fix(singbox): prevent cold-start crash loop on missing community rulesets (#46)

- Bundle universal 17-byte empty SRS stub and add is_valid_srs_file/ensure_empty_srs_stub in rulesets.uc
- Add prepare_community_rulesets in lifecycle.uc to pre-fetch via gh-proxy mirrors or initialize safe local stub before sing-box start
- Support local community rulesets and stubs in generator_routes.uc
- Add fallback to component proxy for list downloads in updates.uc and preserve cached stubs
- Skip non-functional jsdelivr for release downloads and prioritize gh-proxy mirrors in core/url.uc
- Add tests/cold_boot_community_stub.sh testing cold boot fallback behavior

tachyon/files/usr/lib/singbox/generator_routes.uc

@@ -727,17 +727,37 @@ function ensure_custom_ruleset(config, reference) {
         tag_name = "builtin-" + reference + "-ruleset";
         kind = "domains";
         if (!ruleset_registered(config, tag_name)) {
-            let rule_set = {
-                type: "remote",
-                tag: tag_name,
-                format: "binary",
-                url: runtime_rulesets.community_url(reference)
-            };
-            let detour = ctx.download_detour_tag(ctx.runtime_settings());
-            if (is_valid_detour(config, detour))
-                rule_set.download_detour = detour;
-            rule_set.update_interval = remote_ruleset_update_interval();
-            push(config.route.rule_set, rule_set);
+            let folder = ctx.runtime_ruleset_folder || runtime_ruleset_folder;
+            let tmp_srs = folder + "/community-" + reference + ".srs";
+            let etc_srs = "/etc/tachyon/rulesets/community-" + reference + ".srs";
+            let local_path = null;
+
+            if (runtime_rulesets.is_valid_srs_file(tmp_srs) || helpers.file_is_usable(tmp_srs, 16))
+                local_path = tmp_srs;
+            else if (runtime_rulesets.is_valid_srs_file(etc_srs) || helpers.file_is_usable(etc_srs, 16))
+                local_path = etc_srs;
+
+            if (local_path != null) {
+                push(config.route.rule_set, {
+                    type: "local",
+                    tag: tag_name,
+                    format: "binary",
+                    path: local_path
+                });
+            }
+            else {
+                let rule_set = {
+                    type: "remote",
+                    tag: tag_name,
+                    format: "binary",
+                    url: runtime_rulesets.community_url(reference)
+                };
+                let detour = ctx.download_detour_tag(ctx.runtime_settings());
+                if (is_valid_detour(config, detour))
+                    rule_set.download_detour = detour;
+                rule_set.update_interval = remote_ruleset_update_interval();
+                push(config.route.rule_set, rule_set);
+            }
         }
         return { tag: tag_name, kind };
     }
@@ -795,9 +815,9 @@ function ensure_community_ruleset(config, section_name, community) {
         let etc_srs = "/etc/tachyon/rulesets/community-" + community + ".srs";
         let local_path = null;
 
-        if (helpers.file_is_usable(tmp_srs, 100))
+        if (runtime_rulesets.is_valid_srs_file(tmp_srs) || helpers.file_is_usable(tmp_srs, 16))
             local_path = tmp_srs;
-        else if (helpers.file_is_usable(etc_srs, 100))
+        else if (runtime_rulesets.is_valid_srs_file(etc_srs) || helpers.file_is_usable(etc_srs, 16))
             local_path = etc_srs;
 
         if (local_path != null) {

tachyon/files/usr/lib/singbox/rulesets.uc

@@ -1,6 +1,10 @@
 #!/usr/bin/env ucode
 
 let common = require("core.common");
+let fs = require("fs");
+
+const EMPTY_SRS_B64 = "U1JTAXjaYgAEAAD//wABAAE=";
+const EMPTY_SRS_PATH = "/usr/share/tachyon/rulesets/empty.srs";
 
 const SRS_MAIN_URL = "https://github.com/itdoginfo/allow-domains/releases/latest/download";
 const SRS_ADS_HAGEZI_PRO_URL = "https://github.com/zxc-rv/ad-filter/releases/latest/download/adlist.srs";
@@ -126,15 +130,54 @@ function remote_format(reference) {
     return file_extension(reference) == "json" ? "source" : "binary";
 }
 
+function is_valid_srs_file(path) {
+    let p = as_string(path);
+    let st = fs.stat(p);
+    if (!st || st.size < 17)
+        return false;
+    let f = fs.open(p, "r");
+    if (!f)
+        return false;
+    let magic = f.read(3);
+    f.close();
+    return magic == "SRS";
+}
+
+function ensure_empty_srs_stub(target_path) {
+    target_path = as_string(target_path);
+    if (is_valid_srs_file(target_path))
+        return true;
+
+    let slash = rindex(target_path, "/");
+    if (slash > 0)
+        common.ensure_dir(substr(target_path, 0, slash));
+
+    if (is_valid_srs_file(EMPTY_SRS_PATH)) {
+        let content = fs.readfile(EMPTY_SRS_PATH);
+        if (content && fs.writefile(target_path, content) != null)
+            return true;
+    }
+
+    let b = b64dec(EMPTY_SRS_B64);
+    if (b && fs.writefile(target_path, b) != null)
+        return true;
+
+    return false;
+}
+
 function module_exports() {
     return {
+        EMPTY_SRS_PATH,
+        EMPTY_SRS_B64,
         COMMUNITY_SERVICES,
         is_community,
         community_url,
         hash12,
         file_extension,
         kind_from_reference_hint,
-        remote_format
+        remote_format,
+        is_valid_srs_file,
+        ensure_empty_srs_stub
     };
 }
 
@@ -151,7 +194,11 @@ else if (mode == "kind-from-reference-hint")
     print(kind_from_reference_hint(ARGV[1]), "\n");
 else if (mode == "remote-format")
     print(remote_format(ARGV[1]), "\n");
+else if (mode == "is-valid-srs-file")
+    exit(is_valid_srs_file(ARGV[1]) ? 0 : 1);
+else if (mode == "ensure-empty-srs-stub")
+    exit(ensure_empty_srs_stub(ARGV[1]) ? 0 : 1);
 else {
-    warn("Usage: singbox/rulesets.uc <file-extension|is-community|kind-from-reference-hint|remote-format> ...\n");
+    warn("Usage: singbox/rulesets.uc <file-extension|is-community|kind-from-reference-hint|remote-format|is-valid-srs-file|ensure-empty-srs-stub> ...\n");
     exit(1);
 }