fix: check gambatte boot roms from the shipped core

emulators/gambatte.yml

@@ -40,9 +40,9 @@ files:
     description: "Original Game Boy (DMG-01) boot ROM"
     required: false
     hle_fallback: true
-    size: 256
-    validation: {core: [size], upstream: [size, crc32]}
-    source_ref: "libgambatte/libretro/libretro.cpp:1303-1363 (get_bootloader_from_file), libgambatte/src/bootloader.cpp:20-55 (load)"
+    min_size: 256
+    validation: [size]
+    source_ref: "libgambatte/libretro/libretro.cpp:1426-1486 (get_bootloader_from_file), libgambatte/libretro/libretro.cpp:1734-1742, libgambatte/src/bootloader.cpp:30-65 (load)"
     note: "Mapped at 0x0000-0x00FF, swapped out when register 0xFF50 is written."
 
   - name: "gbc_bios.bin"
@@ -50,7 +50,7 @@ files:
     description: "Game Boy Color (CGB-001) boot ROM"
     required: false
     hle_fallback: true
-    size: 2304
-    validation: {core: [size], upstream: [size, crc32]}
-    source_ref: "libgambatte/libretro/libretro.cpp:1303-1363 (get_bootloader_from_file), libgambatte/src/bootloader.cpp:20-55 (load)"
+    min_size: 2304
+    validation: [size]
+    source_ref: "libgambatte/libretro/libretro.cpp:1426-1486 (get_bootloader_from_file), libgambatte/libretro/libretro.cpp:1734-1742, libgambatte/src/bootloader.cpp:30-65 (load)"
     note: "Mapped at 0x0000-0x08FF with cartridge data preserved at 0x0100-0x01FF. Also used for GBA mode with a patch at 0xF2. Presence required for FORCE_CGB flag when hw mode is GBC or GBA."

tests/test_profile_checks.py

@@ -250,5 +250,18 @@ class DolphinForksIplDumps(_Probe):
                 self.assertFalse(self.accepts(emulator, "IPL.bin", data, strict=True))
 
 
+class GambatteBootRoms(_Probe):
+    """get_bootloader_from_file reads 0x100 or 0x900 bytes and gives up on a
+    short read; it never reads past them (libgambatte/libretro/libretro.cpp
+    1426-1486 at d9d6cd0). The upstream crc32 check the profile claimed has
+    no code behind it: sinamas/gambatte was reset to a README in 2021."""
+
+    def test_short_is_refused_and_longer_is_read(self):
+        for name, size in (("gb_bios.bin", 256), ("gbc_bios.bin", 2304)):
+            with self.subTest(name=name):
+                self.assertFalse(self.accepts("gambatte", name, b"\0" * (size - 1)))
+                self.assertTrue(self.accepts("gambatte", name, b"\0" * (size + 512)))
+
+
 if __name__ == "__main__":
     unittest.main()