tools/src/git/git.go - dawn - Git at Google

 // Copyright 2022 The Tint Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 // Package git provides helpers for interfacing with the git tool
 package git

 import (
 	"context"
 	"encoding/hex"
 	"errors"
 	"fmt"
 	"net/url"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
 )

 // Hash is a 20 byte, git object hash.
 type Hash [20]byte

 func (h Hash) String() string { return hex.EncodeToString(h[:]) }

 // IsZero returns true if the hash h is all zeros
 func (h Hash) IsZero() bool {
 	zero := Hash{}
 	return h == zero
 }

 // ParseHash returns a Hash from a hexadecimal string.
 func ParseHash(s string) (Hash, error) {
 	b, err := hex.DecodeString(s)
 	if err != nil {
 		return Hash{}, fmt.Errorf("failed to parse hash '%v':\n  %w", s, err)
 	}
 	h := Hash{}
 	copy(h[:], b)
 	return h, nil
 }

 // The timeout for git operations if no other timeout is specified
 var DefaultTimeout = time.Minute

 // Git wraps the 'git' executable
 type Git struct {
 	// Path to the git executable
 	exe string
 	// Debug flag to print all command to the `git` executable
 	LogAllActions bool
 }

 // New returns a new Git instance
 func New(exe string) (*Git, error) {
 	if _, err := os.Stat(exe); err != nil {
 		return nil, err
 	}
 	return &Git{exe: exe}, nil
 }

 // Credentials holds the user name and password used to perform git operations.
 type Credentials struct {
 	Username string
 	Password string
 }

 // Empty return true if there's no username or password for authentication
 func (a Credentials) Empty() bool {
 	return a.Username == "" && a.Password == ""
 }

 // addToURL returns the url with the credentials appended
 func (c Credentials) addToURL(u string) (string, error) {
 	if !c.Empty() {
 		modified, err := url.Parse(u)
 		if err != nil {
 			return "", fmt.Errorf("failed to parse url '%v': %v", u, err)
 		}
 		modified.User = url.UserPassword(c.Username, c.Password)
 		u = modified.String()
 	}
 	return u, nil
 }

 // ErrRepositoryDoesNotExist indicates that a repository does not exist
 var ErrRepositoryDoesNotExist = errors.New("repository does not exist")

 // Open opens an existing git repo at path. If the repository does not exist at
 // path then ErrRepositoryDoesNotExist is returned.
 func (g Git) Open(path string) (*Repository, error) {
 	info, err := os.Stat(filepath.Join(path, ".git"))
 	if err != nil || !info.IsDir() {
 		return nil, ErrRepositoryDoesNotExist
 	}
 	return &Repository{g, path}, nil
 }

 // Optional settings for Git.Clone
 type CloneOptions struct {
 	// If specified then the given branch will be cloned instead of the default
 	Branch string
 	// Timeout for the operation
 	Timeout time.Duration
 	// Authentication for the clone
 	Credentials Credentials
 }

 // Clone performs a clone of the repository at url to path.
 func (g Git) Clone(path, url string, opt *CloneOptions) (*Repository, error) {
 	if err := os.MkdirAll(path, 0777); err != nil {
 		return nil, err
 	}
 	if opt == nil {
 		opt = &CloneOptions{}
 	}
 	url, err := opt.Credentials.addToURL(url)
 	if err != nil {
 		return nil, err
 	}
 	r := &Repository{g, path}
 	args := []string{"clone", url, "."}
 	if opt.Branch != "" {
 		args = append(args, "--branch", opt.Branch)
 	}
 	if _, err := r.run(nil, opt.Timeout, args...); err != nil {
 		return nil, err
 	}
 	return r, nil
 }

 // Repository points to a git repository
 type Repository struct {
 	// Path to the 'git' executable
 	Git Git
 	// Repo directory
 	Path string
 }

 // Optional settings for Repository.Fetch
 type FetchOptions struct {
 	// The remote name. Defaults to 'origin'
 	Remote string
 	// Timeout for the operation
 	Timeout time.Duration
 	// Git authentication for the remote
 	Credentials Credentials
 }

 // Fetch performs a fetch of a reference from the remote, returning the Hash of
 // the fetched reference.
 func (r Repository) Fetch(ref string, opt *FetchOptions) (Hash, error) {
 	if opt == nil {
 		opt = &FetchOptions{}
 	}
 	if opt.Remote == "" {
 		opt.Remote = "origin"
 	}
 	if _, err := r.run(nil, opt.Timeout, "fetch", opt.Remote, ref); err != nil {
 		return Hash{}, err
 	}
 	out, err := r.run(nil, 0, "rev-parse", "FETCH_HEAD")
 	if err != nil {
 		return Hash{}, err
 	}
 	return ParseHash(out)
 }

 // Optional settings for Repository.Push
 type PushOptions struct {
 	// The remote name. Defaults to 'origin'
 	Remote string
 	// Timeout for the operation
 	Timeout time.Duration
 	// Git authentication for the remote
 	Credentials Credentials
 }

 // Push performs a push of the local reference to the remote reference.
 func (r Repository) Push(localRef, remoteRef string, opt *PushOptions) error {
 	if opt == nil {
 		opt = &PushOptions{}
 	}
 	if opt.Remote == "" {
 		opt.Remote = "origin"
 	}
 	url, err := r.run(nil, opt.Timeout, "remote", "get-url", opt.Remote)
 	if err != nil {
 		return err
 	}
 	url, err = opt.Credentials.addToURL(url)
 	if err != nil {
 		return err
 	}
 	if _, err := r.run(nil, opt.Timeout, "push", url, localRef+":"+remoteRef); err != nil {
 		return err
 	}
 	return nil
 }

 // Optional settings for Repository.Add
 type AddOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 	// Git authentication for the remote
 	Credentials Credentials
 }

 // Add stages the listed files
 func (r Repository) Add(path string, opt *AddOptions) error {
 	if opt == nil {
 		opt = &AddOptions{}
 	}
 	if _, err := r.run(nil, opt.Timeout, "add", path); err != nil {
 		return err
 	}
 	return nil
 }

 // Optional settings for Repository.Commit
 type CommitOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 	// Author name
 	AuthorName string
 	// Author email address
 	AuthorEmail string
 	// Amend last commit?
 	Amend bool
 }

 // Commit commits the staged files with the given message, returning the hash of
 // commit
 func (r Repository) Commit(msg string, opt *CommitOptions) (Hash, error) {
 	if opt == nil {
 		opt = &CommitOptions{}
 	}

 	args := []string{"commit"}
 	if opt.Amend {
 		args = append(args, "--amend")
 	} else {
 		args = append(args, "-m", msg)
 	}

 	var env []string
 	if opt.AuthorName != "" || opt.AuthorEmail != "" {
 		env = []string{
 			fmt.Sprintf("GIT_AUTHOR_NAME=%v", opt.AuthorName),
 			fmt.Sprintf("GIT_AUTHOR_EMAIL=%v", opt.AuthorEmail),
 			fmt.Sprintf("GIT_COMMITTER_NAME=%v", opt.AuthorName),
 			fmt.Sprintf("GIT_COMMITTER_EMAIL=%v", opt.AuthorEmail),
 		}
 	}
 	if _, err := r.run(env, opt.Timeout, "commit", "-m", msg); err != nil {
 		return Hash{}, err
 	}
 	out, err := r.run(nil, 0, "rev-parse", "HEAD")
 	if err != nil {
 		return Hash{}, err
 	}
 	return ParseHash(out)
 }

 // Optional settings for Repository.Checkout
 type CheckoutOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 }

 // Checkout performs a checkout of a reference.
 func (r Repository) Checkout(ref string, opt *CheckoutOptions) error {
 	if opt == nil {
 		opt = &CheckoutOptions{}
 	}
 	if _, err := r.run(nil, opt.Timeout, "checkout", ref); err != nil {
 		return err
 	}
 	return nil
 }

 // Optional settings for Repository.Log
 type LogOptions struct {
 	// The git reference to the oldest commit in the range to query.
 	From string
 	// The git reference to the newest commit in the range to query.
 	To string
 	// Timeout for the operation
 	Timeout time.Duration
 }

 const logPrettyFormatArg = "--pretty=format:ǁ%Hǀ%cIǀ%an <%ae>ǀ%sǀ%b"

 // Log returns the list of commits between two references (inclusive).
 // The first returned commit is the most recent.
 func (r Repository) Log(opt *LogOptions) ([]CommitInfo, error) {
 	if opt == nil {
 		opt = &LogOptions{}
 	}
 	args := []string{"log"}
 	rng := "HEAD"
 	if opt.To != "" {
 		rng = opt.To
 	}
 	if opt.From != "" {
 		rng = opt.From + "^.." + rng
 	}
 	args = append(args, rng, logPrettyFormatArg)
 	out, err := r.run(nil, opt.Timeout, args...)
 	if err != nil {
 		return nil, err
 	}
 	return parseLog(out)
 }

 // Optional settings for Repository.LogBetween
 type LogBetweenOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 }

 // LogBetween returns the list of commits between two timestamps
 // The first returned commit is the most recent.
 func (r Repository) LogBetween(since, until time.Time, opt *LogBetweenOptions) ([]CommitInfo, error) {
 	if opt == nil {
 		opt = &LogBetweenOptions{}
 	}
 	args := []string{"log",
 		"--since", since.Format(time.RFC3339),
 		"--until", until.Format(time.RFC3339),
 		logPrettyFormatArg,
 	}
 	out, err := r.run(nil, opt.Timeout, args...)
 	if err != nil {
 		return nil, err
 	}
 	return parseLog(out)
 }

 // FileStats describes the changes to a given file in a commit
 type FileStats struct {
 	Insertions int
 	Deletions  int
 }

 // CommitStats is a map of file to FileStats
 type CommitStats map[string]FileStats

 // Optional settings for Repository.Stats
 type StatsOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 }

 // StatsOptions returns the statistics for a given change
 func (r Repository) Stats(commit CommitInfo, opt *StatsOptions) (CommitStats, error) {
 	if opt == nil {
 		opt = &StatsOptions{}
 	}

 	hash := commit.Hash.String()
 	args := []string{"diff", "--numstat", hash, hash + "^"}
 	out, err := r.run(nil, opt.Timeout, args...)
 	if err != nil {
 		return nil, err
 	}
 	stats := CommitStats{}
 	for _, line := range strings.Split(out, "\n") {
 		if out == "" {
 			continue
 		}
 		parts := strings.Split(line, "\t")
 		if len(parts) != 3 {
 			return nil, fmt.Errorf("failed to parse stat line: '%v'", line)
 		}
 		insertions, deletions := 0, 0
 		if parts[0] != "-" {
 			insertions, err = strconv.Atoi(parts[0])
 			if err != nil {
 				return nil, fmt.Errorf("failed to stat insertions '%v': %w", parts[0], err)
 			}
 		}
 		if parts[1] != "-" {
 			deletions, err = strconv.Atoi(parts[1])
 			if err != nil {
 				return nil, fmt.Errorf("failed to stat deletions '%v': %w", parts[1], err)
 			}
 		}
 		file := parts[2]
 		stats[file] = FileStats{Insertions: insertions, Deletions: deletions}
 	}
 	return stats, nil
 }

 // CommitInfo describes a single git commit
 type CommitInfo struct {
 	Hash        Hash
 	Date        time.Time
 	Author      string
 	Subject     string
 	Description string
 }

 // Optional settings for Repository.ConfigOptions
 type ConfigOptions struct {
 	// Timeout for the operation
 	Timeout time.Duration
 }

 // Config returns the git configuration values for the repo
 func (r Repository) Config(opt *ConfigOptions) (map[string]string, error) {
 	if opt == nil {
 		opt = &ConfigOptions{}
 	}
 	text, err := r.run(nil, opt.Timeout, "config", "-l")
 	if err != nil {
 		return nil, err
 	}
 	lines := strings.Split(text, "\n")
 	out := make(map[string]string, len(lines))
 	for _, line := range lines {
 		idx := strings.Index(line, "=")
 		if idx > 0 {
 			key, value := line[:idx], line[idx+1:]
 			out[key] = value
 		}
 	}
 	return out, nil
 }

 func (r Repository) run(env []string, timeout time.Duration, args ...string) (string, error) {
 	return r.Git.run(r.Path, env, timeout, args...)
 }

 func (g Git) run(dir string, env []string, timeout time.Duration, args ...string) (string, error) {
 	if timeout == 0 {
 		timeout = DefaultTimeout
 	}
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
 	defer cancel()
 	cmd := exec.CommandContext(ctx, g.exe, args...)
 	cmd.Dir = dir
 	if env != nil {
 		// Godocs for exec.Cmd.Env:
 		// "If Env contains duplicate environment keys, only the last value in
 		// the slice for each duplicate key is used.
 		cmd.Env = append(os.Environ(), env...)
 	}
 	if g.LogAllActions {
 		fmt.Printf("%v> %v %v\n", dir, g.exe, strings.Join(args, " "))
 	}
 	out, err := cmd.CombinedOutput()
 	if g.LogAllActions {
 		fmt.Println(string(out))
 	}
 	if err != nil {
 		return string(out), fmt.Errorf("%v> %v %v failed:\n  %w\n%v",
 			dir, g.exe, strings.Join(args, " "), err, string(out))
 	}
 	return strings.TrimSpace(string(out)), nil
 }

 func parseLog(str string) ([]CommitInfo, error) {
 	msgs := strings.Split(str, "ǁ")
 	cls := make([]CommitInfo, 0, len(msgs))
 	for _, s := range msgs {
 		if parts := strings.Split(s, "ǀ"); len(parts) == 5 {
 			hash, err := ParseHash(parts[0])
 			if err != nil {
 				return nil, err
 			}
 			date, err := time.Parse(time.RFC3339, parts[1])
 			if err != nil {
 				return nil, err
 			}
 			cl := CommitInfo{
 				Hash:        hash,
 				Date:        date,
 				Author:      strings.TrimSpace(parts[2]),
 				Subject:     strings.TrimSpace(parts[3]),
 				Description: strings.TrimSpace(parts[4]),
 			}

 			cls = append(cls, cl)
 		}
 	}
 	return cls, nil
 }
	// Copyright 2022 The Tint Authors.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	// Package git provides helpers for interfacing with the git tool
	package git

	import (
	"context"
	"encoding/hex"
	"errors"
	"fmt"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"time"
	)

	// Hash is a 20 byte, git object hash.
	type Hash [20]byte

	func (h Hash) String() string { return hex.EncodeToString(h[:]) }

	// IsZero returns true if the hash h is all zeros
	func (h Hash) IsZero() bool {
	zero := Hash{}
	return h == zero
	}

	// ParseHash returns a Hash from a hexadecimal string.
	func ParseHash(s string) (Hash, error) {
	b, err := hex.DecodeString(s)
	if err != nil {
	return Hash{}, fmt.Errorf("failed to parse hash '%v':\n %w", s, err)
	}
	h := Hash{}
	copy(h[:], b)
	return h, nil
	}

	// The timeout for git operations if no other timeout is specified
	var DefaultTimeout = time.Minute

	// Git wraps the 'git' executable
	type Git struct {
	// Path to the git executable
	exe string
	// Debug flag to print all command to the `git` executable
	LogAllActions bool
	}

	// New returns a new Git instance
	func New(exe string) (*Git, error) {
	if _, err := os.Stat(exe); err != nil {
	return nil, err
	}
	return &Git{exe: exe}, nil
	}

	// Credentials holds the user name and password used to perform git operations.
	type Credentials struct {
	Username string
	Password string
	}

	// Empty return true if there's no username or password for authentication
	func (a Credentials) Empty() bool {
	return a.Username == "" && a.Password == ""
	}

	// addToURL returns the url with the credentials appended
	func (c Credentials) addToURL(u string) (string, error) {
	if !c.Empty() {
	modified, err := url.Parse(u)
	if err != nil {
	return "", fmt.Errorf("failed to parse url '%v': %v", u, err)
	}
	modified.User = url.UserPassword(c.Username, c.Password)
	u = modified.String()
	}
	return u, nil
	}

	// ErrRepositoryDoesNotExist indicates that a repository does not exist
	var ErrRepositoryDoesNotExist = errors.New("repository does not exist")

	// Open opens an existing git repo at path. If the repository does not exist at
	// path then ErrRepositoryDoesNotExist is returned.
	func (g Git) Open(path string) (*Repository, error) {
	info, err := os.Stat(filepath.Join(path, ".git"))
	if err != nil \|\| !info.IsDir() {
	return nil, ErrRepositoryDoesNotExist
	}
	return &Repository{g, path}, nil
	}

	// Optional settings for Git.Clone
	type CloneOptions struct {
	// If specified then the given branch will be cloned instead of the default
	Branch string
	// Timeout for the operation
	Timeout time.Duration
	// Authentication for the clone
	Credentials Credentials
	}

	// Clone performs a clone of the repository at url to path.
	func (g Git) Clone(path, url string, opt CloneOptions) (Repository, error) {
	if err := os.MkdirAll(path, 0777); err != nil {
	return nil, err
	}
	if opt == nil {
	opt = &CloneOptions{}
	}
	url, err := opt.Credentials.addToURL(url)
	if err != nil {
	return nil, err
	}
	r := &Repository{g, path}
	args := []string{"clone", url, "."}
	if opt.Branch != "" {
	args = append(args, "--branch", opt.Branch)
	}
	if _, err := r.run(nil, opt.Timeout, args...); err != nil {
	return nil, err
	}
	return r, nil
	}

	// Repository points to a git repository
	type Repository struct {
	// Path to the 'git' executable
	Git Git
	// Repo directory
	Path string
	}

	// Optional settings for Repository.Fetch
	type FetchOptions struct {
	// The remote name. Defaults to 'origin'
	Remote string
	// Timeout for the operation
	Timeout time.Duration
	// Git authentication for the remote
	Credentials Credentials
	}

	// Fetch performs a fetch of a reference from the remote, returning the Hash of
	// the fetched reference.
	func (r Repository) Fetch(ref string, opt *FetchOptions) (Hash, error) {
	if opt == nil {
	opt = &FetchOptions{}
	}
	if opt.Remote == "" {
	opt.Remote = "origin"
	}
	if _, err := r.run(nil, opt.Timeout, "fetch", opt.Remote, ref); err != nil {
	return Hash{}, err
	}
	out, err := r.run(nil, 0, "rev-parse", "FETCH_HEAD")
	if err != nil {
	return Hash{}, err
	}
	return ParseHash(out)
	}

	// Optional settings for Repository.Push
	type PushOptions struct {
	// The remote name. Defaults to 'origin'
	Remote string
	// Timeout for the operation
	Timeout time.Duration
	// Git authentication for the remote
	Credentials Credentials
	}

	// Push performs a push of the local reference to the remote reference.
	func (r Repository) Push(localRef, remoteRef string, opt *PushOptions) error {
	if opt == nil {
	opt = &PushOptions{}
	}
	if opt.Remote == "" {
	opt.Remote = "origin"
	}
	url, err := r.run(nil, opt.Timeout, "remote", "get-url", opt.Remote)
	if err != nil {
	return err
	}
	url, err = opt.Credentials.addToURL(url)
	if err != nil {
	return err
	}
	if _, err := r.run(nil, opt.Timeout, "push", url, localRef+":"+remoteRef); err != nil {
	return err
	}
	return nil
	}

	// Optional settings for Repository.Add
	type AddOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	// Git authentication for the remote
	Credentials Credentials
	}

	// Add stages the listed files
	func (r Repository) Add(path string, opt *AddOptions) error {
	if opt == nil {
	opt = &AddOptions{}
	}
	if _, err := r.run(nil, opt.Timeout, "add", path); err != nil {
	return err
	}
	return nil
	}

	// Optional settings for Repository.Commit
	type CommitOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	// Author name
	AuthorName string
	// Author email address
	AuthorEmail string
	// Amend last commit?
	Amend bool
	}

	// Commit commits the staged files with the given message, returning the hash of
	// commit
	func (r Repository) Commit(msg string, opt *CommitOptions) (Hash, error) {
	if opt == nil {
	opt = &CommitOptions{}
	}

	args := []string{"commit"}
	if opt.Amend {
	args = append(args, "--amend")
	} else {
	args = append(args, "-m", msg)
	}

	var env []string
	if opt.AuthorName != "" \|\| opt.AuthorEmail != "" {
	env = []string{
	fmt.Sprintf("GIT_AUTHOR_NAME=%v", opt.AuthorName),
	fmt.Sprintf("GIT_AUTHOR_EMAIL=%v", opt.AuthorEmail),
	fmt.Sprintf("GIT_COMMITTER_NAME=%v", opt.AuthorName),
	fmt.Sprintf("GIT_COMMITTER_EMAIL=%v", opt.AuthorEmail),
	}
	}
	if _, err := r.run(env, opt.Timeout, "commit", "-m", msg); err != nil {
	return Hash{}, err
	}
	out, err := r.run(nil, 0, "rev-parse", "HEAD")
	if err != nil {
	return Hash{}, err
	}
	return ParseHash(out)
	}

	// Optional settings for Repository.Checkout
	type CheckoutOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	}

	// Checkout performs a checkout of a reference.
	func (r Repository) Checkout(ref string, opt *CheckoutOptions) error {
	if opt == nil {
	opt = &CheckoutOptions{}
	}
	if _, err := r.run(nil, opt.Timeout, "checkout", ref); err != nil {
	return err
	}
	return nil
	}

	// Optional settings for Repository.Log
	type LogOptions struct {
	// The git reference to the oldest commit in the range to query.
	From string
	// The git reference to the newest commit in the range to query.
	To string
	// Timeout for the operation
	Timeout time.Duration
	}

	const logPrettyFormatArg = "--pretty=format:ǁ%Hǀ%cIǀ%an <%ae>ǀ%sǀ%b"

	// Log returns the list of commits between two references (inclusive).
	// The first returned commit is the most recent.
	func (r Repository) Log(opt *LogOptions) ([]CommitInfo, error) {
	if opt == nil {
	opt = &LogOptions{}
	}
	args := []string{"log"}
	rng := "HEAD"
	if opt.To != "" {
	rng = opt.To
	}
	if opt.From != "" {
	rng = opt.From + "^.." + rng
	}
	args = append(args, rng, logPrettyFormatArg)
	out, err := r.run(nil, opt.Timeout, args...)
	if err != nil {
	return nil, err
	}
	return parseLog(out)
	}

	// Optional settings for Repository.LogBetween
	type LogBetweenOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	}

	// LogBetween returns the list of commits between two timestamps
	// The first returned commit is the most recent.
	func (r Repository) LogBetween(since, until time.Time, opt *LogBetweenOptions) ([]CommitInfo, error) {
	if opt == nil {
	opt = &LogBetweenOptions{}
	}
	args := []string{"log",
	"--since", since.Format(time.RFC3339),
	"--until", until.Format(time.RFC3339),
	logPrettyFormatArg,
	}
	out, err := r.run(nil, opt.Timeout, args...)
	if err != nil {
	return nil, err
	}
	return parseLog(out)
	}

	// FileStats describes the changes to a given file in a commit
	type FileStats struct {
	Insertions int
	Deletions int
	}

	// CommitStats is a map of file to FileStats
	type CommitStats map[string]FileStats

	// Optional settings for Repository.Stats
	type StatsOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	}

	// StatsOptions returns the statistics for a given change
	func (r Repository) Stats(commit CommitInfo, opt *StatsOptions) (CommitStats, error) {
	if opt == nil {
	opt = &StatsOptions{}
	}

	hash := commit.Hash.String()
	args := []string{"diff", "--numstat", hash, hash + "^"}
	out, err := r.run(nil, opt.Timeout, args...)
	if err != nil {
	return nil, err
	}
	stats := CommitStats{}
	for _, line := range strings.Split(out, "\n") {
	if out == "" {
	continue
	}
	parts := strings.Split(line, "\t")
	if len(parts) != 3 {
	return nil, fmt.Errorf("failed to parse stat line: '%v'", line)
	}
	insertions, deletions := 0, 0
	if parts[0] != "-" {
	insertions, err = strconv.Atoi(parts[0])
	if err != nil {
	return nil, fmt.Errorf("failed to stat insertions '%v': %w", parts[0], err)
	}
	}
	if parts[1] != "-" {
	deletions, err = strconv.Atoi(parts[1])
	if err != nil {
	return nil, fmt.Errorf("failed to stat deletions '%v': %w", parts[1], err)
	}
	}
	file := parts[2]
	stats[file] = FileStats{Insertions: insertions, Deletions: deletions}
	}
	return stats, nil
	}

	// CommitInfo describes a single git commit
	type CommitInfo struct {
	Hash Hash
	Date time.Time
	Author string
	Subject string
	Description string
	}

	// Optional settings for Repository.ConfigOptions
	type ConfigOptions struct {
	// Timeout for the operation
	Timeout time.Duration
	}

	// Config returns the git configuration values for the repo
	func (r Repository) Config(opt *ConfigOptions) (map[string]string, error) {
	if opt == nil {
	opt = &ConfigOptions{}
	}
	text, err := r.run(nil, opt.Timeout, "config", "-l")
	if err != nil {
	return nil, err
	}
	lines := strings.Split(text, "\n")
	out := make(map[string]string, len(lines))
	for _, line := range lines {
	idx := strings.Index(line, "=")
	if idx > 0 {
	key, value := line[:idx], line[idx+1:]
	out[key] = value
	}
	}
	return out, nil
	}

	func (r Repository) run(env []string, timeout time.Duration, args ...string) (string, error) {
	return r.Git.run(r.Path, env, timeout, args...)
	}

	func (g Git) run(dir string, env []string, timeout time.Duration, args ...string) (string, error) {
	if timeout == 0 {
	timeout = DefaultTimeout
	}
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	cmd := exec.CommandContext(ctx, g.exe, args...)
	cmd.Dir = dir
	if env != nil {
	// Godocs for exec.Cmd.Env:
	// "If Env contains duplicate environment keys, only the last value in
	// the slice for each duplicate key is used.
	cmd.Env = append(os.Environ(), env...)
	}
	if g.LogAllActions {
	fmt.Printf("%v> %v %v\n", dir, g.exe, strings.Join(args, " "))
	}
	out, err := cmd.CombinedOutput()
	if g.LogAllActions {
	fmt.Println(string(out))
	}
	if err != nil {
	return string(out), fmt.Errorf("%v> %v %v failed:\n %w\n%v",
	dir, g.exe, strings.Join(args, " "), err, string(out))
	}
	return strings.TrimSpace(string(out)), nil
	}

	func parseLog(str string) ([]CommitInfo, error) {
	msgs := strings.Split(str, "ǁ")
	cls := make([]CommitInfo, 0, len(msgs))
	for _, s := range msgs {
	if parts := strings.Split(s, "ǀ"); len(parts) == 5 {
	hash, err := ParseHash(parts[0])
	if err != nil {
	return nil, err
	}
	date, err := time.Parse(time.RFC3339, parts[1])
	if err != nil {
	return nil, err
	}
	cl := CommitInfo{
	Hash: hash,
	Date: date,
	Author: strings.TrimSpace(parts[2]),
	Subject: strings.TrimSpace(parts[3]),
	Description: strings.TrimSpace(parts[4]),
	}

	cls = append(cls, cl)
	}
	}
	return cls, nil
	}