Removed support for libtiff < 4

Author: radarhere

Tests/test_file_libtiff.py

@@ -242,7 +242,12 @@ def test_additional_metadata(
 
             im.save(out, tiffinfo=new_ifd)
 
-    def test_custom_metadata(self, tmp_path: Path) -> None:
+    @pytest.mark.parametrize("libtiff", (True, False))
+    def test_custom_metadata(
+        self, monkeypatch: pytest.MonkeyPatch, tmp_path: Path, libtiff: bool
+    ) -> None:
+        monkeypatch.setattr(TiffImagePlugin, "WRITE_LIBTIFF", libtiff)
+
         class Tc(NamedTuple):
             value: Any
             type: int
@@ -281,53 +286,43 @@ class Tc(NamedTuple):
             )
         }
 
-        libtiffs = [False]
-        if Image.core.libtiff_support_custom_tags:
-            libtiffs.append(True)
-
-        for libtiff in libtiffs:
-            TiffImagePlugin.WRITE_LIBTIFF = libtiff
-
-            def check_tags(
-                tiffinfo: TiffImagePlugin.ImageFileDirectory_v2 | dict[int, str]
-            ) -> None:
-                im = hopper()
-
-                out = str(tmp_path / "temp.tif")
-                im.save(out, tiffinfo=tiffinfo)
-
-                with Image.open(out) as reloaded:
-                    for tag, value in tiffinfo.items():
-                        reloaded_value = reloaded.tag_v2[tag]
-                        if (
-                            isinstance(reloaded_value, TiffImagePlugin.IFDRational)
-                            and libtiff
-                        ):
-                            # libtiff does not support real RATIONALS
-                            assert (
-                                round(abs(float(reloaded_value) - float(value)), 7) == 0
-                            )
-                            continue
-
-                        assert reloaded_value == value
-
-            # Test with types
-            ifd = TiffImagePlugin.ImageFileDirectory_v2()
-            for tag, tagdata in custom.items():
-                ifd[tag] = tagdata.value
-                ifd.tagtype[tag] = tagdata.type
-            check_tags(ifd)
-
-            # Test without types. This only works for some types, int for example are
-            # always encoded as LONG and not SIGNED_LONG.
-            check_tags(
-                {
-                    tag: tagdata.value
-                    for tag, tagdata in custom.items()
-                    if tagdata.supported_by_default
-                }
-            )
-        TiffImagePlugin.WRITE_LIBTIFF = False
+        def check_tags(
+            tiffinfo: TiffImagePlugin.ImageFileDirectory_v2 | dict[int, str]
+        ) -> None:
+            im = hopper()
+
+            out = str(tmp_path / "temp.tif")
+            im.save(out, tiffinfo=tiffinfo)
+
+            with Image.open(out) as reloaded:
+                for tag, value in tiffinfo.items():
+                    reloaded_value = reloaded.tag_v2[tag]
+                    if (
+                        isinstance(reloaded_value, TiffImagePlugin.IFDRational)
+                        and libtiff
+                    ):
+                        # libtiff does not support real RATIONALS
+                        assert round(abs(float(reloaded_value) - float(value)), 7) == 0
+                        continue
+
+                    assert reloaded_value == value
+
+        # Test with types
+        ifd = TiffImagePlugin.ImageFileDirectory_v2()
+        for tag, tagdata in custom.items():
+            ifd[tag] = tagdata.value
+            ifd.tagtype[tag] = tagdata.type
+        check_tags(ifd)
+
+        # Test without types. This only works for some types, int for example are
+        # always encoded as LONG and not SIGNED_LONG.
+        check_tags(
+            {
+                tag: tagdata.value
+                for tag, tagdata in custom.items()
+                if tagdata.supported_by_default
+            }
+        )
 
     def test_osubfiletype(self, tmp_path: Path) -> None:
         outfile = str(tmp_path / "temp.tif")
@@ -682,8 +677,7 @@ def test_exif_ifd(self, tmp_path: Path) -> None:
             im.save(outfile)
 
         with Image.open(outfile) as reloaded:
-            if Image.core.libtiff_support_custom_tags:
-                assert reloaded.tag_v2[34665] == 125456
+            assert reloaded.tag_v2[34665] == 125456
 
     def test_crashing_metadata(
         self, monkeypatch: pytest.MonkeyPatch, tmp_path: Path
@@ -735,19 +729,7 @@ def test_read_icc(self, monkeypatch: pytest.MonkeyPatch) -> None:
             assert icc_libtiff is not None
         assert icc == icc_libtiff
 
-    @pytest.mark.parametrize(
-        "libtiff",
-        (
-            pytest.param(
-                True,
-                marks=pytest.mark.skipif(
-                    not Image.core.libtiff_support_custom_tags,
-                    reason="Custom tags not supported by older libtiff",
-                ),
-            ),
-            False,
-        ),
-    )
+    @pytest.mark.parametrize("libtiff", (True, False))
     def test_write_icc(
         self, monkeypatch: pytest.MonkeyPatch, tmp_path: Path, libtiff: bool
     ) -> None:

src/PIL/TiffImagePlugin.py

@@ -1823,9 +1823,6 @@ def _save(im, fp, filename):
             # Custom items are supported for int, float, unicode, string and byte
             # values. Other types and tuples require a tagtype.
             if tag not in TiffTags.LIBTIFF_CORE:
-                if not getattr(Image.core, "libtiff_support_custom_tags", False):
-                    continue
-
                 if tag in ifd.tagtype:
                     types[tag] = ifd.tagtype[tag]
                 elif not (isinstance(value, (int, float, str, bytes))):

src/_imaging.c

@@ -4388,16 +4388,6 @@ setup_module(PyObject *m) {
         PyObject *v = PyUnicode_FromString(ImagingTiffVersion());
         PyDict_SetItemString(d, "libtiff_version", v ? v : Py_None);
         Py_XDECREF(v);
-
-        // Test for libtiff 4.0 or later, excluding libtiff 3.9.6 and 3.9.7
-        PyObject *support_custom_tags;
-#if TIFFLIB_VERSION >= 20111221 && TIFFLIB_VERSION != 20120218 && \
-    TIFFLIB_VERSION != 20120922
-        support_custom_tags = Py_True;
-#else
-        support_custom_tags = Py_False;
-#endif
-        PyDict_SetItemString(d, "libtiff_support_custom_tags", support_custom_tags);
     }
 #endif
 

src/libImaging/TiffDecode.c

@@ -824,7 +824,7 @@ ImagingLibTiffMergeFieldInfo(
     // Refer to libtiff docs (http://www.simplesystems.org/libtiff/addingtags.html)
     TIFFSTATE *clientstate = (TIFFSTATE *)state->context;
     uint32_t n;
-    int status = 0;
+    int status;
 
     // custom fields added with ImagingLibTiffMergeFieldInfo are only used for
     // decoding, ignore readcount;
@@ -846,13 +846,7 @@ ImagingLibTiffMergeFieldInfo(
 
     n = sizeof(info) / sizeof(info[0]);
 
-    // Test for libtiff 4.0 or later, excluding libtiff 3.9.6 and 3.9.7
-#if TIFFLIB_VERSION >= 20111221 && TIFFLIB_VERSION != 20120218 && \
-    TIFFLIB_VERSION != 20120922
     status = TIFFMergeFieldInfo(clientstate->tiff, info, n);
-#else
-    TIFFMergeFieldInfo(clientstate->tiff, info, n);
-#endif
     return status;
 }