Added build script to use git for the VERSION string

Cargo.toml

@@ -1,10 +1,12 @@
 [package]
 
 name = "rustation"
-# Exported as VERSION and VERSION_CSTR in the library
-version = "0.0.2"
-authors = ["Lionel Flandrin <lionel.flandrin@gmail.com>"]
 
+# Should match the latest git tag! This version info is used to set
+# the internal `VERSION` string if "git describe" is unavailable.
+version = "0.0.2"
+
+authors = ["Lionel Flandrin <lionel.flandrin@gmail.com>"]
 description = "A PlayStation emulator"
 homepage = "https://github.com/simias/rustation"
 repository = "https://github.com/simias/rustation"
@@ -12,6 +14,7 @@ documentation = "https://github.com/simias/rustation/wiki"
 readme = "README.md"
 license = "GPL-2.0+"
 keywords = ["emulator", "playstation"]
+build = "build.rs"
 
 [features]
 trace = [ "lazy_static" ]

build.rs

@@ -0,0 +1,51 @@
+//! Get the version string using `git describe --dirty` or, if it
+//! fails, using the `CARGO_PKG_VERSION`.
+//!
+//! The `GIT` environment variable can be used to set an alternative
+//! path to the git executable.
+
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+use std::process::Command;
+
+fn main() {
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("version.rs");
+    let mut f = File::create(&dest_path).unwrap();
+
+    let git =
+        env::var("GIT").unwrap_or("git".into());
+
+    let description =
+        Command::new(git)
+        .arg("describe")
+        .arg("--dirty")
+        .output();
+
+    let cargo_version = env!("CARGO_PKG_VERSION").to_owned();
+
+    let mut version =
+        match description {
+            Ok(output) => {
+                if output.status.success() {
+                    format!("git-{}",
+                            String::from_utf8(output.stdout).unwrap())
+                } else {
+                    cargo_version
+                }
+            }
+            _ => cargo_version,
+        };
+
+    // Make sure version is on a single line
+    if let Some(l) = version.find('\n') {
+        version.truncate(l);
+    }
+
+    writeln!(f, "pub const VERSION: &'static str = \
+                 \"{}\";", version).unwrap();
+    writeln!(f, "pub const VERSION_CSTR: &'static str = \
+                 \"{}\\0\";", version).unwrap();
+}

src/lib.rs

@@ -33,9 +33,10 @@ mod timekeeper;
 mod spu;
 mod mdec;
 
-/// Version of the rustation library set in Cargo.toml
-pub const VERSION: &'static str = env!("CARGO_PKG_VERSION");
+mod version {
+    // VERSION and VERSION_CSTR are generated by build.rs
+    include!(concat!(env!("OUT_DIR"), "/version.rs"));
+}
 
-/// Like VERSION but as a `\0`-terminated C string. Useful when you
-/// need a static string in C bindings.
-pub const VERSION_CSTR: &'static str = concat!(env!("CARGO_PKG_VERSION"), '\0');
+pub use version::VERSION;
+pub use version::VERSION_CSTR;