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package gitutil
import (
"bufio"
"bytes"
"context"
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"sort"
"strings"
)
type Git struct {
Dir string
}
func (g Git) command(ctx context.Context, args ...string) *exec.Cmd {
if g.Dir != "" {
args = append([]string{"-C", g.Dir}, args...)
}
// #nosec G204 -- arguments are passed directly to Git without a shell.
return exec.CommandContext(ctx, "git", args...)
}
func (g Git) Run(ctx context.Context, args ...string) ([]byte, error) {
cmd := g.command(ctx, args...)
var stderr bytes.Buffer
cmd.Stderr = &stderr
out, err := cmd.Output()
if err != nil {
message := strings.TrimSpace(stderr.String())
if message == "" {
message = err.Error()
}
return nil, fmt.Errorf("git %s: %s", strings.Join(args, " "), message)
}
return out, nil
}
// RunLimited captures at most limit bytes while continuing to drain Git's
// output. This keeps generated-site features from allocating without bound on
// unusually large objects while still allowing Git to exit cleanly.
func (g Git) RunLimited(ctx context.Context, limit int, args ...string) ([]byte, bool, error) {
cmd := g.command(ctx, args...)
output := limitedOutput{limit: limit}
var stderr bytes.Buffer
cmd.Stdout = &output
cmd.Stderr = &stderr
if err := cmd.Run(); err != nil {
message := strings.TrimSpace(stderr.String())
if message == "" {
message = err.Error()
}
return nil, false, fmt.Errorf("git %s: %s", strings.Join(args, " "), message)
}
return output.Bytes(), output.truncated, nil
}
type limitedOutput struct {
bytes.Buffer
limit int
truncated bool
}
func (w *limitedOutput) Write(value []byte) (int, error) {
written := len(value)
remaining := w.limit - w.Len()
if remaining <= 0 {
w.truncated = w.truncated || written > 0
return written, nil
}
if len(value) > remaining {
value = value[:remaining]
w.truncated = true
}
_, _ = w.Buffer.Write(value)
return written, nil
}
func (g Git) RevParse(ctx context.Context, rev string) (string, error) {
out, err := g.Run(ctx, "rev-parse", "--verify", rev)
if err != nil {
return "", err
}
return strings.TrimSpace(string(out)), nil
}
func (g Git) SymbolicRef(ctx context.Context, name string) (string, error) {
out, err := g.Run(ctx, "symbolic-ref", "--quiet", name)
if err != nil {
return "", err
}
return strings.TrimSpace(string(out)), nil
}
func (g Git) Peel(ctx context.Context, oid string) (string, error) {
out, err := g.Run(ctx, "rev-parse", "--verify", oid+"^{}")
if err != nil {
return "", err
}
return strings.TrimSpace(string(out)), nil
}
func (g Git) ObjectExists(ctx context.Context, oid string) bool {
cmd := g.command(ctx, "cat-file", "-e", oid+"^{object}")
return cmd.Run() == nil
}
func (g Git) IsShallow(ctx context.Context) (bool, error) {
out, err := g.Run(ctx, "rev-parse", "--is-shallow-repository")
if err != nil {
return false, err
}
return strings.TrimSpace(string(out)) == "true", nil
}
func (g Git) IsAncestor(ctx context.Context, older, newer string) (bool, error) {
cmd := g.command(ctx, "merge-base", "--is-ancestor", older, newer)
err := cmd.Run()
if err == nil {
return true, nil
}
var exitErr *exec.ExitError
if errors.As(err, &exitErr) && exitErr.ExitCode() == 1 {
return false, nil
}
return false, fmt.Errorf("check whether %s is an ancestor of %s: %w", older, newer, err)
}
func (g Git) CheckRef(ctx context.Context, ref string) error {
cmd := g.command(ctx, "check-ref-format", ref)
if err := cmd.Run(); err != nil {
return fmt.Errorf("invalid destination ref %q", ref)
}
return nil
}
type Pack struct {
Hash string
PackPath string
IndexPath string
Objects uint32
cleanup func()
}
type LooseObject struct {
OID string
Path string
Size int64
}
func (p *Pack) Close() {
if p != nil && p.cleanup != nil {
p.cleanup()
}
}
func (g Git) PackObjects(ctx context.Context, wants, possibleHaves []string) (*Pack, error) {
wants = unique(wants)
if len(wants) == 0 {
return nil, nil
}
haves := make([]string, 0, len(possibleHaves))
for _, oid := range unique(possibleHaves) {
if g.ObjectExists(ctx, oid) {
haves = append(haves, oid)
}
}
tmpDir, err := os.MkdirTemp("", "dumbforge-pack-*")
if err != nil {
return nil, err
}
cleanup := func() { _ = os.RemoveAll(tmpDir) }
base := filepath.Join(tmpDir, "pack")
cmd := g.command(ctx, "pack-objects", "--revs", "--delta-base-offset", base)
var input strings.Builder
for _, oid := range wants {
fmt.Fprintln(&input, oid)
}
for _, oid := range haves {
fmt.Fprintf(&input, "^%s\n", oid)
}
cmd.Stdin = strings.NewReader(input.String())
var stderr bytes.Buffer
cmd.Stderr = &stderr
out, err := cmd.Output()
if err != nil {
cleanup()
return nil, fmt.Errorf("create incremental pack: %s", strings.TrimSpace(stderr.String()))
}
hash := strings.TrimSpace(string(out))
packPath := base + "-" + hash + ".pack"
indexPath := base + "-" + hash + ".idx"
count, err := packObjectCount(packPath)
if err != nil {
cleanup()
return nil, err
}
return &Pack{
Hash: hash,
PackPath: packPath,
IndexPath: indexPath,
Objects: count,
cleanup: cleanup,
}, nil
}
// SmallLooseObjects returns the objects represented by a small pack when all
// of them still exist in the repository's loose-object store. Recent commits
// normally satisfy this, allowing an object-store remote to avoid publishing a
// pack index and pack-list update for tiny pushes.
func (g Git) SmallLooseObjects(ctx context.Context, pack *Pack, maxObjects int, maxBytes int64) ([]LooseObject, bool, error) {
if pack == nil || pack.Objects == 0 || int(pack.Objects) > maxObjects {
return nil, false, nil
}
out, err := g.Run(ctx, "verify-pack", "-v", pack.IndexPath)
if err != nil {
return nil, false, err
}
var oids []string
for _, line := range strings.Split(string(out), "\n") {
fields := strings.Fields(line)
if len(fields) < 2 || !isObjectID(fields[0]) {
continue
}
oids = append(oids, fields[0])
}
if len(oids) != int(pack.Objects) {
return nil, false, nil
}
objectsOutput, err := g.Run(ctx, "rev-parse", "--path-format=absolute", "--git-path", "objects")
if err != nil {
return nil, false, err
}
objectsDir := strings.TrimSpace(string(objectsOutput))
result := make([]LooseObject, 0, len(oids))
var total int64
for _, oid := range oids {
filename := filepath.Join(objectsDir, oid[:2], oid[2:])
info, err := os.Stat(filename)
if err != nil {
if os.IsNotExist(err) {
return nil, false, nil
}
return nil, false, err
}
if !info.Mode().IsRegular() {
return nil, false, nil
}
total += info.Size()
if total > maxBytes {
return nil, false, nil
}
result = append(result, LooseObject{OID: oid, Path: filename, Size: info.Size()})
}
return result, true, nil
}
func isObjectID(value string) bool {
if len(value) != 40 && len(value) != 64 {
return false
}
for _, char := range []byte(value) {
if (char < '0' || char > '9') && (char < 'a' || char > 'f') {
return false
}
}
return true
}
func packObjectCount(filename string) (uint32, error) {
// #nosec G304 -- filename is an internal path in our private temporary directory.
f, err := os.Open(filename)
if err != nil {
return 0, err
}
defer f.Close()
header := make([]byte, 12)
if _, err := io.ReadFull(f, header); err != nil {
return 0, fmt.Errorf("read pack header: %w", err)
}
if string(header[:4]) != "PACK" {
return 0, fmt.Errorf("invalid pack header")
}
return binary.BigEndian.Uint32(header[8:12]), nil
}
func unique(values []string) []string {
seen := make(map[string]struct{}, len(values))
result := make([]string, 0, len(values))
for _, value := range values {
if value == "" {
continue
}
if _, ok := seen[value]; ok {
continue
}
seen[value] = struct{}{}
result = append(result, value)
}
sort.Strings(result)
return result
}
type NameStatus struct {
Status string
Path string
OldPath string
}
func (g Git) DiffNameStatus(ctx context.Context, oldOID, newOID string) ([]NameStatus, error) {
out, err := g.Run(ctx, "diff", "--name-status", "-z", "--find-renames", oldOID, newOID)
if err != nil {
return nil, err
}
scanner := bufio.NewScanner(bytes.NewReader(out))
scanner.Split(splitNUL)
var result []NameStatus
for scanner.Scan() {
status := scanner.Text()
if !scanner.Scan() {
return nil, fmt.Errorf("malformed git diff output")
}
first := scanner.Text()
entry := NameStatus{Status: status, Path: first}
if strings.HasPrefix(status, "R") || strings.HasPrefix(status, "C") {
if !scanner.Scan() {
return nil, fmt.Errorf("malformed git rename output")
}
entry.OldPath = first
entry.Path = scanner.Text()
}
result = append(result, entry)
}
return result, scanner.Err()
}
func splitNUL(data []byte, atEOF bool) (advance int, token []byte, err error) {
if i := bytes.IndexByte(data, 0); i >= 0 {
return i + 1, data[:i], nil
}
if atEOF && len(data) > 0 {
return len(data), data, nil
}
return 0, nil, nil
}
|
