BFE

BFE is a standalone, sideload-only Android file manager and explorer built around a set of bundled native engines. In one app: a dual-pane "commander" layout; extraction of archives, disc images, GOG/InnoSetup installers and FreeArc repacks; compression to zip/7z/tar/tzst and Winlator .wcp packs; browsing storage normal file managers can't reach — other apps' SAF document providers and, on a rooted device, any installed app's private data; an APK cloner + signer; and a video converter (game FMVs → MP4) powered by a bundled ffmpeg.

It is lifted from the in-app File Manager + archive subsystem of the Bannerlator emulator (Winlator lineage), with all of the emulator machinery (Wine containers, X server, Steam/GOG store plumbing) stripped out and the browse / extract / manage core turned into its own app. GPL-3.0.

Status: early, fast-moving 0.x builds. Every release is CI-built and signature-verified, but the project is not yet broadly device-tested. Grab the latest APK from Releases.

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Features

Browsing & file management

• Browse internal storage, SD cards and USB drives. Landscape shows a collapsible side rail of locations; portrait uses a storage dropdown in the toolbar. Both list your pinned app storages.
• .apk files show their real launcher icon in list, grid and compact views (parsed off the main thread from File, SAF and root locations, like the .exe PE icons).
• New ▾ → Folder / File…: create an empty file on File, SAF and root locations (root creations are chown'd back to the owning app); text-like files offer "Open with…" right away.
• Path / free-space bar, up/back navigation, sort by name / size / date / type (asc/desc), in-folder search, show/hide hidden files.
• Three view modes, cycled from the toolbar and remembered: Grid, List, and a dense Compact list (~2× more rows on screen).
• Multi-select with an action bar: copy, cut, delete, share. Copy/move/delete/rename with real progress, cancel, and conflict handling (overwrite / merge / keep both / skip). New folder.
• Favorites, file properties + read-only toggle, image thumbnails (Coil) and .exe icon extraction (PE resources).
• Open with any file in another app, Share one or many files, and Install .apk files directly.

Dual-pane "commander" mode

• Toolbar toggle → two fully independent panes side by side — in landscape and portrait (fixed 50/50 split).
• One shared toolbar controls the active pane (tap a pane to focus it); each pane keeps its own folder, selection, scroll, view mode and sort, so the two sides can differ (e.g. left Compact, right Grid).
• One-tap Copy → / Move → from the active pane into the other pane's folder.
• Extract into the other pane: extracting an archive defaults its destination to the other pane's folder — "extract here → into there" in one tap.

Extraction (bundled native engines, all on-device)

Engine	Handles
7-Zip (7zz)	.7z, .zip, .rar (incl. multi-part), split volumes (.001, .bin), .tar / .tar.gz / .tar.xz, disc images .iso / .udf / .img, .wcp / .tzst, and more
innoextract	InnoSetup / GOG offline installers — unpacks the game files directly, including automatic DLC batch: sibling setup_*.exe DLC installers in the same folder are detected and extracted into one merged game folder
unarc (FreeArc)	FreeArc / ISDone game repacks (FitGirl / DODI-style Setup-N.bin volumes) decoded natively

• One-tap Fast Extract, or the full Unpack Archive screen (destination picker, options).
• Runs as a background foreground-service job with a progress notification, cancel, and an app-wide minimizable progress pill — survives the app going to the background.
• Extraction targets can be normal storage or a pinned SAF / root location (extracted to a temp folder, then copied into the target with the ownership fix described below).
• BFE registers as an "Open with" / Share target for archives and setup.exe files, so other apps can hand them straight to the extractor.

Compression — create archives

Select files/folders → Compress… → format, name, level, optional password, destination (this pane or the other). Same background job / pill / cancel as extraction.

Format	Engine
zip (optional AES-256 password) · 7z (optional password, encrypted headers) · tar	bundled 7-Zip
tar.gz · tar.xz	two piped 7-Zip processes — no on-disk .tar staging, so a large folder never doubles its footprint
tzst (tar.zst)	streamed Java tar + Zstandard (commons-compress + zstd-jni)
Winlator .wcp	a tar.zst content pack with a profile.json manifest

The Create Winlator pack form collects the pack type (Wine / Proton / DXVK / D7VK / VKD3D / Box64 / WOWBox64 / FEXCore / VEGAS), versionName, versionCode, description (and the wine paths for Wine/Proton packs) and writes the exact profile.json schema Bannerlator/Winlator parse — a pack you build in BFE installs straight into Bannerlator.

App storage — pin other apps' storage as locations

• Storage apps (SAF): the Add app storage picker lists installed apps that expose a DocumentsProvider (SD/USB, Downloads, cloud apps like Drive/Dropbox, and opt-in apps) by app label + package name. Pick one, confirm the folder in Android's picker (it opens at the app's root — a single "Use this folder" tap), and it's pinned as a location you can browse and manage: new folder, rename, delete, copy/move in and out (including cross-pane), share, open-with, multi-select.
• All apps (root): on a rooted device, the same picker lists every installed app. Pick one and BFE drops you straight into its private /data/data/<pkg> (and its Android/data/<pkg> if present) — no folder-picker step. Full management there: browse, copy/move in and out, rename, delete, new folder, share/open-with/install (staged through BFE's cache, since other apps can't read /data/data).
• Ownership safety: anything BFE writes into an app's sandbox as root is automatically chowned back to that app's uid (with chmod 770/660 and restorecon), so the target app keeps working — no root-owned leftovers that make an app crash with permission errors.
• Pinned locations appear in the side rail / storage dropdown with a × to unpin.

APK Cloner + Signer

• Clone any .apk file (⋮ → Clone APK…) or any installed app (Clone installed app… — split/ bundle installs are merged into a single APK first) with a new package name, label, versionCode, versionName and icon, plus an Advanced section (minSdk/targetSdk, debuggable, allowBackup, extractNativeLibs).
• The rename is done properly so clones actually install and run beside the original: relative component class names are made absolute (code keeps resolving), every ContentProvider authority moves to the new package (no provider conflict), package-scoped permissions are renamed, sharedUserId is dropped, taskAffinity is rewritten, and the manifest + resources.arsc package are renamed together. The result lists every fixup applied. Clone & Install in one tap.
• Sign APK… on any .apk — re-signs with APK signature schemes v1 + v2 + v3 (per-sign toggles), zipaligned (16 KB page-aligned native libs when extractNativeLibs=false), then verified.
• Keys: a built-in BFE Test Key (generated once, private to the app) is the default so all your clones share one signature and update in place; or import your own PKCS12 / BKS keystore, or generate a new key in-app. (JKS isn't supported by Android's crypto stack — convert to PKCS12.)
• Verified on a real APK: the pipeline cloned BFE's own release to a new package with v1/v2/v3 all verifying and both provider authorities renamed.
• Inherent limits, shown in-app: apps that verify their own signature, Play-licensed apps, Google-services/Firebase-bound apps, and some split/bundle apps may not run as clones; code that builds a FileProvider authority from BuildConfig.APPLICATION_ID will mismatch after a rename.

Video converter — "Convert to MP4…"

• ⋮ on any video (or multi-select → Convert) transcodes to H.264 + AAC MP4 with the bundled ffmpeg (a static aarch64/bionic GPL build with x264, exec'd like the other native engines). Made for game FMV: Bink 1 (.bik), Smacker (.smk), WMV/ASF, AVI, MKV/WebM, MOV/MP4/M4V, MPEG-PS/TS, OGV, FLV, 3GP, VOB.
• Quality Fast / Balanced / High (x264 veryfast / medium / slow, CRF 26 / 23 / 20), resolution Keep / 1080p / 720p / 480p (aspect kept, even dims), audio keep (AAC 160k) or none, output to this pane or the other one (SAF/root via temp + copy). Batch conversions run one after another as one background job with live percent / speed / ETA in the pill and notification; Cancel kills ffmpeg and removes the partial file.
• Engine: a single static ffmpeg 7.1.5 + x264 binary (~6.8 MB, arm64, built reproducibly by the build-ffmpeg.yml workflow and shipped as libffmpeg.so). Codec coverage — video: H.264, HEVC, VP8, VP9, MPEG-1/2/4, MS-MPEG4 v1–3, WMV1/2/3, VC-1, Theora, VP3, MJPEG, Cinepak, Indeo 3/4/5, H.263, Bink video, Smacker video; audio: AAC, MP3, Vorbis, Opus, WMA v1/v2/Pro, AC-3, Bink audio, Smacker audio, PCM, ADPCM (IMA/MS/QT/Yamaha). Output: MP4 (+faststart, yuv420p) with H.264 + AAC, so it plays on anything.
• Bink 2 (.bk2) is proprietary — there's no open decoder, so BFE says so up front instead of failing. Encoding is software x264 (no hardware encoder): quick for 480p/720p cutscenes, slow for 4K.

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How storage access works

BFE has a pluggable storage layer with three backends behind one file-manager UI:

• File — direct filesystem access via All-Files-Access (the default; what makes native extraction possible).
• SAF — DocumentsContract on a persisted tree URI for pinned document providers.
• Root — libsu (Magisk) for /data/data and anything else, with the chown-back safety above.

Copy/move between any two backends streams through, so you can e.g. copy from a cloud provider into an app's private folder in one operation.

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Requirements

• Android 8.0+ (minSdk 26, targetSdk 28).
• arm64-v8a only — the native extractors are prebuilt for arm64; there is no other ABI.
• All-Files-Access (MANAGE_EXTERNAL_STORAGE) — requested on first run. The native engines write real files and can't go through the scoped-storage picker, so this is required for extraction and compression.
• Root (Magisk) — optional, only for the "All apps (root)" features. The first root action triggers a Magisk prompt; grant BFE root there. Without root everything else works — the root section simply stays unavailable (a one-line notice, no crash).

Install

1. Download the latest BFE-x.y.apk from Releases.
2. Sideload it (allow "install unknown apps" for your browser/file manager if prompted).
3. On first launch, grant All-files access. Grant root in Magisk when the root features ask.

BFE is a separate app (com.the412banner.bfe) — it never touches Bannerlator or any other install.

Signing & integrity

Releases are built by CI (.github/workflows/build.yml) and signed with a bundled, publicly-known TEST key (keystore/bfe-test.jks) using APK signature schemes v1 + v2 + v3, so any BFE build installs over the previous one without uninstalling.

This repository is public, so that signing key is public too — do not treat it as private. Anyone can produce an APK carrying BFE's signature; only install BFE builds you obtained from this repo's Releases (each release lists its APK SHA-256). This is the normal trade-off for a sideload dev tool; a private release key can be added via a CI secret if tamper-resistance is ever needed.

Building from source

./gradlew assembleRelease     # signed with the committed test key

Toolchain: AGP 8.8, Kotlin 2.0.21, Compose BOM 2024.02, Java 17, NDK 29, compileSdk 34. No Hilt, no local .so build step — the prebuilt native binaries live in app/src/main/jniLibs/arm64-v8a/ and are exec'd (not System.loadLibrary'd) from the app's native-lib dir, which is why the manifest keeps android:extractNativeLibs="true" — without it the executables never land on disk and every extraction fails. CI uses Gradle build/configuration caching so warm builds are fast.

Repo map

app/src/main/java/com/the412banner/bfe/
├─ unpack/     7-Zip / innoextract / unarc wrappers, UnpackService (extraction job), FastExtract
├─ pack/       archive creation (7zz, tar+zstd, Winlator .wcp), PackService (compression job)
├─ apk/        APK cloner/editor/signer (ARSCLib rewrite, apksig, keys), ApkJobService
├─ video/      ffmpeg wrapper + ConvertService (video → MP4 job)
├─ storage/    StorageBackend abstraction: File / SAF / Root backends, cross-backend transfer, pins
├─ ui/screens/ FileManagerScreen (panes, shared toolbar, dual-pane), Unpack screen, Compress dialog
└─ ui/         progress pills, theme, components
app/src/main/jniLibs/arm64-v8a/   prebuilt lib7zz / libinnoextract / libunarc / libffmpeg + dependency closure
keystore/bfe-test.jks             public test signing key

Known limitations

• Dual-pane split is a fixed 50/50 (no drag-to-resize yet). Path bar isn't a clickable breadcrumb yet.
• SAF only reaches apps that expose a DocumentsProvider — most ordinary apps don't, and Android blocks SAF from Android/data. Use the root mode for those.
• Extracting from an archive that lives on a SAF/root location isn't supported yet (archives must be on normal storage; extracting into SAF/root works).
• Piped tar.gz / tar.xz compression reports percent but not per-file names.
• Compact rows are ~2× denser than the standard list, not a literal quarter-height (readability floor).
• Video conversion: Bink 2 (.bk2) can't be decoded (proprietary); encoding is software-only (x264), so large/4K sources are slow; output is always H.264 + AAC MP4 (no other output formats yet).
• APK clones of apps that verify their own signature, are Play-licensed, or are bound to Google-services/Firebase may not run; that's inherent to cloning.
• Errors surface as toasts; no predictive-back animation (targetSdk 28).

License

BFE is licensed under the GNU General Public License v3.0 (see LICENSE), inherited from its Winlator/Bannerlator lineage. Bundled third-party components keep their own notices — see NOTICE_7ZIP.txt, NOTICE_INNOEXTRACT.txt, NOTICE_UNARC.txt, NOTICE_FFMPEG.txt (FFmpeg + x264, GPL v2+, built with --enable-gpl --enable-libx264) and License_7zip.txt.