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