forgejo/services/pull/merge_prepare.go

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// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package pull
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"time"
"code.gitea.io/gitea/models"
issues_model "code.gitea.io/gitea/models/issues"
repo_model "code.gitea.io/gitea/models/repo"
user_model "code.gitea.io/gitea/models/user"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
asymkey_service "code.gitea.io/gitea/services/asymkey"
)
type mergeContext struct {
*prContext
doer *user_model.User
sig *git.Signature
committer *git.Signature
signKeyID string // empty for no-sign, non-empty to sign
env []string
}
func (ctx *mergeContext) RunOpts() *git.RunOpts {
ctx.outbuf.Reset()
ctx.errbuf.Reset()
return &git.RunOpts{
Env: ctx.env,
Dir: ctx.tmpBasePath,
Stdout: ctx.outbuf,
Stderr: ctx.errbuf,
}
}
func createTemporaryRepoForMerge(ctx context.Context, pr *issues_model.PullRequest, doer *user_model.User, expectedHeadCommitID string) (mergeCtx *mergeContext, cancel context.CancelFunc, err error) {
// Clone base repo.
prCtx, cancel, err := createTemporaryRepoForPR(ctx, pr)
if err != nil {
log.Error("createTemporaryRepoForPR: %v", err)
return nil, cancel, err
}
mergeCtx = &mergeContext{
prContext: prCtx,
doer: doer,
}
if expectedHeadCommitID != "" {
trackingCommitID, _, err := git.NewCommand(ctx, "show-ref", "--hash").AddDynamicArguments(git.BranchPrefix + trackingBranch).RunStdString(&git.RunOpts{Dir: mergeCtx.tmpBasePath})
if err != nil {
defer cancel()
log.Error("failed to get sha of head branch in %-v: show-ref[%s] --hash refs/heads/tracking: %v", mergeCtx.pr, mergeCtx.tmpBasePath, err)
return nil, nil, fmt.Errorf("unable to get sha of head branch in %v %w", pr, err)
}
if strings.TrimSpace(trackingCommitID) != expectedHeadCommitID {
defer cancel()
return nil, nil, models.ErrSHADoesNotMatch{
GivenSHA: expectedHeadCommitID,
CurrentSHA: trackingCommitID,
}
}
}
mergeCtx.outbuf.Reset()
mergeCtx.errbuf.Reset()
if err := prepareTemporaryRepoForMerge(mergeCtx); err != nil {
defer cancel()
return nil, nil, err
}
mergeCtx.sig = doer.NewGitSig()
mergeCtx.committer = mergeCtx.sig
// Determine if we should sign
sign, keyID, signer, _ := asymkey_service.SignMerge(ctx, mergeCtx.pr, mergeCtx.doer, mergeCtx.tmpBasePath, "HEAD", trackingBranch)
if sign {
mergeCtx.signKeyID = keyID
if pr.BaseRepo.GetTrustModel() == repo_model.CommitterTrustModel || pr.BaseRepo.GetTrustModel() == repo_model.CollaboratorCommitterTrustModel {
mergeCtx.committer = signer
}
}
commitTimeStr := time.Now().Format(time.RFC3339)
// Because this may call hooks we should pass in the environment
mergeCtx.env = append(os.Environ(),
"GIT_AUTHOR_NAME="+mergeCtx.sig.Name,
"GIT_AUTHOR_EMAIL="+mergeCtx.sig.Email,
"GIT_AUTHOR_DATE="+commitTimeStr,
"GIT_COMMITTER_NAME="+mergeCtx.committer.Name,
"GIT_COMMITTER_EMAIL="+mergeCtx.committer.Email,
"GIT_COMMITTER_DATE="+commitTimeStr,
)
return mergeCtx, cancel, nil
}
// prepareTemporaryRepoForMerge takes a repository that has been created using createTemporaryRepo
// it then sets up the sparse-checkout and other things
func prepareTemporaryRepoForMerge(ctx *mergeContext) error {
infoPath := filepath.Join(ctx.tmpBasePath, ".git", "info")
if err := os.MkdirAll(infoPath, 0o700); err != nil {
log.Error("%-v Unable to create .git/info in %s: %v", ctx.pr, ctx.tmpBasePath, err)
return fmt.Errorf("Unable to create .git/info in tmpBasePath: %w", err)
}
// Enable sparse-checkout
// Here we use the .git/info/sparse-checkout file as described in the git documentation
sparseCheckoutListFile, err := os.OpenFile(filepath.Join(infoPath, "sparse-checkout"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o600)
if err != nil {
log.Error("%-v Unable to write .git/info/sparse-checkout file in %s: %v", ctx.pr, ctx.tmpBasePath, err)
return fmt.Errorf("Unable to write .git/info/sparse-checkout file in tmpBasePath: %w", err)
}
defer sparseCheckoutListFile.Close() // we will close it earlier but we need to ensure it is closed if there is an error
if err := getDiffTree(ctx, ctx.tmpBasePath, baseBranch, trackingBranch, sparseCheckoutListFile); err != nil {
log.Error("%-v getDiffTree(%s, %s, %s): %v", ctx.pr, ctx.tmpBasePath, baseBranch, trackingBranch, err)
return fmt.Errorf("getDiffTree: %w", err)
}
if err := sparseCheckoutListFile.Close(); err != nil {
log.Error("%-v Unable to close .git/info/sparse-checkout file in %s: %v", ctx.pr, ctx.tmpBasePath, err)
return fmt.Errorf("Unable to close .git/info/sparse-checkout file in tmpBasePath: %w", err)
}
setConfig := func(key, value string) error {
if err := git.NewCommand(ctx, "config", "--local").AddDynamicArguments(key, value).
Run(ctx.RunOpts()); err != nil {
log.Error("git config [%s -> %q]: %v\n%s\n%s", key, value, err, ctx.outbuf.String(), ctx.errbuf.String())
return fmt.Errorf("git config [%s -> %q]: %w\n%s\n%s", key, value, err, ctx.outbuf.String(), ctx.errbuf.String())
}
ctx.outbuf.Reset()
ctx.errbuf.Reset()
return nil
}
// Switch off LFS process (set required, clean and smudge here also)
if err := setConfig("filter.lfs.process", ""); err != nil {
return err
}
if err := setConfig("filter.lfs.required", "false"); err != nil {
return err
}
if err := setConfig("filter.lfs.clean", ""); err != nil {
return err
}
if err := setConfig("filter.lfs.smudge", ""); err != nil {
return err
}
if err := setConfig("core.sparseCheckout", "true"); err != nil {
return err
}
// Read base branch index
if err := git.NewCommand(ctx, "read-tree", "HEAD").
Run(ctx.RunOpts()); err != nil {
log.Error("git read-tree HEAD: %v\n%s\n%s", err, ctx.outbuf.String(), ctx.errbuf.String())
return fmt.Errorf("Unable to read base branch in to the index: %w\n%s\n%s", err, ctx.outbuf.String(), ctx.errbuf.String())
}
ctx.outbuf.Reset()
ctx.errbuf.Reset()
return nil
}
// getDiffTree returns a string containing all the files that were changed between headBranch and baseBranch
// the filenames are escaped so as to fit the format required for .git/info/sparse-checkout
func getDiffTree(ctx context.Context, repoPath, baseBranch, headBranch string, out io.Writer) error {
diffOutReader, diffOutWriter, err := os.Pipe()
if err != nil {
log.Error("Unable to create os.Pipe for %s", repoPath)
return err
}
defer func() {
_ = diffOutReader.Close()
_ = diffOutWriter.Close()
}()
scanNullTerminatedStrings := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
if atEOF && len(data) == 0 {
return 0, nil, nil
}
if i := bytes.IndexByte(data, '\x00'); i >= 0 {
return i + 1, data[0:i], nil
}
if atEOF {
return len(data), data, nil
}
return 0, nil, nil
}
err = git.NewCommand(ctx, "diff-tree", "--no-commit-id", "--name-only", "-r", "-r", "-z", "--root").AddDynamicArguments(baseBranch, headBranch).
Run(&git.RunOpts{
Dir: repoPath,
Stdout: diffOutWriter,
PipelineFunc: func(ctx context.Context, cancel context.CancelFunc) error {
// Close the writer end of the pipe to begin processing
_ = diffOutWriter.Close()
defer func() {
// Close the reader on return to terminate the git command if necessary
_ = diffOutReader.Close()
}()
// Now scan the output from the command
scanner := bufio.NewScanner(diffOutReader)
scanner.Split(scanNullTerminatedStrings)
for scanner.Scan() {
filepath := scanner.Text()
// escape '*', '?', '[', spaces and '!' prefix
filepath = escapedSymbols.ReplaceAllString(filepath, `\$1`)
// no necessary to escape the first '#' symbol because the first symbol is '/'
fmt.Fprintf(out, "/%s\n", filepath)
}
return scanner.Err()
},
})
return err
}
// rebaseTrackingOnToBase checks out the tracking branch as staging and rebases it on to the base branch
// if there is a conflict it will return a models.ErrRebaseConflicts
func rebaseTrackingOnToBase(ctx *mergeContext, mergeStyle repo_model.MergeStyle) error {
// Checkout head branch
if err := git.NewCommand(ctx, "checkout", "-b").AddDynamicArguments(stagingBranch, trackingBranch).
Run(ctx.RunOpts()); err != nil {
return fmt.Errorf("unable to git checkout tracking as staging in temp repo for %v: %w\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
}
ctx.outbuf.Reset()
ctx.errbuf.Reset()
// Rebase before merging
if err := git.NewCommand(ctx, "rebase").AddDynamicArguments(baseBranch).
Run(ctx.RunOpts()); err != nil {
// Rebase will leave a REBASE_HEAD file in .git if there is a conflict
if _, statErr := os.Stat(filepath.Join(ctx.tmpBasePath, ".git", "REBASE_HEAD")); statErr == nil {
var commitSha string
ok := false
failingCommitPaths := []string{
filepath.Join(ctx.tmpBasePath, ".git", "rebase-apply", "original-commit"), // Git < 2.26
filepath.Join(ctx.tmpBasePath, ".git", "rebase-merge", "stopped-sha"), // Git >= 2.26
}
for _, failingCommitPath := range failingCommitPaths {
if _, statErr := os.Stat(failingCommitPath); statErr == nil {
commitShaBytes, readErr := os.ReadFile(failingCommitPath)
if readErr != nil {
// Abandon this attempt to handle the error
return fmt.Errorf("unable to git rebase staging on to base in temp repo for %v: %w\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
}
commitSha = strings.TrimSpace(string(commitShaBytes))
ok = true
break
}
}
if !ok {
log.Error("Unable to determine failing commit sha for failing rebase in temp repo for %-v. Cannot cast as models.ErrRebaseConflicts.", ctx.pr)
return fmt.Errorf("unable to git rebase staging on to base in temp repo for %v: %w\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
}
log.Debug("Conflict when rebasing staging on to base in %-v at %s: %v\n%s\n%s", ctx.pr, commitSha, err, ctx.outbuf.String(), ctx.errbuf.String())
return models.ErrRebaseConflicts{
CommitSHA: commitSha,
Style: mergeStyle,
StdOut: ctx.outbuf.String(),
StdErr: ctx.errbuf.String(),
Err: err,
}
}
return fmt.Errorf("unable to git rebase staging on to base in temp repo for %v: %w\n%s\n%s", ctx.pr, err, ctx.outbuf.String(), ctx.errbuf.String())
}
ctx.outbuf.Reset()
ctx.errbuf.Reset()
return nil
}