Adding upstream version 9.0.3.

Signed-off-by: Daniel Baumann <daniel@debian.org>

1 files changed, 972 insertions, 0 deletions

diff --git a/routers/web/repo/compare.go b/routers/web/repo/compare.go
new file mode 100644
index 0000000..38d6004
--- /dev/null
+++ b/routers/web/repo/compare.go
@@ -0,0 +1,972 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package repo
+
+import (
+	"bufio"
+	gocontext "context"
+	"encoding/csv"
+	"errors"
+	"fmt"
+	"html"
+	"io"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strings"
+
+	"code.gitea.io/gitea/models/db"
+	git_model "code.gitea.io/gitea/models/git"
+	issues_model "code.gitea.io/gitea/models/issues"
+	access_model "code.gitea.io/gitea/models/perm/access"
+	repo_model "code.gitea.io/gitea/models/repo"
+	"code.gitea.io/gitea/models/unit"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/charset"
+	csv_module "code.gitea.io/gitea/modules/csv"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/optional"
+	"code.gitea.io/gitea/modules/setting"
+	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/typesniffer"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/routers/common"
+	"code.gitea.io/gitea/services/context"
+	"code.gitea.io/gitea/services/context/upload"
+	"code.gitea.io/gitea/services/gitdiff"
+)
+
+const (
+	tplCompare     base.TplName = "repo/diff/compare"
+	tplBlobExcerpt base.TplName = "repo/diff/blob_excerpt"
+	tplDiffBox     base.TplName = "repo/diff/box"
+)
+
+// setCompareContext sets context data.
+func setCompareContext(ctx *context.Context, before, head *git.Commit, headOwner, headName string) {
+	ctx.Data["BeforeCommit"] = before
+	ctx.Data["HeadCommit"] = head
+
+	ctx.Data["GetBlobByPathForCommit"] = func(commit *git.Commit, path string) *git.Blob {
+		if commit == nil {
+			return nil
+		}
+
+		blob, err := commit.GetBlobByPath(path)
+		if err != nil {
+			return nil
+		}
+		return blob
+	}
+
+	ctx.Data["GetSniffedTypeForBlob"] = func(blob *git.Blob) typesniffer.SniffedType {
+		st := typesniffer.SniffedType{}
+
+		if blob == nil {
+			return st
+		}
+
+		st, err := blob.GuessContentType()
+		if err != nil {
+			log.Error("GuessContentType failed: %v", err)
+			return st
+		}
+		return st
+	}
+
+	setPathsCompareContext(ctx, before, head, headOwner, headName)
+	setImageCompareContext(ctx)
+	setCsvCompareContext(ctx)
+}
+
+// SourceCommitURL creates a relative URL for a commit in the given repository
+func SourceCommitURL(owner, name string, commit *git.Commit) string {
+	return setting.AppSubURL + "/" + url.PathEscape(owner) + "/" + url.PathEscape(name) + "/src/commit/" + url.PathEscape(commit.ID.String())
+}
+
+// RawCommitURL creates a relative URL for the raw commit in the given repository
+func RawCommitURL(owner, name string, commit *git.Commit) string {
+	return setting.AppSubURL + "/" + url.PathEscape(owner) + "/" + url.PathEscape(name) + "/raw/commit/" + url.PathEscape(commit.ID.String())
+}
+
+// setPathsCompareContext sets context data for source and raw paths
+func setPathsCompareContext(ctx *context.Context, base, head *git.Commit, headOwner, headName string) {
+	ctx.Data["SourcePath"] = SourceCommitURL(headOwner, headName, head)
+	ctx.Data["RawPath"] = RawCommitURL(headOwner, headName, head)
+	if base != nil {
+		ctx.Data["BeforeSourcePath"] = SourceCommitURL(headOwner, headName, base)
+		ctx.Data["BeforeRawPath"] = RawCommitURL(headOwner, headName, base)
+	}
+}
+
+// setImageCompareContext sets context data that is required by image compare template
+func setImageCompareContext(ctx *context.Context) {
+	ctx.Data["IsSniffedTypeAnImage"] = func(st typesniffer.SniffedType) bool {
+		return st.IsImage() && (setting.UI.SVG.Enabled || !st.IsSvgImage())
+	}
+}
+
+// setCsvCompareContext sets context data that is required by the CSV compare template
+func setCsvCompareContext(ctx *context.Context) {
+	ctx.Data["IsCsvFile"] = func(diffFile *gitdiff.DiffFile) bool {
+		extension := strings.ToLower(filepath.Ext(diffFile.Name))
+		return extension == ".csv" || extension == ".tsv"
+	}
+
+	type CsvDiffResult struct {
+		Sections []*gitdiff.TableDiffSection
+		Error    string
+	}
+
+	ctx.Data["CreateCsvDiff"] = func(diffFile *gitdiff.DiffFile, baseBlob, headBlob *git.Blob) CsvDiffResult {
+		if diffFile == nil {
+			return CsvDiffResult{nil, ""}
+		}
+
+		errTooLarge := errors.New(ctx.Locale.TrString("repo.error.csv.too_large"))
+
+		csvReaderFromCommit := func(ctx *markup.RenderContext, blob *git.Blob) (*csv.Reader, io.Closer, error) {
+			if blob == nil {
+				// It's ok for blob to be nil (file added or deleted)
+				return nil, nil, nil
+			}
+
+			if setting.UI.CSV.MaxFileSize != 0 && setting.UI.CSV.MaxFileSize < blob.Size() {
+				return nil, nil, errTooLarge
+			}
+
+			reader, err := blob.DataAsync()
+			if err != nil {
+				return nil, nil, err
+			}
+
+			csvReader, err := csv_module.CreateReaderAndDetermineDelimiter(ctx, charset.ToUTF8WithFallbackReader(reader, charset.ConvertOpts{}))
+			return csvReader, reader, err
+		}
+
+		baseReader, baseBlobCloser, err := csvReaderFromCommit(&markup.RenderContext{Ctx: ctx, RelativePath: diffFile.OldName}, baseBlob)
+		if baseBlobCloser != nil {
+			defer baseBlobCloser.Close()
+		}
+		if err != nil {
+			if err == errTooLarge {
+				return CsvDiffResult{nil, err.Error()}
+			}
+			log.Error("error whilst creating csv.Reader from file %s in base commit %s in %s: %v", diffFile.Name, baseBlob.ID.String(), ctx.Repo.Repository.Name, err)
+			return CsvDiffResult{nil, "unable to load file"}
+		}
+
+		headReader, headBlobCloser, err := csvReaderFromCommit(&markup.RenderContext{Ctx: ctx, RelativePath: diffFile.Name}, headBlob)
+		if headBlobCloser != nil {
+			defer headBlobCloser.Close()
+		}
+		if err != nil {
+			if err == errTooLarge {
+				return CsvDiffResult{nil, err.Error()}
+			}
+			log.Error("error whilst creating csv.Reader from file %s in head commit %s in %s: %v", diffFile.Name, headBlob.ID.String(), ctx.Repo.Repository.Name, err)
+			return CsvDiffResult{nil, "unable to load file"}
+		}
+
+		sections, err := gitdiff.CreateCsvDiff(diffFile, baseReader, headReader)
+		if err != nil {
+			errMessage, err := csv_module.FormatError(err, ctx.Locale)
+			if err != nil {
+				log.Error("CreateCsvDiff FormatError failed: %v", err)
+				return CsvDiffResult{nil, "unknown csv diff error"}
+			}
+			return CsvDiffResult{nil, errMessage}
+		}
+		return CsvDiffResult{sections, ""}
+	}
+}
+
+// ParseCompareInfo parse compare info between two commit for preparing comparing references
+func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
+	baseRepo := ctx.Repo.Repository
+	ci := &common.CompareInfo{}
+
+	fileOnly := ctx.FormBool("file-only")
+
+	// Get compared branches information
+	// A full compare url is of the form:
+	//
+	// 1. /{:baseOwner}/{:baseRepoName}/compare/{:baseBranch}...{:headBranch}
+	// 2. /{:baseOwner}/{:baseRepoName}/compare/{:baseBranch}...{:headOwner}:{:headBranch}
+	// 3. /{:baseOwner}/{:baseRepoName}/compare/{:baseBranch}...{:headOwner}/{:headRepoName}:{:headBranch}
+	// 4. /{:baseOwner}/{:baseRepoName}/compare/{:headBranch}
+	// 5. /{:baseOwner}/{:baseRepoName}/compare/{:headOwner}:{:headBranch}
+	// 6. /{:baseOwner}/{:baseRepoName}/compare/{:headOwner}/{:headRepoName}:{:headBranch}
+	//
+	// Here we obtain the infoPath "{:baseBranch}...[{:headOwner}/{:headRepoName}:]{:headBranch}" as ctx.Params("*")
+	// with the :baseRepo in ctx.Repo.
+	//
+	// Note: Generally :headRepoName is not provided here - we are only passed :headOwner.
+	//
+	// How do we determine the :headRepo?
+	//
+	// 1. If :headOwner is not set then the :headRepo = :baseRepo
+	// 2. If :headOwner is set - then look for the fork of :baseRepo owned by :headOwner
+	// 3. But... :baseRepo could be a fork of :headOwner's repo - so check that
+	// 4. Now, :baseRepo and :headRepos could be forks of the same repo - so check that
+	//
+	// format: <base branch>...[<head repo>:]<head branch>
+	// base<-head: master...head:feature
+	// same repo: master...feature
+
+	var (
+		isSameRepo bool
+		infoPath   string
+		err        error
+	)
+
+	infoPath = ctx.Params("*")
+	var infos []string
+	if infoPath == "" {
+		infos = []string{baseRepo.DefaultBranch, baseRepo.DefaultBranch}
+	} else {
+		infos = strings.SplitN(infoPath, "...", 2)
+		if len(infos) != 2 {
+			if infos = strings.SplitN(infoPath, "..", 2); len(infos) == 2 {
+				ci.DirectComparison = true
+				ctx.Data["PageIsComparePull"] = false
+			} else {
+				infos = []string{baseRepo.DefaultBranch, infoPath}
+			}
+		}
+	}
+
+	ctx.Data["BaseName"] = baseRepo.OwnerName
+	ci.BaseBranch = infos[0]
+	ctx.Data["BaseBranch"] = ci.BaseBranch
+
+	// If there is no head repository, it means compare between same repository.
+	headInfos := strings.Split(infos[1], ":")
+	if len(headInfos) == 1 {
+		isSameRepo = true
+		ci.HeadUser = ctx.Repo.Owner
+		ci.HeadBranch = headInfos[0]
+	} else if len(headInfos) == 2 {
+		headInfosSplit := strings.Split(headInfos[0], "/")
+		if len(headInfosSplit) == 1 {
+			ci.HeadUser, err = user_model.GetUserByName(ctx, headInfos[0])
+			if err != nil {
+				if user_model.IsErrUserNotExist(err) {
+					ctx.NotFound("GetUserByName", nil)
+				} else {
+					ctx.ServerError("GetUserByName", err)
+				}
+				return nil
+			}
+			ci.HeadBranch = headInfos[1]
+			isSameRepo = ci.HeadUser.ID == ctx.Repo.Owner.ID
+			if isSameRepo {
+				ci.HeadRepo = baseRepo
+			}
+		} else {
+			ci.HeadRepo, err = repo_model.GetRepositoryByOwnerAndName(ctx, headInfosSplit[0], headInfosSplit[1])
+			if err != nil {
+				if repo_model.IsErrRepoNotExist(err) {
+					ctx.NotFound("GetRepositoryByOwnerAndName", nil)
+				} else {
+					ctx.ServerError("GetRepositoryByOwnerAndName", err)
+				}
+				return nil
+			}
+			if err := ci.HeadRepo.LoadOwner(ctx); err != nil {
+				if user_model.IsErrUserNotExist(err) {
+					ctx.NotFound("GetUserByName", nil)
+				} else {
+					ctx.ServerError("GetUserByName", err)
+				}
+				return nil
+			}
+			ci.HeadBranch = headInfos[1]
+			ci.HeadUser = ci.HeadRepo.Owner
+			isSameRepo = ci.HeadRepo.ID == ctx.Repo.Repository.ID
+		}
+	} else {
+		ctx.NotFound("CompareAndPullRequest", nil)
+		return nil
+	}
+	ctx.Data["HeadUser"] = ci.HeadUser
+	ctx.Data["HeadBranch"] = ci.HeadBranch
+	ctx.Repo.PullRequest.SameRepo = isSameRepo
+
+	// Check if base branch is valid.
+	baseIsCommit := ctx.Repo.GitRepo.IsCommitExist(ci.BaseBranch)
+	baseIsBranch := ctx.Repo.GitRepo.IsBranchExist(ci.BaseBranch)
+	baseIsTag := ctx.Repo.GitRepo.IsTagExist(ci.BaseBranch)
+
+	if !baseIsCommit && !baseIsBranch && !baseIsTag {
+		// Check if baseBranch is short sha commit hash
+		if baseCommit, _ := ctx.Repo.GitRepo.GetCommit(ci.BaseBranch); baseCommit != nil {
+			ci.BaseBranch = baseCommit.ID.String()
+			ctx.Data["BaseBranch"] = ci.BaseBranch
+			baseIsCommit = true
+		} else if ci.BaseBranch == ctx.Repo.GetObjectFormat().EmptyObjectID().String() {
+			if isSameRepo {
+				ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadBranch))
+			} else {
+				ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadRepo.FullName()) + ":" + util.PathEscapeSegments(ci.HeadBranch))
+			}
+			return nil
+		} else {
+			ctx.NotFound("IsRefExist", nil)
+			return nil
+		}
+	}
+	ctx.Data["BaseIsCommit"] = baseIsCommit
+	ctx.Data["BaseIsBranch"] = baseIsBranch
+	ctx.Data["BaseIsTag"] = baseIsTag
+	ctx.Data["IsPull"] = true
+
+	// Now we have the repository that represents the base
+
+	// The current base and head repositories and branches may not
+	// actually be the intended branches that the user wants to
+	// create a pull-request from - but also determining the head
+	// repo is difficult.
+
+	// We will want therefore to offer a few repositories to set as
+	// our base and head
+
+	// 1. First if the baseRepo is a fork get the "RootRepo" it was
+	// forked from
+	var rootRepo *repo_model.Repository
+	if baseRepo.IsFork {
+		err = baseRepo.GetBaseRepo(ctx)
+		if err != nil {
+			if !repo_model.IsErrRepoNotExist(err) {
+				ctx.ServerError("Unable to find root repo", err)
+				return nil
+			}
+		} else {
+			rootRepo = baseRepo.BaseRepo
+		}
+	}
+
+	// 2. Now if the current user is not the owner of the baseRepo,
+	// check if they have a fork of the base repo and offer that as
+	// "OwnForkRepo"
+	var ownForkRepo *repo_model.Repository
+	if ctx.Doer != nil && baseRepo.OwnerID != ctx.Doer.ID {
+		repo := repo_model.GetForkedRepo(ctx, ctx.Doer.ID, baseRepo.ID)
+		if repo != nil {
+			ownForkRepo = repo
+			ctx.Data["OwnForkRepo"] = ownForkRepo
+		}
+	}
+
+	has := ci.HeadRepo != nil
+	// 3. If the base is a forked from "RootRepo" and the owner of
+	// the "RootRepo" is the :headUser - set headRepo to that
+	if !has && rootRepo != nil && rootRepo.OwnerID == ci.HeadUser.ID {
+		ci.HeadRepo = rootRepo
+		has = true
+	}
+
+	// 4. If the ctx.Doer has their own fork of the baseRepo and the headUser is the ctx.Doer
+	// set the headRepo to the ownFork
+	if !has && ownForkRepo != nil && ownForkRepo.OwnerID == ci.HeadUser.ID {
+		ci.HeadRepo = ownForkRepo
+		has = true
+	}
+
+	// 5. If the headOwner has a fork of the baseRepo - use that
+	if !has {
+		ci.HeadRepo = repo_model.GetForkedRepo(ctx, ci.HeadUser.ID, baseRepo.ID)
+		has = ci.HeadRepo != nil
+	}
+
+	// 6. If the baseRepo is a fork and the headUser has a fork of that use that
+	if !has && baseRepo.IsFork {
+		ci.HeadRepo = repo_model.GetForkedRepo(ctx, ci.HeadUser.ID, baseRepo.ForkID)
+		has = ci.HeadRepo != nil
+	}
+
+	// 7. Otherwise if we're not the same repo and haven't found a repo give up
+	if !isSameRepo && !has {
+		ctx.Data["PageIsComparePull"] = false
+	}
+
+	// 8. Finally open the git repo
+	if isSameRepo {
+		ci.HeadRepo = ctx.Repo.Repository
+		ci.HeadGitRepo = ctx.Repo.GitRepo
+	} else if has {
+		ci.HeadGitRepo, err = gitrepo.OpenRepository(ctx, ci.HeadRepo)
+		if err != nil {
+			ctx.ServerError("OpenRepository", err)
+			return nil
+		}
+		defer ci.HeadGitRepo.Close()
+	} else {
+		ctx.NotFound("ParseCompareInfo", nil)
+		return nil
+	}
+
+	ctx.Data["HeadRepo"] = ci.HeadRepo
+	ctx.Data["BaseCompareRepo"] = ctx.Repo.Repository
+
+	// Now we need to assert that the ctx.Doer has permission to read
+	// the baseRepo's code and pulls
+	// (NOT headRepo's)
+	permBase, err := access_model.GetUserRepoPermission(ctx, baseRepo, ctx.Doer)
+	if err != nil {
+		ctx.ServerError("GetUserRepoPermission", err)
+		return nil
+	}
+	if !permBase.CanRead(unit.TypeCode) {
+		if log.IsTrace() {
+			log.Trace("Permission Denied: User: %-v cannot read code in Repo: %-v\nUser in baseRepo has Permissions: %-+v",
+				ctx.Doer,
+				baseRepo,
+				permBase)
+		}
+		ctx.NotFound("ParseCompareInfo", nil)
+		return nil
+	}
+
+	// If we're not merging from the same repo:
+	if !isSameRepo {
+		// Assert ctx.Doer has permission to read headRepo's codes
+		permHead, err := access_model.GetUserRepoPermission(ctx, ci.HeadRepo, ctx.Doer)
+		if err != nil {
+			ctx.ServerError("GetUserRepoPermission", err)
+			return nil
+		}
+		if !permHead.CanRead(unit.TypeCode) {
+			if log.IsTrace() {
+				log.Trace("Permission Denied: User: %-v cannot read code in Repo: %-v\nUser in headRepo has Permissions: %-+v",
+					ctx.Doer,
+					ci.HeadRepo,
+					permHead)
+			}
+			ctx.NotFound("ParseCompareInfo", nil)
+			return nil
+		}
+		ctx.Data["CanWriteToHeadRepo"] = permHead.CanWrite(unit.TypeCode)
+	}
+
+	// If we have a rootRepo and it's different from:
+	// 1. the computed base
+	// 2. the computed head
+	// then get the branches of it
+	if rootRepo != nil &&
+		rootRepo.ID != ci.HeadRepo.ID &&
+		rootRepo.ID != baseRepo.ID {
+		canRead := access_model.CheckRepoUnitUser(ctx, rootRepo, ctx.Doer, unit.TypeCode)
+		if canRead {
+			ctx.Data["RootRepo"] = rootRepo
+			if !fileOnly {
+				branches, tags, err := getBranchesAndTagsForRepo(ctx, rootRepo)
+				if err != nil {
+					ctx.ServerError("GetBranchesForRepo", err)
+					return nil
+				}
+
+				ctx.Data["RootRepoBranches"] = branches
+				ctx.Data["RootRepoTags"] = tags
+			}
+		}
+	}
+
+	// If we have a ownForkRepo and it's different from:
+	// 1. The computed base
+	// 2. The computed head
+	// 3. The rootRepo (if we have one)
+	// then get the branches from it.
+	if ownForkRepo != nil &&
+		ownForkRepo.ID != ci.HeadRepo.ID &&
+		ownForkRepo.ID != baseRepo.ID &&
+		(rootRepo == nil || ownForkRepo.ID != rootRepo.ID) {
+		canRead := access_model.CheckRepoUnitUser(ctx, ownForkRepo, ctx.Doer, unit.TypeCode)
+		if canRead {
+			ctx.Data["OwnForkRepo"] = ownForkRepo
+			if !fileOnly {
+				branches, tags, err := getBranchesAndTagsForRepo(ctx, ownForkRepo)
+				if err != nil {
+					ctx.ServerError("GetBranchesForRepo", err)
+					return nil
+				}
+				ctx.Data["OwnForkRepoBranches"] = branches
+				ctx.Data["OwnForkRepoTags"] = tags
+			}
+		}
+	}
+
+	// Check if head branch is valid.
+	headIsCommit := ci.HeadGitRepo.IsCommitExist(ci.HeadBranch)
+	headIsBranch := ci.HeadGitRepo.IsBranchExist(ci.HeadBranch)
+	headIsTag := ci.HeadGitRepo.IsTagExist(ci.HeadBranch)
+	if !headIsCommit && !headIsBranch && !headIsTag {
+		// Check if headBranch is short sha commit hash
+		if headCommit, _ := ci.HeadGitRepo.GetCommit(ci.HeadBranch); headCommit != nil {
+			ci.HeadBranch = headCommit.ID.String()
+			ctx.Data["HeadBranch"] = ci.HeadBranch
+			headIsCommit = true
+		} else {
+			ctx.NotFound("IsRefExist", nil)
+			return nil
+		}
+	}
+	ctx.Data["HeadIsCommit"] = headIsCommit
+	ctx.Data["HeadIsBranch"] = headIsBranch
+	ctx.Data["HeadIsTag"] = headIsTag
+
+	// Treat as pull request if both references are branches
+	if ctx.Data["PageIsComparePull"] == nil {
+		ctx.Data["PageIsComparePull"] = headIsBranch && baseIsBranch
+	}
+
+	if ctx.Data["PageIsComparePull"] == true && !permBase.CanReadIssuesOrPulls(true) {
+		if log.IsTrace() {
+			log.Trace("Permission Denied: User: %-v cannot create/read pull requests in Repo: %-v\nUser in baseRepo has Permissions: %-+v",
+				ctx.Doer,
+				baseRepo,
+				permBase)
+		}
+		ctx.NotFound("ParseCompareInfo", nil)
+		return nil
+	}
+
+	baseBranchRef := ci.BaseBranch
+	if baseIsBranch {
+		baseBranchRef = git.BranchPrefix + ci.BaseBranch
+	} else if baseIsTag {
+		baseBranchRef = git.TagPrefix + ci.BaseBranch
+	}
+	headBranchRef := ci.HeadBranch
+	if headIsBranch {
+		headBranchRef = git.BranchPrefix + ci.HeadBranch
+	} else if headIsTag {
+		headBranchRef = git.TagPrefix + ci.HeadBranch
+	}
+
+	ci.CompareInfo, err = ci.HeadGitRepo.GetCompareInfo(baseRepo.RepoPath(), baseBranchRef, headBranchRef, ci.DirectComparison, fileOnly)
+	if err != nil {
+		ctx.ServerError("GetCompareInfo", err)
+		return nil
+	}
+	if ci.DirectComparison {
+		ctx.Data["BeforeCommitID"] = ci.CompareInfo.BaseCommitID
+	} else {
+		ctx.Data["BeforeCommitID"] = ci.CompareInfo.MergeBase
+	}
+
+	return ci
+}
+
+// PrepareCompareDiff renders compare diff page
+func PrepareCompareDiff(
+	ctx *context.Context,
+	ci *common.CompareInfo,
+	whitespaceBehavior git.TrustedCmdArgs,
+) bool {
+	var (
+		repo  = ctx.Repo.Repository
+		err   error
+		title string
+	)
+
+	// Get diff information.
+	ctx.Data["CommitRepoLink"] = ci.HeadRepo.Link()
+
+	headCommitID := ci.CompareInfo.HeadCommitID
+
+	ctx.Data["AfterCommitID"] = headCommitID
+
+	if (headCommitID == ci.CompareInfo.MergeBase && !ci.DirectComparison) ||
+		headCommitID == ci.CompareInfo.BaseCommitID {
+		ctx.Data["IsNothingToCompare"] = true
+		if unit, err := repo.GetUnit(ctx, unit.TypePullRequests); err == nil {
+			config := unit.PullRequestsConfig()
+
+			if !config.AutodetectManualMerge {
+				allowEmptyPr := !(ci.BaseBranch == ci.HeadBranch && ctx.Repo.Repository.Name == ci.HeadRepo.Name)
+				ctx.Data["AllowEmptyPr"] = allowEmptyPr
+
+				return !allowEmptyPr
+			}
+
+			ctx.Data["AllowEmptyPr"] = false
+		}
+		return true
+	}
+
+	beforeCommitID := ci.CompareInfo.MergeBase
+	if ci.DirectComparison {
+		beforeCommitID = ci.CompareInfo.BaseCommitID
+	}
+
+	maxLines, maxFiles := setting.Git.MaxGitDiffLines, setting.Git.MaxGitDiffFiles
+	files := ctx.FormStrings("files")
+	if len(files) == 2 || len(files) == 1 {
+		maxLines, maxFiles = -1, -1
+	}
+
+	diff, err := gitdiff.GetDiff(ctx, ci.HeadGitRepo,
+		&gitdiff.DiffOptions{
+			BeforeCommitID:     beforeCommitID,
+			AfterCommitID:      headCommitID,
+			SkipTo:             ctx.FormString("skip-to"),
+			MaxLines:           maxLines,
+			MaxLineCharacters:  setting.Git.MaxGitDiffLineCharacters,
+			MaxFiles:           maxFiles,
+			WhitespaceBehavior: whitespaceBehavior,
+			DirectComparison:   ci.DirectComparison,
+		}, ctx.FormStrings("files")...)
+	if err != nil {
+		ctx.ServerError("GetDiffRangeWithWhitespaceBehavior", err)
+		return false
+	}
+	ctx.Data["Diff"] = diff
+	ctx.Data["DiffNotAvailable"] = diff.NumFiles == 0
+
+	headCommit, err := ci.HeadGitRepo.GetCommit(headCommitID)
+	if err != nil {
+		ctx.ServerError("GetCommit", err)
+		return false
+	}
+
+	baseGitRepo := ctx.Repo.GitRepo
+
+	beforeCommit, err := baseGitRepo.GetCommit(beforeCommitID)
+	if err != nil {
+		ctx.ServerError("GetCommit", err)
+		return false
+	}
+
+	commits := processGitCommits(ctx, ci.CompareInfo.Commits)
+	ctx.Data["Commits"] = commits
+	ctx.Data["CommitCount"] = len(commits)
+
+	if len(commits) == 1 {
+		c := commits[0]
+		title = strings.TrimSpace(c.UserCommit.Summary())
+
+		body := strings.Split(strings.TrimSpace(c.UserCommit.Message()), "\n")
+		if len(body) > 1 {
+			ctx.Data["content"] = strings.Join(body[1:], "\n")
+		}
+	} else {
+		title = ci.HeadBranch
+	}
+	if len(title) > 255 {
+		var trailer string
+		title, trailer = util.SplitStringAtByteN(title, 255)
+		if len(trailer) > 0 {
+			if ctx.Data["content"] != nil {
+				ctx.Data["content"] = fmt.Sprintf("%s\n\n%s", trailer, ctx.Data["content"])
+			} else {
+				ctx.Data["content"] = trailer + "\n"
+			}
+		}
+	}
+
+	ctx.Data["title"] = title
+	ctx.Data["Username"] = ci.HeadUser.Name
+	ctx.Data["Reponame"] = ci.HeadRepo.Name
+
+	setCompareContext(ctx, beforeCommit, headCommit, ci.HeadUser.Name, ci.HeadRepo.Name)
+
+	return false
+}
+
+func getBranchesAndTagsForRepo(ctx gocontext.Context, repo *repo_model.Repository) (branches, tags []string, err error) {
+	gitRepo, err := gitrepo.OpenRepository(ctx, repo)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer gitRepo.Close()
+
+	branches, err = git_model.FindBranchNames(ctx, git_model.FindBranchOptions{
+		RepoID:          repo.ID,
+		ListOptions:     db.ListOptionsAll,
+		IsDeletedBranch: optional.Some(false),
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+	tags, err = gitRepo.GetTags(0, 0)
+	if err != nil {
+		return nil, nil, err
+	}
+	return branches, tags, nil
+}
+
+// CompareDiff show different from one commit to another commit
+func CompareDiff(ctx *context.Context) {
+	ci := ParseCompareInfo(ctx)
+	defer func() {
+		if ci != nil && ci.HeadGitRepo != nil {
+			ci.HeadGitRepo.Close()
+		}
+	}()
+	if ctx.Written() {
+		return
+	}
+
+	ctx.Data["PullRequestWorkInProgressPrefixes"] = setting.Repository.PullRequest.WorkInProgressPrefixes
+	ctx.Data["DirectComparison"] = ci.DirectComparison
+	ctx.Data["OtherCompareSeparator"] = ".."
+	ctx.Data["CompareSeparator"] = "..."
+	if ci.DirectComparison {
+		ctx.Data["CompareSeparator"] = ".."
+		ctx.Data["OtherCompareSeparator"] = "..."
+	}
+
+	nothingToCompare := PrepareCompareDiff(ctx, ci,
+		gitdiff.GetWhitespaceFlag(ctx.Data["WhitespaceBehavior"].(string)))
+	if ctx.Written() {
+		return
+	}
+
+	baseTags, err := repo_model.GetTagNamesByRepoID(ctx, ctx.Repo.Repository.ID)
+	if err != nil {
+		ctx.ServerError("GetTagNamesByRepoID", err)
+		return
+	}
+	ctx.Data["Tags"] = baseTags
+
+	fileOnly := ctx.FormBool("file-only")
+	if fileOnly {
+		ctx.HTML(http.StatusOK, tplDiffBox)
+		return
+	}
+
+	headBranches, err := git_model.FindBranchNames(ctx, git_model.FindBranchOptions{
+		RepoID:          ci.HeadRepo.ID,
+		ListOptions:     db.ListOptionsAll,
+		IsDeletedBranch: optional.Some(false),
+	})
+	if err != nil {
+		ctx.ServerError("GetBranches", err)
+		return
+	}
+	ctx.Data["HeadBranches"] = headBranches
+
+	// For compare repo branches
+	PrepareBranchList(ctx)
+	if ctx.Written() {
+		return
+	}
+
+	headTags, err := repo_model.GetTagNamesByRepoID(ctx, ci.HeadRepo.ID)
+	if err != nil {
+		ctx.ServerError("GetTagNamesByRepoID", err)
+		return
+	}
+	ctx.Data["HeadTags"] = headTags
+
+	if ctx.Data["PageIsComparePull"] == true {
+		pr, err := issues_model.GetUnmergedPullRequest(ctx, ci.HeadRepo.ID, ctx.Repo.Repository.ID, ci.HeadBranch, ci.BaseBranch, issues_model.PullRequestFlowGithub)
+		if err != nil {
+			if !issues_model.IsErrPullRequestNotExist(err) {
+				ctx.ServerError("GetUnmergedPullRequest", err)
+				return
+			}
+		} else {
+			ctx.Data["HasPullRequest"] = true
+			if err := pr.LoadIssue(ctx); err != nil {
+				ctx.ServerError("LoadIssue", err)
+				return
+			}
+			ctx.Data["PullRequest"] = pr
+			ctx.HTML(http.StatusOK, tplCompareDiff)
+			return
+		}
+
+		if !nothingToCompare {
+			// Setup information for new form.
+			RetrieveRepoMetas(ctx, ctx.Repo.Repository, true)
+			if ctx.Written() {
+				return
+			}
+		}
+	}
+	beforeCommitID := ctx.Data["BeforeCommitID"].(string)
+	afterCommitID := ctx.Data["AfterCommitID"].(string)
+
+	separator := "..."
+	if ci.DirectComparison {
+		separator = ".."
+	}
+	ctx.Data["Title"] = "Comparing " + base.ShortSha(beforeCommitID) + separator + base.ShortSha(afterCommitID)
+
+	ctx.Data["IsDiffCompare"] = true
+	_, templateErrs := setTemplateIfExists(ctx, pullRequestTemplateKey, pullRequestTemplateCandidates)
+
+	if len(templateErrs) > 0 {
+		ctx.Flash.Warning(renderErrorOfTemplates(ctx, templateErrs), true)
+	}
+
+	if content, ok := ctx.Data["content"].(string); ok && content != "" {
+		// If a template content is set, prepend the "content". In this case that's only
+		// applicable if you have one commit to compare and that commit has a message.
+		// In that case the commit message will be prepend to the template body.
+		if templateContent, ok := ctx.Data[pullRequestTemplateKey].(string); ok && templateContent != "" {
+			// Reuse the same key as that's prioritized over the "content" key.
+			// Add two new lines between the content to ensure there's always at least
+			// one empty line between them.
+			ctx.Data[pullRequestTemplateKey] = content + "\n\n" + templateContent
+		}
+
+		// When using form fields, also add content to field with id "body".
+		if fields, ok := ctx.Data["Fields"].([]*api.IssueFormField); ok {
+			for _, field := range fields {
+				if field.ID == "body" {
+					if fieldValue, ok := field.Attributes["value"].(string); ok && fieldValue != "" {
+						field.Attributes["value"] = content + "\n\n" + fieldValue
+					} else {
+						field.Attributes["value"] = content
+					}
+				}
+			}
+		}
+	}
+
+	ctx.Data["IsProjectsEnabled"] = ctx.Repo.CanWrite(unit.TypeProjects)
+	ctx.Data["IsAttachmentEnabled"] = setting.Attachment.Enabled
+	upload.AddUploadContext(ctx, "comment")
+
+	ctx.Data["HasIssuesOrPullsWritePermission"] = ctx.Repo.CanWrite(unit.TypePullRequests)
+
+	if unit, err := ctx.Repo.Repository.GetUnit(ctx, unit.TypePullRequests); err == nil {
+		config := unit.PullRequestsConfig()
+		ctx.Data["AllowMaintainerEdit"] = config.DefaultAllowMaintainerEdit
+	} else {
+		ctx.Data["AllowMaintainerEdit"] = false
+	}
+
+	ctx.HTML(http.StatusOK, tplCompare)
+}
+
+// ExcerptBlob render blob excerpt contents
+func ExcerptBlob(ctx *context.Context) {
+	commitID := ctx.Params("sha")
+	lastLeft := ctx.FormInt("last_left")
+	lastRight := ctx.FormInt("last_right")
+	idxLeft := ctx.FormInt("left")
+	idxRight := ctx.FormInt("right")
+	leftHunkSize := ctx.FormInt("left_hunk_size")
+	rightHunkSize := ctx.FormInt("right_hunk_size")
+	anchor := ctx.FormString("anchor")
+	direction := ctx.FormString("direction")
+	filePath := ctx.FormString("path")
+	gitRepo := ctx.Repo.GitRepo
+	if ctx.FormBool("wiki") {
+		var err error
+		gitRepo, err = gitrepo.OpenWikiRepository(ctx, ctx.Repo.Repository)
+		if err != nil {
+			ctx.ServerError("OpenRepository", err)
+			return
+		}
+		defer gitRepo.Close()
+	}
+	chunkSize := gitdiff.BlobExcerptChunkSize
+	commit, err := gitRepo.GetCommit(commitID)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "GetCommit")
+		return
+	}
+	section := &gitdiff.DiffSection{
+		FileName: filePath,
+		Name:     filePath,
+	}
+	if direction == "up" && (idxLeft-lastLeft) > chunkSize {
+		idxLeft -= chunkSize
+		idxRight -= chunkSize
+		leftHunkSize += chunkSize
+		rightHunkSize += chunkSize
+		section.Lines, err = getExcerptLines(commit, filePath, idxLeft-1, idxRight-1, chunkSize)
+	} else if direction == "down" && (idxLeft-lastLeft) > chunkSize {
+		section.Lines, err = getExcerptLines(commit, filePath, lastLeft, lastRight, chunkSize)
+		lastLeft += chunkSize
+		lastRight += chunkSize
+	} else {
+		offset := -1
+		if direction == "down" {
+			offset = 0
+		}
+		section.Lines, err = getExcerptLines(commit, filePath, lastLeft, lastRight, idxRight-lastRight+offset)
+		leftHunkSize = 0
+		rightHunkSize = 0
+		idxLeft = lastLeft
+		idxRight = lastRight
+	}
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "getExcerptLines")
+		return
+	}
+	if idxRight > lastRight {
+		lineText := " "
+		if rightHunkSize > 0 || leftHunkSize > 0 {
+			lineText = fmt.Sprintf("@@ -%d,%d +%d,%d @@\n", idxLeft, leftHunkSize, idxRight, rightHunkSize)
+		}
+		lineText = html.EscapeString(lineText)
+		lineSection := &gitdiff.DiffLine{
+			Type:    gitdiff.DiffLineSection,
+			Content: lineText,
+			SectionInfo: &gitdiff.DiffLineSectionInfo{
+				Path:          filePath,
+				LastLeftIdx:   lastLeft,
+				LastRightIdx:  lastRight,
+				LeftIdx:       idxLeft,
+				RightIdx:      idxRight,
+				LeftHunkSize:  leftHunkSize,
+				RightHunkSize: rightHunkSize,
+			},
+		}
+		if direction == "up" {
+			section.Lines = append([]*gitdiff.DiffLine{lineSection}, section.Lines...)
+		} else if direction == "down" {
+			section.Lines = append(section.Lines, lineSection)
+		}
+	}
+	ctx.Data["section"] = section
+	ctx.Data["FileNameHash"] = git.HashFilePathForWebUI(filePath)
+	ctx.Data["AfterCommitID"] = commitID
+	ctx.Data["Anchor"] = anchor
+	ctx.HTML(http.StatusOK, tplBlobExcerpt)
+}
+
+func getExcerptLines(commit *git.Commit, filePath string, idxLeft, idxRight, chunkSize int) ([]*gitdiff.DiffLine, error) {
+	blob, err := commit.Tree.GetBlobByPath(filePath)
+	if err != nil {
+		return nil, err
+	}
+	reader, err := blob.DataAsync()
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+	scanner := bufio.NewScanner(reader)
+	var diffLines []*gitdiff.DiffLine
+	for line := 0; line < idxRight+chunkSize; line++ {
+		if ok := scanner.Scan(); !ok {
+			break
+		}
+		if line < idxRight {
+			continue
+		}
+		lineText := scanner.Text()
+		diffLine := &gitdiff.DiffLine{
+			LeftIdx:  idxLeft + (line - idxRight) + 1,
+			RightIdx: line + 1,
+			Type:     gitdiff.DiffLinePlain,
+			Content:  " " + lineText,
+		}
+		diffLines = append(diffLines, diffLine)
+	}
+	if err = scanner.Err(); err != nil {
+		return nil, fmt.Errorf("getExcerptLines scan: %w", err)
+	}
+	return diffLines, nil
+}