forgejo/services/pull/patch.go
zeripath 92e81e97e8
Detect conflicts with 3way merge (#18536)
* Detect conflicts with 3way merge

Unforunately git apply --3way reports conflicts differently than standard patches
resulting in conflicts being missed.

Adjust the conflict detection code to account for this different error reporting.

Fix #18514

Signed-off-by: Andrew Thornton <art27@cantab.net>

* and three-way failed

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
2022-02-02 12:46:10 +08:00

523 lines
17 KiB
Go

// Copyright 2019 The Gitea Authors.
// All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package pull
import (
"bufio"
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"code.gitea.io/gitea/models"
"code.gitea.io/gitea/models/unit"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/graceful"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/process"
"code.gitea.io/gitea/modules/util"
"github.com/gobwas/glob"
)
// DownloadDiffOrPatch will write the patch for the pr to the writer
func DownloadDiffOrPatch(ctx context.Context, pr *models.PullRequest, w io.Writer, patch, binary bool) error {
if err := pr.LoadBaseRepo(); err != nil {
log.Error("Unable to load base repository ID %d for pr #%d [%d]", pr.BaseRepoID, pr.Index, pr.ID)
return err
}
gitRepo, closer, err := git.RepositoryFromContextOrOpen(ctx, pr.BaseRepo.RepoPath())
if err != nil {
return fmt.Errorf("OpenRepository: %v", err)
}
defer closer.Close()
if err := gitRepo.GetDiffOrPatch(pr.MergeBase, pr.GetGitRefName(), w, patch, binary); err != nil {
log.Error("Unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
return fmt.Errorf("Unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
}
return nil
}
var patchErrorSuffices = []string{
": already exists in index",
": patch does not apply",
": already exists in working directory",
"unrecognized input",
}
// TestPatch will test whether a simple patch will apply
func TestPatch(pr *models.PullRequest) error {
ctx, _, finished := process.GetManager().AddContext(graceful.GetManager().HammerContext(), fmt.Sprintf("TestPatch: Repo[%d]#%d", pr.BaseRepoID, pr.Index))
defer finished()
// Clone base repo.
tmpBasePath, err := createTemporaryRepo(ctx, pr)
if err != nil {
log.Error("CreateTemporaryPath: %v", err)
return err
}
defer func() {
if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
log.Error("Merge: RemoveTemporaryPath: %s", err)
}
}()
gitRepo, err := git.OpenRepositoryCtx(ctx, tmpBasePath)
if err != nil {
return fmt.Errorf("OpenRepository: %v", err)
}
defer gitRepo.Close()
// 1. update merge base
pr.MergeBase, err = git.NewCommandContext(ctx, "merge-base", "--", "base", "tracking").RunInDir(tmpBasePath)
if err != nil {
var err2 error
pr.MergeBase, err2 = gitRepo.GetRefCommitID(git.BranchPrefix + "base")
if err2 != nil {
return fmt.Errorf("GetMergeBase: %v and can't find commit ID for base: %v", err, err2)
}
}
pr.MergeBase = strings.TrimSpace(pr.MergeBase)
// 2. Check for conflicts
if conflicts, err := checkConflicts(pr, gitRepo, tmpBasePath); err != nil || conflicts || pr.Status == models.PullRequestStatusEmpty {
return err
}
// 3. Check for protected files changes
if err = checkPullFilesProtection(pr, gitRepo); err != nil {
return fmt.Errorf("pr.CheckPullFilesProtection(): %v", err)
}
if len(pr.ChangedProtectedFiles) > 0 {
log.Trace("Found %d protected files changed", len(pr.ChangedProtectedFiles))
}
pr.Status = models.PullRequestStatusMergeable
return nil
}
type errMergeConflict struct {
filename string
}
func (e *errMergeConflict) Error() string {
return fmt.Sprintf("conflict detected at: %s", e.filename)
}
func attemptMerge(ctx context.Context, file *unmergedFile, tmpBasePath string, gitRepo *git.Repository) error {
switch {
case file.stage1 != nil && (file.stage2 == nil || file.stage3 == nil):
// 1. Deleted in one or both:
//
// Conflict <==> the stage1 !SameAs to the undeleted one
if (file.stage2 != nil && !file.stage1.SameAs(file.stage2)) || (file.stage3 != nil && !file.stage1.SameAs(file.stage3)) {
// Conflict!
return &errMergeConflict{file.stage1.path}
}
// Not a genuine conflict and we can simply remove the file from the index
return gitRepo.RemoveFilesFromIndex(file.stage1.path)
case file.stage1 == nil && file.stage2 != nil && (file.stage3 == nil || file.stage2.SameAs(file.stage3)):
// 2. Added in ours but not in theirs or identical in both
//
// Not a genuine conflict just add to the index
if err := gitRepo.AddObjectToIndex(file.stage2.mode, git.MustIDFromString(file.stage2.sha), file.stage2.path); err != nil {
return err
}
return nil
case file.stage1 == nil && file.stage2 != nil && file.stage3 != nil && file.stage2.sha == file.stage3.sha && file.stage2.mode != file.stage3.mode:
// 3. Added in both with the same sha but the modes are different
//
// Conflict! (Not sure that this can actually happen but we should handle)
return &errMergeConflict{file.stage2.path}
case file.stage1 == nil && file.stage2 == nil && file.stage3 != nil:
// 4. Added in theirs but not ours:
//
// Not a genuine conflict just add to the index
return gitRepo.AddObjectToIndex(file.stage3.mode, git.MustIDFromString(file.stage3.sha), file.stage3.path)
case file.stage1 == nil:
// 5. Created by new in both
//
// Conflict!
return &errMergeConflict{file.stage2.path}
case file.stage2 != nil && file.stage3 != nil:
// 5. Modified in both - we should try to merge in the changes but first:
//
if file.stage2.mode == "120000" || file.stage3.mode == "120000" {
// 5a. Conflicting symbolic link change
return &errMergeConflict{file.stage2.path}
}
if file.stage2.mode == "160000" || file.stage3.mode == "160000" {
// 5b. Conflicting submodule change
return &errMergeConflict{file.stage2.path}
}
if file.stage2.mode != file.stage3.mode {
// 5c. Conflicting mode change
return &errMergeConflict{file.stage2.path}
}
// Need to get the objects from the object db to attempt to merge
root, err := git.NewCommandContext(ctx, "unpack-file", file.stage1.sha).RunInDir(tmpBasePath)
if err != nil {
return fmt.Errorf("unable to get root object: %s at path: %s for merging. Error: %w", file.stage1.sha, file.stage1.path, err)
}
root = strings.TrimSpace(root)
defer func() {
_ = util.Remove(filepath.Join(tmpBasePath, root))
}()
base, err := git.NewCommandContext(ctx, "unpack-file", file.stage2.sha).RunInDir(tmpBasePath)
if err != nil {
return fmt.Errorf("unable to get base object: %s at path: %s for merging. Error: %w", file.stage2.sha, file.stage2.path, err)
}
base = strings.TrimSpace(filepath.Join(tmpBasePath, base))
defer func() {
_ = util.Remove(base)
}()
head, err := git.NewCommandContext(ctx, "unpack-file", file.stage3.sha).RunInDir(tmpBasePath)
if err != nil {
return fmt.Errorf("unable to get head object:%s at path: %s for merging. Error: %w", file.stage3.sha, file.stage3.path, err)
}
head = strings.TrimSpace(head)
defer func() {
_ = util.Remove(filepath.Join(tmpBasePath, head))
}()
// now git merge-file annoyingly takes a different order to the merge-tree ...
_, conflictErr := git.NewCommandContext(ctx, "merge-file", base, root, head).RunInDir(tmpBasePath)
if conflictErr != nil {
return &errMergeConflict{file.stage2.path}
}
// base now contains the merged data
hash, err := git.NewCommandContext(ctx, "hash-object", "-w", "--path", file.stage2.path, base).RunInDir(tmpBasePath)
if err != nil {
return err
}
hash = strings.TrimSpace(hash)
return gitRepo.AddObjectToIndex(file.stage2.mode, git.MustIDFromString(hash), file.stage2.path)
default:
if file.stage1 != nil {
return &errMergeConflict{file.stage1.path}
} else if file.stage2 != nil {
return &errMergeConflict{file.stage2.path}
} else if file.stage3 != nil {
return &errMergeConflict{file.stage3.path}
}
}
return nil
}
func checkConflicts(pr *models.PullRequest, gitRepo *git.Repository, tmpBasePath string) (bool, error) {
ctx, cancel, finished := process.GetManager().AddContext(graceful.GetManager().HammerContext(), fmt.Sprintf("checkConflicts: pr[%d] %s/%s#%d", pr.ID, pr.BaseRepo.OwnerName, pr.BaseRepo.Name, pr.Index))
defer finished()
// First we use read-tree to do a simple three-way merge
if _, err := git.NewCommandContext(ctx, "read-tree", "-m", pr.MergeBase, "base", "tracking").RunInDir(tmpBasePath); err != nil {
log.Error("Unable to run read-tree -m! Error: %v", err)
return false, fmt.Errorf("unable to run read-tree -m! Error: %v", err)
}
// Then we use git ls-files -u to list the unmerged files and collate the triples in unmergedfiles
unmerged := make(chan *unmergedFile)
go unmergedFiles(ctx, tmpBasePath, unmerged)
defer func() {
cancel()
for range unmerged {
// empty the unmerged channel
}
}()
numberOfConflicts := 0
pr.ConflictedFiles = make([]string, 0, 5)
conflict := false
for file := range unmerged {
if file == nil {
break
}
if file.err != nil {
cancel()
return false, file.err
}
// OK now we have the unmerged file triplet attempt to merge it
if err := attemptMerge(ctx, file, tmpBasePath, gitRepo); err != nil {
if conflictErr, ok := err.(*errMergeConflict); ok {
log.Trace("Conflict: %s in PR[%d] %s/%s#%d", conflictErr.filename, pr.ID, pr.BaseRepo.OwnerName, pr.BaseRepo.Name, pr.Index)
conflict = true
if numberOfConflicts < 10 {
pr.ConflictedFiles = append(pr.ConflictedFiles, conflictErr.filename)
}
numberOfConflicts++
continue
}
return false, err
}
}
if !conflict {
treeHash, err := git.NewCommandContext(ctx, "write-tree").RunInDir(tmpBasePath)
if err != nil {
return false, err
}
treeHash = strings.TrimSpace(treeHash)
baseTree, err := gitRepo.GetTree("base")
if err != nil {
return false, err
}
if treeHash == baseTree.ID.String() {
log.Debug("PullRequest[%d]: Patch is empty - ignoring", pr.ID)
pr.Status = models.PullRequestStatusEmpty
pr.ConflictedFiles = []string{}
pr.ChangedProtectedFiles = []string{}
}
return false, nil
}
// OK read-tree has failed so we need to try a different thing - this might actually succeed where the above fails due to whitespace handling.
// 1. Create a plain patch from head to base
tmpPatchFile, err := os.CreateTemp("", "patch")
if err != nil {
log.Error("Unable to create temporary patch file! Error: %v", err)
return false, fmt.Errorf("unable to create temporary patch file! Error: %v", err)
}
defer func() {
_ = util.Remove(tmpPatchFile.Name())
}()
if err := gitRepo.GetDiffBinary(pr.MergeBase, "tracking", tmpPatchFile); err != nil {
tmpPatchFile.Close()
log.Error("Unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
return false, fmt.Errorf("unable to get patch file from %s to %s in %s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.FullName(), err)
}
stat, err := tmpPatchFile.Stat()
if err != nil {
tmpPatchFile.Close()
return false, fmt.Errorf("unable to stat patch file: %v", err)
}
patchPath := tmpPatchFile.Name()
tmpPatchFile.Close()
// 1a. if the size of that patch is 0 - there can be no conflicts!
if stat.Size() == 0 {
log.Debug("PullRequest[%d]: Patch is empty - ignoring", pr.ID)
pr.Status = models.PullRequestStatusEmpty
pr.ConflictedFiles = []string{}
pr.ChangedProtectedFiles = []string{}
return false, nil
}
log.Trace("PullRequest[%d].testPatch (patchPath): %s", pr.ID, patchPath)
// 2. preset the pr.Status as checking (this is not save at present)
pr.Status = models.PullRequestStatusChecking
// 3. Read the base branch in to the index of the temporary repository
_, err = git.NewCommandContext(gitRepo.Ctx, "read-tree", "base").RunInDir(tmpBasePath)
if err != nil {
return false, fmt.Errorf("git read-tree %s: %v", pr.BaseBranch, err)
}
// 4. Now get the pull request configuration to check if we need to ignore whitespace
prUnit, err := pr.BaseRepo.GetUnit(unit.TypePullRequests)
if err != nil {
return false, err
}
prConfig := prUnit.PullRequestsConfig()
// 5. Prepare the arguments to apply the patch against the index
args := []string{"apply", "--check", "--cached"}
if prConfig.IgnoreWhitespaceConflicts {
args = append(args, "--ignore-whitespace")
}
is3way := false
if git.CheckGitVersionAtLeast("2.32.0") == nil {
args = append(args, "--3way")
is3way = true
}
args = append(args, patchPath)
pr.ConflictedFiles = make([]string, 0, 5)
// 6. Prep the pipe:
// - Here we could do the equivalent of:
// `git apply --check --cached patch_file > conflicts`
// Then iterate through the conflicts. However, that means storing all the conflicts
// in memory - which is very wasteful.
// - alternatively we can do the equivalent of:
// `git apply --check ... | grep ...`
// meaning we don't store all of the conflicts unnecessarily.
stderrReader, stderrWriter, err := os.Pipe()
if err != nil {
log.Error("Unable to open stderr pipe: %v", err)
return false, fmt.Errorf("unable to open stderr pipe: %v", err)
}
defer func() {
_ = stderrReader.Close()
_ = stderrWriter.Close()
}()
// 7. Run the check command
conflict = false
err = git.NewCommandContext(gitRepo.Ctx, args...).
RunInDirTimeoutEnvFullPipelineFunc(
nil, -1, tmpBasePath,
nil, stderrWriter, nil,
func(ctx context.Context, cancel context.CancelFunc) error {
// Close the writer end of the pipe to begin processing
_ = stderrWriter.Close()
defer func() {
// Close the reader on return to terminate the git command if necessary
_ = stderrReader.Close()
}()
const prefix = "error: patch failed:"
const errorPrefix = "error: "
const threewayFailed = "Failed to perform three-way merge..."
const appliedPatchPrefix = "Applied patch to '"
const withConflicts = "' with conflicts."
conflictMap := map[string]bool{}
// Now scan the output from the command
scanner := bufio.NewScanner(stderrReader)
for scanner.Scan() {
line := scanner.Text()
if strings.HasPrefix(line, prefix) {
conflict = true
filepath := strings.TrimSpace(strings.Split(line[len(prefix):], ":")[0])
conflictMap[filepath] = true
} else if is3way && line == threewayFailed {
conflict = true
} else if strings.HasPrefix(line, errorPrefix) {
conflict = true
for _, suffix := range patchErrorSuffices {
if strings.HasSuffix(line, suffix) {
filepath := strings.TrimSpace(strings.TrimSuffix(line[len(errorPrefix):], suffix))
if filepath != "" {
conflictMap[filepath] = true
}
break
}
}
} else if is3way && strings.HasPrefix(line, appliedPatchPrefix) && strings.HasSuffix(line, withConflicts) {
conflict = true
filepath := strings.TrimPrefix(strings.TrimSuffix(line, withConflicts), appliedPatchPrefix)
if filepath != "" {
conflictMap[filepath] = true
}
}
// only list 10 conflicted files
if len(conflictMap) >= 10 {
break
}
}
if len(conflictMap) > 0 {
pr.ConflictedFiles = make([]string, 0, len(conflictMap))
for key := range conflictMap {
pr.ConflictedFiles = append(pr.ConflictedFiles, key)
}
}
return nil
})
// 8. If there is a conflict the `git apply` command will return a non-zero error code - so there will be a positive error.
if err != nil {
if conflict {
pr.Status = models.PullRequestStatusConflict
log.Trace("Found %d files conflicted: %v", len(pr.ConflictedFiles), pr.ConflictedFiles)
return true, nil
}
return false, fmt.Errorf("git apply --check: %v", err)
}
return false, nil
}
// CheckFileProtection check file Protection
func CheckFileProtection(repo *git.Repository, oldCommitID, newCommitID string, patterns []glob.Glob, limit int, env []string) ([]string, error) {
if len(patterns) == 0 {
return nil, nil
}
affectedFiles, err := git.GetAffectedFiles(repo, oldCommitID, newCommitID, env)
if err != nil {
return nil, err
}
changedProtectedFiles := make([]string, 0, limit)
for _, affectedFile := range affectedFiles {
lpath := strings.ToLower(affectedFile)
for _, pat := range patterns {
if pat.Match(lpath) {
changedProtectedFiles = append(changedProtectedFiles, lpath)
break
}
}
if len(changedProtectedFiles) >= limit {
break
}
}
if len(changedProtectedFiles) > 0 {
err = models.ErrFilePathProtected{
Path: changedProtectedFiles[0],
}
}
return changedProtectedFiles, err
}
// CheckUnprotectedFiles check if the commit only touches unprotected files
func CheckUnprotectedFiles(repo *git.Repository, oldCommitID, newCommitID string, patterns []glob.Glob, env []string) (bool, error) {
if len(patterns) == 0 {
return false, nil
}
affectedFiles, err := git.GetAffectedFiles(repo, oldCommitID, newCommitID, env)
if err != nil {
return false, err
}
for _, affectedFile := range affectedFiles {
lpath := strings.ToLower(affectedFile)
unprotected := false
for _, pat := range patterns {
if pat.Match(lpath) {
unprotected = true
break
}
}
if !unprotected {
return false, nil
}
}
return true, nil
}
// checkPullFilesProtection check if pr changed protected files and save results
func checkPullFilesProtection(pr *models.PullRequest, gitRepo *git.Repository) error {
if err := pr.LoadProtectedBranch(); err != nil {
return err
}
if pr.ProtectedBranch == nil {
pr.ChangedProtectedFiles = nil
return nil
}
var err error
pr.ChangedProtectedFiles, err = CheckFileProtection(gitRepo, pr.MergeBase, "tracking", pr.ProtectedBranch.GetProtectedFilePatterns(), 10, os.Environ())
if err != nil && !models.IsErrFilePathProtected(err) {
return err
}
return nil
}