Initial support for building libaom

It relies on a git submodule to fetch the sources.

Issue #2.

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "aom-sys/data/aom"]
+	path = aom-sys/data/aom
+	url = https://aomedia.googlesource.com/aom

Cargo.toml

@@ -11,6 +11,7 @@ keywords = ["libaom","av1"]
 [features]
 default = ["codec-trait"]
 codec-trait = ["av-codec"]
+build = ["aom-sys/build"]
 
 [dependencies]
 aom-sys = { version = "0.1.0", path = "aom-sys" }

README.md

@@ -6,7 +6,9 @@ It is a simple [binding][1] and safe abstraction over [libaom][2].
 
 ## Building
 
-The bindings are generated using the headers and libraries that ought to be present in the system.
+By default the bindings are generated using the headers and libraries that ought to be present in the system.
+
+The `build` feature is available to automatically fetch and build [libaom][2].
 
 ## TODO
 - [x] Simple bindings

aom-sys/Cargo.toml

@@ -8,9 +8,13 @@ repository = "https://github.com/rust-av/aom-rs"
 
 build = "build.rs"
 
+[features]
+build = ["cmake"]
+
 [build-dependencies]
 bindgen = "0.30"
 metadeps = "1.1"
+cmake = { version = "0.1.29", optional = true }
 
 [package.metadata.pkg-config]
 aom = "0.1.0"

aom-sys/build.rs

@@ -1,6 +1,9 @@
 extern crate bindgen;
 extern crate metadeps;
 
+#[cfg(feature="build")]
+extern crate cmake;
+
 use std::fs::OpenOptions;
 use std::io::Write;
 
@@ -30,7 +33,36 @@ fn common_builder() -> bindgen::Builder {
         .raw_line("#![allow(non_upper_case_globals)]")
 }
 
+
+#[cfg(feature="build")]
+fn build_sources() {
+    use cmake::Config;
+    use std::env;
+    use std::path::Path;
+    use std::process::Command;
+
+    let build_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
+
+    Command::new("git")
+        .args(&["submodule", "update", "--recommend-shallow", "--init"])
+        .spawn()
+        .expect("Update failed");
+
+    let build_path = Path::new(&build_dir).join("data/aom");
+
+    let cfg = Config::new(build_path).build();
+
+    env::set_var("PKG_CONFIG_PATH", cfg.join("lib/pkgconfig"));
+}
+
+#[cfg(not(feature="build"))]
+fn build_sources() {}
+
 fn main() {
+    if cfg!(feature="build") {
+        build_sources()
+    }
+
     let libs = metadeps::probe().unwrap();
     let headers = libs.get("aom").unwrap().include_paths.clone();
     // let buildver = libs.get("vpx").unwrap().version.split(".").nth(1).unwrap();