fix: replay absent core claims when narrowing

install.ps1

@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "61ffed8fddf816c02c1b45268dfd9bfdff9daeb1da2adedf2e13d14472f8654d"
+$defaultInstallSha256 = "2e9e93d9809d9276a84209cfd421ad9b0d55853ce9c9d6761beb2ef21044ef2f"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }

install.py

@@ -1151,6 +1151,27 @@ _COPY_FIELDS = (
 )
 
 
+def _check_omission(entry: dict, dest: str) -> None:
+    """The fields of a file left out: an omitted entry, or the claim of a core
+    with nothing held at a destination another core's copy serves."""
+    if not isinstance(entry.get("name"), str) or not entry["name"]:
+        raise ValueError(f"invalid omitted file name for {dest}")
+    if not isinstance(entry.get("system", ""), str):
+        raise ValueError(f"invalid omitted system for {dest}")
+    if not isinstance(entry.get("required"), bool):
+        raise ValueError(f"invalid omitted required flag for {dest}")
+    if entry.get("reason") not in OMISSION_REASONS:
+        raise ValueError(f"invalid omission reason for {dest}")
+    cores = entry.get("cores")
+    if cores is not None and (
+        not isinstance(cores, list)
+        or not all(isinstance(core, str) for core in cores)
+    ):
+        raise ValueError(f"invalid omitted cores list for {dest}")
+    for field in SELECTION_FIELDS:
+        _check_tags(entry, field, dest)
+
+
 def _check_download(entry: dict, where: str, dest: str) -> int:
     """The size, hashes, source and cores of one downloadable copy; its size."""
     size = entry.get("size")
@@ -1271,6 +1292,13 @@ def _validate_manifest(data: object, plat: str) -> dict:
             # Narrowing can swap in any copy: the cap holds for the largest.
             size = max(size, _check_download(alternative, where, dest))
         size = max(size, _check_slot(entry, f"files[{index}]", dest))
+        absent = entry.get("absent_claims", [])
+        if not isinstance(absent, list) or len(absent) > MAX_SELECTION_TAGS:
+            raise ValueError(f"invalid absent claims for {dest}")
+        for claim in absent:
+            if not isinstance(claim, dict):
+                raise ValueError(f"invalid absent claim for {dest}")
+            _check_omission(claim, dest)
         largest_total += size
         if largest_total > MAX_TOTAL_DOWNLOAD_SIZE:
             raise ValueError("manifest total size exceeds safety limit")
@@ -1299,20 +1327,7 @@ def _validate_manifest(data: object, plat: str) -> dict:
         if dest in seen_destinations or dest in seen_omitted:
             raise ValueError(f"duplicate or conflicting omitted destination: {dest}")
         seen_omitted.add(dest)
-        if not isinstance(entry.get("name"), str) or not entry["name"]:
-            raise ValueError(f"invalid omitted file name for {dest}")
-        if not isinstance(entry.get("system", ""), str):
-            raise ValueError(f"invalid omitted system for {dest}")
-        if not isinstance(entry.get("required"), bool):
-            raise ValueError(f"invalid omitted required flag for {dest}")
-        if entry.get("reason") not in OMISSION_REASONS:
-            raise ValueError(f"invalid omission reason for {dest}")
-        cores = entry.get("cores")
-        if cores is not None and (
-            not isinstance(cores, list)
-            or not all(isinstance(core, str) for core in cores)
-        ):
-            raise ValueError(f"invalid omitted cores list for {dest}")
+        _check_omission(entry, dest)
         claims = entry.get("alternatives", [])
         if not isinstance(claims, list) or len(claims) > MAX_SELECTION_TAGS:
             raise ValueError(f"invalid omitted alternatives for {dest}")
@@ -1566,6 +1581,8 @@ def narrow_to_cores(
     def kept_system(system: str) -> bool:
         return system not in reach or bool(cores.intersection(reach[system]))
 
+    displaced: list[dict] = []
+
     def kept(entries: list[dict]) -> list[dict]:
         result: list[dict] = []
         for entry in entries:
@@ -1573,6 +1590,16 @@ def narrow_to_cores(
                 copy = _for_cores(entry, cores)
                 if copy is not None:
                     result.append(copy)
+                    continue
+                # None of the cores served here is named: a named core that
+                # wants the slot and has nothing held is a file left out.
+                claim = next(
+                    (c for c in entry.get("absent_claims", [])
+                     if cores.intersection(c.get("cores") or [])),
+                    None,
+                )
+                if claim is not None:
+                    displaced.append({"dest": entry["dest"], **claim})
                 continue
             # The systems declaring the file, where they are fewer than the
             # ones reading it.
@@ -1589,7 +1616,8 @@ def narrow_to_cores(
 
     files = manifest.get("files", []) if files is None else files
     omitted = manifest.get("omitted_files", []) if omitted is None else omitted
-    return kept(files), kept(omitted)
+    kept_files = kept(files)
+    return kept_files, kept(omitted) + displaced
 
 
 def canonical_region(raw: str) -> str:

install.sh

@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="61ffed8fddf816c02c1b45268dfd9bfdff9daeb1da2adedf2e13d14472f8654d"
+DEFAULT_INSTALL_SHA256="2e9e93d9809d9276a84209cfd421ad9b0d55853ce9c9d6761beb2ef21044ef2f"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {

scripts/generate_pack.py

@@ -3299,6 +3299,20 @@ def _attach_claims(
             dest_hint=claim.get("destination", ""), offline=offline,
         )
         if claim_status in ("not_found", "external", "user_provided") or not claim_path:
+            # Nothing held for this core: narrowed to it without the cores
+            # served above, the slot is a file left out (installer replays it).
+            systems = _extra_system_ids(claim)
+            entry.setdefault("absent_claims", []).append({
+                "name": str(claim.get("name") or ""),
+                "system": systems[0] if systems else "",
+                "required": bool(claim.get("required", True)),
+                "reason": (
+                    claim_status
+                    if claim_status in ("not_found", "external", "user_provided")
+                    else "not_found"
+                ),
+                "cores": [claim_emu],
+            })
             continue
         claim_path, _ = validated_choice(
             claim, claim_path, db, validation_index or {}, bios_dir, None, dest, owners,
@@ -3495,7 +3509,14 @@ def _manifest_core_entries(
         )
 
         manifest_files.append(entry)
-        omitted_by_destination.pop(full_dest, None)
+        displaced = omitted_by_destination.pop(full_dest, None)
+        if displaced and displaced.get("cores"):
+            # A core that wants this slot and has nothing held: a pack built
+            # without the cores served here leaves the slot to it, missing,
+            # and the installer narrowing to those cores has to say so too.
+            entry.setdefault("absent_claims", []).append(
+                {k: v for k, v in displaced.items() if k != "dest"}
+            )
         total_size += file_size
         seen_destinations.add(full_dest)
         _register_path(full_dest, seen_destinations, seen_parents)

tests/test_install_selection.py

@@ -630,5 +630,26 @@ class InstallMatchesATargetManifest(unittest.TestCase):
                 )
 
 
+
+class ACoreWithNothingHeldIsAnOmission(unittest.TestCase):
+    """DOSBox serves SC-55/WAVEROM3.BIN, DOSBox Pure wants it and nothing is
+    held for it. A pack built for a target without DOSBox lists it as left
+    out; narrowed from the full manifest, it had vanished."""
+
+    MANIFEST = {"files": [{
+        "dest": "SC-55/WAVEROM3.BIN", "cores": ["dosbox"], "sha1": "1" * 40,
+        "absent_claims": [{"name": "WAVEROM3.BIN", "system": "dos", "required": False,
+                           "reason": "not_found", "cores": ["dosbox_pure"]}],
+    }], "omitted_files": []}
+
+    def test_narrowing_away_the_holder_leaves_the_omission(self):
+        files, omitted = install.narrow_to_cores(self.MANIFEST, ["dosbox_pure"])
+        self.assertEqual(files, [])
+        self.assertEqual([o["dest"] for o in omitted], ["SC-55/WAVEROM3.BIN"])
+        files, omitted = install.narrow_to_cores(self.MANIFEST, ["dosbox", "dosbox_pure"])
+        self.assertEqual(len(files), 1)
+        self.assertEqual(omitted, [])
+
+
 if __name__ == "__main__":
     unittest.main()