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package main
import (
"bytes"
"context"
"errors"
"os/exec"
"path"
"strconv"
"strings"
"time"
"unicode/utf8"
)
type Git struct {
Dir string
}
type Commit struct {
Hash string
Author string
Email string
Time time.Time
Subject string
Body string
Parents []string
}
type Entry struct {
Mode string
Type string
Hash string
Size int64
Name string
}
type Ref struct {
Name string
Hash string
Time time.Time
}
type Line struct {
Kind string
Old int
New int
Text string
}
type Hunk struct {
Header string
Lines []Line
}
type File struct {
Old string
New string
Status string
Binary bool
Hunks []Hunk
Added int
Removed int
}
var ErrMissing = errors.New("missing")
func (g Git) run(stdin []byte, args ...string) ([]byte, error) {
ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
defer cancel()
cmd := exec.CommandContext(ctx, "git", append([]string{"-C", g.Dir}, args...)...)
cmd.Env = []string{"GIT_CONFIG_NOSYSTEM=1", "HOME=/nonexistent", "LC_ALL=C.UTF-8"}
if stdin != nil {
cmd.Stdin = bytes.NewReader(stdin)
}
var out, errb bytes.Buffer
cmd.Stdout = &out
cmd.Stderr = &errb
if err := cmd.Run(); err != nil {
msg := strings.TrimSpace(errb.String())
if msg == "" {
msg = err.Error()
}
return nil, errors.New(msg)
}
return out.Bytes(), nil
}
func initRepo(dir string) error {
_, err := Git{Dir: "/"}.run(nil, "init", "--bare", "--quiet", "-b", "main", dir)
return err
}
func (g Git) Empty() bool {
_, err := g.run(nil, "rev-parse", "--verify", "--quiet", "HEAD^{commit}")
return err != nil
}
func (g Git) Head() string {
out, err := g.run(nil, "symbolic-ref", "--short", "HEAD")
if err != nil {
return "main"
}
return strings.TrimSpace(string(out))
}
func (g Git) Resolve(ref string) (string, error) {
if strings.HasPrefix(ref, "-") {
return "", ErrMissing
}
out, err := g.run(nil, "rev-parse", "--verify", "--quiet", "--end-of-options", ref+"^{commit}")
if err != nil {
return "", ErrMissing
}
return strings.TrimSpace(string(out)), nil
}
const logFormat = "%H%x00%an%x00%ae%x00%at%x00%P%x00%s%x00%b%x00"
func parseCommits(out []byte) []Commit {
fields := strings.Split(string(out), "\x00")
var commits []Commit
for len(fields) >= 7 {
t, _ := strconv.ParseInt(fields[3], 10, 64)
c := Commit{Hash: fields[0], Author: fields[1], Email: fields[2], Time: time.Unix(t, 0), Subject: fields[5], Body: strings.TrimSpace(fields[6])}
if fields[4] != "" {
c.Parents = strings.Split(fields[4], " ")
}
commits = append(commits, c)
fields = fields[7:]
if len(fields) > 0 {
fields[0] = strings.TrimLeft(fields[0], "\n")
}
}
return commits
}
func (g Git) Log(commit string, n int, filePath string) ([]Commit, error) {
args := []string{"log", "--format=" + logFormat, "-n", strconv.Itoa(n), commit}
if filePath != "" {
args = append(args, "--", filePath)
}
out, err := g.run(nil, args...)
if err != nil {
return nil, err
}
return parseCommits(out), nil
}
func (g Git) Commit(hash string) (Commit, error) {
out, err := g.run(nil, "log", "--format="+logFormat, "-n", "1", hash)
if err != nil {
return Commit{}, ErrMissing
}
commits := parseCommits(out)
if len(commits) == 0 {
return Commit{}, ErrMissing
}
return commits[0], nil
}
func (g Git) Tree(commit, dir string) ([]Entry, error) {
spec := commit + ":" + dir
out, err := g.run(nil, "ls-tree", "-l", "-z", spec)
if err != nil {
return nil, ErrMissing
}
var entries []Entry
for _, rec := range bytes.Split(out, []byte{0}) {
if len(rec) == 0 {
continue
}
meta, name, ok := strings.Cut(string(rec), "\t")
if !ok {
continue
}
f := strings.Fields(meta)
if len(f) != 4 {
continue
}
e := Entry{Mode: f[0], Type: f[1], Hash: f[2], Name: name}
if f[3] != "-" {
e.Size, _ = strconv.ParseInt(f[3], 10, 64)
}
entries = append(entries, e)
}
return entries, nil
}
func (g Git) Blob(commit, filePath string) ([]byte, error) {
out, err := g.run(nil, "cat-file", "blob", commit+":"+filePath)
if err != nil {
return nil, ErrMissing
}
return out, nil
}
func (g Git) Kind(commit, filePath string) string {
out, err := g.run(nil, "cat-file", "-t", commit+":"+filePath)
if err != nil {
return ""
}
return strings.TrimSpace(string(out))
}
func (g Git) Refs(prefix string) ([]Ref, error) {
out, err := g.run(nil, "for-each-ref", "--sort=-creatordate", "--format=%(refname:short)%00%(objectname)%00%(creatordate:unix)", prefix)
if err != nil {
return nil, err
}
var refs []Ref
for _, line := range strings.Split(strings.TrimSpace(string(out)), "\n") {
f := strings.Split(line, "\x00")
if len(f) != 3 {
continue
}
t, _ := strconv.ParseInt(f[2], 10, 64)
refs = append(refs, Ref{Name: f[0], Hash: f[1], Time: time.Unix(t, 0)})
}
return refs, nil
}
func (g Git) Readme(commit string) (string, []byte) {
entries, err := g.Tree(commit, "")
if err != nil {
return "", nil
}
for _, name := range []string{"README.md", "README", "readme.md", "README.txt", "readme"} {
for _, e := range entries {
if e.Name == name && e.Type == "blob" {
data, err := g.Blob(commit, name)
if err == nil {
return name, data
}
}
}
}
return "", nil
}
func (g Git) Diff(hash string) ([]File, error) {
out, err := g.run(nil, "diff-tree", "-p", "--root", "-M", "--no-color", "--find-renames", hash)
if err != nil {
return nil, err
}
return parseDiff(string(out)), nil
}
func parseDiff(text string) []File {
var files []File
var cur *File
var hunk *Hunk
oldN, newN := 0, 0
for _, line := range strings.Split(text, "\n") {
switch {
case strings.HasPrefix(line, "diff --git "):
files = append(files, File{Status: "modified"})
cur = &files[len(files)-1]
hunk = nil
rest := strings.TrimPrefix(line, "diff --git ")
if a, b, ok := strings.Cut(rest, " b/"); ok {
cur.Old = strings.TrimPrefix(a, "a/")
cur.New = b
}
case cur == nil:
continue
case strings.HasPrefix(line, "new file mode"):
cur.Status = "added"
case strings.HasPrefix(line, "deleted file mode"):
cur.Status = "deleted"
case strings.HasPrefix(line, "rename from "):
cur.Status = "renamed"
cur.Old = strings.TrimPrefix(line, "rename from ")
case strings.HasPrefix(line, "rename to "):
cur.New = strings.TrimPrefix(line, "rename to ")
case strings.HasPrefix(line, "Binary files"):
cur.Binary = true
case strings.HasPrefix(line, "--- ") || strings.HasPrefix(line, "+++ ") || strings.HasPrefix(line, "index ") || strings.HasPrefix(line, "similarity ") || strings.HasPrefix(line, "old mode") || strings.HasPrefix(line, "new mode"):
continue
case strings.HasPrefix(line, "@@"):
cur.Hunks = append(cur.Hunks, Hunk{Header: line})
hunk = &cur.Hunks[len(cur.Hunks)-1]
oldN, newN = hunkStart(line)
case hunk == nil:
continue
case strings.HasPrefix(line, "+"):
hunk.Lines = append(hunk.Lines, Line{Kind: "add", New: newN, Text: line[1:]})
newN++
cur.Added++
case strings.HasPrefix(line, "-"):
hunk.Lines = append(hunk.Lines, Line{Kind: "del", Old: oldN, Text: line[1:]})
oldN++
cur.Removed++
case strings.HasPrefix(line, " "):
hunk.Lines = append(hunk.Lines, Line{Kind: "ctx", Old: oldN, New: newN, Text: line[1:]})
oldN++
newN++
case strings.HasPrefix(line, "\\"):
hunk.Lines = append(hunk.Lines, Line{Kind: "meta", Text: line})
}
}
return files
}
func hunkStart(header string) (int, int) {
f := strings.Fields(header)
if len(f) < 3 {
return 0, 0
}
parse := func(s string) int {
s = strings.TrimLeft(s, "-+")
if i := strings.Index(s, ","); i >= 0 {
s = s[:i]
}
n, _ := strconv.Atoi(s)
return n
}
return parse(f[1]), parse(f[2])
}
func isBinary(data []byte) bool {
head := data
if len(head) > 8000 {
head = head[:8000]
}
return bytes.IndexByte(head, 0) >= 0 || !utf8.Valid(head)
}
func cleanPath(p string) (string, bool) {
p = strings.Trim(p, "/")
if p == "" {
return "", true
}
c := path.Clean(p)
if c != p || strings.HasPrefix(c, "..") || strings.Contains(c, "/../") || strings.HasPrefix(c, "-") {
return "", false
}
return c, true
}
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