Patch the ring build script to enable builds from source code

Turns out that ring includes pre-generated objects in cargo releases. It uses logic in its build scripts to determine whether the build is from a version published on cargo, or from source code. This logic is somewhat naively implemented by checking for the absence of a `.git` directory. This check falesly leads ring to believe it is building from a version published on crates.io, and fails when it tries to include the pregenerated files not present in the source code. To build from source code we must patch this flag.

Author: Juliette Pretot

third_party/ring/build.rs

@@ -322,6 +322,15 @@ fn ring_build_rs_main() {
     // Published builds are always built in release mode.
     let is_debug = is_git && env::var("DEBUG").unwrap() != "false";
 
+    // ring includes pre-generated objects in cargo releases. It uses logic in
+    // its build scripts to determine whether the build is from a version
+    // published on cargo, or from source code. This logic is somewhat naively
+    // implemented by checking for the absence of a `.git` directory. This
+    // check falesly leads ring to believe it is building from a version
+    // published on crates.io, and fails when it tries to include the
+    // pregenerated files not present in the source code. To build from source
+    // code we must patch this flag.
+
     // If `.git` exists then assume this is the "local hacking" case where
     // we want to make it easy to build *ring* using `cargo build`/`cargo test`
     // without a prerequisite `package` step, at the cost of needing additional
@@ -330,7 +339,17 @@ fn ring_build_rs_main() {
     // If `.git` doesn't exist then assume that this is a packaged build where
     // we want to optimize for minimizing the build tools required: No Perl,
     // no nasm, etc.
-    let use_pregenerated = !is_git;
+    //
+    // Oak Note:
+    // ring includes pre-generated objects in cargo releases. It uses logic in
+    // its build scripts to determine whether the build is from a version
+    // published on cargo, or from source code. This logic is somewhat naively
+    // implemented by checking for the absence of a `.git` directory. This
+    // check falesly leads ring to believe it is building from a version
+    // published on crates.io, and fails when it tries to include the
+    // pregenerated files not present in the source code. To build from source
+    // code we must patch this flag.
+    let use_pregenerated = false;
 
     // During local development, force warnings in non-Rust code to be treated
     // as errors. Since warnings are highly compiler-dependent and compilers