Add support for updating git repos

src/cargo/sources/git.rs

@@ -2,6 +2,7 @@
 
 use url::Url;
 use util::{CargoResult,ProcessBuilder,io_error,human_error,process};
+use std::fmt::Show;
 use std::str;
 use std::io::{UserDir,AllPermissions};
 use std::io::fs::{mkdir_recursive,rmdir_recursive,chmod};
@@ -67,65 +68,130 @@ impl GitCommand {
         GitCommand { config: GitConfig { path: path, uri: uri, reference: reference } }
     }
 
+    pub fn get_cwd<'a>(&'a self) -> &'a Path {
+        &self.config.path
+    }
+
     pub fn checkout(&self) -> CargoResult<GitRepo> {
-        let config = &self.config;
-
-        if config.path.exists() {
-            git!(*config, "fetch --force --quiet --tags {} refs/heads/*:refs/heads/*", config.uri);
+        if self.config.path.exists() {
+            // TODO: If the revision we have is a rev, avoid unnecessarily fetching if we have the rev already
+            try!(self.fetch());
         } else {
-            let dirname = Path::new(config.path.dirname());
-            let mut checkout_config = self.config.clone();
-            checkout_config.path = dirname;
-
-            try!(mkdir_recursive(&checkout_config.path, UserDir).map_err(|err|
-                human_error(format!("Couldn't recursively create `{}`", checkout_config.path.display()), format!("path={}", checkout_config.path.display()), io_error(err))));
-
-            git!(checkout_config, "clone {} {} --bare --no-hardlinks --quiet", config.uri, config.path.display());
+            try!(self.clone());
         }
 
-        Ok(GitRepo { config: config.clone(), revision: try!(rev_for(config)) })
+        Ok(GitRepo { config: self.config.clone(), revision: try!(rev_for(&self.config)) })
+    }
+
+    fn fetch(&self) -> CargoResult<()> {
+        Ok(git!(self.config.path, "fetch --force --quiet --tags {} refs/heads/*:refs/heads/*", self.config.uri))
+    }
+
+    fn clone(&self) -> CargoResult<()> {
+        let dirname = Path::new(self.config.path.dirname());
+
+        try!(mkdir_recursive(&self.config.path, UserDir).map_err(|err|
+            human_error(format!("Couldn't recursively create `{}`", dirname.display()), format!("path={}", dirname.display()), io_error(err))));
+
+        Ok(git!(dirname, "clone {} {} --bare --no-hardlinks --quiet", self.config.uri, self.config.path.display()))
+    }
+}
+
+struct GitCheckout<'a> {
+    location: Path,
+    repo: &'a GitRepo
+}
+
+impl<'a> GitCheckout<'a> {
+    fn clone<'a>(into: Path, repo: &'a GitRepo) -> CargoResult<GitCheckout<'a>> {
+        let checkout = GitCheckout { location: into, repo: repo };
+
+        // If the git checkout already exists, we don't need to clone it again
+        if !checkout.location.join(".git").exists() {
+            try!(checkout.clone_repo());
+        }
+
+        Ok(checkout)
+    }
+
+    fn get_source<'a>(&'a self) -> &'a Path {
+        self.repo.get_path()
+    }
+
+    fn clone_repo(&self) -> CargoResult<()> {
+        try!(mkdir_recursive(&Path::new(self.location.dirname()), UserDir).map_err(io_error));
+        try!(rmdir_recursive(&self.location).map_err(io_error));
+
+        git!(self.location, "clone --no-checkout --quiet {} {}", self.get_source().display(), self.location.display());
+        try!(chmod(&self.location, AllPermissions).map_err(io_error));
+
+        Ok(())
+    }
+
+    fn fetch(&self) -> CargoResult<()> {
+        Ok(git!(self.location, "fetch --force --quiet --tags {}", self.get_source().display()))
+    }
+
+    fn reset<T: Show>(&self, revision: T) -> CargoResult<()> {
+        Ok(git!(self.location, "reset --hard {}", revision))
+    }
+
+    fn update_submodules(&self) -> CargoResult<()> {
+        Ok(git!(self.location, "submodule update --init --recursive"))
     }
 }
 
 impl GitRepo {
+    fn get_path<'a>(&'a self) -> &'a Path {
+        &self.config.path
+    }
+
     #[allow(unused_variable)]
-    fn copy_to(destination: &Path) -> CargoResult<()> {
-        Ok(())
+    fn copy_to<'a>(&'a self, dest: Path) -> CargoResult<GitCheckout<'a>> {
+        let checkout = try!(GitCheckout::clone(dest, self));
+
+        try!(checkout.fetch());
+        try!(checkout.reset(self.revision.as_slice()));
+        try!(checkout.update_submodules());
+
+        Ok(checkout)
     }
 
     fn clone_to(&self, destination: &Path) -> CargoResult<()> {
         try!(mkdir_recursive(&Path::new(destination.dirname()), UserDir).map_err(io_error));
         try!(rmdir_recursive(destination).map_err(io_error));
-        git!(self.config, "clone --no-checkout --quiet {} {}", self.config.path.display(), destination.display());
+        git!(self.config.path, "clone --no-checkout --quiet {} {}", self.config.path.display(), destination.display());
         try!(chmod(destination, AllPermissions).map_err(io_error));
 
-        let mut dest_config = self.config.clone();
-        dest_config.path = destination.clone();
-
-        git!(dest_config, "fetch --force --quiet --tags {}", self.config.path.display());
-        git!(dest_config, "reset --hard {}", self.revision);
-        git!(dest_config, "submodule update --init --recursive");
+        git!(*destination, "fetch --force --quiet --tags {}", self.config.path.display());
+        git!(*destination, "reset --hard {}", self.revision);
+        git!(*destination, "submodule update --init --recursive");
 
         Ok(())
     }
 }
 
 fn rev_for(config: &GitConfig) -> CargoResult<String> {
-    Ok(git_output!(*config, "rev-parse {}", config.reference))
+    Ok(git_output!(config.path, "rev-parse {}", config.reference))
 }
 
-fn git(config: &GitConfig, str: &str) -> ProcessBuilder {
-    println!("Executing git {} @ {}", str, config.path.display());
-    process("git").args(str.split(' ').collect::<Vec<&str>>().as_slice()).cwd(config.path.clone())
+#[allow(dead_code)]
+fn has_rev<T: Show>(path: &Path, rev: T) -> bool {
+    git_output(path, format!("cat-file -e {}", rev)).is_ok()
 }
 
-fn git_inherit(config: &GitConfig, str: String) -> CargoResult<()> {
-    git(config, str.as_slice()).exec().map_err(|err|
+fn git(path: &Path, str: &str) -> ProcessBuilder {
+    println!("Executing git {} @ {}", str, path.display());
+    process("git").args(str.split(' ').collect::<Vec<&str>>().as_slice()).cwd(path.clone())
+}
+
+fn git_inherit(path: &Path, str: String) -> CargoResult<()> {
+    git(path, str.as_slice()).exec().map_err(|err|
         human_error(format!("Couldn't execute `git {}`: {}", str, err), None::<&str>, err))
 }
 
-fn git_output(config: &GitConfig, str: String) -> CargoResult<String> {
-    let output = try!(git(config, str.as_slice()).exec_with_output().map_err(|err|
+fn git_output(path: &Path, str: String) -> CargoResult<String> {
+    let output = try!(git(path, str.as_slice()).exec_with_output().map_err(|err|
         human_error(format!("Couldn't execute `git {}`", str), None::<&str>, err)));
 
     Ok(to_str(output.output.as_slice()))