Bug 2004947 - Remove cargo dependency from embedded-uniffi-bindgen (#7124)

Instead we do some parsing of the `Cargo.toml` files ourselves.  I ran
`cargo uniffi-bindgen generate -l kotlin --library ~/application-services/target/debug/libmegazord.so` 
with both the old and new version and the contents were identical.

Author: bendk

Cargo.lock

@@ -10,4 +10,11 @@ license = "MPL-2.0"
 name = "embedded-uniffi-bindgen"
 
 [dependencies]
-uniffi = { version = "0.29.0", features = ["cli"] }
+anyhow = "1"
+camino = "1"
+glob = "0.3"
+toml = "0.5"
+clap = {version = "4.2", default-features = false, features = ["std", "derive"]}
+serde = { version = "1", features = ["derive"] }
+uniffi_bindgen = { version = "0.29.3" }
+uniffi_pipeline = { version = "0.29.3" }

tools/embedded-uniffi-bindgen/Cargo.toml

@@ -0,0 +1,186 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// This is the only significant difference from vanilla UniFFI,
+//
+// We define our own config supplier than parses `Cargo.toml` files directly to avoid a dependency
+// on `cargo`.  This code tries to parse as little as possible to make this work.
+//
+// We could move this code into the main uniffi repo and add a flag to use it instead of the
+// cargo-based config supplier.
+
+use std::{
+    collections::{HashMap, HashSet},
+    env, fs,
+    sync::LazyLock,
+};
+
+use anyhow::{anyhow, Context, Result};
+use camino::{Utf8Path, Utf8PathBuf};
+use serde::Deserialize;
+use uniffi_bindgen::BindgenCrateConfigSupplier;
+
+pub struct NoCargoConfigSupplier;
+
+impl BindgenCrateConfigSupplier for NoCargoConfigSupplier {
+    fn get_toml(&self, crate_name: &str) -> Result<Option<toml::value::Table>> {
+        match self.get_toml_path(crate_name) {
+            None => Ok(None),
+            Some(path) => Ok(Some(toml::from_str(&fs::read_to_string(path)?)?)),
+        }
+    }
+
+    fn get_toml_path(&self, crate_name: &str) -> Option<Utf8PathBuf> {
+        let crate_map = CRATE_MAP.as_ref().expect("Error parsing Cargo.toml files");
+        let crate_root = crate_map.get(crate_name)?;
+        let toml_path = crate_root.join("uniffi.toml");
+        toml_path.exists().then_some(toml_path)
+    }
+
+    /// Obtains the contents of the named UDL file which was referenced by the type metadata.
+    fn get_udl(&self, crate_name: &str, udl_name: &str) -> Result<String> {
+        let crate_map = CRATE_MAP.as_ref().expect("Error parsing Cargo.toml files");
+        let crate_root = crate_map
+            .get(crate_name)
+            .ok_or_else(|| anyhow!("Unknown crate: {crate_name}"))?;
+        let udl_path = crate_root.join(format!("src/{udl_name}.udl"));
+        fs::read_to_string(&udl_path).context(format!("Error reading {udl_path}"))
+    }
+}
+
+static CRATE_MAP: LazyLock<Result<HashMap<String, Utf8PathBuf>>> =
+    LazyLock::new(find_workspace_crates);
+
+/// Find all crates in this workspace and return a map of crate_name => crate_root_path
+fn find_workspace_crates() -> Result<HashMap<String, Utf8PathBuf>> {
+    let workspace_toml = find_workspace_toml()?;
+
+    let mut toml_paths_to_process = vec![];
+    for path in workspace_toml.data.workspace.unwrap().members {
+        toml_paths_to_process.extend(join_and_glob(&workspace_toml.dir, path)?)
+    }
+    let mut toml_paths_processed = HashSet::new();
+    let mut map = HashMap::new();
+
+    loop {
+        let Some(crate_dir) = toml_paths_to_process.pop() else {
+            break;
+        };
+        let toml_path = join(&crate_dir, "Cargo.toml")?;
+        if !toml_paths_processed.insert(toml_path.clone()) {
+            continue;
+        }
+
+        let toml = CargoToml::from_path(&toml_path)?;
+        let new_paths = find_other_cargo_toml_paths(&crate_dir, &toml)?;
+        toml_paths_to_process.extend(new_paths);
+
+        // Add both the package name and library name to the map
+        if let Some(package) = toml.package {
+            map.insert(package.name.replace("-", "_"), crate_dir.clone());
+        }
+
+        if let Some(CargoLibrary { name: Some(name) }) = toml.lib {
+            map.insert(name.replace("-", "_"), crate_dir);
+        }
+    }
+    Ok(map)
+}
+
+/// Find the workspace Cargo.toml file.
+///
+/// Returns the parsed TOML data plus the directory of the file
+fn find_workspace_toml() -> Result<CargoTomlFile> {
+    let current_dir = camino::Utf8PathBuf::from_path_buf(env::current_dir()?)
+        .map_err(|_| anyhow!("path is not UTF8"))?;
+    let mut dir = current_dir.as_path();
+    loop {
+        let path = dir.join("Cargo.toml");
+        if path.exists() {
+            let toml = CargoToml::from_path(&path)?;
+            if toml.workspace.is_some() {
+                return Ok(CargoTomlFile {
+                    data: toml,
+                    dir: dir.to_path_buf(),
+                });
+            }
+        }
+        dir = dir
+            .parent()
+            .ok_or_else(|| anyhow!("Couldn't find workspace Cargo.toml"))?;
+    }
+}
+
+/// Process Cargo.toml data and return all crate paths referenced in it
+fn find_other_cargo_toml_paths(crate_dir: &Utf8Path, toml: &CargoToml) -> Result<Vec<Utf8PathBuf>> {
+    toml.dependencies
+        .iter()
+        .flat_map(|d| d.values())
+        .filter_map(|dep| match dep {
+            CargoDependency::Detailed { path: Some(path) } => Some(join(crate_dir, path)),
+            _ => None,
+        })
+        .collect()
+}
+
+fn join(dir: &Utf8Path, child: impl AsRef<str>) -> Result<Utf8PathBuf> {
+    let child = child.as_ref();
+    dir.join(child)
+        .canonicalize_utf8()
+        .map_err(|p| anyhow!("Invalid path: {p} {dir}, {child}"))
+}
+
+fn join_and_glob(dir: &Utf8Path, child: impl AsRef<str>) -> Result<Vec<Utf8PathBuf>> {
+    let child = child.as_ref();
+    glob::glob(dir.join(child).as_str())?
+        .map(|entry| anyhow::Ok(Utf8PathBuf::try_from(entry?)?))
+        .map(|path| Ok(path?.canonicalize_utf8()?))
+        .collect()
+}
+
+#[derive(Debug)]
+struct CargoTomlFile {
+    data: CargoToml,
+    dir: Utf8PathBuf,
+}
+
+#[derive(Debug, Deserialize)]
+struct CargoToml {
+    package: Option<CargoPackage>,
+    lib: Option<CargoLibrary>,
+    workspace: Option<CargoWorkspace>,
+    dependencies: Option<HashMap<String, CargoDependency>>,
+}
+
+impl CargoToml {
+    fn from_path(path: &Utf8Path) -> Result<Self> {
+        let contents = fs::read_to_string(path).context(format!("reading {path}"))?;
+        toml::from_str(&contents).context(format!("parsing {path}"))
+    }
+}
+
+#[derive(Debug, Deserialize)]
+struct CargoPackage {
+    name: String,
+}
+
+#[derive(Debug, Deserialize)]
+struct CargoLibrary {
+    name: Option<String>,
+}
+
+#[derive(Debug, Deserialize)]
+struct CargoWorkspace {
+    members: Vec<Utf8PathBuf>,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+enum CargoDependency {
+    #[allow(dead_code)]
+    Simple(String),
+    Detailed {
+        path: Option<Utf8PathBuf>,
+    },
+}

tools/embedded-uniffi-bindgen/src/config_supplier.rs

@@ -2,6 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-fn main() {
-    uniffi::uniffi_bindgen_main()
+pub mod config_supplier;
+mod uniffi_bindgen;
+
+fn main() -> anyhow::Result<()> {
+    uniffi_bindgen::run_main()
 }