build: add an API with which to retrieve build metadata [WPB-11001]

This data is stringly typed due to passing through the environment
between being generated and being incorporated into the program.
No attempt is made to parse it in order to keep things simple;
the expected use case for this data is just log information anyway.

This adds more information that was strictly requested by the PR,
in the assumption that this information is negligibly cheap to store and
can only help with reducing parsing demand.

crypto-ffi/src/generic/mod.rs

@@ -49,6 +49,44 @@ pub fn version() -> String {
     VERSION.to_string()
 }
 
+#[derive(uniffi::Record)]
+/// Metadata describing the conditions of the build of this software.
+pub struct BuildMetadata {
+    /// Build Timestamp
+    pub timestamp: String,
+    /// Whether this build was in Debug mode (true) or Release mode (false)
+    pub cargo_debug: String,
+    /// Features enabled for this build
+    pub cargo_features: String,
+    /// Optimization level
+    pub opt_level: String,
+    /// Build target triple
+    pub target_triple: String,
+    /// Git branch
+    pub git_branch: String,
+    /// Output of `git describe`
+    pub git_describe: String,
+    /// Hash of current git commit
+    pub git_sha: String,
+    /// `true` when the source code differed from the commit at the most recent git hash
+    pub git_dirty: String,
+}
+
+#[uniffi::export]
+pub fn build_metadata() -> BuildMetadata {
+    BuildMetadata {
+        timestamp: core_crypto::BUILD_METADATA.timestamp.to_string(),
+        cargo_debug: core_crypto::BUILD_METADATA.cargo_debug.to_string(),
+        cargo_features: core_crypto::BUILD_METADATA.cargo_features.to_string(),
+        opt_level: core_crypto::BUILD_METADATA.opt_level.to_string(),
+        target_triple: core_crypto::BUILD_METADATA.target_triple.to_string(),
+        git_branch: core_crypto::BUILD_METADATA.git_branch.to_string(),
+        git_describe: core_crypto::BUILD_METADATA.git_describe.to_string(),
+        git_sha: core_crypto::BUILD_METADATA.git_sha.to_string(),
+        git_dirty: core_crypto::BUILD_METADATA.git_dirty.to_string(),
+    }
+}
+
 #[derive(Debug, thiserror::Error, uniffi::Error)]
 pub enum CoreCryptoError {
     #[error(transparent)]

crypto-ffi/src/wasm/mod.rs

@@ -38,6 +38,9 @@ use wasm_bindgen_futures::future_to_promise;
 #[allow(dead_code)]
 pub(super) const VERSION: &str = env!("CARGO_PKG_VERSION");
 
+#[allow(dead_code)]
+pub(super) use core_crypto::BUILD_METADATA;
+
 // This is intended to hotfix this import:
 // ❯ wasmer inspect bindings/js/wasm/core-crypto-ffi_bg.wasm | grep env
 //    "env"."__stack_chk_fail": [] -> []

crypto/Cargo.toml

@@ -128,3 +128,10 @@ harness = false
 [[bench]]
 name = "mls_proteus"
 harness = false
+
+[build-dependencies]
+anyhow = "1.0.93"
+# this is appropriate if we always and only build in environments where `git`
+# is available on the command line. If not, we should replace this with
+# `vergen-gix` or `vergen-git2`.
+vergen-gitcl = { version = "1.0.1", features = ["build", "cargo"] }

crypto/build.rs

@@ -14,7 +14,9 @@
 // You should have received a copy of the GNU General Public License
 // along with this program. If not, see http://www.gnu.org/licenses/.
 
-fn main() {
+use vergen_gitcl::{BuildBuilder, CargoBuilder, Emitter, GitclBuilder};
+
+fn main() -> anyhow::Result<()> {
     // Target aliases
     #[cfg(target_os = "ios")]
     println!("cargo:rustc-cfg=ios");
@@ -28,4 +30,29 @@ fn main() {
     if let Ok(profile) = std::env::var("PROFILE") {
         println!("cargo:rustc-cfg=build=\"{profile}\"");
     }
+
+    // collect a bunch of build/git information and emit it into the build environment,
+    // from whence we can extract it and make it public
+    let build = BuildBuilder::default().build_timestamp(true).build()?;
+    let cargo = CargoBuilder::default()
+        .debug(true)
+        .features(true)
+        .opt_level(true)
+        .target_triple(true)
+        .build()?;
+    let git = GitclBuilder::default()
+        .branch(true)
+        .sha(false)
+        .dirty(false)
+        .describe(true, true, Some("v*"))
+        .build()?;
+
+    Emitter::default()
+        .fail_on_error()
+        .add_instructions(&build)?
+        .add_instructions(&cargo)?
+        .add_instructions(&git)?
+        .emit()?;
+
+    Ok(())
 }