Added support for decoding plain PPM formats

Tests/test_file_ppm.py

@@ -3,7 +3,7 @@
 
 import pytest
 
-from PIL import Image, UnidentifiedImageError
+from PIL import Image, PpmImagePlugin
 
 from .helper import assert_image_equal_tofile, assert_image_similar, hopper
 
@@ -22,6 +22,21 @@ def test_sanity():
 @pytest.mark.parametrize(
     "data, mode, pixels",
     (
+        (b"P2 3 1 4 0 2 4", "L", (0, 128, 255)),
+        (b"P2 3 1 257 0 128 257", "I", (0, 32640, 65535)),
+        # P3 with maxval < 255
+        (
+            b"P3 3 1 17 0 1 2 8 9 10 15 16 17",
+            "RGB",
+            ((0, 15, 30), (120, 135, 150), (225, 240, 255)),
+        ),
+        # P3 with maxval > 255
+        # Scale down to 255, since there is no RGB mode with more than 8-bit
+        (
+            b"P3 3 1 257 0 1 2 128 129 130 256 257 257",
+            "RGB",
+            ((0, 1, 2), (127, 128, 129), (254, 255, 255)),
+        ),
         (b"P5 3 1 4 \x00\x02\x04", "L", (0, 128, 255)),
         (b"P5 3 1 257 \x00\x00\x00\x80\x01\x01", "I", (0, 32640, 65535)),
         # P6 with maxval < 255
@@ -35,7 +50,6 @@ def test_sanity():
             ),
         ),
         # P6 with maxval > 255
-        # Scale down to 255, since there is no RGB mode with more than 8-bit
         (
             b"P6 3 1 257 \x00\x00\x00\x01\x00\x02"
             b"\x00\x80\x00\x81\x00\x82\x01\x00\x01\x01\xFF\xFF",
@@ -85,14 +99,111 @@ def test_pnm(tmp_path):
         assert_image_equal_tofile(im, f)
 
 
-def test_magic(tmp_path):
+@pytest.mark.parametrize(
+    "plain_path, raw_path",
+    (
+        (
+            "Tests/images/hopper_1bit_plain.pbm",  # P1
+            "Tests/images/hopper_1bit.pbm",  # P4
+        ),
+        (
+            "Tests/images/hopper_8bit_plain.pgm",  # P2
+            "Tests/images/hopper_8bit.pgm",  # P5
+        ),
+        (
+            "Tests/images/hopper_8bit_plain.ppm",  # P3
+            "Tests/images/hopper_8bit.ppm",  # P6
+        ),
+    ),
+)
+def test_plain(plain_path, raw_path):
+    with Image.open(plain_path) as im:
+        assert_image_equal_tofile(im, raw_path)
+
+
+def test_16bit_plain_pgm():
+    # P2 with maxval 2 ** 16 - 1
+    with Image.open("Tests/images/hopper_16bit_plain.pgm") as im:
+        assert im.mode == "I"
+        assert im.size == (128, 128)
+        assert im.get_format_mimetype() == "image/x-portable-graymap"
+
+        # P5 with maxval 2 ** 16 - 1
+        assert_image_equal_tofile(im, "Tests/images/hopper_16bit.pgm")
+
+
+@pytest.mark.parametrize(
+    "header, data, comment_count",
+    (
+        (b"P1\n2 2", b"1010", 10**6),
+        (b"P2\n3 1\n4", b"0 2 4", 1),
+        (b"P3\n2 2\n255", b"0 0 0 001 1 1 2 2 2 255 255 255", 10**6),
+    ),
+)
+def test_plain_data_with_comment(tmp_path, header, data, comment_count):
+    path1 = str(tmp_path / "temp1.ppm")
+    path2 = str(tmp_path / "temp2.ppm")
+    comment = b"# comment" * comment_count
+    with open(path1, "wb") as f1, open(path2, "wb") as f2:
+        f1.write(header + b"\n\n" + data)
+        f2.write(header + b"\n" + comment + b"\n" + data + comment)
+
+    with Image.open(path1) as im:
+        assert_image_equal_tofile(im, path2)
+
+
+@pytest.mark.parametrize("data", (b"P1\n128 128\n", b"P3\n128 128\n255\n"))
+def test_plain_truncated_data(tmp_path, data):
     path = str(tmp_path / "temp.ppm")
     with open(path, "wb") as f:
-        f.write(b"PyInvalid")
+        f.write(data)
 
-    with pytest.raises(UnidentifiedImageError):
-        with Image.open(path):
-            pass
+    with Image.open(path) as im:
+        with pytest.raises(ValueError):
+            im.load()
+
+
+@pytest.mark.parametrize("data", (b"P1\n128 128\n1009", b"P3\n128 128\n255\n100A"))
+def test_plain_invalid_data(tmp_path, data):
+    path = str(tmp_path / "temp.ppm")
+    with open(path, "wb") as f:
+        f.write(data)
+
+    with Image.open(path) as im:
+        with pytest.raises(ValueError):
+            im.load()
+
+
+@pytest.mark.parametrize(
+    "data",
+    (
+        b"P3\n128 128\n255\n012345678910",  # half token too long
+        b"P3\n128 128\n255\n012345678910 0",  # token too long
+    ),
+)
+def test_plain_ppm_token_too_long(tmp_path, data):
+    path = str(tmp_path / "temp.ppm")
+    with open(path, "wb") as f:
+        f.write(data)
+
+    with Image.open(path) as im:
+        with pytest.raises(ValueError):
+            im.load()
+
+
+def test_plain_ppm_value_too_large(tmp_path):
+    path = str(tmp_path / "temp.ppm")
+    with open(path, "wb") as f:
+        f.write(b"P3\n128 128\n255\n256")
+
+    with Image.open(path) as im:
+        with pytest.raises(ValueError):
+            im.load()
+
+
+def test_magic():
+    with pytest.raises(SyntaxError):
+        PpmImagePlugin.PpmImageFile(fp=BytesIO(b"PyInvalid"))
 
 
 def test_header_with_comments(tmp_path):
@@ -114,7 +225,7 @@ def test_non_integer_token(tmp_path):
             pass
 
 
-def test_token_too_long(tmp_path):
+def test_header_token_too_long(tmp_path):
     path = str(tmp_path / "temp.ppm")
     with open(path, "wb") as f:
         f.write(b"P6\n 01234567890")