From b13018306ccb1cbbfb5c1040dd7862e6b022531a Mon Sep 17 00:00:00 2001
From: sneak <sneak@sneak.berlin>
Date: Fri, 2 Oct 2026 03:18:20 +0000
Subject: [PATCH] Test the GPS hemisphere rules readPhotoExif applies

Two readPhotoExif tests on hand-built GPS IFDs: a GPSLatitude with
GPSLatitudeRef "S" gives a negative gpsLatitude, and a GPSLatitude and
GPSLongitude without their reference tags give neither field.

Model: opus-5-5
---
 test/cli/metadata-exif.test.ts | 63 ++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/test/cli/metadata-exif.test.ts b/test/cli/metadata-exif.test.ts
index a21ad6a..509f1d8 100644
--- a/test/cli/metadata-exif.test.ts
+++ b/test/cli/metadata-exif.test.ts
@@ -67,6 +67,51 @@ const TIFF_ALTITUDE_WITHOUT_REF = [
     ...[0x00, 0x00, 0x00, 0x19, 0x00, 0x00, 0x00, 0x02], // 25/2, at 44
 ];
 
+// A big-endian TIFF block holding a GPSLatitude of 33° 30' 0" and a
+// GPSLatitudeRef of "S".
+const TIFF_SOUTHERN_LATITUDE = [
+    ...[0x4d, 0x4d, 0x00, 0x2a, 0x00, 0x00, 0x00, 0x08], // the first IFD at 8
+    // The first IFD, at 8: one entry, then no next IFD.
+    ...[0x00, 0x01],
+    // The GPS IFD's offset (0x8825), LONG, 26.
+    ...[0x88, 0x25, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x1a],
+    ...[0x00, 0x00, 0x00, 0x00],
+    // The GPS IFD, at 26: two entries, then no next IFD.
+    ...[0x00, 0x02],
+    // GPSLatitudeRef (0x0001), 2 ASCII bytes: "S".
+    ...[0x00, 0x01, 0x00, 0x02, 0x00, 0x00, 0x00, 0x02, 0x53, 0x00, 0x00, 0x00],
+    // GPSLatitude (0x0002), three RATIONALs at 56.
+    ...[0x00, 0x02, 0x00, 0x05, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x38],
+    ...[0x00, 0x00, 0x00, 0x00],
+    ...[0x00, 0x00, 0x00, 0x21, 0x00, 0x00, 0x00, 0x01], // 33/1, at 56
+    ...[0x00, 0x00, 0x00, 0x1e, 0x00, 0x00, 0x00, 0x01], // 30/1
+    ...[0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01], // 0/1
+];
+
+// A big-endian TIFF block holding a GPSLatitude of 40° 26' 46" and a
+// GPSLongitude of 79° 58' 56", and neither GPSLatitudeRef nor GPSLongitudeRef.
+const TIFF_POSITION_WITHOUT_REFS = [
+    ...[0x4d, 0x4d, 0x00, 0x2a, 0x00, 0x00, 0x00, 0x08], // the first IFD at 8
+    // The first IFD, at 8: one entry, then no next IFD.
+    ...[0x00, 0x01],
+    // The GPS IFD's offset (0x8825), LONG, 26.
+    ...[0x88, 0x25, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x1a],
+    ...[0x00, 0x00, 0x00, 0x00],
+    // The GPS IFD, at 26: two entries, then no next IFD.
+    ...[0x00, 0x02],
+    // GPSLatitude (0x0002), three RATIONALs at 56.
+    ...[0x00, 0x02, 0x00, 0x05, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x38],
+    // GPSLongitude (0x0004), three RATIONALs at 80.
+    ...[0x00, 0x04, 0x00, 0x05, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x50],
+    ...[0x00, 0x00, 0x00, 0x00],
+    ...[0x00, 0x00, 0x00, 0x28, 0x00, 0x00, 0x00, 0x01], // 40/1, at 56
+    ...[0x00, 0x00, 0x00, 0x1a, 0x00, 0x00, 0x00, 0x01], // 26/1
+    ...[0x00, 0x00, 0x00, 0x2e, 0x00, 0x00, 0x00, 0x01], // 46/1
+    ...[0x00, 0x00, 0x00, 0x4f, 0x00, 0x00, 0x00, 0x01], // 79/1, at 80
+    ...[0x00, 0x00, 0x00, 0x3a, 0x00, 0x00, 0x00, 0x01], // 58/1
+    ...[0x00, 0x00, 0x00, 0x38, 0x00, 0x00, 0x00, 0x01], // 56/1
+];
+
 // A big-endian TIFF block holding Orientation 6 and a Make whose value lies
 // past the end of the file.
 const TIFF_MAKE_PAST_END = [
@@ -182,6 +227,24 @@ describe("readPhotoExif", () => {
         });
     });
 
+    it("reads a GPSLatitude with GPSLatitudeRef S as south of the equator", () => {
+        const data = [...EXIF_HEADER, ...TIFF_SOUTHERN_LATITUDE];
+        expect(
+            readPhotoExif(readAllExifTags(bytes(SOI, app1(data), SOS))),
+        ).toStrictEqual({
+            gpsLatitude: -33.5,
+        });
+    });
+
+    it("gives no gpsLatitude or gpsLongitude without their reference tags", () => {
+        const data = [...EXIF_HEADER, ...TIFF_POSITION_WITHOUT_REFS];
+        const tags = readAllExifTags(bytes(SOI, app1(data), SOS));
+        // The position is read; only its hemisphere is unknown.
+        expect(tags.GPSLatitude?.computed).toStrictEqual([40, 26, 46]);
+        expect(tags.GPSLongitude?.computed).toStrictEqual([79, 58, 56]);
+        expect(readPhotoExif(tags)).toStrictEqual({});
+    });
+
     it("gives no make for a Make whose value lies past the end of the file", () => {
         const data = [...EXIF_HEADER, ...TIFF_MAKE_PAST_END];
         expect(