1 files changed, 152 insertions, 0 deletions

diff --git a/services/pull/temp_repo.go b/services/pull/temp_repo.go
new file mode 100644
index 0000000000..bb6ce2921e
--- /dev/null
+++ b/services/pull/temp_repo.go
@@ -0,0 +1,152 @@
+// 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 (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+)
+
+func createTemporaryRepo(pr *models.PullRequest) (string, error) {
+	if err := pr.GetHeadRepo(); err != nil {
+		log.Error("GetHeadRepo: %v", err)
+		return "", fmt.Errorf("GetHeadRepo: %v", err)
+	} else if pr.HeadRepo == nil {
+		log.Error("Pr %d HeadRepo %d does not exist", pr.ID, pr.HeadRepoID)
+		return "", &models.ErrRepoNotExist{
+			ID: pr.HeadRepoID,
+		}
+	} else if err := pr.GetBaseRepo(); err != nil {
+		log.Error("GetBaseRepo: %v", err)
+		return "", fmt.Errorf("GetBaseRepo: %v", err)
+	} else if pr.BaseRepo == nil {
+		log.Error("Pr %d BaseRepo %d does not exist", pr.ID, pr.BaseRepoID)
+		return "", &models.ErrRepoNotExist{
+			ID: pr.BaseRepoID,
+		}
+	} else if err := pr.HeadRepo.GetOwner(); err != nil {
+		log.Error("HeadRepo.GetOwner: %v", err)
+		return "", fmt.Errorf("HeadRepo.GetOwner: %v", err)
+	} else if err := pr.BaseRepo.GetOwner(); err != nil {
+		log.Error("BaseRepo.GetOwner: %v", err)
+		return "", fmt.Errorf("BaseRepo.GetOwner: %v", err)
+	}
+
+	// Clone base repo.
+	tmpBasePath, err := models.CreateTemporaryPath("pull")
+	if err != nil {
+		log.Error("CreateTemporaryPath: %v", err)
+		return "", err
+	}
+
+	baseRepoPath := pr.BaseRepo.RepoPath()
+	headRepoPath := pr.HeadRepo.RepoPath()
+
+	if err := git.InitRepository(tmpBasePath, false); err != nil {
+		log.Error("git init tmpBasePath: %v", err)
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", err
+	}
+
+	remoteRepoName := "head_repo"
+	baseBranch := "base"
+
+	// Add head repo remote.
+	addCacheRepo := func(staging, cache string) error {
+		p := filepath.Join(staging, ".git", "objects", "info", "alternates")
+		f, err := os.OpenFile(p, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0600)
+		if err != nil {
+			log.Error("Could not create .git/objects/info/alternates file in %s: %v", staging, err)
+			return err
+		}
+		defer f.Close()
+		data := filepath.Join(cache, "objects")
+		if _, err := fmt.Fprintln(f, data); err != nil {
+			log.Error("Could not write to .git/objects/info/alternates file in %s: %v", staging, err)
+			return err
+		}
+		return nil
+	}
+
+	if err := addCacheRepo(tmpBasePath, baseRepoPath); err != nil {
+		log.Error("Unable to add base repository to temporary repo [%s -> %s]: %v", pr.BaseRepo.FullName(), tmpBasePath, err)
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to add base repository to temporary repo [%s -> tmpBasePath]: %v", pr.BaseRepo.FullName(), err)
+	}
+
+	var outbuf, errbuf strings.Builder
+	if err := git.NewCommand("remote", "add", "-t", pr.BaseBranch, "-m", pr.BaseBranch, "origin", baseRepoPath).RunInDirPipeline(tmpBasePath, &outbuf, &errbuf); err != nil {
+		log.Error("Unable to add base repository as origin [%s -> %s]: %v\n%s\n%s", pr.BaseRepo.FullName(), tmpBasePath, err, outbuf.String(), errbuf.String())
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to add base repository as origin [%s -> tmpBasePath]: %v\n%s\n%s", pr.BaseRepo.FullName(), err, outbuf.String(), errbuf.String())
+	}
+	outbuf.Reset()
+	errbuf.Reset()
+
+	if err := git.NewCommand("fetch", "origin", "--no-tags", pr.BaseBranch+":"+baseBranch, pr.BaseBranch+":original_"+baseBranch).RunInDirPipeline(tmpBasePath, &outbuf, &errbuf); err != nil {
+		log.Error("Unable to fetch origin base branch [%s:%s -> base, original_base in %s]: %v:\n%s\n%s", pr.BaseRepo.FullName(), pr.BaseBranch, tmpBasePath, err, outbuf.String(), errbuf.String())
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to fetch origin base branch [%s:%s -> base, original_base in tmpBasePath]: %v\n%s\n%s", pr.BaseRepo.FullName(), pr.BaseBranch, err, outbuf.String(), errbuf.String())
+	}
+	outbuf.Reset()
+	errbuf.Reset()
+
+	if err := git.NewCommand("symbolic-ref", "HEAD", git.BranchPrefix+baseBranch).RunInDirPipeline(tmpBasePath, &outbuf, &errbuf); err != nil {
+		log.Error("Unable to set HEAD as base branch [%s]: %v\n%s\n%s", tmpBasePath, err, outbuf.String(), errbuf.String())
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to set HEAD as base branch [tmpBasePath]: %v\n%s\n%s", err, outbuf.String(), errbuf.String())
+	}
+	outbuf.Reset()
+	errbuf.Reset()
+
+	if err := addCacheRepo(tmpBasePath, headRepoPath); err != nil {
+		log.Error("Unable to add head repository to temporary repo [%s -> %s]: %v", pr.HeadRepo.FullName(), tmpBasePath, err)
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to head base repository to temporary repo [%s -> tmpBasePath]: %v", pr.HeadRepo.FullName(), err)
+	}
+
+	if err := git.NewCommand("remote", "add", remoteRepoName, headRepoPath).RunInDirPipeline(tmpBasePath, &outbuf, &errbuf); err != nil {
+		log.Error("Unable to add head repository as head_repo [%s -> %s]: %v\n%s\n%s", pr.HeadRepo.FullName(), tmpBasePath, err, outbuf.String(), errbuf.String())
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to add head repository as head_repo [%s -> tmpBasePath]: %v\n%s\n%s", pr.HeadRepo.FullName(), err, outbuf.String(), errbuf.String())
+	}
+	outbuf.Reset()
+	errbuf.Reset()
+
+	trackingBranch := "tracking"
+	// Fetch head branch
+	if err := git.NewCommand("fetch", "--no-tags", remoteRepoName, pr.HeadBranch+":"+trackingBranch).RunInDirPipeline(tmpBasePath, &outbuf, &errbuf); err != nil {
+		log.Error("Unable to fetch head_repo head branch [%s:%s -> tracking in %s]: %v:\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, tmpBasePath, err, outbuf.String(), errbuf.String())
+		if err := models.RemoveTemporaryPath(tmpBasePath); err != nil {
+			log.Error("CreateTempRepo: RemoveTemporaryPath: %s", err)
+		}
+		return "", fmt.Errorf("Unable to fetch head_repo head branch [%s:%s -> tracking in tmpBasePath]: %v\n%s\n%s", pr.HeadRepo.FullName(), pr.HeadBranch, err, outbuf.String(), errbuf.String())
+	}
+	outbuf.Reset()
+	errbuf.Reset()
+
+	return tmpBasePath, nil
+}