collection();
+        assert_eq!(
+            metadata!(col, "\u{feff}#separator:tab\n").delimiter(),
+            Delimiter::Tab
+        );
+        assert_eq!(metadata!(col, "\u{feff}tags:foo\n").global_tags, ["foo"]);
+    }
 }

rslib/src/text.rs

@@ -62,6 +62,10 @@ impl<'a, B: ?Sized + 'a + ToOwned> CowMapping<'a, B> for Cow<'a, B> {
     }
 }
 
+pub(crate) fn strip_utf8_bom(s: &str) -> &str {
+    s.strip_prefix('\u{feff}').unwrap_or(s)
+}
+
 #[derive(Debug, PartialEq)]
 pub enum AvTag {
     SoundOrVideo(String),