feat: record pcsx2's relative bios folder

configureINI writes [Folders] Bios = ../../../bios/ps2 into
inis/PCSX2.ini, which PCSX2 and AetherSX2 resolve against the config
folder configgen hands it. relative_folders reads the call, the ini
path and the value, and records the resolved /userdata/bios/ps2 as a
passes_path for pcsx2 and aethersx2.

platforms/knulli.yml

@@ -5732,6 +5732,24 @@ launchers:
   depends_on_option: neocd_bios
   source_ref: "package/system/knulli-configgen/configgen/configgen/generators/libretro/libretroOptions.py:2558-2559,\
     \ 2566-2569"
+- emulator: pcsx2
+  build: standalone
+  kind: passes_path
+  names: []
+  search_dir: /userdata/bios/ps2
+  passes_to: "inis/PCSX2.ini [Folders] Bios = ../../../bios/ps2, relative to /userdata/system/configs/PCSX2"
+  fails_when_missing: false
+  source_ref: "package/system/knulli-configgen/configgen/configgen/generators/pcsx2/pcsx2Generator.py:92,\
+    \ 176, 213"
+- emulator: aethersx2
+  build: standalone
+  kind: passes_path
+  names: []
+  search_dir: /userdata/bios/ps2
+  passes_to: "inis/PCSX2.ini [Folders] Bios = ../../../bios/ps2, relative to /userdata/system/.config/aethersx2"
+  fails_when_missing: false
+  source_ref: "package/system/knulli-configgen/configgen/configgen/generators/aethersx2/aethersx2Generator.py:71,\
+    \ 182, 219"
 - emulator: lexaloffle
   build: standalone
   kind: moves

scripts/scraper/knulli_launchers.py

@@ -20,6 +20,7 @@ LauncherShapeError, as every other extractor does.
 from __future__ import annotations
 
 import ast
+import posixpath
 import re
 from collections.abc import Callable, Iterator
 from dataclasses import dataclass, field
@@ -834,8 +835,82 @@ def bios_sites(cg: Configgen, spec: GenericSites) -> list[Launcher]:
     return launchers
 
 
+# Generators that write a [Folders] path relative to the config folder they
+# are given. PCSX2 and AetherSX2 resolve those paths against their data root,
+# the folder holding inis/, which configureINI receives as config_directory.
+RELATIVE_FOLDERS = (
+    ("pcsx2/pcsx2Generator.py", "configureINI"),
+    ("aethersx2/aethersx2Generator.py", "configureINI"),
+)
+
+
+def relative_folders(
+    cg: Configgen, specs: tuple[tuple[str, str], ...] = RELATIVE_FOLDERS
+) -> list[Launcher]:
+    """parser.set(section, key, "../<path>") resolved against config_directory."""
+    launchers = []
+    for path, function_name in specs:
+        src = cg.source(f"{cg.generators}/{path}")
+        reader = _Reader(cg, src)
+        function = src.function(function_name)
+        if not function.args.args:
+            src.fail(f"{function_name} takes no config folder")
+        folder = function.args.args[0].arg
+        ini = [
+            node for node in ast.walk(function)
+            if isinstance(node, ast.Assign) and isinstance(node.value, ast.BinOp)
+            and ast.unparse(node.value).startswith(f"{folder} /")
+            and ast.unparse(node.value).endswith(".ini'")
+        ]
+        if len(ini) != 1:
+            src.fail(f"{function_name} builds no one ini path under {folder}")
+        parts = sorted(
+            (n for n in ast.walk(ini[0].value)
+             if isinstance(n, ast.Constant) and isinstance(n.value, str)),
+            key=lambda n: (n.lineno, n.col_offset),
+        )
+        ini_name = posixpath.join(*(str(n.value) for n in parts))
+        calls = [
+            node for node in ast.walk(src.tree)
+            if isinstance(node, ast.Call) and isinstance(node.func, ast.Name)
+            and node.func.id == function_name and node.args
+        ]
+        if len(calls) != 1:
+            src.fail(f"expected one call of {function_name}, found {len(calls)}")
+        base = reader.resolve(calls[0].args[0])
+        if base is None or not base.startswith("/"):
+            src.fail(f"{function_name} is given a folder that is not a path")
+        found = 0
+        for call in ast.walk(function):
+            if not (
+                isinstance(call, ast.Call) and isinstance(call.func, ast.Attribute)
+                and call.func.attr == "set" and len(call.args) == 3
+                and all(isinstance(a, ast.Constant) for a in call.args)
+            ):
+                continue
+            section, key, value = (str(a.value) for a in call.args)  # type: ignore[attr-defined]
+            if not value.startswith("../"):
+                continue
+            resolved = posixpath.normpath(posixpath.join(base, value))
+            if not reader.under_bios(resolved):
+                continue
+            found += 1
+            launchers.append(Launcher(
+                emulator=cg.emulator(path.removesuffix(".py").replace("/", ".")),
+                build="standalone", kind="passes_path", names=[], search_dir=resolved,
+                passes_to=f"{ini_name} [{section}] {key} = {value}, relative to {base}",
+                fails_when_missing=False,
+                source_ref=src.ref([
+                    src.span(reader.statement_of(calls[0])), src.span(ini[0]), _lines(call),
+                ]),
+            ))
+        if not found:
+            src.fail(f"{function_name} writes no relative folder under {cg.bios}")
+    return launchers
+
+
 EXTRACTORS: tuple[Callable[[Configgen], list[Launcher]], ...] = (
-    *SHARED, lexaloffle, core_file_options,
+    *SHARED, lexaloffle, core_file_options, relative_folders,
 )
 
 

tests/test_launchers_knulli.py

@@ -59,6 +59,7 @@ IMPORTER = text(
         'openmsx': ('openmsx.openmsxGenerator', 'OpenmsxGenerator'),
         'hatari': ('hatari.hatariGenerator', 'HatariGenerator'),
         'melonds': ('melonds.melondsGenerator', 'MelonDSGenerator'),
+        'pcsx2': ('pcsx2.pcsx2Generator', 'Pcsx2Generator'),
     }
     """
 )
@@ -305,6 +306,29 @@ MELONDS = text(
 )
 
 
+# pcsx2Generator.py: the default patches copied into BIOS when absent, and
+# the BIOS folder written relative to the config folder.
+PCSX2 = text(
+    """
+    from ...batoceraPaths import BIOS, CONFIGS, DATAINIT_DIR
+
+    _PCSX2_CONFIG: Final = CONFIGS / "PCSX2"
+    _PCSX2_BIOS: Final = BIOS / "ps2"
+
+    class Pcsx2Generator(Generator):
+        def generate(self, system, rom, playersControllers, metadata, guns, wheels, gameResolution):
+            pcsx2Patches = _PCSX2_BIOS / "patches.zip"
+            configureINI(_PCSX2_CONFIG, _PCSX2_BIOS, system)
+            if not pcsx2Patches.exists():
+                shutil.copy(DATAINIT_DIR / "bios" / "ps2" / "patches.zip", pcsx2Patches)
+
+    def configureINI(config_directory, bios_directory, system):
+        configFileName = config_directory / 'inis' / "PCSX2.ini"
+        pcsx2INIConfig.set("Folders", "Bios", "../../../bios/ps2")
+        pcsx2INIConfig.set("Folders", "Logs", "../../logs")
+    """
+)
+
 def tree(**overrides: str) -> dict[str, str]:
     files = {
         f"{kl.CONFIGGEN}/batoceraPaths.py": PATHS,
@@ -322,6 +346,7 @@ def tree(**overrides: str) -> dict[str, str]:
         f"{G}/libretro/libretroMAMEConfig.py": MAME_CONFIG,
         f"{G}/hatari/hatariGenerator.py": HATARI,
         f"{G}/melonds/melondsGenerator.py": MELONDS,
+        f"{G}/pcsx2/pcsx2Generator.py": PCSX2,
     }
     files.update(overrides)
     return files
@@ -498,6 +523,33 @@ class BiosSites(unittest.TestCase):
             kl.bios_sites(kl.configgen(files.__getitem__), spec)
 
 
+class CopiesAndFolders(unittest.TestCase):
+    def test_a_copy_into_bios_reads_from_the_folder_it_comes_from(self):
+        (record,) = sites("pcsx2/pcsx2Generator.py", "fixed_name")
+        self.assertEqual(record["kind"], "copies")
+        self.assertEqual(record["names"], ["patches.zip"])
+        self.assertEqual(record["search_dir"], "/usr/share/knulli/datainit/bios/ps2")
+        self.assertEqual(record["passes_to"], "/userdata/bios/ps2/patches.zip")
+        self.assertEqual(record["depends_on_option"], "not pcsx2Patches.exists()")
+
+    def test_a_relative_folder_resolved_against_the_config_folder(self):
+        (record,) = kl.relative_folders(configgen(), kl.RELATIVE_FOLDERS[:1])
+        self.assertEqual(record.kind, "passes_path")
+        self.assertEqual(record.search_dir, "/userdata/bios/ps2")
+        self.assertEqual(
+            record.passes_to,
+            "inis/PCSX2.ini [Folders] Bios = ../../../bios/ps2, relative to /userdata/system/configs/PCSX2",
+        )
+        self.assertEqual(record.source_ref, f"{G}/pcsx2/pcsx2Generator.py:9, 14-15")
+
+    def test_a_folder_written_outside_bios_raises(self):
+        broken = PCSX2.replace("../../../bios/ps2", "../../../saves/ps2")
+        with self.assertRaises(LauncherShapeError):
+            kl.relative_folders(
+                configgen(**{f"{G}/pcsx2/pcsx2Generator.py": broken}), kl.RELATIVE_FOLDERS[:1]
+            )
+
+
 class PlatformFile(unittest.TestCase):
     @classmethod
     def setUpClass(cls) -> None: