Use the protobuf_build crate to simplify build process.

Removes external dependency on rust-protobuf, which prevents version
mismatch between the runtime and the compiler.

protocol/Cargo.toml

@@ -8,3 +8,5 @@ build = "build.rs"
 mod_path = "~0.1.6"
 protobuf = "~1.0.10"
 
+[build-dependencies.protobuf_build]
+git = "https://github.com/plietar/rust-protobuf-build.git"

protocol/build.rs

@@ -1,50 +1,22 @@
+extern crate protobuf_build;
+
 use std::env;
-use std::process::{Command, Stdio};
-use std::path::{Path,PathBuf};
-
-#[derive(Debug)]
-enum ProtobufError {
-    IoError(::std::io::Error),
-    Other
-}
-
-impl std::convert::From<::std::io::Error> for ProtobufError {
-    fn from(e: ::std::io::Error) -> ProtobufError {
-        ProtobufError::IoError(e)
-    }
-}
-
-fn compile(prefix : &Path, files : &[&Path]) -> Result<(),ProtobufError>{
-    let mut c = Command::new("protoc");
-    c.arg("--rust_out").arg(env::var("OUT_DIR").unwrap())
-        .arg("--proto_path").arg(prefix.to_str().unwrap());
-
-    for f in files.iter() {
-        c.arg(f.to_str().unwrap());
-    }
-
-    //c.stdout(Stdio::inherit());
-    c.stderr(Stdio::inherit());
-
-    let mut p = try!(c.spawn());
-    let r = try!(p.wait());
-    return match r.success() {
-        true => Ok(()),
-        false => Err(ProtobufError::Other),
-    };
-}
+use std::path::PathBuf;
 
 fn main() {
-    let root = PathBuf::from(&env::var("CARGO_MANIFEST_DIR").unwrap());
+    let root = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
+    let out = PathBuf::from(env::var("OUT_DIR").unwrap());
     let proto = root.join("proto");
 
-    compile(&proto, &[
-            &proto.join("keyexchange.proto"),
-            &proto.join("authentication.proto"),
-            &proto.join("mercury.proto"),
-            &proto.join("metadata.proto"),
-            &proto.join("pubsub.proto"),
-            &proto.join("spirc.proto"),
-    ]).unwrap();
+    let mut compiler = protobuf_build::Compiler::new(&proto, &out);
+
+    for file in &["keyexchange.proto",
+                  "authentication.proto",
+                  "mercury.proto",
+                  "metadata.proto",
+                  "pubsub.proto",
+                  "spirc.proto"] {
+        compiler.compile(file).unwrap();
+    }
 }