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// Copyright 2019 The Gitea Authors.
// All rights reserved.
// SPDX-License-Identifier: MIT
package pull
import (
"bufio"
"context"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"code.gitea.io/gitea/models"
git_model "code.gitea.io/gitea/models/git"
issues_model "code.gitea.io/gitea/models/issues"
"code.gitea.io/gitea/models/unit"
"code.gitea.io/gitea/modules/container"
"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/setting"
"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 *issues_model.PullRequest, w io.Writer, patch, binary bool) error {
if err := pr.LoadBaseRepo(ctx); 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: %w", 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: %w", 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",
": No such file or directory",
": does not exist in index",
}
// TestPatch will test whether a simple patch will apply
func TestPatch(pr *issues_model.PullRequest) error {
ctx, _, finished := process.GetManager().AddContext(graceful.GetManager().HammerContext(), fmt.Sprintf("TestPatch: %s", pr))
defer finished()
// Clone base repo.
prCtx, cancel, err := createTemporaryRepoForPR(ctx, pr)
if err != nil {
log.Error("createTemporaryRepoForPR %-v: %v", pr, err)
return err
}
defer cancel()
gitRepo, err := git.OpenRepository(ctx, prCtx.tmpBasePath)
if err != nil {
return fmt.Errorf("OpenRepository: %w", err)
}
defer gitRepo.Close()
// 1. update merge base
pr.MergeBase, _, err = git.NewCommand(ctx, "merge-base", "--", "base", "tracking").RunStdString(&git.RunOpts{Dir: prCtx.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: %w", err, err2)
}
}
pr.MergeBase = strings.TrimSpace(pr.MergeBase)
if pr.HeadCommitID, err = gitRepo.GetRefCommitID(git.BranchPrefix + "tracking"); err != nil {
return fmt.Errorf("GetBranchCommitID: can't find commit ID for head: %w", err)
}
if pr.HeadCommitID == pr.MergeBase {
pr.Status = issues_model.PullRequestStatusAncestor
return nil
}
// 2. Check for conflicts
if conflicts, err := checkConflicts(ctx, pr, gitRepo, prCtx.tmpBasePath); err != nil || conflicts || pr.Status == issues_model.PullRequestStatusEmpty {
return err
}
// 3. Check for protected files changes
if err = checkPullFilesProtection(ctx, 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 = issues_model.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 {
log.Trace("Attempt to merge:\n%v", file)
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.NewCommand(ctx, "unpack-file").AddDynamicArguments(file.stage1.sha).RunStdString(&git.RunOpts{Dir: 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.NewCommand(ctx, "unpack-file").AddDynamicArguments(file.stage2.sha).RunStdString(&git.RunOpts{Dir: 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.NewCommand(ctx, "unpack-file").AddDynamicArguments(file.stage3.sha).RunStdString(&git.RunOpts{Dir: 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.NewCommand(ctx, "merge-file").AddDynamicArguments(base, root, head).RunStdString(&git.RunOpts{Dir: tmpBasePath})
if conflictErr != nil {
return &errMergeConflict{file.stage2.path}
}
// base now contains the merged data
hash, _, err := git.NewCommand(ctx, "hash-object", "-w", "--path").AddDynamicArguments(file.stage2.path, base).RunStdString(&git.RunOpts{Dir: 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
}
// AttemptThreeWayMerge will attempt to three way merge using git read-tree and then follow the git merge-one-file algorithm to attempt to resolve basic conflicts
func AttemptThreeWayMerge(ctx context.Context, gitPath string, gitRepo *git.Repository, base, ours, theirs, description string) (bool, []string, error) {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// First we use read-tree to do a simple three-way merge
if _, _, err := git.NewCommand(ctx, "read-tree", "-m").AddDynamicArguments(base, ours, theirs).RunStdString(&git.RunOpts{Dir: gitPath}); err != nil {
log.Error("Unable to run read-tree -m! Error: %v", err)
return false, nil, fmt.Errorf("unable to run read-tree -m! Error: %w", 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, gitPath, unmerged)
defer func() {
cancel()
for range unmerged {
// empty the unmerged channel
}
}()
numberOfConflicts := 0
conflict := false
conflictedFiles := make([]string, 0, 5)
for file := range unmerged {
if file == nil {
break
}
if file.err != nil {
cancel()
return false, nil, file.err
}
// OK now we have the unmerged file triplet attempt to merge it
if err := attemptMerge(ctx, file, gitPath, gitRepo); err != nil {
if conflictErr, ok := err.(*errMergeConflict); ok {
log.Trace("Conflict: %s in %s", conflictErr.filename, description)
conflict = true
if numberOfConflicts < 10 {
conflictedFiles = append(conflictedFiles, conflictErr.filename)
}
numberOfConflicts++
continue
}
return false, nil, err
}
}
return conflict, conflictedFiles, nil
}
func checkConflicts(ctx context.Context, pr *issues_model.PullRequest, gitRepo *git.Repository, tmpBasePath string) (bool, error) {
// 1. checkConflicts resets the conflict status - therefore - reset the conflict status
pr.ConflictedFiles = nil
// 2. AttemptThreeWayMerge first - this is much quicker than plain patch to base
description := fmt.Sprintf("PR[%d] %s/%s#%d", pr.ID, pr.BaseRepo.OwnerName, pr.BaseRepo.Name, pr.Index)
conflict, conflictFiles, err := AttemptThreeWayMerge(ctx,
tmpBasePath, gitRepo, pr.MergeBase, "base", "tracking", description)
if err != nil {
return false, err
}
if !conflict {
// No conflicts detected so we need to check if the patch is empty...
// a. Write the newly merged tree and check the new tree-hash
var treeHash string
treeHash, _, err = git.NewCommand(ctx, "write-tree").RunStdString(&git.RunOpts{Dir: tmpBasePath})
if err != nil {
lsfiles, _, _ := git.NewCommand(ctx, "ls-files", "-u").RunStdString(&git.RunOpts{Dir: tmpBasePath})
return false, fmt.Errorf("unable to write unconflicted tree: %w\n`git ls-files -u`:\n%s", err, lsfiles)
}
treeHash = strings.TrimSpace(treeHash)
baseTree, err := gitRepo.GetTree("base")
if err != nil {
return false, err
}
// b. compare the new tree-hash with the base tree hash
if treeHash == baseTree.ID.String() {
log.Debug("PullRequest[%d]: Patch is empty - ignoring", pr.ID)
pr.Status = issues_model.PullRequestStatusEmpty
}
return false, nil
}
// 3. OK the three-way merge method has detected conflicts
// 3a. Are still testing with GitApply? If not set the conflict status and move on
if !setting.Repository.PullRequest.TestConflictingPatchesWithGitApply {
pr.Status = issues_model.PullRequestStatusConflict
pr.ConflictedFiles = conflictFiles
log.Trace("Found %d files conflicted: %v", len(pr.ConflictedFiles), pr.ConflictedFiles)
return true, nil
}
// 3b. 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: %w", 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: %w", 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: %w", err)
}
patchPath := tmpPatchFile.Name()
tmpPatchFile.Close()
// 3c. 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 = issues_model.PullRequestStatusEmpty
return false, nil
}
log.Trace("PullRequest[%d].testPatch (patchPath): %s", pr.ID, patchPath)
// 4. Read the base branch in to the index of the temporary repository
_, _, err = git.NewCommand(gitRepo.Ctx, "read-tree", "base").RunStdString(&git.RunOpts{Dir: tmpBasePath})
if err != nil {
return false, fmt.Errorf("git read-tree %s: %w", pr.BaseBranch, err)
}
// 5. Now get the pull request configuration to check if we need to ignore whitespace
prUnit, err := pr.BaseRepo.GetUnit(ctx, unit.TypePullRequests)
if err != nil {
return false, err
}
prConfig := prUnit.PullRequestsConfig()
// 6. Prepare the arguments to apply the patch against the index
cmdApply := git.NewCommand(gitRepo.Ctx, "apply", "--check", "--cached")
if prConfig.IgnoreWhitespaceConflicts {
cmdApply.AddArguments("--ignore-whitespace")
}
is3way := false
if git.CheckGitVersionAtLeast("2.32.0") == nil {
cmdApply.AddArguments("--3way")
is3way = true
}
cmdApply.AddDynamicArguments(patchPath)
// 7. 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: %w", err)
}
defer func() {
_ = stderrReader.Close()
_ = stderrWriter.Close()
}()
// 8. Run the check command
conflict = false
err = cmdApply.Run(&git.RunOpts{
Dir: tmpBasePath,
Stderr: stderrWriter,
PipelineFunc: 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."
conflicts := make(container.Set[string])
// Now scan the output from the command
scanner := bufio.NewScanner(stderrReader)
for scanner.Scan() {
line := scanner.Text()
log.Trace("PullRequest[%d].testPatch: stderr: %s", pr.ID, line)
if strings.HasPrefix(line, prefix) {
conflict = true
filepath := strings.TrimSpace(strings.Split(line[len(prefix):], ":")[0])
conflicts.Add(filepath)
} 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 != "" {
conflicts.Add(filepath)
}
break
}
}
} else if is3way && strings.HasPrefix(line, appliedPatchPrefix) && strings.HasSuffix(line, withConflicts) {
conflict = true
filepath := strings.TrimPrefix(strings.TrimSuffix(line, withConflicts), appliedPatchPrefix)
if filepath != "" {
conflicts.Add(filepath)
}
}
// only list 10 conflicted files
if len(conflicts) >= 10 {
break
}
}
if len(conflicts) > 0 {
pr.ConflictedFiles = make([]string, 0, len(conflicts))
for key := range conflicts {
pr.ConflictedFiles = append(pr.ConflictedFiles, key)
}
}
return nil
},
})
// 9. Check if the found conflictedfiles is non-zero, "err" could be non-nil, so we should ignore it if we found conflicts.
// Note: `"err" could be non-nil` is due that if enable 3-way merge, it doesn't return any error on found conflicts.
if len(pr.ConflictedFiles) > 0 {
if conflict {
pr.Status = issues_model.PullRequestStatusConflict
log.Trace("Found %d files conflicted: %v", len(pr.ConflictedFiles), pr.ConflictedFiles)
return true, nil
}
} else if err != nil {
return false, fmt.Errorf("git apply --check: %w", 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(ctx context.Context, pr *issues_model.PullRequest, gitRepo *git.Repository) error {
if pr.Status == issues_model.PullRequestStatusEmpty {
pr.ChangedProtectedFiles = nil
return nil
}
pb, err := git_model.GetFirstMatchProtectedBranchRule(ctx, pr.BaseRepoID, pr.BaseBranch)
if err != nil {
return err
}
if pb == nil {
pr.ChangedProtectedFiles = nil
return nil
}
pr.ChangedProtectedFiles, err = CheckFileProtection(gitRepo, pr.MergeBase, "tracking", pb.GetProtectedFilePatterns(), 10, os.Environ())
if err != nil && !models.IsErrFilePathProtected(err) {
return err
}
return nil
}
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