From 815fc1e110a7adf7428a1cc46b9acd5827848d1c Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Thu, 27 Feb 2025 19:02:33 -0800
Subject: [PATCH 1/3] pngdec.c: add missing #ifdef for png_get_iCCP

png_get_iCCP is an optional part of the API. Protect its usage with
PNG_iCCP_SUPPORTED.

Change-Id: I1ac777d1c2a200bb3e1303b3d095cc0d67633bd4
---
 imageio/pngdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/imageio/pngdec.c b/imageio/pngdec.c
index cdd99883..f63cbebc 100644
--- a/imageio/pngdec.c
+++ b/imageio/pngdec.c
@@ -192,6 +192,7 @@ static int ExtractMetadataFromPNG(png_structp png,
         }
       }
     }
+#ifdef PNG_iCCP_SUPPORTED
     // Look for an ICC profile.
     {
       png_charp name;
@@ -208,6 +209,7 @@ static int ExtractMetadataFromPNG(png_structp png,
         if (!MetadataCopy((const char*)profile, len, &metadata->iccp)) return 0;
       }
     }
+#endif  // PNG_iCCP_SUPPORTED
   }
   return 1;
 }

From 319860e919d5fcce13a3bebe77dcff88abbc78d5 Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Thu, 27 Feb 2025 19:09:28 -0800
Subject: [PATCH 2/3] pngdec.c: support ImageMagick app1 exif text data

Test file created with ImageMagick 6.9.13-12:

```
convert test_exif.png test_app1_exif.png
```

Bug: webp:398066379
Change-Id: I10a20de5699fabb0906045994d7d1f4b9e951973
---
 imageio/pngdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/imageio/pngdec.c b/imageio/pngdec.c
index f63cbebc..8dc3c6c7 100644
--- a/imageio/pngdec.c
+++ b/imageio/pngdec.c
@@ -139,6 +139,8 @@ static const struct {
   { "Raw profile type xmp",  ProcessRawProfile, METADATA_OFFSET(xmp) },
   // Exiftool puts exif data in APP1 chunk, too.
   { "Raw profile type APP1", ProcessRawProfile, METADATA_OFFSET(exif) },
+  // ImageMagick uses lowercase app1.
+  { "Raw profile type app1", ProcessRawProfile, METADATA_OFFSET(exif) },
   // XMP Specification Part 3, Section 3 #PNG
   { "XML:com.adobe.xmp",     MetadataCopy,      METADATA_OFFSET(xmp) },
   { NULL, NULL, 0 },

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 3/3] 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;