Droid-VM · BigfootACA · Jul 7, 2026 · Jul 5, 2026 · Jul 5, 2026 · Jul 5, 2026
diff --git a/.github/workflows/checks.yml b/.github/workflows/checks.yml
@@ -0,0 +1,35 @@
+name: Checks
+
+on:
+  push:
+    branches: [ "**" ]
+  pull_request:
+    branches: [ "**" ]
+  workflow_dispatch:
+
+concurrency:
+  group: checks-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        # No submodules: these checks only look at this repo's own sources.
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+
+      - name: No non-ASCII in code/config
+        run: python3 scripts/ci/check_ascii.py
+
+      - name: Translations complete across all locales
+        run: python3 scripts/ci/check_translations.py
+
+      - name: Use fmt() instead of string concatenation
+        run: python3 scripts/ci/check_string_concat.py
diff --git a/app/src/main/assets/prebuilts b/app/src/main/assets/prebuilts
diff --git a/app/src/main/java/cn/classfun/droidvm/daemon/display/DaemonSystemContext.java b/app/src/main/java/cn/classfun/droidvm/daemon/display/DaemonSystemContext.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.daemon.display;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.os.Looper;
@@ -34,7 +35,7 @@ public static synchronized void init() {
         try {
             if (Looper.myLooper() == null) Looper.prepareMainLooper();
         } catch (Throwable t) {
-            Log.w(TAG, "prepareMainLooper: " + t);
+            Log.w(TAG, fmt("prepareMainLooper: %s", t));
         }
         try {
             Class<?> at = Class.forName("android.app.ActivityThread");

diff --git a/app/src/main/java/cn/classfun/droidvm/daemon/display/NativeDisplayBinder.java b/app/src/main/java/cn/classfun/droidvm/daemon/display/NativeDisplayBinder.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.daemon.display;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import static cn.classfun.droidvm.BuildConfig.APPLICATION_ID;
 
 import android.content.Intent;
@@ -78,7 +79,7 @@ private static void broadcast(@NonNull IBinder binder, @NonNull String nonce) {
         intent.setPackage(APPLICATION_ID);
         intent.putExtra(NativeDisplay.EXTRA_BUNDLE, bundle);
         context.sendBroadcast(intent);
-        Log.i(TAG, "broadcast native-display binder (nonce=" + nonce + ")");
+        Log.i(TAG, fmt("broadcast native-display binder (nonce=%s)", nonce));
     }
 
     private static IBinder smCall(@NonNull String method, @NonNull String name) {
@@ -87,14 +88,14 @@ private static IBinder smCall(@NonNull String method, @NonNull String name) {
             Method m = sm.getMethod(method, String.class);
             return (IBinder) m.invoke(null, name);
         } catch (Exception e) {
-            Log.w(TAG, method + " reflection failed: " + e.getMessage());
+            Log.w(TAG, fmt("%s reflection failed: %s", method, e.getMessage()));
             return null;
         }
     }
 
     private static IBinder waitForServiceWithTimeout(@NonNull String name, long timeoutMs) {
         var holder = new IBinder[1];
-        var t = new Thread(() -> holder[0] = smCall("waitForService", name), "WaitSvc-" + name);
+        var t = new Thread(() -> holder[0] = smCall("waitForService", name), fmt("WaitSvc-%s", name));
         t.setDaemon(true);
         t.start();
         try {
@@ -105,7 +106,7 @@ private static IBinder waitForServiceWithTimeout(@NonNull String name, long time
     }
 
     private static IBinder doWaitForDisplayBinder(@NonNull String serviceName) {
-        Log.i(TAG, "waitForDisplayBinder('" + serviceName + "')");
+        Log.i(TAG, fmt("waitForDisplayBinder('%s')", serviceName));
         var direct = smCall("checkService", serviceName);
         if (direct != null) {
             Log.i(TAG, "OK: got display binder directly from ServiceManager");
@@ -117,8 +118,8 @@ private static IBinder doWaitForDisplayBinder(@NonNull String serviceName) {
             Log.i(TAG, "OK: got display binder via waitForService");
             return waited;
         }
-        Log.e(TAG, "'" + serviceName + "' not found - is crosvm running with "
-            + "--android-display-service " + serviceName + "?");
+        Log.e(TAG, fmt("'%s' not found - is crosvm running with "
+            + "--android-display-service %s?", serviceName, serviceName));
         return null;
     }
 }
diff --git a/app/src/main/java/cn/classfun/droidvm/daemon/network/NetworkInstanceStore.java b/app/src/main/java/cn/classfun/droidvm/daemon/network/NetworkInstanceStore.java
@@ -52,8 +52,7 @@ protected boolean load(@NonNull DataStore<NetworkInstance> store, @NonNull JSONO
             JsonUtils.forEachArray(obj, getTypeName(), (JSONObject entry) -> {
                 var migrated = NetworkConfig.migrate(entry);
                 if (migrated == null) {
-                    Log.w(TAG, "Skipping network config with unsupported schema: "
-                        + entry.optString("name"));
+                    Log.w(TAG, fmt("Skipping network config with unsupported schema: %s", entry.optString("name")));
                     return;
                 }
                 if (migrated != entry) {
@@ -63,8 +62,7 @@ protected boolean load(@NonNull DataStore<NetworkInstance> store, @NonNull JSONO
                     try {
                         NetworkConfigValidator.validate(new NetworkConfig(migrated));
                     } catch (Exception e) {
-                        Log.w(TAG, "Skipping legacy network that failed migration/validation: "
-                            + entry.optString("name"), e);
+                        Log.w(TAG, fmt("Skipping legacy network that failed migration/validation: %s", entry.optString("name")), e);
                         return;
                     }
                 }

diff --git a/app/src/main/java/cn/classfun/droidvm/daemon/network/backend/DefaultRouterWatcher.java b/app/src/main/java/cn/classfun/droidvm/daemon/network/backend/DefaultRouterWatcher.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.daemon.network.backend;
 
+import static cn.classfun.droidvm.lib.utils.FileUtils.shellReadFile;
 import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 
 import android.util.Log;
@@ -24,6 +25,7 @@
 import cn.classfun.droidvm.lib.store.network.BridgeType;
 import cn.classfun.droidvm.lib.store.network.NetworkState;
 import cn.classfun.droidvm.lib.store.network.UplinkMode;
+import cn.classfun.droidvm.lib.utils.RunUtils;
 
 public final class DefaultRouterWatcher {
     private static final String TAG = "DefaultRouterWatcher";
@@ -192,7 +194,7 @@ private void reconcileRules(boolean ipv6, @NonNull List<String> tables) {
         // lowest priority so it is evaluated first.
         var desired = new ArrayList<String>();
         for (int i = 0; i < tables.size(); i++)
-            desired.add((RULE_PRIORITY_BASE + i) + " " + tables.get(i));
+            desired.add(fmt("%d %s", RULE_PRIORITY_BASE + i, tables.get(i)));
 
         // Group our installed rules per device as "priority table" specs. Ours
         // are the plain rules: an iif owned by a bridge, a lookup action, no
@@ -213,7 +215,7 @@ private void reconcileRules(boolean ipv6, @NonNull List<String> tables) {
                 if (dev.startsWith(br)) { ours = true; break; }
             if (!ours) continue;
             installed.computeIfAbsent(dev, k -> new ArrayList<>())
-                .add(r.optInt("priority", 0) + " " + r.optInt("table", 0));
+                .add(fmt("%d %d", r.optInt("priority", 0), r.optInt("table", 0)));
             if (r.optBoolean("detached", false)) detached.add(dev);
         }
         installed.values().forEach(specs -> specs.sort(Comparator.comparingInt(
@@ -253,6 +255,64 @@ private synchronized void runOnce() {
         ensureHostIpMonitor();
         updateHostIps();
         updateDefaultRouter();
+        reassertForwarding();
+    }
+
+    /**
+     * Re-asserts the kernel forwarding sysctls that guest L3 routing depends
+     * on. netd owns these globally and clears them whenever it retunes
+     * tethering, which silently black-holes every forwarded guest packet.
+     * {@link cn.classfun.droidvm.daemon.network.backend.iptables.IptablesBackend}
+     * enables them once at init; this keeps them enabled for as long as a
+     * Linux-bridge L3 network is running.
+     *
+     * <p>Gated on {@link #hasL3LinuxBridge()} -- the same "running LINUX + L3"
+     * condition the routing rules use. With no such network there is nothing
+     * to forward, so netd's value is left alone rather than forcing global
+     * forwarding on the phone. Both families are covered because netd flips
+     * v4 and v6 together (as does {@code enableIpForward}). Reads before
+     * writing: an untouched value costs one cheap cat and stays silent; only a
+     * value netd actually reset is corrected and logged (it means netd raced
+     * us). Never throws out of the tick -- a transient shell failure must not
+     * tear down the routing rules.
+     */
+    private void reassertForwarding() {
+        try {
+            if (!hasL3LinuxBridge()) return;
+            ensureSysctlOne("/proc/sys/net/ipv4/ip_forward", "net.ipv4.ip_forward");
+            ensureSysctlOne("/proc/sys/net/ipv6/conf/all/forwarding",
+                "net.ipv6.conf.all.forwarding");
+        } catch (Exception e) {
+            Log.w(TAG, "Failed to re-assert forwarding sysctls", e);
+        }
+    }
+
+    /**
+     * Writes 1 to {@code path} only if it is not already 1; logs corrections.
+     * The read ({@code shellReadFile}) and the write ({@code runQuiet}) are both
+     * quiet, so the 5s poll stays out of logcat -- {@code RunContext.run} would
+     * otherwise log a "Running command: cat ..." line every tick. The only line
+     * this emits on a normal tick is the warning below, and only when netd
+     * actually reset the value.
+     */
+    private void ensureSysctlOne(@NonNull String path, @NonNull String name) {
+        var cur = shellReadFile(path);
+        if ("1".equals(cur)) return;
+        Log.w(TAG, fmt("%s=%s (netd reset it); re-enabling forwarding",
+            name, cur.isEmpty() ? "?" : cur));
+        RunUtils.runQuiet(fmt("echo 1 > %s", path));
+    }
+
+    /** True while any RUNNING Linux-bridge L3 network needs kernel forwarding. */
+    private boolean hasL3LinuxBridge() {
+        var found = new boolean[]{false};
+        context.getNetworks().forEach((uuid, inst) -> {
+            if (inst.getState() == NetworkState.RUNNING
+                && inst.getBridgeType() == BridgeType.LINUX
+                && inst.getUplinkMode() == UplinkMode.L3)
+                found[0] = true;
+        });
+        return found[0];
     }
 
     private void updateDefaultRouter() {

diff --git a/app/src/main/java/cn/classfun/droidvm/daemon/network/backend/gvisor/GvisorBridgeBackend.java b/app/src/main/java/cn/classfun/droidvm/daemon/network/backend/gvisor/GvisorBridgeBackend.java
@@ -377,7 +377,7 @@ private void postForward(
                         fmt("/api/v1/gateways/%d/forwards", vlanId), rule);
                     if (resp.isSuccess()) {
                         var id = resp.json().optString("id", "");
-                        if (!id.isEmpty()) ids.add(vlanId + "/" + id);
+                        if (!id.isEmpty()) ids.add(fmt("%d/%s", vlanId, id));
                     } else {
                         failures.add(fmt("%s %s (%s)", proto, bind, briefBody(resp.body)));
                     }

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/download/DiskDownloadManager.java b/app/src/main/java/cn/classfun/droidvm/lib/download/DiskDownloadManager.java
@@ -231,7 +231,7 @@ static void runDownload(@NonNull Context context, long id) {
         var ctx = context.getApplicationContext();
         var d = JOBS.get(id);
         if (d == null) return;
-        var part = new File(d.folder, d.name + ".part");
+        var part = new File(d.folder, fmt("%s.part", d.name));
         var dest = new File(d.folder, d.name);
         try {
             var parent = dest.getParentFile();
@@ -285,15 +285,15 @@ private static void downloadOnce(Download d, File part) throws IOException {
         conn.setInstanceFollowRedirects(true);
         conn.setRequestProperty("User-Agent", d.userAgent);
         conn.setRequestProperty("Accept-Encoding", "identity");
-        if (existing > 0) conn.setRequestProperty("Range", "bytes=" + existing + "-");
+        if (existing > 0) conn.setRequestProperty("Range", fmt("bytes=%d-", existing));
         d.activeConn = conn;
         try {
             int code = conn.getResponseCode();
             boolean resumed = code == HttpURLConnection.HTTP_PARTIAL; // 206
             if (code != HttpURLConnection.HTTP_OK && code != HttpURLConnection.HTTP_PARTIAL)
-                throw new IOException("HTTP " + code);
+                throw new IOException(fmt("HTTP %d", code));
             Log.i(TAG, fmt("Download #%d %s from %s (HTTP %d)",
-                d.id, existing > 0 ? "resuming@" + existing : "starting", conn.getURL(), code));
+                d.id, existing > 0 ? fmt("resuming@%d", existing) : "starting", conn.getURL(), code));
             // Server ignored our Range and is sending the whole file again.
             long start = resumed ? existing : 0;
             d.total = resolveTotal(conn, resumed, start);

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/download/DiskDownloadService.java b/app/src/main/java/cn/classfun/droidvm/lib/download/DiskDownloadService.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.lib.download;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import static cn.classfun.droidvm.lib.size.SizeUtils.formatSize;
 import static cn.classfun.droidvm.lib.utils.StringUtils.formatDuration;
 

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/store/network/NetworkConfig.java b/app/src/main/java/cn/classfun/droidvm/lib/store/network/NetworkConfig.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.lib.store.network;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import android.util.Log;
 
 import androidx.annotation.NonNull;
@@ -30,7 +31,7 @@ public NetworkConfig() {
     public NetworkConfig(@NonNull JSONObject obj) throws JSONException {
         item.set(obj);
         if (!isSupportedSchema(obj)) throw new JSONException(
-            "Unsupported network config schema (expected " + SCHEMA_VERSION + ")"
+            fmt("Unsupported network config schema (expected %s)", SCHEMA_VERSION)
         );
     }
 
@@ -57,7 +58,7 @@ public static JSONObject migrate(@NonNull JSONObject obj) {
         try {
             return migrateLegacyToV2(obj);
         } catch (Exception e) {
-            Log.w(TAG, "Failed to migrate legacy network config: " + obj.optString("name"), e);
+            Log.w(TAG, fmt("Failed to migrate legacy network config: %s", obj.optString("name")), e);
             return null;
         }
     }

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/store/network/NetworkStore.java b/app/src/main/java/cn/classfun/droidvm/lib/store/network/NetworkStore.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.lib.store.network;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import android.content.Context;
 import android.util.Log;
 
@@ -42,8 +43,7 @@ protected boolean load(@NonNull DataStore<NetworkConfig> store, @NonNull JSONObj
             JsonUtils.forEachArray(obj, getTypeName(), (JSONObject entry) -> {
                 var migrated = NetworkConfig.migrate(entry);
                 if (migrated == null) {
-                    Log.w(TAG, "Skipping network config with unsupported schema: "
-                        + entry.optString("name"));
+                    Log.w(TAG, fmt("Skipping network config with unsupported schema: %s", entry.optString("name")));
                     return;
                 }
                 if (migrated == entry) { // already current schema
@@ -58,8 +58,7 @@ protected boolean load(@NonNull DataStore<NetworkConfig> store, @NonNull JSONObj
                     cfg = new NetworkConfig(migrated);
                     NetworkConfigValidator.validate(cfg);
                 } catch (Exception e) {
-                    Log.w(TAG, "Skipping legacy network that failed migration/validation: "
-                        + entry.optString("name"), e);
+                    Log.w(TAG, fmt("Skipping legacy network that failed migration/validation: %s", entry.optString("name")), e);
                     return;
                 }
                 store.add(cfg);

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/store/vm/NativeDisplay.java b/app/src/main/java/cn/classfun/droidvm/lib/store/vm/NativeDisplay.java
@@ -50,7 +50,7 @@ public static String serviceName(@NonNull VMConfig config) {
     /** Same as {@link #serviceName(VMConfig)} but from a raw VM id (e.g. an Intent extra). */
     @NonNull
     public static String serviceNameFromId(@NonNull String vmId) {
-        return "droidvm_disp_" + sanitize(vmId);
+        return fmt("droidvm_disp_%s", sanitize(vmId));
     }
 
     /** The socket path crosvm connects to for [vmKey]'s [channel]. Must match across all callers. */

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/ui/termux/TerminalFonts.java b/app/src/main/java/cn/classfun/droidvm/lib/ui/termux/TerminalFonts.java
@@ -1,5 +1,6 @@
 package cn.classfun.droidvm.lib.ui.termux;
 
+import static cn.classfun.droidvm.lib.utils.StringUtils.fmt;
 import android.content.Context;
 import android.graphics.Typeface;
 import android.util.Log;
@@ -49,7 +50,7 @@ public static Typeface load(@NonNull Context ctx) {
             try {
                 return Typeface.createFromFile(userFont);
             } catch (Exception e) {
-                Log.w(TAG, "Ignoring unreadable user font " + userFont, e);
+                Log.w(TAG, fmt("Ignoring unreadable user font %s", userFont), e);
             }
         }
         if (bundled == null) {

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/utils/AssetUtils.java b/app/src/main/java/cn/classfun/droidvm/lib/utils/AssetUtils.java
@@ -316,7 +316,7 @@ private static void extractTarXz(@NonNull InputStream rawIn, @NonNull File destR
                 if (isZeroBlock(header)) break;
                 var name = cString(header, 0, 100);
                 var prefix = cString(header, 345, 155);
-                var path = prefix.isEmpty() ? name : prefix + "/" + name;
+                var path = prefix.isEmpty() ? name : pathJoin(prefix, name);
                 var size = parseOctal(header, 124, 12);
                 var mode = (int) parseOctal(header, 100, 8);
                 var type = (char) (header[156] & 0xff);

diff --git a/app/src/main/java/cn/classfun/droidvm/lib/utils/StringUtils.java b/app/src/main/java/cn/classfun/droidvm/lib/utils/StringUtils.java
@@ -137,7 +137,7 @@ public static String extensionLower(@NonNull String path) {
     public static String pathJoin(@NonNull String base, @NonNull String child) {
         if (base.endsWith("/")) base = base.substring(0, base.length() - 1);
         if (child.startsWith("/")) child = child.substring(1);
-        return base + "/" + child;
+        return base + "/" + child; // concat-ok: the canonical path join; fmt() would be a hot-path perf hit
     }
 
     @NonNull
+1 −1		prebuilt-arm64-v8a.json
+ −		prebuilt-arm64-v8a.tar.xz