Scripts: Stop pattern-table rebuilds duplicating addresses

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Problem

build_block reused addresses from every block in the existing table whose identity matched the executable. When a table held two blocks for one image, each rebuild recorded every reused match once per block, so the entries doubled with every rebuild. HogwartsMP's Steam block reached 8 copies of each match (11,096 entries for 925 matches, a 227 KB table). The client dedupes hints as it seeds them (InsertHint), so this was dead weight rather than wrong hooks.

The second block came from the storefront tag. An executable named with --exe or --exe-env was tagged file:<name>, and a game's Steam and Epic copies share a file name (HogwartsLegacy.exe):

• --exe <Steam> --exe <Epic> wrote two file: blocks. The next build-time rebuild (--steam-app) kept the old Steam one beside its new steam:<app> block.
• --exe <Steam> alone read the Epic block as Steam's superseded build and dropped it.

Fix

• Reuse collects each hash's addresses into a set, so a match is recorded once however many blocks hold it.
• A known block for an image rebuilt in this run is dropped whatever its tag. The client seeds only the first block whose identity matches, so a second one could never be read.
• An executable named by path is tagged with its store when the path shows it: steam:<appid> inside a Steam library (from the library's appmanifest_*.acf, the same tag --steam-app gives) and epic:<AppName> inside an Epic Games Launcher install (from %ProgramData%\Epic\UnrealEngineLauncher\LauncherInstalled.dat). Anything else keeps file:<name>.

Tests

check_pattern_table.py --regenerate on scratch copies of HogwartsMP's table, with its Steam and Epic executables:

Starting table	Arguments	Result
bloated steam: block, stale file: Steam block, file: Epic block	build form (--exe-env … --steam-app 990080 …)	Steam 11,096 → 1,850 entries, stale Steam block dropped, Epic kept
same	--exe <Steam> --exe <Epic>	steam:990080 and epic:<app> blocks, one entry per match
steam: + file: Epic, one pattern added	--exe <Steam>	Epic block kept (it used to be dropped)
same	--steam-app 990080 … --exe <Epic>	Epic retagged epic:<app>, the old file: block replaced
previous result, another pattern added	build form	epic: block kept

Tag inference gives steam:990080 for the Steam path, epic:<app> for the Epic path in any letter case, and file:<name> for a path outside both or when LauncherInstalled.dat is missing.

Summary by CodeRabbit

• Improvements
  • Pattern tables now distinguish explicitly identified Steam and Epic executables, keeping their entries separate.
  • Reusable address data is carried over only when all recorded addresses still match. Existing entries for storefronts not installed on the machine are retained, while superseded or untagged entries are removed.

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Reviewing files that changed from the base of the PR and between 427b756 and 4c5f80b.

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• scripts/build_pattern_table.py

Walkthrough

The script now identifies Steam and Epic storefronts for named executables. It also deduplicates reusable RVAs and changes how it selects known blocks during table rebuilding.

Changes

Pattern Table Rebuild

Layer / File(s)	Summary
Identify executable storefronts scripts/build_pattern_table.py	The script checks Steam manifests and Epic installation metadata to tag named executable paths. Other paths receive a file:<name> tag.
Reuse and retain pattern blocks scripts/build_pattern_table.py	The script deduplicates reusable RVAs and reuses entries only when every recorded address matches. During rebuilding, it skips known blocks whose image identity is already represented and retains only blocks tagged for storefronts absent from the current build.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: segfaultd

Merge Risk: 🔵 Low · up to 427b7

The rebuild script can stop when storefront metadata is unreadable or malformed. These bounded failures should be fixed or accepted before merging.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly describes the primary change: preventing pattern-table rebuilds from duplicating addresses. It matches the pull request objectives and is concise.
Docstring Coverage		Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 1 files.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks each game path with care,
Steam and Epic tags appear there.
Duplicate addresses hop away,
Matching blocks return to play.
The table keeps the tags it needs,
Then bounds through fields of pattern seeds.}

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Actionable comments posted: 2

---

• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @scripts/build_pattern_table.py:
- Around line 413-416: Update the InstallationList iteration in the Epic install
lookup to handle malformed external data: iterate only when installs is a list
and skip entries that are not dictionaries before calling install.get. Preserve
the existing location and app matching behavior for valid entries.
- Around line 398-406: Update the Steam manifest loop in named_storefront to
catch OSError from manifest.read_text and skip that manifest, allowing lookup to
continue and unresolved paths to fall back to file:<name>.

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• scripts/build_pattern_table.py

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