Add flag for enabling only new storage and use in aflags

Change-Id: I73218de38d005d77987d5103364a102cec3abc07
Test: m && cargo t
Bug: 324436145
diff --git a/tools/aconfig/aflags/Android.bp b/tools/aconfig/aflags/Android.bp
index c48585a..2040cc6 100644
--- a/tools/aconfig/aflags/Android.bp
+++ b/tools/aconfig/aflags/Android.bp
@@ -10,6 +10,7 @@
     srcs: ["src/main.rs"],
     rustlibs: [
         "libaconfig_device_paths",
+        "libaconfig_flags",
         "libaconfig_protos",
         "libaconfigd_protos",
         "libaconfig_storage_read_api",
@@ -24,6 +25,7 @@
 
 rust_binary {
     name: "aflags",
+    host_supported: true,
     defaults: ["aflags.defaults"],
 }
 
diff --git a/tools/aconfig/aflags/Cargo.toml b/tools/aconfig/aflags/Cargo.toml
index 7dc3436..7efce6d 100644
--- a/tools/aconfig/aflags/Cargo.toml
+++ b/tools/aconfig/aflags/Cargo.toml
@@ -15,3 +15,4 @@
 aconfig_storage_read_api = { version = "0.1.0", path = "../aconfig_storage_read_api" }
 clap = {version = "4.5.2" }
 aconfig_device_paths = { version = "0.1.0", path = "../aconfig_device_paths" }
+aconfig_flags = { version = "0.1.0", path = "../aconfig_flags" }
\ No newline at end of file
diff --git a/tools/aconfig/aflags/src/main.rs b/tools/aconfig/aflags/src/main.rs
index d8912a9..a726cc0 100644
--- a/tools/aconfig/aflags/src/main.rs
+++ b/tools/aconfig/aflags/src/main.rs
@@ -164,10 +164,6 @@
 enum Command {
     /// List all aconfig flags on this device.
     List {
-        /// Read from the new flag storage.
-        #[clap(long)]
-        use_new_storage: bool,
-
         /// Optionally filter by container name.
         #[clap(short = 'c', long = "container")]
         container: Option<String>,
@@ -184,6 +180,9 @@
         /// <package>.<flag_name>
         qualified_name: String,
     },
+
+    /// Display which flag storage backs aconfig flags.
+    WhichBacking,
 }
 
 struct PaddingInfo {
@@ -282,21 +281,31 @@
     Ok(result)
 }
 
+fn display_which_backing() -> String {
+    if aconfig_flags::auto_generated::enable_only_new_storage() {
+        "aconfig_storage".to_string()
+    } else {
+        "device_config".to_string()
+    }
+}
+
 fn main() -> Result<()> {
     ensure!(nix::unistd::Uid::current().is_root(), "must be root");
 
     let cli = Cli::parse();
     let output = match cli.command {
-        Command::List { use_new_storage: true, container } => {
-            list(FlagSourceType::AconfigStorage, container)
-                .map_err(|err| anyhow!("storage may not be enabled: {err}"))
-                .map(Some)
-        }
-        Command::List { use_new_storage: false, container } => {
-            list(FlagSourceType::DeviceConfig, container).map(Some)
+        Command::List { container } => {
+            if aconfig_flags::auto_generated::enable_only_new_storage() {
+                list(FlagSourceType::AconfigStorage, container)
+                    .map_err(|err| anyhow!("storage may not be enabled: {err}"))
+                    .map(Some)
+            } else {
+                list(FlagSourceType::DeviceConfig, container).map(Some)
+            }
         }
         Command::Enable { qualified_name } => set_flag(&qualified_name, "true").map(|_| None),
         Command::Disable { qualified_name } => set_flag(&qualified_name, "false").map(|_| None),
+        Command::WhichBacking => Ok(Some(display_which_backing())),
     };
     match output {
         Ok(Some(text)) => println!("{text}"),