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// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
// Package git provides helper functions for working with git repositories.
package git
import (
"bytes"
"fmt"
"os"
"regexp"
"strings"
"time"
"github.com/google/syzkaller/pkg/osutil"
)
const timeout = time.Hour // timeout for all git invocations
// Poll checkouts the specified repository/branch in dir.
// This involves fetching/resetting/cloning as necessary to recover from all possible problems.
// Returns hash of the HEAD commit in the specified branch.
func Poll(dir, repo, branch string) (string, error) {
runSandboxed(dir, "git", "reset", "--hard")
origin, err := runSandboxed(dir, "git", "remote", "get-url", "origin")
if err != nil || strings.TrimSpace(string(origin)) != repo {
// The repo is here, but it has wrong origin (e.g. repo in config has changed), re-clone.
if err := clone(dir, repo, branch); err != nil {
return "", err
}
}
// Use origin/branch for the case the branch was force-pushed,
// in such case branch is not the same is origin/branch and we will
// stuck with the local version forever (git checkout won't fail).
if _, err := runSandboxed(dir, "git", "checkout", "origin/"+branch); err != nil {
// No such branch (e.g. branch in config has changed), re-clone.
if err := clone(dir, repo, branch); err != nil {
return "", err
}
}
if _, err := runSandboxed(dir, "git", "fetch", "--no-tags"); err != nil {
// Something else is wrong, re-clone.
if err := clone(dir, repo, branch); err != nil {
return "", err
}
}
if _, err := runSandboxed(dir, "git", "checkout", "origin/"+branch); err != nil {
return "", err
}
return HeadCommit(dir)
}
// Checkout checkouts the specified repository/branch in dir.
// It does not fetch history and efficiently supports checkouts of different repos in the same dir.
func Checkout(dir, repo, branch string) (string, error) {
if _, err := runSandboxed(dir, "git", "reset", "--hard"); err != nil {
if err := initRepo(dir); err != nil {
return "", err
}
}
_, err := runSandboxed(dir, "git", "fetch", "--no-tags", "--depth=1", repo, branch)
if err != nil {
return "", err
}
if _, err := runSandboxed(dir, "git", "checkout", "FETCH_HEAD"); err != nil {
return "", err
}
return HeadCommit(dir)
}
func clone(dir, repo, branch string) error {
if err := initRepo(dir); err != nil {
return err
}
if _, err := runSandboxed(dir, "git", "remote", "add", "origin", repo); err != nil {
return err
}
if _, err := runSandboxed(dir, "git", "fetch", "origin", branch); err != nil {
return err
}
return nil
}
func initRepo(dir string) error {
if err := os.RemoveAll(dir); err != nil {
return fmt.Errorf("failed to remove repo dir: %v", err)
}
if err := osutil.MkdirAll(dir); err != nil {
return fmt.Errorf("failed to create repo dir: %v", err)
}
if err := osutil.SandboxChown(dir); err != nil {
return err
}
if _, err := runSandboxed(dir, "git", "init"); err != nil {
return err
}
return nil
}
// HeadCommit returns hash of the HEAD commit of the current branch of git repository in dir.
func HeadCommit(dir string) (string, error) {
output, err := runSandboxed(dir, "git", "log", "--pretty=format:%H", "-n", "1")
if err != nil {
return "", err
}
if len(output) != 0 && output[len(output)-1] == '\n' {
output = output[:len(output)-1]
}
if len(output) != 40 {
return "", fmt.Errorf("unexpected git log output, want commit hash: %q", output)
}
return string(output), nil
}
// ListRecentCommits returns list of recent commit titles starting from baseCommit.
func ListRecentCommits(dir, baseCommit string) ([]string, error) {
// On upstream kernel this produces ~11MB of output.
// Somewhat inefficient to collect whole output in a slice
// and then convert to string, but should be bearable.
output, err := runSandboxed(dir, "git", "log",
"--pretty=format:%s", "--no-merges", "-n", "200000", baseCommit)
if err != nil {
return nil, err
}
return strings.Split(string(output), "\n"), nil
}
// CanonicalizeCommit returns commit title that can be used when checking
// if a particular commit is present in a git tree.
// Some trees add prefixes to commit titles during backporting,
// so we want e.g. commit "foo bar" match "BACKPORT: foo bar".
func CanonicalizeCommit(title string) string {
for _, prefix := range commitPrefixes {
if strings.HasPrefix(title, prefix) {
title = title[len(prefix):]
break
}
}
return strings.TrimSpace(title)
}
var commitPrefixes = []string{
"UPSTREAM:",
"CHROMIUM:",
"FROMLIST:",
"BACKPORT:",
"FROMGIT:",
"net-backports:",
}
func Patch(dir string, patch []byte) error {
// Do --dry-run first to not mess with partially consistent state.
cmd := osutil.Command("patch", "-p1", "--force", "--ignore-whitespace", "--dry-run")
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Stdin = bytes.NewReader(patch)
cmd.Dir = dir
if output, err := cmd.CombinedOutput(); err != nil {
// If it reverses clean, then it's already applied
// (seems to be the easiest way to detect it).
cmd = osutil.Command("patch", "-p1", "--force", "--ignore-whitespace", "--reverse", "--dry-run")
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Stdin = bytes.NewReader(patch)
cmd.Dir = dir
if _, err := cmd.CombinedOutput(); err == nil {
return fmt.Errorf("patch is already applied")
}
return fmt.Errorf("failed to apply patch:\n%s", output)
}
// Now apply for real.
cmd = osutil.Command("patch", "-p1", "--force", "--ignore-whitespace")
if err := osutil.Sandbox(cmd, true, true); err != nil {
return err
}
cmd.Stdin = bytes.NewReader(patch)
cmd.Dir = dir
if output, err := cmd.CombinedOutput(); err != nil {
return fmt.Errorf("failed to apply patch after dry run:\n%s", output)
}
return nil
}
func runSandboxed(dir, command string, args ...string) ([]byte, error) {
cmd := osutil.Command(command, args...)
cmd.Dir = dir
if err := osutil.Sandbox(cmd, true, false); err != nil {
return nil, err
}
return osutil.Run(timeout, cmd)
}
// CheckRepoAddress does a best-effort approximate check of a git repo address.
func CheckRepoAddress(repo string) bool {
return gitRepoRe.MatchString(repo)
}
var gitRepoRe = regexp.MustCompile("^(git|ssh|http|https|ftp|ftps)://[a-zA-Z0-9-_]+(\\.[a-zA-Z0-9-_]+)+(:[0-9]+)?/[a-zA-Z0-9-_./]+\\.git(/)?$")
// CheckBranch does a best-effort approximate check of a git branch name.
func CheckBranch(branch string) bool {
return gitBranchRe.MatchString(branch)
}
var gitBranchRe = regexp.MustCompile("^[a-zA-Z0-9-_/.]{2,200}$")
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