aconfig: add create-device-config-sysprops command

Add a new "create-device-config-sysprops" command that works like
"create-device-config-defaults" but for system properties.

DeviceConfig is a Java service, and will mirror (some of) its values by
setting system properties in the persist.device_config namespace. Native
code will access DeviceConfig (actually, the system properties) via the
server_configurable_flags library.

The new command writes a file that can be appended to /system/build.prop
to pre-populate persist.device_config before DeviceConfig has started.

Like create-device-config-defaults, the new command skips READ_ONLY
flags.

Bug: 285468565
Test: atest aconfig.test
Change-Id: I311c7c5e0b03dc897b09204137d43cc182324717

tools/aconfig/src/commands.rs

@@ -123,6 +123,24 @@ pub fn create_device_config_defaults(caches: Vec<Cache>) -> Result<Vec<u8>> {
     Ok(output)
 }
 
+pub fn create_device_config_sysprops(caches: Vec<Cache>) -> Result<Vec<u8>> {
+    let mut output = Vec::new();
+    for item in sort_and_iter_items(caches).filter(|item| item.permission == Permission::ReadWrite)
+    {
+        let line = format!(
+            "persist.device_config.{}.{}={}\n",
+            item.namespace,
+            item.name,
+            match item.state {
+                FlagState::Enabled => "true",
+                FlagState::Disabled => "false",
+            }
+        );
+        output.extend_from_slice(line.as_bytes());
+    }
+    Ok(output)
+}
+
 #[derive(Copy, Clone, Debug, PartialEq, Eq, ValueEnum)]
 pub enum DumpFormat {
     Text,
@@ -234,6 +252,14 @@ mod tests {
         assert_eq!("test/disabled_rw:disabled\ntest/enabled_rw:enabled\n", text);
     }
 
+    #[test]
+    fn test_create_device_config_sysprops() {
+        let caches = vec![crate::test::create_cache()];
+        let bytes = create_device_config_sysprops(caches).unwrap();
+        let text = std::str::from_utf8(&bytes).unwrap();
+        assert_eq!("persist.device_config.test.disabled_rw=false\npersist.device_config.test.enabled_rw=true\n", text);
+    }
+
     #[test]
     fn test_dump_text_format() {
         let caches = vec![create_test_cache_ns1()];

tools/aconfig/src/main.rs

@@ -69,6 +69,11 @@ fn cli() -> Command {
                 .arg(Arg::new("cache").long("cache").action(ArgAction::Append).required(true))
                 .arg(Arg::new("out").long("out").default_value("-")),
         )
+        .subcommand(
+            Command::new("create-device-config-sysprops")
+                .arg(Arg::new("cache").long("cache").action(ArgAction::Append).required(true))
+                .arg(Arg::new("out").long("out").default_value("-")),
+        )
         .subcommand(
             Command::new("dump")
                 .arg(Arg::new("cache").long("cache").action(ArgAction::Append).required(true))
@@ -172,6 +177,17 @@ fn main() -> Result<()> {
             let path = get_required_arg::<String>(sub_matches, "out")?;
             write_output_to_file_or_stdout(path, &output)?;
         }
+        Some(("create-device-config-sysprops", sub_matches)) => {
+            let mut caches = Vec::new();
+            for path in sub_matches.get_many::<String>("cache").unwrap_or_default() {
+                let file = fs::File::open(path)?;
+                let cache = Cache::read_from_reader(file)?;
+                caches.push(cache);
+            }
+            let output = commands::create_device_config_sysprops(caches)?;
+            let path = get_required_arg::<String>(sub_matches, "out")?;
+            write_output_to_file_or_stdout(path, &output)?;
+        }
         Some(("dump", sub_matches)) => {
             let mut caches = Vec::new();
             for path in sub_matches.get_many::<String>("cache").unwrap_or_default() {