patch_sync: Base code, version control managing

This is the base code addition for the patch_sync project. This
project attempts to synchronize LLVM patches and ChromeOS. This
code is not meant to run, but simply be the starting point so
that we break up the large code dump.

This code is meant to compile, but is not meant to be run. It
only adds the version control code which manages `repo`
interactions.

Additionally, this adds the full Cargo.toml (at least for
the current patch stack).

BUG=b:209493133
TEST=cargo build

Change-Id: I903edba6e633ec53a7fa4d2e7b0c2aac1094933a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3339404
Reviewed-by: George Burgess <gbiv@chromium.org>
Tested-by: Jordan Abrahams <ajordanr@google.com>
Commit-Queue: Jordan Abrahams <ajordanr@google.com>

5 files changed, 818 insertions, 0 deletions

diff --git a/llvm_tools/patch_sync/.gitignore b/llvm_tools/patch_sync/.gitignore
new file mode 100644
index 00000000..2f7896d1
--- /dev/null
+++ b/llvm_tools/patch_sync/.gitignore
@@ -0,0 +1 @@
+target/
diff --git a/llvm_tools/patch_sync/Cargo.lock b/llvm_tools/patch_sync/Cargo.lock
new file mode 100644
index 00000000..63a9fcf8
--- /dev/null
+++ b/llvm_tools/patch_sync/Cargo.lock
@@ -0,0 +1,453 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
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diff --git a/llvm_tools/patch_sync/Cargo.toml b/llvm_tools/patch_sync/Cargo.toml
new file mode 100644
index 00000000..43082627
--- /dev/null
+++ b/llvm_tools/patch_sync/Cargo.toml
@@ -0,0 +1,20 @@
+[package]
+name = "patch_sync"
+version = "0.1.0"
+authors = ["Jordan R Abrahams-Whitehead <ajordanr@google.com>"]
+edition = "2018"
+
+[profile.release]
+panic = "abort"
+
+[dependencies]
+anyhow = "1.0"
+regex = "1.5"
+serde = {version = "1.0", features = ["derive"]}
+serde_json = "1.0"
+sha2 = "0.9"
+structopt = "0.3"
+time = "0.3"
+
+[dev-dependencies]
+rand = "0.8"
diff --git a/llvm_tools/patch_sync/src/main.rs b/llvm_tools/patch_sync/src/main.rs
new file mode 100644
index 00000000..8eedaaa8
--- /dev/null
+++ b/llvm_tools/patch_sync/src/main.rs
@@ -0,0 +1,106 @@
+mod version_control;
+
+use anyhow::{Context, Result};
+use std::path::PathBuf;
+use structopt::StructOpt;
+
+fn main() -> Result<()> {
+    match Opt::from_args() {
+        Opt::Show { .. } => todo!("Opt show is not implemented yet"),
+        Opt::Transpose {
+            cros_checkout_path,
+            old_cros_ref,
+            android_checkout_path,
+            old_android_ref,
+            verbose,
+            dry_run,
+            no_commit,
+        } => transpose_subcmd(TransposeOpt {
+            cros_checkout_path,
+            old_cros_ref,
+            android_checkout_path,
+            old_android_ref,
+            verbose,
+            dry_run,
+            no_commit,
+        }),
+    }
+}
+
+#[allow(dead_code)]
+struct TransposeOpt {
+    cros_checkout_path: PathBuf,
+    old_cros_ref: String,
+    android_checkout_path: PathBuf,
+    old_android_ref: String,
+    verbose: bool,
+    dry_run: bool,
+    no_commit: bool,
+}
+
+fn transpose_subcmd(args: TransposeOpt) -> Result<()> {
+    let ctx = version_control::RepoSetupContext {
+        cros_checkout: args.cros_checkout_path,
+        android_checkout: args.android_checkout_path,
+        sync_before: false,
+    };
+    ctx.setup()?;
+    let _cros_patches_path = ctx.cros_patches_path();
+    let _android_patches_path = ctx.android_patches_path();
+
+    if !args.no_commit {
+        return Ok(());
+    }
+    // Commit and upload for review.
+    ctx.cros_repo_upload()
+        .context("uploading chromiumos changes")?;
+    ctx.android_repo_upload()
+        .context("uploading android changes")?;
+    Ok(())
+}
+
+#[derive(Debug, structopt::StructOpt)]
+#[structopt(name = "patch_sync", about = "A pipeline for syncing the patch code")]
+enum Opt {
+    /// Show a combined view of the PATCHES.json file, without making any changes.
+    #[allow(dead_code)]
+    Show {
+        #[structopt(parse(from_os_str))]
+        cros_checkout_path: PathBuf,
+        #[structopt(parse(from_os_str))]
+        android_checkout_path: PathBuf,
+    },
+    /// Transpose patches from two PATCHES.json files
+    /// to each other.
+    Transpose {
+        #[structopt(long = "cros-checkout", parse(from_os_str))]
+        /// Path to the ChromiumOS source repo checkout.
+        cros_checkout_path: PathBuf,
+
+        #[structopt(long = "overlay-base-ref")]
+        /// Git ref (e.g. hash) for the ChromiumOS overlay to use as the base.
+        old_cros_ref: String,
+
+        #[structopt(long = "aosp-checkout", parse(from_os_str))]
+        /// Path to the Android Open Source Project source repo checkout.
+        android_checkout_path: PathBuf,
+
+        #[structopt(long = "aosp-base-ref")]
+        /// Git ref (e.g. hash) for the llvm_android repo to use as the base.
+        old_android_ref: String,
+
+        #[structopt(short, long)]
+        /// Print information to stdout
+        verbose: bool,
+
+        #[structopt(long)]
+        /// Do not change any files. Useful in combination with `--verbose`
+        /// Implies `--no-commit` and `--no-upload`.
+        dry_run: bool,
+
+        #[structopt(long)]
+        /// Do not commit any changes made.
+        /// Implies `--no-upload`.
+        no_commit: bool,
+    },
+}
diff --git a/llvm_tools/patch_sync/src/version_control.rs b/llvm_tools/patch_sync/src/version_control.rs
new file mode 100644
index 00000000..3dc5aae9
--- /dev/null
+++ b/llvm_tools/patch_sync/src/version_control.rs
@@ -0,0 +1,238 @@
+use anyhow::{anyhow, bail, ensure, Context, Result};
+use regex::Regex;
+use std::ffi::OsStr;
+use std::fs;
+use std::path::{Path, PathBuf};
+use std::process::{Command, Output};
+
+const CHROMIUMOS_OVERLAY_REL_PATH: &str = "src/third_party/chromiumos-overlay";
+const ANDROID_LLVM_REL_PATH: &str = "toolchain/llvm_android";
+
+/// Context struct to keep track of both Chromium OS and Android checkouts.
+#[derive(Debug)]
+pub struct RepoSetupContext {
+    pub cros_checkout: PathBuf,
+    pub android_checkout: PathBuf,
+    /// Run `repo sync` before doing any comparisons.
+    pub sync_before: bool,
+}
+
+impl RepoSetupContext {
+    pub fn setup(&self) -> Result<()> {
+        if self.sync_before {
+            repo_cd_cmd(&self.cros_checkout, &["sync", CHROMIUMOS_OVERLAY_REL_PATH])?;
+            repo_cd_cmd(&self.android_checkout, &["sync", ANDROID_LLVM_REL_PATH])?;
+        }
+        Ok(())
+    }
+
+    pub fn cros_repo_upload(&self) -> Result<()> {
+        let llvm_dir = self
+            .cros_checkout
+            .join(&CHROMIUMOS_OVERLAY_REL_PATH)
+            .join("sys-devel/llvm");
+        ensure!(
+            llvm_dir.is_dir(),
+            "CrOS LLVM dir {} is not a directory",
+            llvm_dir.display()
+        );
+        Self::rev_bump_llvm(&llvm_dir)?;
+        Self::repo_upload(
+            &self.cros_checkout,
+            CHROMIUMOS_OVERLAY_REL_PATH,
+            &Self::build_commit_msg("android", "chromiumos", "BUG=None\nTEST=CQ"),
+        )
+    }
+
+    pub fn android_repo_upload(&self) -> Result<()> {
+        Self::repo_upload(
+            &self.android_checkout,
+            ANDROID_LLVM_REL_PATH,
+            &Self::build_commit_msg("chromiumos", "android", "Test: N/A"),
+        )
+    }
+
+    fn repo_upload(path: &Path, git_wd: &str, commit_msg: &str) -> Result<()> {
+        // TODO(ajordanr): Need to clean up if there's any failures during upload.
+        let git_path = &path.join(&git_wd);
+        ensure!(
+            git_path.is_dir(),
+            "git_path {} is not a directory",
+            git_path.display()
+        );
+        repo_cd_cmd(path, &["start", "patch_sync_branch", git_wd])?;
+        git_cd_cmd(git_path, &["add", "."])?;
+        git_cd_cmd(git_path, &["commit", "-m", commit_msg])?;
+        repo_cd_cmd(path, &["upload", "-y", "--verify", git_wd])?;
+        Ok(())
+    }
+
+    pub fn android_patches_path(&self) -> PathBuf {
+        self.android_checkout
+            .join(&ANDROID_LLVM_REL_PATH)
+            .join("patches/PATCHES.json")
+    }
+
+    pub fn cros_patches_path(&self) -> PathBuf {
+        self.cros_checkout
+            .join(&CHROMIUMOS_OVERLAY_REL_PATH)
+            .join("sys-devel/llvm/files/PATCHES.json")
+    }
+
+    /// Increment LLVM's revision number
+    fn rev_bump_llvm(llvm_dir: &Path) -> Result<PathBuf> {
+        let ebuild = find_ebuild(llvm_dir)
+            .with_context(|| format!("finding ebuild in {} to rev bump", llvm_dir.display()))?;
+        let ebuild_dir = ebuild.parent().unwrap();
+        let suffix_matcher = Regex::new(r"-r([0-9]+)\.ebuild").unwrap();
+        let ebuild_name = ebuild
+            .file_name()
+            .unwrap()
+            .to_str()
+            .ok_or_else(|| anyhow!("converting ebuild filename to utf-8"))?;
+        let new_path = if let Some(captures) = suffix_matcher.captures(ebuild_name) {
+            let full_suffix = captures.get(0).unwrap().as_str();
+            let cur_version = captures.get(1).unwrap().as_str().parse::<u32>().unwrap();
+            let new_filename =
+                ebuild_name.replace(full_suffix, &format!("-r{}.ebuild", cur_version + 1_u32));
+            let new_path = ebuild_dir.join(new_filename);
+            fs::rename(&ebuild, &new_path)?;
+            new_path
+        } else {
+            // File did not end in a revision. We should append -r1 to the end.
+            let new_filename = ebuild.file_stem().unwrap().to_string_lossy() + "-r1.ebuild";
+            let new_path = ebuild_dir.join(new_filename.as_ref());
+            fs::rename(&ebuild, &new_path)?;
+            new_path
+        };
+        Ok(new_path)
+    }
+
+    /// Return the contents of the old PATCHES.json from Chromium OS
+    #[allow(dead_code)]
+    pub fn old_cros_patch_contents(&self, hash: &str) -> Result<String> {
+        Self::old_file_contents(
+            hash,
+            &self.cros_checkout.join(CHROMIUMOS_OVERLAY_REL_PATH),
+            Path::new("sys-devel/llvm/files/PATCHES.json"),
+        )
+    }
+
+    /// Return the contents of the old PATCHES.json from android
+    #[allow(dead_code)]
+    pub fn old_android_patch_contents(&self, hash: &str) -> Result<String> {
+        Self::old_file_contents(
+            hash,
+            &self.android_checkout.join(ANDROID_LLVM_REL_PATH),
+            Path::new("patches/PATCHES.json"),
+        )
+    }
+
+    /// Return the contents of an old file in git
+    #[allow(dead_code)]
+    fn old_file_contents(hash: &str, pwd: &Path, file: &Path) -> Result<String> {
+        let git_ref = format!(
+            "{}:{}",
+            hash,
+            file.to_str()
+                .ok_or_else(|| anyhow!("failed to convert filepath to str"))?
+        );
+        let output = git_cd_cmd(pwd, &["show", &git_ref])?;
+        if !output.status.success() {
+            bail!("could not get old file contents for {}", &git_ref)
+        }
+        String::from_utf8(output.stdout)
+            .with_context(|| format!("converting {} file contents to UTF-8", &git_ref))
+    }
+
+    /// Create the commit message
+    fn build_commit_msg(from: &str, to: &str, footer: &str) -> String {
+        format!(
+            "[patch_sync] Synchronize patches from {}\n\n\
+        Copies new PATCHES.json changes from {} to {}\n\n{}",
+            from, from, to, footer
+        )
+    }
+}
+
+/// Return the path of an ebuild located within the given directory.
+fn find_ebuild(dir: &Path) -> Result<PathBuf> {
+    // TODO(ajordanr): Maybe use OnceCell for this regex?
+    let ebuild_matcher = Regex::new(r"(-r[0-9]+)?\.ebuild").unwrap();
+    for entry in fs::read_dir(dir)? {
+        let path = entry?.path();
+        if let Some(name) = path.file_name() {
+            if ebuild_matcher.is_match(
+                name.to_str()
+                    .ok_or_else(|| anyhow!("converting filepath to UTF-8"))?,
+            ) {
+                return Ok(path);
+            }
+        }
+    }
+    bail!("could not find ebuild")
+}
+
+/// Run a given git command from inside a specified git dir.
+pub fn git_cd_cmd<I, S>(pwd: &Path, args: I) -> Result<Output>
+where
+    I: IntoIterator<Item = S>,
+    S: AsRef<OsStr>,
+{
+    let output = Command::new("git").current_dir(&pwd).args(args).output()?;
+    if !output.status.success() {
+        bail!("git command failed")
+    }
+    Ok(output)
+}
+
+pub fn repo_cd_cmd<I, S>(pwd: &Path, args: I) -> Result<()>
+where
+    I: IntoIterator<Item = S>,
+    S: AsRef<OsStr>,
+{
+    let status = Command::new("repo").current_dir(&pwd).args(args).status()?;
+    if !status.success() {
+        bail!("repo command failed")
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use rand::prelude::Rng;
+    use std::env;
+    use std::fs::File;
+
+    #[test]
+    fn test_revbump_ebuild() {
+        // Random number to append at the end of the test folder to prevent conflicts.
+        let rng: u32 = rand::thread_rng().gen();
+        let llvm_dir = env::temp_dir().join(format!("patch_sync_test_{}", rng));
+        fs::create_dir(&llvm_dir).expect("creating llvm dir in temp directory");
+
+        {
+            // With revision
+            let ebuild_name = "llvm-13.0_pre433403_p20211019-r10.ebuild";
+            let ebuild_path = llvm_dir.join(ebuild_name);
+            File::create(&ebuild_path).expect("creating test ebuild file");
+            let new_ebuild_path =
+                RepoSetupContext::rev_bump_llvm(&llvm_dir).expect("rev bumping the ebuild");
+            assert!(new_ebuild_path.ends_with("llvm-13.0_pre433403_p20211019-r11.ebuild"));
+            fs::remove_file(new_ebuild_path).expect("removing renamed ebuild file");
+        }
+        {
+            // Without revision
+            let ebuild_name = "llvm-13.0_pre433403_p20211019.ebuild";
+            let ebuild_path = llvm_dir.join(ebuild_name);
+            File::create(&ebuild_path).expect("creating test ebuild file");
+            let new_ebuild_path =
+                RepoSetupContext::rev_bump_llvm(&llvm_dir).expect("rev bumping the ebuild");
+            assert!(new_ebuild_path.ends_with("llvm-13.0_pre433403_p20211019-r1.ebuild"));
+            fs::remove_file(new_ebuild_path).expect("removing renamed ebuild file");
+        }
+
+        fs::remove_dir(&llvm_dir).expect("removing temp test dir");
+    }
+}