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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::borrow::Cow;
use std::ffi::OsStr;
use std::fmt::{self, Display};
use std::io;
use std::path::{Path, PathBuf};
use std::process::{Command, Stdio};
use log::debug;
use thiserror::Error;
use crate::prepare::{GitWorkArea, WorkAreaResult};
/// The Git object id of a commit.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct CommitId(String);
/// Errors which may occur when working with workareas.
#[derive(Debug, Error)]
#[non_exhaustive]
pub enum GitError {
/// Command preparation failure.
#[error("failed to construct 'git {}' command", subcommand)]
Subcommand {
/// The git subcommand which failed.
subcommand: &'static str,
/// The root cause of the failure.
#[source]
source: io::Error,
},
/// A git error occurred.
#[error("git error: '{}'", msg)]
Git {
/// Message describing what failed.
msg: Cow<'static, str>,
/// The root cause of the failure (if available).
#[source]
source: Option<io::Error>,
},
/// An invalid ref was used.
#[error("invalid git ref: '{}'", ref_)]
InvalidRef {
/// The invalid ref (or description of what was wrong).
ref_: Cow<'static, str>,
},
}
impl GitError {
/// Convenience method for constructing an error for a git subcommand failure.
pub fn subcommand(subcommand: &'static str, source: io::Error) -> Self {
GitError::Subcommand {
subcommand,
source,
}
}
pub(crate) fn git<M>(msg: M) -> Self
where
M: Into<Cow<'static, str>>,
{
GitError::Git {
msg: msg.into(),
source: None,
}
}
pub(crate) fn git_with_source<M>(msg: M, source: io::Error) -> Self
where
M: Into<Cow<'static, str>>,
{
GitError::Git {
msg: msg.into(),
source: Some(source),
}
}
pub(crate) fn invalid_ref<R>(ref_: R) -> Self
where
R: Into<Cow<'static, str>>,
{
GitError::InvalidRef {
ref_: ref_.into(),
}
}
}
pub(crate) type GitResult<T> = Result<T, GitError>;
impl CommitId {
/// Create a new `CommitId`.
pub fn new<I>(id: I) -> Self
where
I: Into<String>,
{
CommitId(id.into())
}
/// The commit as a string reference.
pub fn as_str(&self) -> &str {
&self.0
}
}
impl Display for CommitId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{}", self.as_str())
}
}
/// A context for performing git commands.
#[derive(Debug, Clone)]
pub struct GitContext {
/// The path to the `.git` directory.
///
/// Note that this must not be the path to a checkout. It is treated as a bare repository.
gitdir: PathBuf,
/// The path to the configuration file.
config: Option<PathBuf>,
}
/// An identity for creating git commits.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Identity {
/// The name.
pub name: String,
/// The email address.
pub email: String,
}
impl Identity {
/// Create a new identity.
pub fn new<N, E>(name: N, email: E) -> Self
where
N: Into<String>,
E: Into<String>,
{
Self {
name: name.into(),
email: email.into(),
}
}
}
impl Display for Identity {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{} <{}>", self.name, self.email)
}
}
/// Status of a merge check.
#[derive(Debug)]
pub enum MergeStatus {
/// The branches do not contain common history.
NoCommonHistory,
/// The branch has already been merged.
AlreadyMerged,
/// The branch is mergeable with the given hashes as merge bases.
Mergeable(Vec<CommitId>),
}
impl Display for MergeStatus {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{}",
match *self {
MergeStatus::NoCommonHistory => "no common history",
MergeStatus::AlreadyMerged => "already merged",
MergeStatus::Mergeable(_) => "mergeable",
},
)
}
}
impl GitContext {
/// Create a new context for the given directory.
pub fn new<P>(gitdir: P) -> Self
where
P: Into<PathBuf>,
{
Self {
gitdir: gitdir.into(),
config: None,
}
}
/// Create a new context for the given directory with git configuration.
pub fn new_with_config<P, C>(gitdir: P, config: C) -> Self
where
P: Into<PathBuf>,
C: Into<PathBuf>,
{
Self {
gitdir: gitdir.into(),
config: Some(config.into()),
}
}
/// Run a git command in the context.
///
/// This builds a `Command` with the proper environment to operate within the context.
pub fn git(&self) -> Command {
let mut git = Command::new("git");
git.env("GIT_DIR", &self.gitdir);
self.config
.as_ref()
.map(|config| git.env("GIT_CONFIG", config));
git
}
/// Fetch references from the given remote.
///
/// The remote is interpreted by Git, so it can be a remote or a specific URL.
pub fn fetch<R, I, N>(&self, remote: R, refnames: I) -> GitResult<()>
where
R: AsRef<str>,
I: IntoIterator<Item = N>,
N: AsRef<OsStr>,
{
let fetch = self
.git()
.arg("fetch")
.arg(remote.as_ref())
.args(refnames.into_iter())
.output()
.map_err(|err| GitError::subcommand("fetch", err))?;
if !fetch.status.success() {
return Err(GitError::git(format!(
"fetch from {} failed: {}",
remote.as_ref(),
String::from_utf8_lossy(&fetch.stderr)
)));
}
Ok(())
}
/// Fetch a commit from the given remote into a specific local refname.
pub fn fetch_into<R, N, T>(&self, remote: R, refname: N, target: T) -> GitResult<()>
where
R: AsRef<str>,
N: AsRef<str>,
T: AsRef<str>,
{
self.fetch(
remote,
[&format!("{}:{}", refname.as_ref(), target.as_ref())],
)
}
/// Fetch a commit from the given remote into a specific local refname, allowing rewinds.
pub fn force_fetch_into<R, N, T>(&self, remote: R, refname: N, target: T) -> GitResult<()>
where
R: AsRef<str>,
N: AsRef<str>,
T: AsRef<str>,
{
self.fetch_into(remote, format!("+{}", refname.as_ref()), target)
}
/// Determine the "default branch" for the repository.
pub fn default_branch(&self) -> GitResult<Option<String>> {
// Read the configuration value provided for this purpose.
let default_branch_name = self
.git()
.arg("config")
.arg("--get")
.arg("init.defaultBranchName")
.output()
.map_err(|err| GitError::subcommand("config --get init.defaultBranchName", err))?;
if default_branch_name.status.success() {
return Ok(Some(
String::from_utf8_lossy(&default_branch_name.stdout)
.trim()
.into(),
));
}
// Check `origin/HEAD` if it exists to avoid remote access.
let origin_head = self
.git()
.arg("symbolic-ref")
.arg("--short")
.arg("refs/remotes/origin/HEAD")
.output()
.map_err(|err| GitError::subcommand("symbolic-ref origin/HEAD", err))?;
if origin_head.status.success() {
const ORIGIN_PREFIX: &str = "origin/";
let full_refname = String::from_utf8_lossy(&origin_head.stdout);
let refname = full_refname.trim();
if let Some(on_origin) = refname.strip_prefix(ORIGIN_PREFIX) {
return Ok(Some(on_origin.into()));
}
}
// Ask the remote directly what its default branch is.
let ls_origin_head = self
.git()
.arg("ls-remote")
.arg("--symref")
.arg("origin")
.arg("HEAD")
.output()
.map_err(|err| GitError::subcommand("ls-remote --symref origin", err))?;
if ls_origin_head.status.success() {
const SYMREF_PREFIX: &str = "ref: refs/heads/";
const SYMREF_SUFFIX: &str = "\tHEAD";
let full_output = String::from_utf8_lossy(&ls_origin_head.stdout);
for line in full_output.lines() {
if line.starts_with(SYMREF_PREFIX) && line.ends_with(SYMREF_SUFFIX) {
let refname = &line[SYMREF_PREFIX.len()..(line.len() - SYMREF_SUFFIX.len())];
return Ok(Some(refname.into()));
}
}
}
// Unknown remote; use the local `HEAD` as the default.
let head = self
.git()
.arg("symbolic-ref")
.arg("--short")
.arg("HEAD")
.output()
.map_err(|err| GitError::subcommand("symbolic-ref HEAD", err))?;
if head.status.success() {
return Ok(Some(String::from_utf8_lossy(&head.stdout).trim().into()));
}
Ok(None)
}
/// Create a tree where further work on the given revision can occur.
pub fn prepare(&self, rev: &CommitId) -> WorkAreaResult<GitWorkArea> {
GitWorkArea::new(self.clone(), rev)
}
/// Reserve a refname for the given commit.
///
/// Returns the name of the reserved ref pointing to the given commit and its ID.
///
/// The reserved reference is created as `refs/{name}/heads/{id}` where `id` is a unique
/// integer (which is also returned).
pub fn reserve_ref<N>(&self, name: N, commit: &CommitId) -> GitResult<(String, usize)>
where
N: AsRef<str>,
{
let ref_prefix = format!("refs/{}/heads", name.as_ref());
debug!(target: "git", "reserving ref under {}", ref_prefix);
loop {
let for_each_ref = self
.git()
.arg("for-each-ref")
.arg("--format=%(refname)")
.arg("--")
.arg(&ref_prefix)
.output()
.map_err(|err| GitError::subcommand("for-each-ref", err))?;
if !for_each_ref.status.success() {
return Err(GitError::git(format!(
"listing all {} refs: {}",
ref_prefix,
String::from_utf8_lossy(&for_each_ref.stderr)
)));
}
let refs = String::from_utf8_lossy(&for_each_ref.stdout);
let nrefs = refs.lines().count();
let new_ref = format!("{}/{}", ref_prefix, nrefs);
debug!(target: "git", "trying to reserve ref {}", new_ref);
let lock_ref = self
.git()
.arg("update-ref")
.arg(&new_ref)
.arg(commit.as_str())
.arg("0000000000000000000000000000000000000000")
.stdout(Stdio::null())
.output()
.map_err(|err| GitError::git_with_source("update-ref", err))?;
if lock_ref.status.success() {
debug!(target: "git", "successfully reserved {}", new_ref);
return Ok((new_ref, nrefs));
}
let err = String::from_utf8_lossy(&lock_ref.stderr);
if err.contains("with nonexistent object") {
return Err(GitError::invalid_ref("no such commit"));
} else if err.contains("not a valid SHA1") {
return Err(GitError::invalid_ref("invalid SHA"));
}
}
}
/// Reserve two refnames for the given commit.
///
/// Returns the names of the two reserved refs, the first pointing to the given commit and the
/// second available for further work.
///
/// The reserved references are created as `refs/{name}/heads/{id}` and
/// `refs/{name}/bases/{id}` where the `bases` reference is available to point to an object
/// associated with the `heads` reference.
///
/// It is assumed that the `bases` refs are aligned with the `heads` references and not used
/// for other purposes.
pub fn reserve_refs<N>(&self, name: N, commit: &CommitId) -> GitResult<(String, String)>
where
N: AsRef<str>,
{
let (new_ref, id) = self.reserve_ref(name.as_ref(), commit)?;
let new_base = format!("refs/{}/bases/{}", name.as_ref(), id);
debug!(target: "git", "successfully reserved {} and {}", new_ref, new_base);
Ok((new_ref, new_base))
}
/// Check if a topic commit is mergeable into a target branch.
pub fn mergeable(&self, base: &CommitId, topic: &CommitId) -> GitResult<MergeStatus> {
let merge_base = self
.git()
.arg("merge-base")
.arg("--all") // find all merge bases
.arg(base.as_str())
.arg(topic.as_str())
.output()
.map_err(|err| GitError::subcommand("merge-base", err))?;
if !merge_base.status.success() {
return Ok(MergeStatus::NoCommonHistory);
}
let bases = String::from_utf8_lossy(&merge_base.stdout);
let bases = bases
.split_whitespace()
.map(CommitId::new)
.collect::<Vec<_>>();
Ok(if Some(topic) == bases.first() {
MergeStatus::AlreadyMerged
} else {
MergeStatus::Mergeable(bases)
})
}
/// The path to the git repository.
pub fn gitdir(&self) -> &Path {
&self.gitdir
}
}