1 files changed, 216 insertions, 0 deletions

diff --git a/services/pull/patch.go b/services/pull/patch.go
new file mode 100644
index 0000000000..cb8d014486
--- /dev/null
+++ b/services/pull/patch.go
@@ -0,0 +1,216 @@
+// 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"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+)
+
+// DownloadDiff will write the patch for the pr to the writer
+func DownloadDiff(pr *models.PullRequest, w io.Writer, patch bool) error {
+	return DownloadDiffOrPatch(pr, w, false)
+}
+
+// DownloadPatch will write the patch for the pr to the writer
+func DownloadPatch(pr *models.PullRequest, w io.Writer, patch bool) error {
+	return DownloadDiffOrPatch(pr, w, true)
+}
+
+// DownloadDiffOrPatch will write the patch for the pr to the writer
+func DownloadDiffOrPatch(pr *models.PullRequest, w io.Writer, patch bool) error {
+	// Clone base repo.
+	tmpBasePath, err := createTemporaryRepo(pr)
+	if err != nil {
+		log.Error("CreateTemporaryPath: %v", err)
+		return err
+	}
+	defer func() {
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("DownloadDiff: RemoveTemporaryPath: %s", err)
+		}
+	}()
+
+	gitRepo, err := git.OpenRepository(tmpBasePath)
+	if err != nil {
+		return fmt.Errorf("OpenRepository: %v", err)
+	}
+	defer gitRepo.Close()
+
+	pr.MergeBase, err = git.NewCommand("merge-base", "--", "base", "tracking").RunInDir(tmpBasePath)
+	if err != nil {
+		pr.MergeBase = "base"
+	}
+	pr.MergeBase = strings.TrimSpace(pr.MergeBase)
+	if err := gitRepo.GetDiffOrPatch(pr.MergeBase, "tracking", w, patch); err != nil {
+		log.Error("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, err)
+		return fmt.Errorf("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, 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 {
+	// Clone base repo.
+	tmpBasePath, err := createTemporaryRepo(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.OpenRepository(tmpBasePath)
+	if err != nil {
+		return fmt.Errorf("OpenRepository: %v", err)
+	}
+	defer gitRepo.Close()
+
+	pr.MergeBase, err = git.NewCommand("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)
+	tmpPatchFile, err := ioutil.TempFile("", "patch")
+	if err != nil {
+		log.Error("Unable to create temporary patch file! Error: %v", err)
+		return fmt.Errorf("Unable to create temporary patch file! Error: %v", err)
+	}
+	defer func() {
+		_ = os.Remove(tmpPatchFile.Name())
+	}()
+
+	if err := gitRepo.GetDiff(pr.MergeBase, "tracking", tmpPatchFile); err != nil {
+		tmpPatchFile.Close()
+		log.Error("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, err)
+		return fmt.Errorf("Unable to get patch file from %s to %s in %s/%s Error: %v", pr.MergeBase, pr.HeadBranch, pr.BaseRepo.MustOwner().Name, pr.BaseRepo.Name, err)
+	}
+	stat, err := tmpPatchFile.Stat()
+	if err != nil {
+		tmpPatchFile.Close()
+		return fmt.Errorf("Unable to stat patch file: %v", err)
+	}
+	patchPath := tmpPatchFile.Name()
+	tmpPatchFile.Close()
+
+	if stat.Size() == 0 {
+		log.Debug("PullRequest[%d]: Patch is empty - ignoring", pr.ID)
+		pr.Status = models.PullRequestStatusMergeable
+		pr.ConflictedFiles = []string{}
+		return nil
+	}
+
+	log.Trace("PullRequest[%d].testPatch (patchPath): %s", pr.ID, patchPath)
+
+	pr.Status = models.PullRequestStatusChecking
+
+	_, err = git.NewCommand("read-tree", "base").RunInDir(tmpBasePath)
+	if err != nil {
+		return fmt.Errorf("git read-tree %s: %v", pr.BaseBranch, err)
+	}
+
+	prUnit, err := pr.BaseRepo.GetUnit(models.UnitTypePullRequests)
+	if err != nil {
+		return err
+	}
+	prConfig := prUnit.PullRequestsConfig()
+
+	args := []string{"apply", "--check", "--cached"}
+	if prConfig.IgnoreWhitespaceConflicts {
+		args = append(args, "--ignore-whitespace")
+	}
+	args = append(args, patchPath)
+	pr.ConflictedFiles = make([]string, 0, 5)
+
+	stderrReader, stderrWriter, err := os.Pipe()
+	if err != nil {
+		log.Error("Unable to open stderr pipe: %v", err)
+		return fmt.Errorf("Unable to open stderr pipe: %v", err)
+	}
+	defer func() {
+		_ = stderrReader.Close()
+		_ = stderrWriter.Close()
+	}()
+	conflict := false
+	err = git.NewCommand(args...).
+		RunInDirTimeoutEnvFullPipelineFunc(
+			nil, -1, tmpBasePath,
+			nil, stderrWriter, nil,
+			func(ctx context.Context, cancel context.CancelFunc) {
+				_ = stderrWriter.Close()
+				const prefix = "error: patch failed:"
+				const errorPrefix = "error: "
+				conflictMap := map[string]bool{}
+
+				scanner := bufio.NewScanner(stderrReader)
+				for scanner.Scan() {
+					line := scanner.Text()
+					fmt.Printf("%s\n", line)
+					if strings.HasPrefix(line, prefix) {
+						conflict = true
+						filepath := strings.TrimSpace(strings.Split(line[len(prefix):], ":")[0])
+						conflictMap[filepath] = 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
+							}
+						}
+					}
+					// 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)
+					}
+				}
+				_ = stderrReader.Close()
+			})
+
+	if err != nil {
+		if conflict {
+			pr.Status = models.PullRequestStatusConflict
+			log.Trace("Found %d files conflicted: %v", len(pr.ConflictedFiles), pr.ConflictedFiles)
+			return nil
+		}
+		return fmt.Errorf("git apply --check: %v", err)
+	}
+	pr.Status = models.PullRequestStatusMergeable
+
+	return nil
+}