From 21c7ac8d6ab53f4fe9a5ba449feafa904b3863ca Mon Sep 17 00:00:00 2001
From: Hugo Osvaldo Barrera <hugo@barrera.io>
Date: Tue, 11 Aug 2020 03:08:25 +0200
Subject: [PATCH] Don't raise IndexError when GPS IFD tag is missing

When images are missing this tag (this is apparently common for many
images generated by phones), running them through
`ImageOps.exif_transpose` raises `IndexError`.

The root cause here is they're missing some tags in the EXIF metadata,
and this isn't handled very gracefully.

Fixes #4215
---
 Tests/images/exif-gps-ifd-missing.jpeg | Bin 0 -> 1087 bytes
 Tests/test_file_jpeg.py                |   8 ++++++++
 src/PIL/TiffImagePlugin.py             |   9 +++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 Tests/images/exif-gps-ifd-missing.jpeg

diff --git a/Tests/images/exif-gps-ifd-missing.jpeg b/Tests/images/exif-gps-ifd-missing.jpeg
new file mode 100644
index 0000000000000000000000000000000000000000..28f180b8743a97318161e5caa47e5bcdc3fd5fbc
GIT binary patch
literal 1087
zcmb7DL2DC16n^t&wux!6*|aLugKI$)Pn&H_(i{{NiwZ3mFCu!dq{1Fb5kx!}rNN8o
z+*(kUDvEm23I_3DwI^@hs$TRUcoF;o>iXX9>?BApzGQa3{pNdb-n@AmZ^d7rcxLMK
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zvv6(Bn>@!0bcSTNWDfkmZ}_!FQ1i-_My1-Q)B*M_u4Z{)bMdal7uw^!oZ1Id+@f%u
z^o+_60>2}(TyeIeEWW-hk~%1X610Fqng!n0Xya=wEx)Rj#cSHJnkPEf%R%Q2-UXm{
z7+fS=u=?k^ljJ~mfUoqj#c#E?_<fY+U-tdT+#lB{!mOslQ6w`w*o~YF<A=39W?$0Z
zPtQm#0Pp|}&sg?h$KWyI2YNio*w~eOWSvH9yW820BbQ&)g5SyK5&OmQ?{7TQV52Te
zd4SSQ*465MwSENP-x+CpZdlcvq&C3x!h9+UM==(Eh7<fX^cyBG{KU+pRFVymfnr1H
zI7-o9DGp)+kQXXRs{gk54Y+w~l7bZDfUc0Ph&N$(@~LLo@+?Jxc&`XTL5}NdjLz!r
zFO?^bpS`;Aj1;5Ey=ALBD`wq3mvk}y1VfU&r3=SkV`64yJ@@YDQ}<%CI&$k}_s-)>
KD?hxY_~Tzl{d_zC

literal 0
HcmV?d00001

diff --git a/Tests/test_file_jpeg.py b/Tests/test_file_jpeg.py
index 03a2dba51..2fad3b812 100644
--- a/Tests/test_file_jpeg.py
+++ b/Tests/test_file_jpeg.py
@@ -735,6 +735,14 @@ class TestFileJpeg:
         # Assert the entire file has not been read
         assert 0 < buffer.max_pos < size
 
+    def test_missing_gps_ifd(self):
+        # This image is missing its gps ifd data.
+        with Image.open("Tests/images/exif-gps-ifd-missing.jpeg") as im:
+
+            # This should return the default, and not a IndexError when a tag is
+            # missing.
+            assert im.info.get("dpi") == (72, 72)
+
 
 @pytest.mark.skipif(not is_win32(), reason="Windows only")
 @skip_unless_feature("jpg")
diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index 6a772e48b..a282a23f1 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -587,15 +587,20 @@ class ImageFileDirectory_v2(MutableMapping):
                 TiffTags.SIGNED_RATIONAL,
             ]:  # rationals
                 values = (values,)
-            try:
+
+            if len(values) == 1:
                 (dest[tag],) = values
-            except ValueError:
+            elif len(values) > 1:
                 # We've got a builtin tag with 1 expected entry
                 warnings.warn(
                     "Metadata Warning, tag %s had too many entries: %s, expected 1"
                     % (tag, len(values))
                 )
                 dest[tag] = values[0]
+            else:
+                warnings.warn(
+                    "Metadata Warning, tag %s had no entries, expected 1" % tag
+                )
 
         else:
             # Spec'd length > 1 or undefined