From 443a73b100b71b14de180c0772112c7405130534 Mon Sep 17 00:00:00 2001
From: Jooyung Han <jooyung@google.com>
Date: Tue, 1 Aug 2023 11:58:34 +0900
Subject: [PATCH] Use apexservice to get the list of apexes

In this change, the logic to get the list of apexes is replaced with
the query to apexservice, which is the source of truth. This dedups
the manual scanning of /apex for the apex list, which should be
internal to apexd. (Note how vold_prepare_subdirs filtered out
directories with "@" character).

This also makes vold_prepare_subdirs immune to the upcoming changes:
/apex directory containing only bootstrap APEXes in the bootstrap NS.

Until now, getting the list of apexes by scanning /apex was okay
because of the accidental fact that /apex directory has directories
for all the apexes, not only bootstrap apexes.

Bug: 293949266
Bug: 293546778
Test: CtsPackageSettingHostTestCases
Change-Id: I3fe373ca6f4c2281439bb2449845a1a14357131e
---
 Android.bp               |  5 ++++-
 vold_prepare_subdirs.cpp | 41 +++++++++++++++++++++++++++-------------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/Android.bp b/Android.bp
index 7e41f22..1240efc 100644
--- a/Android.bp
+++ b/Android.bp
@@ -239,7 +239,10 @@ cc_binary {
 
 cc_binary {
     name: "vold_prepare_subdirs",
-    defaults: ["vold_default_flags"],
+    defaults: [
+        "vold_default_flags",
+        "libapexservice-deps",
+    ],
 
     srcs: [
         "vold_prepare_subdirs.cpp",
diff --git a/vold_prepare_subdirs.cpp b/vold_prepare_subdirs.cpp
index 60e82f5..e41e994 100644
--- a/vold_prepare_subdirs.cpp
+++ b/vold_prepare_subdirs.cpp
@@ -30,7 +30,11 @@
 #include <sys/types.h>
 
 #include <android-base/logging.h>
+#include <android-base/result.h>
 #include <android-base/scopeguard.h>
+#include <android/apex/ApexInfo.h>
+#include <android/apex/IApexService.h>
+#include <binder/IServiceManager.h>
 
 #include <cutils/fs.h>
 #include <selinux/android.h>
@@ -141,24 +145,35 @@ static bool rmrf_contents(const std::string& path) {
     }
 }
 
+static android::base::Result<std::vector<std::string>> get_apex_list() {
+    auto sm = android::defaultServiceManager();
+    auto binder = sm->waitForService(android::String16("apexservice"));
+    if (binder == nullptr) {
+        return android::base::Error() << "Failed to get apexservice";
+    }
+    auto service = android::interface_cast<android::apex::IApexService>(binder);
+    std::vector<android::apex::ApexInfo> list;
+    auto status = service->getActivePackages(&list);
+    if (!status.isOk()) {
+        return android::base::Error() << status.exceptionMessage().c_str();
+    }
+    std::vector<std::string> names;
+    names.reserve(list.size());
+    for (const auto& apex_info : list) {
+        names.push_back(apex_info.moduleName);
+    }
+    return names;
+}
+
 static bool prepare_apex_subdirs(struct selabel_handle* sehandle, const std::string& path) {
     if (!prepare_dir(sehandle, 0711, 0, 0, path + "/apexdata")) return false;
 
-    auto dirp = std::unique_ptr<DIR, int (*)(DIR*)>(opendir("/apex"), closedir);
-    if (!dirp) {
-        PLOG(ERROR) << "Unable to open apex directory";
+    auto apex_list = get_apex_list();
+    if (!apex_list.ok()) {
+        LOG(ERROR) << apex_list.error();
         return false;
     }
-    struct dirent* entry;
-    while ((entry = readdir(dirp.get())) != nullptr) {
-        if (entry->d_type != DT_DIR) continue;
-
-        const char* name = entry->d_name;
-        // skip any starting with "."
-        if (name[0] == '.') continue;
-
-        if (strchr(name, '@') != NULL) continue;
-
+    for (const auto& name : *apex_list) {
         if (!prepare_dir(sehandle, 0771, AID_ROOT, AID_SYSTEM, path + "/apexdata/" + name)) {
             return false;
         }