Adds an init host lib for use in host_apex_verifier.

Includes extracting the APEX-specific SDK version naming scheme filter
logic so it can be reused when host_apex_verifier looks at rc files
inside the APEX.

Bug: 222121216
Test: Use in host_apex_verifier
Change-Id: I0396a455f30d2de71525ccd3fa69c75576054048

init/Android.bp

@@ -532,8 +532,8 @@ genrule {
     cmd: "$(location host_builtin_map.py) --builtins $(location builtins.cpp) --check_builtins $(location check_builtins.cpp) > $(out)",
 }
 
-cc_binary {
-    name: "host_init_verifier",
+cc_defaults {
+    name: "init_host_defaults",
     host_supported: true,
     cflags: [
         "-Wall",
@@ -556,7 +556,6 @@ cc_binary {
         "libprocessgroup",
         "libprotobuf-cpp-lite",
     ],
-    srcs: init_common_sources + init_host_sources,
     proto: {
         type: "lite",
     },
@@ -574,6 +573,26 @@ cc_binary {
     },
 }
 
+cc_binary {
+    name: "host_init_verifier",
+    defaults: ["init_host_defaults"],
+    srcs: init_common_sources + init_host_sources,
+}
+
+cc_library_host_static {
+    name: "libinit_host",
+    defaults: ["init_host_defaults"],
+    srcs: init_common_sources,
+    export_include_dirs: ["."],
+    proto: {
+        export_proto_headers: true,
+    },
+    visibility: [
+        // host_apex_verifier performs a subset of init.rc validation
+        "//system/apex/tools",
+    ],
+}
+
 sh_binary {
     name: "extra_free_kbytes.sh",
     src: "extra_free_kbytes.sh",

init/builtins.cpp

@@ -1306,58 +1306,11 @@ static Result<void> parse_apex_configs() {
     }
     globfree(&glob_result);
 
-    // Compare all files /apex/path.#rc and /apex/path.rc with the same "/apex/path" prefix,
-    // choosing the one with the highest # that doesn't exceed the system's SDK.
-    // (.rc == .0rc for ranking purposes)
-    //
     int active_sdk = android::base::GetIntProperty("ro.build.version.sdk", INT_MAX);
 
-    std::map<std::string, std::pair<std::string, int>> script_map;
-
-    for (const auto& c : configs) {
-        int sdk = 0;
-        const std::vector<std::string> parts = android::base::Split(c, ".");
-        std::string base;
-        if (parts.size() < 2) {
-            continue;
-        }
-
-        // parts[size()-1], aka the suffix, should be "rc" or "#rc"
-        // any other pattern gets discarded
-
-        const auto& suffix = parts[parts.size() - 1];
-        if (suffix == "rc") {
-            sdk = 0;
-        } else {
-            char trailer[9] = {0};
-            int r = sscanf(suffix.c_str(), "%d%8s", &sdk, trailer);
-            if (r != 2) {
-                continue;
-            }
-            if (strlen(trailer) > 2 || strcmp(trailer, "rc") != 0) {
-                continue;
-            }
-        }
-
-        if (sdk < 0 || sdk > active_sdk) {
-            continue;
-        }
-
-        base = parts[0];
-        for (unsigned int i = 1; i < parts.size() - 1; i++) {
-            base = base + "." + parts[i];
-        }
-
-        // is this preferred over what we already have
-        auto it = script_map.find(base);
-        if (it == script_map.end() || it->second.second < sdk) {
-            script_map[base] = std::make_pair(c, sdk);
-        }
-    }
-
     bool success = true;
-    for (const auto& m : script_map) {
-        success &= parser.ParseConfigFile(m.second.first);
+    for (const auto& c : parser.FilterVersionedConfigs(configs, active_sdk)) {
+        success &= parser.ParseConfigFile(c);
     }
     ServiceList::GetInstance().MarkServicesUpdate();
     if (success) {

init/parser.cpp

@@ -18,6 +18,8 @@
 
 #include <dirent.h>
 
+#include <map>
+
 #include <android-base/chrono_utils.h>
 #include <android-base/file.h>
 #include <android-base/logging.h>
@@ -154,6 +156,58 @@ bool Parser::ParseConfigFile(const std::string& path) {
     return true;
 }
 
+std::vector<std::string> Parser::FilterVersionedConfigs(const std::vector<std::string>& configs,
+                                                        int active_sdk) {
+    std::vector<std::string> filtered_configs;
+
+    std::map<std::string, std::pair<std::string, int>> script_map;
+    for (const auto& c : configs) {
+        int sdk = 0;
+        const std::vector<std::string> parts = android::base::Split(c, ".");
+        std::string base;
+        if (parts.size() < 2) {
+            continue;
+        }
+
+        // parts[size()-1], aka the suffix, should be "rc" or "#rc"
+        // any other pattern gets discarded
+
+        const auto& suffix = parts[parts.size() - 1];
+        if (suffix == "rc") {
+            sdk = 0;
+        } else {
+            char trailer[9] = {0};
+            int r = sscanf(suffix.c_str(), "%d%8s", &sdk, trailer);
+            if (r != 2) {
+                continue;
+            }
+            if (strlen(trailer) > 2 || strcmp(trailer, "rc") != 0) {
+                continue;
+            }
+        }
+
+        if (sdk < 0 || sdk > active_sdk) {
+            continue;
+        }
+
+        base = parts[0];
+        for (unsigned int i = 1; i < parts.size() - 1; i++) {
+            base = base + "." + parts[i];
+        }
+
+        // is this preferred over what we already have
+        auto it = script_map.find(base);
+        if (it == script_map.end() || it->second.second < sdk) {
+            script_map[base] = std::make_pair(c, sdk);
+        }
+    }
+
+    for (const auto& m : script_map) {
+        filtered_configs.push_back(m.second.first);
+    }
+    return filtered_configs;
+}
+
 bool Parser::ParseConfigDir(const std::string& path) {
     LOG(INFO) << "Parsing directory " << path << "...";
     std::unique_ptr<DIR, decltype(&closedir)> config_dir(opendir(path.c_str()), closedir);

init/parser.h

@@ -76,6 +76,12 @@ class Parser {
     void AddSectionParser(const std::string& name, std::unique_ptr<SectionParser> parser);
     void AddSingleLineParser(const std::string& prefix, LineCallback callback);
 
+    // Compare all files */path.#rc and */path.rc with the same path prefix.
+    // Keep the one with the highest # that doesn't exceed the system's SDK.
+    // (.rc == .0rc for ranking purposes)
+    std::vector<std::string> FilterVersionedConfigs(const std::vector<std::string>& configs,
+                                                    int active_sdk);
+
     // Host init verifier check file permissions.
     bool ParseConfigFileInsecure(const std::string& path);