From 565da148829ce8ad951baf5190b2b718d6ee35c0 Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Fri, 28 Feb 2025 12:53:41 -0800
Subject: [PATCH] pngdec.c: add support for 'eXIf' tag

Test file created with exiftool 12.76:

```
exiftool test_app1_exif.png -exif:all \
  -exif:DocumentName=test_multi_exif.png -o test_multi_exif.png
```

Bug: webp:398066379
Change-Id: I1437390a70f5708421683eb69c588624bb376baa
---
 imageio/pngdec.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/imageio/pngdec.c b/imageio/pngdec.c
index 8dc3c6c7..049acd7c 100644
--- a/imageio/pngdec.c
+++ b/imageio/pngdec.c
@@ -161,6 +161,20 @@ static int ExtractMetadataFromPNG(png_structp png,
     png_textp text = NULL;
     const png_uint_32 num = png_get_text(png, info, &text, NULL);
     png_uint_32 i;
+
+#ifdef PNG_eXIf_SUPPORTED
+    // Look for an 'eXIf' tag. Preference is given to this tag as it's newer
+    // than the TextualData tags.
+    {
+      png_bytep exif;
+      png_uint_32 len;
+
+      if (png_get_eXIf_1(png, info, &len, &exif) == PNG_INFO_eXIf) {
+        if (!MetadataCopy((const char*)exif, len, &metadata->exif)) return 0;
+      }
+    }
+#endif  // PNG_eXIf_SUPPORTED
+
     // Look for EXIF / XMP metadata.
     for (i = 0; i < num; ++i, ++text) {
       int j;