1 files changed, 55 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/extras/exif.cc b/third_party/jpeg-xl/lib/extras/exif.cc
new file mode 100644
index 0000000000..7d926558c3
--- /dev/null
+++ b/third_party/jpeg-xl/lib/extras/exif.cc
@@ -0,0 +1,55 @@
+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "lib/extras/exif.h"
+
+#include "lib/jxl/base/byte_order.h"
+
+namespace jxl {
+
+constexpr uint16_t kExifOrientationTag = 274;
+
+void ResetExifOrientation(std::vector<uint8_t>& exif) {
+  if (exif.size() < 12) return;  // not enough bytes for a valid exif blob
+  bool bigendian;
+  uint8_t* t = exif.data();
+  if (LoadLE32(t) == 0x2A004D4D) {
+    bigendian = true;
+  } else if (LoadLE32(t) == 0x002A4949) {
+    bigendian = false;
+  } else {
+    return;  // not a valid tiff header
+  }
+  t += 4;
+  uint32_t offset = (bigendian ? LoadBE32(t) : LoadLE32(t));
+  if (exif.size() < 12 + offset + 2 || offset < 8) return;
+  t += offset - 4;
+  uint16_t nb_tags = (bigendian ? LoadBE16(t) : LoadLE16(t));
+  t += 2;
+  while (nb_tags > 0) {
+    if (t + 12 >= exif.data() + exif.size()) return;
+    uint16_t tag = (bigendian ? LoadBE16(t) : LoadLE16(t));
+    t += 2;
+    if (tag == kExifOrientationTag) {
+      uint16_t type = (bigendian ? LoadBE16(t) : LoadLE16(t));
+      t += 2;
+      uint32_t count = (bigendian ? LoadBE32(t) : LoadLE32(t));
+      t += 4;
+      if (type == 3 && count == 1) {
+        if (bigendian) {
+          StoreBE16(1, t);
+        } else {
+          StoreLE16(1, t);
+        }
+      }
+      return;
+    } else {
+      t += 10;
+      nb_tags--;
+    }
+  }
+}
+
+}  // namespace jxl