From cad7175e0628b239f760c837719cf1dc5acb5c30 Mon Sep 17 00:00:00 2001
From: Stephen Sykes <sdsykes@gmail.com>
Date: Thu, 2 Jan 2025 20:25:48 +0000
Subject: [PATCH] Handle tiff format with long dimension values, fixes #158

---
 lib/fastimage/fastimage_parsing/exif.rb |  13 ++++++++++---
 test/fixtures/test.dng                  | Bin 0 -> 512 bytes
 test/test.rb                            |   1 +
 3 files changed, 11 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/test.dng

diff --git a/lib/fastimage/fastimage_parsing/exif.rb b/lib/fastimage/fastimage_parsing/exif.rb
index 8761a1b..ecf22e4 100644
--- a/lib/fastimage/fastimage_parsing/exif.rb
+++ b/lib/fastimage/fastimage_parsing/exif.rb
@@ -30,8 +30,16 @@ def parse_exif_ifd
       tag_count = @stream.read(2).unpack(@short)[0]
       tag_count.downto(1) do
         type = @stream.read(2).unpack(@short)[0]
-        @stream.read(6)
-        data = @stream.read(2).unpack(@short)[0]
+        data_type = @stream.read(2).unpack(@short)[0]
+        @stream.read(4)
+
+        if data_type == 4
+          data = @stream.read(4).unpack(@long)[0]
+        else
+          data = @stream.read(2).unpack(@short)[0]
+          @stream.read(2)
+        end
+
         case type
         when 0x0100 # image width
           @width = data
@@ -43,7 +51,6 @@ def parse_exif_ifd
         if @width && @height && @orientation
           return # no need to parse more
         end
-        @stream.read(2)
       end
     end
   
diff --git a/test/fixtures/test.dng b/test/fixtures/test.dng
new file mode 100644
index 0000000000000000000000000000000000000000..fc9bb77b2bf6d508e1d7a31e81a8c41f577ffbba
GIT binary patch
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literal 0
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diff --git a/test/test.rb b/test/test.rb
index 169f49b..ecdbe96 100644
--- a/test/test.rb
+++ b/test/test.rb
@@ -60,6 +60,7 @@
   "avif/red_green_flash.avif" => [:avif, [256, 256]],
   "isobmff.jxl" => [:jxl, [1280,1600]],
   "naked.jxl" => [:jxl, [1000,1000]],
+  "test.dng" => [:tiff, [4032, 3024]]
 }
 
 BadFixtures = [