diff --git a/tools/aconfig/.gitignore b/tools/aconfig/.gitignore
new file mode 100644
index 0000000000..1b72444aef
--- /dev/null
+++ b/tools/aconfig/.gitignore
@@ -0,0 +1,2 @@
+/Cargo.lock
+/target
diff --git a/tools/aconfig/Android.bp b/tools/aconfig/Android.bp
index b3813bfe5e..e762f331f6 100644
--- a/tools/aconfig/Android.bp
+++ b/tools/aconfig/Android.bp
@@ -18,7 +18,11 @@ rust_defaults {
     srcs: ["src/main.rs"],
     rustlibs: [
         "libaconfig_protos",
+        "libanyhow",
+        "libclap",
         "libprotobuf",
+        "libserde",
+        "libserde_json",
     ],
 }
 
diff --git a/tools/aconfig/Cargo.toml b/tools/aconfig/Cargo.toml
new file mode 100644
index 0000000000..b439858c9a
--- /dev/null
+++ b/tools/aconfig/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "aconfig"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+
+[features]
+default = ["cargo"]
+cargo = []
+
+[dependencies]
+anyhow = "1.0.69"
+clap = { version = "4.1.8", features = ["derive"] }
+protobuf = "3.2.0"
+serde = { version = "1.0.152", features = ["derive"] }
+serde_json = "1.0.93"
+
+[build-dependencies]
+protobuf-codegen = "3.2.0"
diff --git a/tools/aconfig/build.rs b/tools/aconfig/build.rs
new file mode 100644
index 0000000000..5ef5b6090f
--- /dev/null
+++ b/tools/aconfig/build.rs
@@ -0,0 +1,17 @@
+use protobuf_codegen::Codegen;
+
+fn main() {
+    let proto_files = vec!["protos/aconfig.proto"];
+
+    // tell cargo to only re-run the build script if any of the proto files has changed
+    for path in &proto_files {
+        println!("cargo:rerun-if-changed={}", path);
+    }
+
+    Codegen::new()
+        .pure()
+        .include("protos")
+        .inputs(proto_files)
+        .cargo_out_dir("aconfig_proto")
+        .run_from_script();
+}
diff --git a/tools/aconfig/protos/aconfig.proto b/tools/aconfig/protos/aconfig.proto
index 989c39866c..65817ca682 100644
--- a/tools/aconfig/protos/aconfig.proto
+++ b/tools/aconfig/protos/aconfig.proto
@@ -12,12 +12,34 @@
 // See the License for the specific language governing permissions and
 // limitations under the License
 
-// Placeholder proto file. Will be replaced by actual contents.
+// This is the schema definition for of Aconfig files. Modifications need to be
+// either backwards compatible, or include updates to all Aconfig files in the
+// Android tree.
 
-syntax = "proto3";
+syntax = "proto2";
 
 package android.aconfig;
 
-message Placeholder {
-  string name = 1;
+message value {
+  required bool value = 1;
+  optional uint32 since = 2;
 }
+
+message flag {
+  required string id = 1;
+  required string description = 2;
+  repeated value value = 3;
+};
+
+message android_config {
+  repeated flag flag = 1;
+};
+
+message override {
+  required string id = 1;
+  required bool value = 2;
+};
+
+message override_config {
+  repeated override override = 1;
+};
diff --git a/tools/aconfig/src/aconfig.rs b/tools/aconfig/src/aconfig.rs
new file mode 100644
index 0000000000..22fcb884b1
--- /dev/null
+++ b/tools/aconfig/src/aconfig.rs
@@ -0,0 +1,284 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use anyhow::{anyhow, Context, Error, Result};
+
+use crate::protos::{
+    ProtoAndroidConfig, ProtoFlag, ProtoOverride, ProtoOverrideConfig, ProtoValue,
+};
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct Value {
+    value: bool,
+    since: Option<u32>,
+}
+
+#[allow(dead_code)] // only used in unit tests
+impl Value {
+    pub fn new(value: bool, since: u32) -> Value {
+        Value { value, since: Some(since) }
+    }
+
+    pub fn default(value: bool) -> Value {
+        Value { value, since: None }
+    }
+}
+
+impl TryFrom<ProtoValue> for Value {
+    type Error = Error;
+
+    fn try_from(proto: ProtoValue) -> Result<Self, Self::Error> {
+        let Some(value) = proto.value else {
+            return Err(anyhow!("missing 'value' field"));
+        };
+        Ok(Value { value, since: proto.since })
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct Flag {
+    pub id: String,
+    pub description: String,
+
+    // ordered by Value.since; guaranteed to contain at least one item (the default value, with
+    // since == None)
+    pub values: Vec<Value>,
+}
+
+impl Flag {
+    #[allow(dead_code)] // only used in unit tests
+    pub fn try_from_text_proto(text_proto: &str) -> Result<Flag> {
+        let proto: ProtoFlag = crate::protos::try_from_text_proto(text_proto)
+            .with_context(|| text_proto.to_owned())?;
+        proto.try_into()
+    }
+
+    pub fn try_from_text_proto_list(text_proto: &str) -> Result<Vec<Flag>> {
+        let proto: ProtoAndroidConfig = crate::protos::try_from_text_proto(text_proto)
+            .with_context(|| text_proto.to_owned())?;
+        proto.flag.into_iter().map(|proto_flag| proto_flag.try_into()).collect()
+    }
+
+    pub fn resolve_value(&self, build_id: u32) -> bool {
+        let mut value = self.values[0].value;
+        for candidate in self.values.iter().skip(1) {
+            let since = candidate.since.expect("invariant: non-defaults values have Some(since)");
+            if since <= build_id {
+                value = candidate.value;
+            }
+        }
+        value
+    }
+}
+
+impl TryFrom<ProtoFlag> for Flag {
+    type Error = Error;
+
+    fn try_from(proto: ProtoFlag) -> Result<Self, Self::Error> {
+        let Some(id) = proto.id else {
+            return Err(anyhow!("missing 'id' field"));
+        };
+        let Some(description) = proto.description else {
+            return Err(anyhow!("missing 'description' field"));
+        };
+        if proto.value.is_empty() {
+            return Err(anyhow!("missing 'value' field"));
+        }
+
+        let mut values: Vec<Value> = vec![];
+        for proto_value in proto.value.into_iter() {
+            let v: Value = proto_value.try_into()?;
+            if values.iter().any(|w| v.since == w.since) {
+                let msg = match v.since {
+                    None => format!("flag {}: multiple default values", id),
+                    Some(x) => format!("flag {}: multiple values for since={}", id, x),
+                };
+                return Err(anyhow!(msg));
+            }
+            values.push(v);
+        }
+        values.sort_by_key(|v| v.since);
+
+        Ok(Flag { id, description, values })
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct Override {
+    pub id: String,
+    pub value: bool,
+}
+
+impl Override {
+    #[allow(dead_code)] // only used in unit tests
+    pub fn try_from_text_proto(text_proto: &str) -> Result<Override> {
+        let proto: ProtoOverride = crate::protos::try_from_text_proto(text_proto)?;
+        proto.try_into()
+    }
+
+    pub fn try_from_text_proto_list(text_proto: &str) -> Result<Vec<Override>> {
+        let proto: ProtoOverrideConfig = crate::protos::try_from_text_proto(text_proto)?;
+        proto.override_.into_iter().map(|proto_flag| proto_flag.try_into()).collect()
+    }
+}
+
+impl TryFrom<ProtoOverride> for Override {
+    type Error = Error;
+
+    fn try_from(proto: ProtoOverride) -> Result<Self, Self::Error> {
+        let Some(id) = proto.id else {
+            return Err(anyhow!("missing 'id' field"));
+        };
+        let Some(value) = proto.value else {
+            return Err(anyhow!("missing 'value' field"));
+        };
+        Ok(Override { id, value })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_flag_try_from_text_proto() {
+        let expected = Flag {
+            id: "1234".to_owned(),
+            description: "Description of the flag".to_owned(),
+            values: vec![Value::default(false), Value::new(true, 8)],
+        };
+
+        let s = r#"
+        id: "1234"
+        description: "Description of the flag"
+        value {
+            value: false
+        }
+        value {
+            value: true
+            since: 8
+        }
+        "#;
+        let actual = Flag::try_from_text_proto(s).unwrap();
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn test_flag_try_from_text_proto_bad_input() {
+        let s = r#"
+        id: "a"
+        description: "Description of the flag"
+        "#;
+        let error = Flag::try_from_text_proto(s).unwrap_err();
+        assert_eq!(format!("{:?}", error), "missing 'value' field");
+
+        let s = r#"
+        description: "Description of the flag"
+        value {
+            value: true
+        }
+        "#;
+        let error = Flag::try_from_text_proto(s).unwrap_err();
+        assert!(format!("{:?}", error).contains("Message not initialized"));
+
+        let s = r#"
+        id: "a"
+        description: "Description of the flag"
+        value {
+            value: true
+        }
+        value {
+            value: true
+        }
+        "#;
+        let error = Flag::try_from_text_proto(s).unwrap_err();
+        assert_eq!(format!("{:?}", error), "flag a: multiple default values");
+    }
+
+    #[test]
+    fn test_flag_try_from_text_proto_list() {
+        let expected = vec![
+            Flag {
+                id: "a".to_owned(),
+                description: "A".to_owned(),
+                values: vec![Value::default(true)],
+            },
+            Flag {
+                id: "b".to_owned(),
+                description: "B".to_owned(),
+                values: vec![Value::default(false)],
+            },
+        ];
+
+        let s = r#"
+        flag {
+            id: "a"
+            description: "A"
+            value {
+                value: true
+            }
+        }
+        flag {
+            id: "b"
+            description: "B"
+            value {
+                value: false
+            }
+        }
+        "#;
+        let actual = Flag::try_from_text_proto_list(s).unwrap();
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn test_override_try_from_text_proto_list() {
+        let expected = Override { id: "1234".to_owned(), value: true };
+
+        let s = r#"
+        id: "1234"
+        value: true
+        "#;
+        let actual = Override::try_from_text_proto(s).unwrap();
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn test_resolve_value() {
+        let flag = Flag {
+            id: "a".to_owned(),
+            description: "A".to_owned(),
+            values: vec![
+                Value::default(true),
+                Value::new(false, 10),
+                Value::new(true, 20),
+                Value::new(false, 30),
+            ],
+        };
+        assert!(flag.resolve_value(0));
+        assert!(flag.resolve_value(9));
+        assert!(!flag.resolve_value(10));
+        assert!(!flag.resolve_value(11));
+        assert!(!flag.resolve_value(19));
+        assert!(flag.resolve_value(20));
+        assert!(flag.resolve_value(21));
+        assert!(flag.resolve_value(29));
+        assert!(!flag.resolve_value(30));
+        assert!(!flag.resolve_value(10_000));
+    }
+}
diff --git a/tools/aconfig/src/cache.rs b/tools/aconfig/src/cache.rs
new file mode 100644
index 0000000000..d27459dcf5
--- /dev/null
+++ b/tools/aconfig/src/cache.rs
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use anyhow::{anyhow, Result};
+use serde::{Deserialize, Serialize};
+use std::io::{Read, Write};
+
+use crate::aconfig::{Flag, Override};
+use crate::commands::Source;
+
+#[derive(Serialize, Deserialize)]
+pub struct Item {
+    pub id: String,
+    pub description: String,
+    pub value: bool,
+    pub debug: Vec<String>,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct Cache {
+    build_id: u32,
+    items: Vec<Item>,
+}
+
+impl Cache {
+    pub fn new(build_id: u32) -> Cache {
+        Cache { build_id, items: vec![] }
+    }
+
+    pub fn read_from_reader(reader: impl Read) -> Result<Cache> {
+        serde_json::from_reader(reader).map_err(|e| e.into())
+    }
+
+    pub fn write_to_writer(&self, writer: impl Write) -> Result<()> {
+        serde_json::to_writer(writer, self).map_err(|e| e.into())
+    }
+
+    pub fn add_flag(&mut self, source: Source, flag: Flag) -> Result<()> {
+        if self.items.iter().any(|item| item.id == flag.id) {
+            return Err(anyhow!(
+                "failed to add flag {} from {}: flag already defined",
+                flag.id,
+                source,
+            ));
+        }
+        let value = flag.resolve_value(self.build_id);
+        self.items.push(Item {
+            id: flag.id.clone(),
+            description: flag.description,
+            value,
+            debug: vec![format!("{}:{}", source, value)],
+        });
+        Ok(())
+    }
+
+    pub fn add_override(&mut self, source: Source, override_: Override) -> Result<()> {
+        let Some(existing_item) = self.items.iter_mut().find(|item| item.id == override_.id) else {
+            return Err(anyhow!("failed to override flag {}: unknown flag", override_.id));
+        };
+        existing_item.value = override_.value;
+        existing_item.debug.push(format!("{}:{}", source, override_.value));
+        Ok(())
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &Item> {
+        self.items.iter()
+    }
+}
+
+impl Item {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::aconfig::Value;
+
+    #[test]
+    fn test_add_flag() {
+        let mut cache = Cache::new(1);
+        cache
+            .add_flag(
+                Source::File("first.txt".to_string()),
+                Flag {
+                    id: "foo".to_string(),
+                    description: "desc".to_string(),
+                    values: vec![Value::default(true)],
+                },
+            )
+            .unwrap();
+        let error = cache
+            .add_flag(
+                Source::File("second.txt".to_string()),
+                Flag {
+                    id: "foo".to_string(),
+                    description: "desc".to_string(),
+                    values: vec![Value::default(false)],
+                },
+            )
+            .unwrap_err();
+        assert_eq!(
+            &format!("{:?}", error),
+            "failed to add flag foo from second.txt: flag already defined"
+        );
+    }
+
+    #[test]
+    fn test_add_override() {
+        fn check_value(cache: &Cache, id: &str, expected: bool) -> bool {
+            cache.iter().find(|&item| item.id == id).unwrap().value == expected
+        }
+
+        let mut cache = Cache::new(1);
+        let error = cache
+            .add_override(Source::Memory, Override { id: "foo".to_string(), value: true })
+            .unwrap_err();
+        assert_eq!(&format!("{:?}", error), "failed to override flag foo: unknown flag");
+
+        cache
+            .add_flag(
+                Source::File("first.txt".to_string()),
+                Flag {
+                    id: "foo".to_string(),
+                    description: "desc".to_string(),
+                    values: vec![Value::default(true)],
+                },
+            )
+            .unwrap();
+        assert!(check_value(&cache, "foo", true));
+
+        cache
+            .add_override(Source::Memory, Override { id: "foo".to_string(), value: false })
+            .unwrap();
+        assert!(check_value(&cache, "foo", false));
+
+        cache
+            .add_override(Source::Memory, Override { id: "foo".to_string(), value: true })
+            .unwrap();
+        assert!(check_value(&cache, "foo", true));
+    }
+}
diff --git a/tools/aconfig/src/commands.rs b/tools/aconfig/src/commands.rs
new file mode 100644
index 0000000000..76b853b405
--- /dev/null
+++ b/tools/aconfig/src/commands.rs
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use anyhow::{Context, Result};
+use clap::ValueEnum;
+use serde::{Deserialize, Serialize};
+use std::fmt;
+use std::io::Read;
+
+use crate::aconfig::{Flag, Override};
+use crate::cache::Cache;
+
+#[derive(Clone, Serialize, Deserialize)]
+pub enum Source {
+    #[allow(dead_code)] // only used in unit tests
+    Memory,
+    File(String),
+}
+
+impl fmt::Display for Source {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Self::Memory => write!(f, "<memory>"),
+            Self::File(path) => write!(f, "{}", path),
+        }
+    }
+}
+
+pub struct Input {
+    pub source: Source,
+    pub reader: Box<dyn Read>,
+}
+
+pub fn create_cache(build_id: u32, aconfigs: Vec<Input>, overrides: Vec<Input>) -> Result<Cache> {
+    let mut cache = Cache::new(build_id);
+
+    for mut input in aconfigs {
+        let mut contents = String::new();
+        input.reader.read_to_string(&mut contents)?;
+        let flags = Flag::try_from_text_proto_list(&contents)
+            .with_context(|| format!("Failed to parse {}", input.source))?;
+        for flag in flags {
+            cache.add_flag(input.source.clone(), flag)?;
+        }
+    }
+
+    for mut input in overrides {
+        let mut contents = String::new();
+        input.reader.read_to_string(&mut contents)?;
+        let overrides = Override::try_from_text_proto_list(&contents)
+            .with_context(|| format!("Failed to parse {}", input.source))?;
+        for override_ in overrides {
+            cache.add_override(input.source.clone(), override_)?;
+        }
+    }
+
+    Ok(cache)
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, ValueEnum)]
+pub enum Format {
+    Text,
+    Debug,
+}
+
+pub fn dump_cache(cache: Cache, format: Format) -> Result<()> {
+    match format {
+        Format::Text => {
+            for item in cache.iter() {
+                println!("{}: {}", item.id, item.value);
+            }
+        }
+        Format::Debug => {
+            for item in cache.iter() {
+                println!("{}: {} ({:?})", item.id, item.value, item.debug);
+            }
+        }
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_create_cache() {
+        let s = r#"
+        flag {
+            id: "a"
+            description: "Description of a"
+            value {
+                value: true
+            }
+        }
+        "#;
+        let aconfigs = vec![Input { source: Source::Memory, reader: Box::new(s.as_bytes()) }];
+        let o = r#"
+        override {
+            id: "a"
+            value: false
+        }
+        "#;
+        let overrides = vec![Input { source: Source::Memory, reader: Box::new(o.as_bytes()) }];
+        let cache = create_cache(1, aconfigs, overrides).unwrap();
+        let value = cache.iter().find(|&item| item.id == "a").unwrap().value;
+        assert!(!value);
+    }
+}
diff --git a/tools/aconfig/src/main.rs b/tools/aconfig/src/main.rs
index 2f7255edab..3ce974781e 100644
--- a/tools/aconfig/src/main.rs
+++ b/tools/aconfig/src/main.rs
@@ -16,38 +16,75 @@
 
 //! `aconfig` is a build time tool to manage build time configurations, such as feature flags.
 
-use aconfig_protos::aconfig::Placeholder;
-use protobuf::text_format::{parse_from_str, ParseError};
+use anyhow::Result;
+use clap::{builder::ArgAction, builder::EnumValueParser, Arg, Command};
+use std::fs;
 
-fn foo() -> Result<String, ParseError> {
-    let placeholder = parse_from_str::<Placeholder>(r#"name: "aconfig""#)?;
-    Ok(placeholder.name)
+mod aconfig;
+mod cache;
+mod commands;
+mod protos;
+
+use crate::cache::Cache;
+use commands::{Input, Source};
+
+fn cli() -> Command {
+    Command::new("aconfig")
+        .subcommand_required(true)
+        .subcommand(
+            Command::new("create-cache")
+                .arg(
+                    Arg::new("build-id")
+                        .long("build-id")
+                        .value_parser(clap::value_parser!(u32))
+                        .required(true),
+                )
+                .arg(Arg::new("aconfig").long("aconfig").action(ArgAction::Append))
+                .arg(Arg::new("override").long("override").action(ArgAction::Append))
+                .arg(Arg::new("cache").long("cache").required(true)),
+        )
+        .subcommand(
+            Command::new("dump").arg(Arg::new("cache").long("cache").required(true)).arg(
+                Arg::new("format")
+                    .long("format")
+                    .value_parser(EnumValueParser::<commands::Format>::new())
+                    .default_value("text"),
+            ),
+        )
 }
 
-fn main() {
-    println!("{:?}", foo());
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_foo() {
-        assert_eq!("aconfig", foo().unwrap());
-    }
-
-    #[test]
-    fn test_binary_protobuf() {
-        use protobuf::Message;
-        let mut buffer = Vec::new();
-
-        let mut original = Placeholder::new();
-        original.name = "test".to_owned();
-        original.write_to_writer(&mut buffer).unwrap();
-
-        let copy = Placeholder::parse_from_reader(&mut buffer.as_slice()).unwrap();
-
-        assert_eq!(original, copy);
+fn main() -> Result<()> {
+    let matches = cli().get_matches();
+    match matches.subcommand() {
+        Some(("create-cache", sub_matches)) => {
+            let mut aconfigs = vec![];
+            let build_id = *sub_matches.get_one::<u32>("build-id").unwrap();
+            for path in
+                sub_matches.get_many::<String>("aconfig").unwrap_or_default().collect::<Vec<_>>()
+            {
+                let file = Box::new(fs::File::open(path)?);
+                aconfigs.push(Input { source: Source::File(path.to_string()), reader: file });
+            }
+            let mut overrides = vec![];
+            for path in
+                sub_matches.get_many::<String>("override").unwrap_or_default().collect::<Vec<_>>()
+            {
+                let file = Box::new(fs::File::open(path)?);
+                overrides.push(Input { source: Source::File(path.to_string()), reader: file });
+            }
+            let cache = commands::create_cache(build_id, aconfigs, overrides)?;
+            let path = sub_matches.get_one::<String>("cache").unwrap();
+            let file = fs::File::create(path)?;
+            cache.write_to_writer(file)?;
+        }
+        Some(("dump", sub_matches)) => {
+            let path = sub_matches.get_one::<String>("cache").unwrap();
+            let file = fs::File::open(path)?;
+            let cache = Cache::read_from_reader(file)?;
+            let format = sub_matches.get_one("format").unwrap();
+            commands::dump_cache(cache, *format)?;
+        }
+        _ => unreachable!(),
     }
+    Ok(())
 }
diff --git a/tools/aconfig/src/protos.rs b/tools/aconfig/src/protos.rs
new file mode 100644
index 0000000000..3c156b3d90
--- /dev/null
+++ b/tools/aconfig/src/protos.rs
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// When building with the Android tool-chain
+//
+//   - an external crate `aconfig_protos` will be generated
+//   - the feature "cargo" will be disabled
+//
+// When building with cargo
+//
+//   - a local sub-module will be generated in OUT_DIR and included in this file
+//   - the feature "cargo" will be enabled
+//
+// This module hides these differences from the rest of aconfig.
+
+// ---- When building with the Android tool-chain ----
+#[cfg(not(feature = "cargo"))]
+pub use aconfig_protos::aconfig::Android_config as ProtoAndroidConfig;
+
+#[cfg(not(feature = "cargo"))]
+pub use aconfig_protos::aconfig::Value as ProtoValue;
+
+#[cfg(not(feature = "cargo"))]
+pub use aconfig_protos::aconfig::Flag as ProtoFlag;
+
+#[cfg(not(feature = "cargo"))]
+pub use aconfig_protos::aconfig::Override_config as ProtoOverrideConfig;
+
+#[cfg(not(feature = "cargo"))]
+pub use aconfig_protos::aconfig::Override as ProtoOverride;
+
+// ---- When building with cargo ----
+#[cfg(feature = "cargo")]
+include!(concat!(env!("OUT_DIR"), "/aconfig_proto/mod.rs"));
+
+#[cfg(feature = "cargo")]
+pub use aconfig::Android_config as ProtoAndroidConfig;
+
+#[cfg(feature = "cargo")]
+pub use aconfig::Value as ProtoValue;
+
+#[cfg(feature = "cargo")]
+pub use aconfig::Flag as ProtoFlag;
+
+#[cfg(feature = "cargo")]
+pub use aconfig::Override_config as ProtoOverrideConfig;
+
+#[cfg(feature = "cargo")]
+pub use aconfig::Override as ProtoOverride;
+
+// ---- Common for both the Android tool-chain and cargo ----
+use anyhow::Result;
+
+pub fn try_from_text_proto<T>(s: &str) -> Result<T>
+where
+    T: protobuf::MessageFull,
+{
+    // warning: parse_from_str does not check if required fields are set
+    protobuf::text_format::parse_from_str(s).map_err(|e| e.into())
+}