Add more mounting options to updater mount function.

If enabling the oem partition, it will be mounted by updater before
reading product properties from it. To be safety, we want to enable AVB
to this oem partition. But this means the oem partition can never be
mounted to writable. Otherwise, that partition will be corrupted to AVB
verifying.
This change follows fs_mgr to allow to pass more mounting options to the
updater.

BUG: 150156957
Test: make ota package which mounts AVB oem partition to read only and
run OTA.

Change-Id: I2ebbe3c8ac53c70112f3fed2703fcba9170405a6

updater/updater_runtime.cpp

@@ -43,10 +43,62 @@ std::string UpdaterRuntime::FindBlockDeviceName(const std::string_view name) con
   return std::string(name);
 }
 
+static struct {
+  const char* name;
+  unsigned flag;
+} mount_flags_list[] = {
+  { "noatime", MS_NOATIME },
+  { "noexec", MS_NOEXEC },
+  { "nosuid", MS_NOSUID },
+  { "nodev", MS_NODEV },
+  { "nodiratime", MS_NODIRATIME },
+  { "ro", MS_RDONLY },
+  { "rw", 0 },
+  { "remount", MS_REMOUNT },
+  { "bind", MS_BIND },
+  { "rec", MS_REC },
+  { "unbindable", MS_UNBINDABLE },
+  { "private", MS_PRIVATE },
+  { "slave", MS_SLAVE },
+  { "shared", MS_SHARED },
+  { "defaults", 0 },
+  { 0, 0 },
+};
+
+static bool setMountFlag(const std::string& flag, unsigned* mount_flags) {
+  for (const auto& [name, value] : mount_flags_list) {
+    if (flag == name) {
+      *mount_flags |= value;
+      return true;
+    }
+  }
+  return false;
+}
+
+static bool parseMountFlags(const std::string& flags, unsigned* mount_flags,
+                            std::string* fs_options) {
+  bool is_flag_set = false;
+  std::vector<std::string> flag_list;
+  for (const auto& flag : android::base::Split(flags, ",")) {
+    if (!setMountFlag(flag, mount_flags)) {
+      // Unknown flag, so it must be a filesystem specific option.
+      flag_list.push_back(flag);
+    } else {
+      is_flag_set = true;
+    }
+  }
+  *fs_options = android::base::Join(flag_list, ',');
+  return is_flag_set;
+}
+
 int UpdaterRuntime::Mount(const std::string_view location, const std::string_view mount_point,
                           const std::string_view fs_type, const std::string_view mount_options) {
   std::string mount_point_string(mount_point);
+  std::string mount_options_string(mount_options);
   char* secontext = nullptr;
+  unsigned mount_flags = 0;
+  std::string fs_options;
+
   if (sehandle_) {
     selabel_lookup(sehandle_, &secontext, mount_point_string.c_str(), 0755);
     setfscreatecon(secontext);
@@ -59,9 +111,13 @@ int UpdaterRuntime::Mount(const std::string_view location, const std::string_vie
     setfscreatecon(nullptr);
   }
 
+  if (!parseMountFlags(mount_options_string, &mount_flags, &fs_options)) {
+    // Fall back to default
+    mount_flags = MS_NOATIME | MS_NODEV | MS_NODIRATIME;
+  }
+
   return mount(std::string(location).c_str(), mount_point_string.c_str(),
-               std::string(fs_type).c_str(), MS_NOATIME | MS_NODEV | MS_NODIRATIME,
-               std::string(mount_options).c_str());
+               std::string(fs_type).c_str(), mount_flags, fs_options.c_str());
 }
 
 bool UpdaterRuntime::IsMounted(const std::string_view mount_point) const {