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Improve TestPatch to use git read-tree -m and implement git-merge-one-file functionality (#18004)

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The current TestPatch conflict code uses a plain git apply which does not properly
account for 3-way merging. However, we can improve things using `git read-tree -m` to
do a three-way merge then follow the algorithm used in merge-one-file. We can also use 
`--patience` and/or `--histogram` to generate a nicer diff for applying patches too.

Fix #13679
Fix #6417

Signed-off-by: Andrew Thornton <art27@cantab.net>
This commit is contained in:
zeripath 2021-12-19 04:19:25 +00:00 • committed by GitHub
commit f1e85622da
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 377 additions and 6 deletions
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6
modules/git/repo_compare.go
View file

@ -237,7 +237,11 @@ func (repo *Repository) GetDiff(base, head string, w io.Writer) error {
// GetDiffBinary generates and returns patch data between given revisions, including binary diffs.
func (repo *Repository) GetDiffBinary(base, head string, w io.Writer) error {
return NewCommandContext(repo.Ctx, "diff", "-p", "--binary", base, head).
if CheckGitVersionAtLeast("1.7.7") == nil {
return NewCommandContext(repo.Ctx, "diff", "-p", "--binary", "--histogram", base, head).
RunInDirPipeline(repo.Path, w, nil)
}
return NewCommandContext(repo.Ctx, "diff", "-p", "--binary", "--patience", base, head).
RunInDirPipeline(repo.Path, w, nil)
}

197
services/pull/patch.go
View file

@ -11,12 +11,15 @@ import (
"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"
@ -98,12 +101,193 @@ func TestPatch(pr *models.PullRequest) error {
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
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)
return false, fmt.Errorf("unable to create temporary patch file! Error: %v", err)
}
defer func() {
_ = util.Remove(tmpPatchFile.Name())
@ -112,12 +296,12 @@ func checkConflicts(pr *models.PullRequest, gitRepo *git.Repository, tmpBasePath
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)
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)
return false, fmt.Errorf("unable to stat patch file: %v", err)
}
patchPath := tmpPatchFile.Name()
tmpPatchFile.Close()
@ -154,6 +338,9 @@ func checkConflicts(pr *models.PullRequest, gitRepo *git.Repository, tmpBasePath
if prConfig.IgnoreWhitespaceConflicts {
args = append(args, "--ignore-whitespace")
}
if git.CheckGitVersionAtLeast("2.32.0") == nil {
args = append(args, "--3way")
}
args = append(args, patchPath)
pr.ConflictedFiles = make([]string, 0, 5)
@ -168,7 +355,7 @@ func checkConflicts(pr *models.PullRequest, gitRepo *git.Repository, tmpBasePath
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)
return false, fmt.Errorf("unable to open stderr pipe: %v", err)
}
defer func() {
_ = stderrReader.Close()
@ -176,7 +363,7 @@ func checkConflicts(pr *models.PullRequest, gitRepo *git.Repository, tmpBasePath
}()
// 7. Run the check command
conflict := false
conflict = false
err = git.NewCommand(args...).
RunInDirTimeoutEnvFullPipelineFunc(
nil, -1, tmpBasePath,

180
services/pull/patch_unmerged.go Normal file
View file

@ -0,0 +1,180 @@
// Copyright 2021 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"
"strconv"
"strings"
"code.gitea.io/gitea/modules/git"
"code.gitea.io/gitea/modules/log"
)
// lsFileLine is a Quadruplet struct (+error) representing a partially parsed line from ls-files
type lsFileLine struct {
mode string
sha string
stage int
path string
err error
}
// SameAs checks if two lsFileLines are referring to the same path, sha and mode (ignoring stage)
func (line *lsFileLine) SameAs(other *lsFileLine) bool {
if line == nil || other == nil {
return false
}
if line.err != nil || other.err != nil {
return false
}
return line.mode == other.mode &&
line.sha == other.sha &&
line.path == other.path
}
// readUnmergedLsFileLines calls git ls-files -u -z and parses the lines into mode-sha-stage-path quadruplets
// it will push these to the provided channel closing it at the end
func readUnmergedLsFileLines(ctx context.Context, tmpBasePath string, outputChan chan *lsFileLine) {
defer func() {
// Always close the outputChan at the end of this function
close(outputChan)
}()
lsFilesReader, lsFilesWriter, err := os.Pipe()
if err != nil {
log.Error("Unable to open stderr pipe: %v", err)
outputChan <- &lsFileLine{err: fmt.Errorf("unable to open stderr pipe: %v", err)}
return
}
defer func() {
_ = lsFilesWriter.Close()
_ = lsFilesReader.Close()
}()
stderr := &strings.Builder{}
err = git.NewCommandContext(ctx, "ls-files", "-u", "-z").
RunInDirTimeoutEnvFullPipelineFunc(
nil, -1, tmpBasePath,
lsFilesWriter, stderr, nil,
func(_ context.Context, _ context.CancelFunc) error {
_ = lsFilesWriter.Close()
defer func() {
_ = lsFilesReader.Close()
}()
bufferedReader := bufio.NewReader(lsFilesReader)
for {
line, err := bufferedReader.ReadString('\000')
if err != nil {
if err == io.EOF {
return nil
}
return err
}
toemit := &lsFileLine{}
split := strings.SplitN(line, " ", 3)
if len(split) < 3 {
return fmt.Errorf("malformed line: %s", line)
}
toemit.mode = split[0]
toemit.sha = split[1]
if len(split[2]) < 4 {
return fmt.Errorf("malformed line: %s", line)
}
toemit.stage, err = strconv.Atoi(split[2][0:1])
if err != nil {
return fmt.Errorf("malformed line: %s", line)
}
toemit.path = split[2][2 : len(split[2])-1]
outputChan <- toemit
}
})
if err != nil {
outputChan <- &lsFileLine{err: fmt.Errorf("git ls-files -u -z: %v", git.ConcatenateError(err, stderr.String()))}
}
}
// unmergedFile is triple (+error) of lsFileLines split into stages 1,2 & 3.
type unmergedFile struct {
stage1 *lsFileLine
stage2 *lsFileLine
stage3 *lsFileLine
err error
}
// unmergedFiles will collate the output from readUnstagedLsFileLines in to file triplets and send them
// to the provided channel, closing at the end.
func unmergedFiles(ctx context.Context, tmpBasePath string, unmerged chan *unmergedFile) {
defer func() {
// Always close the channel
close(unmerged)
}()
ctx, cancel := context.WithCancel(ctx)
lsFileLineChan := make(chan *lsFileLine, 10) // give lsFileLineChan a buffer
go readUnmergedLsFileLines(ctx, tmpBasePath, lsFileLineChan)
defer func() {
cancel()
for range lsFileLineChan {
// empty channel
}
}()
next := &unmergedFile{}
for line := range lsFileLineChan {
if line.err != nil {
log.Error("Unable to run ls-files -u -z! Error: %v", line.err)
unmerged <- &unmergedFile{err: fmt.Errorf("unable to run ls-files -u -z! Error: %v", line.err)}
return
}
// stages are always emitted 1,2,3 but sometimes 1, 2 or 3 are dropped
switch line.stage {
case 0:
// Should not happen as this represents successfully merged file - we will tolerate and ignore though
case 1:
if next.stage1 != nil {
// We need to handle the unstaged file stage1,stage2,stage3
unmerged <- next
}
next = &unmergedFile{stage1: line}
case 2:
if next.stage3 != nil || next.stage2 != nil || (next.stage1 != nil && next.stage1.path != line.path) {
// We need to handle the unstaged file stage1,stage2,stage3
unmerged <- next
next = &unmergedFile{}
}
next.stage2 = line
case 3:
if next.stage3 != nil || (next.stage1 != nil && next.stage1.path != line.path) || (next.stage2 != nil && next.stage2.path != line.path) {
// We need to handle the unstaged file stage1,stage2,stage3
unmerged <- next
next = &unmergedFile{}
}
next.stage3 = line
default:
log.Error("Unexpected stage %d for path %s in run ls-files -u -z!", line.stage, line.path)
unmerged <- &unmergedFile{err: fmt.Errorf("unexpected stage %d for path %s in git ls-files -u -z", line.stage, line.path)}
return
}
}
// We need to handle the unstaged file stage1,stage2,stage3
if next.stage1 != nil || next.stage2 != nil || next.stage3 != nil {
unmerged <- next
}
}