Rename payload metadata partition

/dev/block/by-name/metadata is used by others as well.

Renamed it as payload-metadata.

Bug: 191097666
Test: MicrodroidHostTestCases
Change-Id: I873ee2acbe38772e59c96b3904023ac0d1573621

microdroid/payload/README.md

@@ -7,7 +7,7 @@ mounts/activates APK/APEXes and executes a binary within the APK.
 
 Payload disk has 1 + N(number of APEX/APK payloads) partitions.
 
-The first partition is a "metadata" partition which describes other partitions.
+The first partition is a "payload-metadata" partition which describes other partitions.
 And APEXes and an APK are following as separate partitions.
 
 For now, the order of partitions are important.

microdroid/payload/metadata/Android.bp

@@ -10,6 +10,7 @@ rust_library {
     prefer_rlib: true,
     edition: "2018",
     rustlibs: [
+        "libanyhow",
         "libmicrodroid_metadata_proto_rust",
         "libprotobuf",
     ],

microdroid/payload/metadata/src/lib.rs

@@ -18,15 +18,15 @@
 //!   4 bytes : size(N) in big endian
 //!   N bytes : protobuf message for Metadata
 
+use anyhow::Result;
 use protobuf::Message;
-use std::io;
 use std::io::Read;
 use std::io::Write;
 
 pub use microdroid_metadata::metadata::{ApexPayload, ApkPayload, Metadata};
 
 /// Reads a metadata from a reader
-pub fn read_metadata<T: Read>(mut r: T) -> io::Result<Metadata> {
+pub fn read_metadata<T: Read>(mut r: T) -> Result<Metadata> {
     let mut buf = [0u8; 4];
     r.read_exact(&mut buf)?;
     let size = i32::from_be_bytes(buf);
@@ -34,9 +34,10 @@ pub fn read_metadata<T: Read>(mut r: T) -> io::Result<Metadata> {
 }
 
 /// Writes a metadata to a writer
-pub fn write_metadata<T: Write>(metadata: &Metadata, mut w: T) -> io::Result<()> {
+pub fn write_metadata<T: Write>(metadata: &Metadata, mut w: T) -> Result<()> {
     let mut buf = Vec::new();
     metadata.write_to_writer(&mut buf)?;
     w.write_all(&(buf.len() as i32).to_be_bytes())?;
-    w.write_all(&buf)
+    w.write_all(&buf)?;
+    Ok(())
 }

microdroid/payload/mk_payload.cc

@@ -302,7 +302,7 @@ Result<void> MakePayload(const Config& config, const std::string& metadata_file,
 
     // put metadata at the first partition
     partitions.push_back(MultipleImagePartition{
-            .label = "metadata",
+            .label = "payload-metadata",
             .image_file_paths = {metadata_file},
             .type = kLinuxFilesystem,
             .read_only = true,

microdroid/sepolicy/system/private/apkdmverity.te

@@ -6,7 +6,7 @@ type apkdmverity_exec, exec_type, file_type, system_file_type;
 # allow domain transition from init
 init_daemon_domain(apkdmverity)
 
-# apkdmverity accesses /dev/block/by-name/metadata which points to
+# apkdmverity accesses "payload metadata disk" which points to
 # a /dev/vd* block device file.
 allow apkdmverity block_device:dir r_dir_perms;
 allow apkdmverity block_device:lnk_file r_file_perms;

microdroid/sepolicy/system/private/microdroid_manager.te

@@ -6,8 +6,7 @@ type microdroid_manager_exec, exec_type, file_type, system_file_type;
 # allow domain transition from init
 init_daemon_domain(microdroid_manager)
 
-# microdroid_manager accesses /dev/block/by-name/metadata which points to
-# a /dev/vd* block device file.
+# microdroid_manager accesses a virtual disk block device to read VM payload
 allow microdroid_manager block_device:dir r_dir_perms;
 allow microdroid_manager block_device:lnk_file r_file_perms;
 allow microdroid_manager vd_device:blk_file r_file_perms;

microdroid_manager/src/metadata.rs

@@ -12,17 +12,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//! Payload metadata from /dev/block/by-name/metadata
+//! Payload metadata from /dev/block/by-name/payload-metadata
 
+use anyhow::Result;
 use log::info;
 use microdroid_metadata::{read_metadata, Metadata};
 use std::fs::File;
-use std::io;
 
-const METADATA_PATH: &str = "/dev/block/by-name/metadata";
+const PAYLOAD_METADATA_PATH: &str = "/dev/block/by-name/payload-metadata";
 
-/// loads payload metadata from /dev/block/by-name/metadata
-pub fn load() -> io::Result<Metadata> {
+/// loads payload metadata from /dev/block/by-name/paylaod-metadata
+pub fn load() -> Result<Metadata> {
     info!("loading payload metadata...");
-    read_metadata(File::open(METADATA_PATH)?)
+    read_metadata(File::open(PAYLOAD_METADATA_PATH)?)
 }

virtualizationservice/src/payload.rs

@@ -158,7 +158,7 @@ pub fn make_payload_disk(
 
     // put metadata at the first partition
     let mut partitions = vec![Partition {
-        label: "metadata".to_owned(),
+        label: "payload-metadata".to_owned(),
         paths: vec![metadata_path],
         writable: false,
     }];