Refactor Parsing compare path parameters

routers/api/v1/repo/compare.go

@@ -4,12 +4,18 @@
 package repo
 
 import (
+	"errors"
 	"net/http"
-	"strings"
 
+	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/gitrepo"
+	"code.gitea.io/gitea/modules/log"
 	api "code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/util"
+	"code.gitea.io/gitea/routers/common"
 	"code.gitea.io/gitea/services/context"
 	"code.gitea.io/gitea/services/convert"
 )
@@ -53,33 +59,84 @@ func CompareDiff(ctx *context.APIContext) {
 		defer gitRepo.Close()
 	}
 
-	infoPath := ctx.PathParam("*")
+	pathParam := ctx.PathParam("*")
-	infos := []string{ctx.Repo.Repository.DefaultBranch, ctx.Repo.Repository.DefaultBranch}
+	baseRepo := ctx.Repo.Repository
-	if infoPath != "" {
+	ci, err := common.ParseComparePathParams(ctx, pathParam, baseRepo, ctx.Repo.GitRepo)
-		infos = strings.SplitN(infoPath, "...", 2)
+	if err != nil {
-		if len(infos) != 2 {
+		switch {
-			if infos = strings.SplitN(infoPath, "..", 2); len(infos) != 2 {
+		case user_model.IsErrUserNotExist(err):
-				infos = []string{ctx.Repo.Repository.DefaultBranch, infoPath}
+			ctx.NotFound("GetUserByName")
+		case repo_model.IsErrRepoNotExist(err):
+			ctx.NotFound("GetRepositoryByOwnerAndName")
+		case errors.Is(err, util.ErrInvalidArgument):
+			ctx.NotFound("ParseComparePathParams")
+		default:
+			ctx.ServerError("GetRepositoryByOwnerAndName", err)
 		}
+		return
+	}
+	defer ci.Close()
+
+	// remove the check when we support compare with carets
+	if ci.CaretTimes > 0 {
+		ctx.NotFound("Unsupported compare")
+		return
+	}
+
+	if !ci.IsSameRepo() {
+		// user should have permission to read headrepo's codes
+		permHead, err := access_model.GetUserRepoPermission(ctx, ci.HeadRepo, ctx.Doer)
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err)
+			return
+		}
+		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("Can't read headRepo UnitTypeCode")
+			return
 		}
 	}
 
-	_, headGitRepo, ci, _, _ := parseCompareInfo(ctx, api.CreatePullRequestOption{
+	ctx.Repo.PullRequest.SameRepo = ci.IsSameRepo()
-		Base: infos[0],
+	log.Trace("Repo path: %q, base branch: %q, head branch: %q", ctx.Repo.GitRepo.Path, ci.BaseOriRef, ci.HeadOriRef)
-		Head: infos[1],
+
-	})
+	// Check if current user has fork of repository or in the same repository.
-	if ctx.Written() {
+	/*headRepo := repo_model.GetForkedRepo(ctx, ci.HeadUser.ID, ctx.Repo.Repository.ID)
+	if headRepo == nil && !ci.IsSameRepo() {
+		err := ctx.Repo.Repository.GetBaseRepo(ctx)
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "GetBaseRepo", err)
+			return nil, nil, nil, "", ""
+		}
+
+		// Check if baseRepo's base repository is the same as headUser's repository.
+		if baseRepo.BaseRepo == nil || baseRepo.BaseRepo.OwnerID != headUser.ID {
+			log.Trace("parseCompareInfo[%d]: does not have fork or in same repository", baseRepo.ID)
+			ctx.NotFound("GetBaseRepo")
+			return nil, nil, nil, "", ""
+		}
+		// Assign headRepo so it can be used below.
+		headRepo = baseRepo.BaseRepo
+	}*/
+
+	ci.CompareInfo, err = ci.HeadGitRepo.GetCompareInfo(repo_model.RepoPath(baseRepo.Owner.Name, baseRepo.Name), ci.BaseOriRef, ci.HeadOriRef, false, false)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, "GetCompareInfo", err)
 		return
 	}
-	defer headGitRepo.Close()
 
 	verification := ctx.FormString("verification") == "" || ctx.FormBool("verification")
 	files := ctx.FormString("files") == "" || ctx.FormBool("files")
 
-	apiCommits := make([]*api.Commit, 0, len(ci.Commits))
+	apiCommits := make([]*api.Commit, 0, len(ci.CompareInfo.Commits))
 	userCache := make(map[string]*user_model.User)
-	for i := 0; i < len(ci.Commits); i++ {
+	for i := 0; i < len(ci.CompareInfo.Commits); i++ {
-		apiCommit, err := convert.ToCommit(ctx, ctx.Repo.Repository, ctx.Repo.GitRepo, ci.Commits[i], userCache,
+		apiCommit, err := convert.ToCommit(ctx, ctx.Repo.Repository, ctx.Repo.GitRepo, ci.CompareInfo.Commits[i], userCache,
 			convert.ToCommitOptions{
 				Stat:         true,
 				Verification: verification,
@@ -93,7 +150,7 @@ func CompareDiff(ctx *context.APIContext) {
 	}
 
 	ctx.JSON(http.StatusOK, &api.Compare{
-		TotalCommits: len(ci.Commits),
+		TotalCommits: len(ci.CompareInfo.Commits),
 		Commits:      apiCommits,
 	})
 }

routers/api/v1/repo/pull.go

@@ -28,8 +28,10 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	api "code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/routers/api/v1/utils"
+	"code.gitea.io/gitea/routers/common"
 	asymkey_service "code.gitea.io/gitea/services/asymkey"
 	"code.gitea.io/gitea/services/automerge"
 	"code.gitea.io/gitea/services/context"
@@ -401,14 +403,48 @@ func CreatePullRequest(ctx *context.APIContext) {
 	)
 
 	// Get repo/branch information
-	headRepo, headGitRepo, compareInfo, baseBranch, headBranch := parseCompareInfo(ctx, form)
+	ci, err := common.ParseComparePathParams(ctx, form.Base+"..."+form.Head, repo, ctx.Repo.GitRepo)
-	if ctx.Written() {
+	if err != nil {
+		switch {
+		case user_model.IsErrUserNotExist(err):
+			ctx.NotFound("GetUserByName")
+		case repo_model.IsErrRepoNotExist(err):
+			ctx.NotFound("GetRepositoryByOwnerAndName")
+		case errors.Is(err, util.ErrInvalidArgument):
+			ctx.NotFound("ParseComparePathParams")
+		default:
+			ctx.ServerError("GetRepositoryByOwnerAndName", err)
+		}
 		return
 	}
-	defer headGitRepo.Close()
+	defer ci.Close()
+
+	if ci.IsPull() {
+		ctx.Error(http.StatusUnprocessableEntity, "Bad base or head refs", "Only support branch to branch comparison")
+		return
+	}
+
+	if !ci.IsSameRepo() {
+		// user should have permission to read headrepo's codes
+		permHead, err := access_model.GetUserRepoPermission(ctx, ci.HeadRepo, ctx.Doer)
+		if err != nil {
+			ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err)
+			return
+		}
+		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("Can't read headRepo UnitTypeCode")
+			return
+		}
+	}
 
 	// Check if another PR exists with the same targets
-	existingPr, err := issues_model.GetUnmergedPullRequest(ctx, headRepo.ID, ctx.Repo.Repository.ID, headBranch, baseBranch, issues_model.PullRequestFlowGithub)
+	existingPr, err := issues_model.GetUnmergedPullRequest(ctx, ci.HeadRepo.ID, ctx.Repo.Repository.ID, ci.HeadOriRef, ci.BaseOriRef, issues_model.PullRequestFlowGithub)
 	if err != nil {
 		if !issues_model.IsErrPullRequestNotExist(err) {
 			ctx.Error(http.StatusInternalServerError, "GetUnmergedPullRequest", err)
@@ -484,13 +520,13 @@ func CreatePullRequest(ctx *context.APIContext) {
 		DeadlineUnix: deadlineUnix,
 	}
 	pr := &issues_model.PullRequest{
-		HeadRepoID: headRepo.ID,
+		HeadRepoID: ci.HeadRepo.ID,
 		BaseRepoID: repo.ID,
-		HeadBranch: headBranch,
+		HeadBranch: ci.HeadOriRef,
-		BaseBranch: baseBranch,
+		BaseBranch: ci.BaseOriRef,
-		HeadRepo:   headRepo,
+		HeadRepo:   ci.HeadRepo,
 		BaseRepo:   repo,
-		MergeBase:  compareInfo.MergeBase,
+		MergeBase:  ci.CompareInfo.MergeBase,
 		Type:       issues_model.PullRequestGitea,
 	}
 
@@ -1080,143 +1116,6 @@ func MergePullRequest(ctx *context.APIContext) {
 	ctx.Status(http.StatusOK)
 }
 
-func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption) (*repo_model.Repository, *git.Repository, *git.CompareInfo, string, string) {
-	baseRepo := ctx.Repo.Repository
-
-	// Get compared branches information
-	// format: <base branch>...[<head repo>:]<head branch>
-	// base<-head: master...head:feature
-	// same repo: master...feature
-
-	// TODO: Validate form first?
-
-	baseBranch := form.Base
-
-	var (
-		headUser   *user_model.User
-		headBranch string
-		isSameRepo bool
-		err        error
-	)
-
-	// If there is no head repository, it means pull request between same repository.
-	headInfos := strings.Split(form.Head, ":")
-	if len(headInfos) == 1 {
-		isSameRepo = true
-		headUser = ctx.Repo.Owner
-		headBranch = headInfos[0]
-	} else if len(headInfos) == 2 {
-		headUser, err = user_model.GetUserByName(ctx, headInfos[0])
-		if err != nil {
-			if user_model.IsErrUserNotExist(err) {
-				ctx.NotFound("GetUserByName")
-			} else {
-				ctx.Error(http.StatusInternalServerError, "GetUserByName", err)
-			}
-			return nil, nil, nil, "", ""
-		}
-		headBranch = headInfos[1]
-		// The head repository can also point to the same repo
-		isSameRepo = ctx.Repo.Owner.ID == headUser.ID
-	} else {
-		ctx.NotFound()
-		return nil, nil, nil, "", ""
-	}
-
-	ctx.Repo.PullRequest.SameRepo = isSameRepo
-	log.Trace("Repo path: %q, base branch: %q, head branch: %q", ctx.Repo.GitRepo.Path, baseBranch, headBranch)
-	// Check if base branch is valid.
-	if !ctx.Repo.GitRepo.IsBranchExist(baseBranch) && !ctx.Repo.GitRepo.IsTagExist(baseBranch) {
-		ctx.NotFound("BaseNotExist")
-		return nil, nil, nil, "", ""
-	}
-
-	// Check if current user has fork of repository or in the same repository.
-	headRepo := repo_model.GetForkedRepo(ctx, headUser.ID, baseRepo.ID)
-	if headRepo == nil && !isSameRepo {
-		err := baseRepo.GetBaseRepo(ctx)
-		if err != nil {
-			ctx.Error(http.StatusInternalServerError, "GetBaseRepo", err)
-			return nil, nil, nil, "", ""
-		}
-
-		// Check if baseRepo's base repository is the same as headUser's repository.
-		if baseRepo.BaseRepo == nil || baseRepo.BaseRepo.OwnerID != headUser.ID {
-			log.Trace("parseCompareInfo[%d]: does not have fork or in same repository", baseRepo.ID)
-			ctx.NotFound("GetBaseRepo")
-			return nil, nil, nil, "", ""
-		}
-		// Assign headRepo so it can be used below.
-		headRepo = baseRepo.BaseRepo
-	}
-
-	var headGitRepo *git.Repository
-	if isSameRepo {
-		headRepo = ctx.Repo.Repository
-		headGitRepo = ctx.Repo.GitRepo
-	} else {
-		headGitRepo, err = gitrepo.OpenRepository(ctx, headRepo)
-		if err != nil {
-			ctx.Error(http.StatusInternalServerError, "OpenRepository", err)
-			return nil, nil, nil, "", ""
-		}
-	}
-
-	// user should have permission to read baseRepo's codes and pulls, NOT headRepo's
-	permBase, err := access_model.GetUserRepoPermission(ctx, baseRepo, ctx.Doer)
-	if err != nil {
-		headGitRepo.Close()
-		ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err)
-		return nil, nil, nil, "", ""
-	}
-	if !permBase.CanReadIssuesOrPulls(true) || !permBase.CanRead(unit.TypeCode) {
-		if log.IsTrace() {
-			log.Trace("Permission Denied: User %-v cannot create/read pull requests or cannot read code in Repo %-v\nUser in baseRepo has Permissions: %-+v",
-				ctx.Doer,
-				baseRepo,
-				permBase)
-		}
-		headGitRepo.Close()
-		ctx.NotFound("Can't read pulls or can't read UnitTypeCode")
-		return nil, nil, nil, "", ""
-	}
-
-	// user should have permission to read headrepo's codes
-	permHead, err := access_model.GetUserRepoPermission(ctx, headRepo, ctx.Doer)
-	if err != nil {
-		headGitRepo.Close()
-		ctx.Error(http.StatusInternalServerError, "GetUserRepoPermission", err)
-		return nil, nil, 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,
-				headRepo,
-				permHead)
-		}
-		headGitRepo.Close()
-		ctx.NotFound("Can't read headRepo UnitTypeCode")
-		return nil, nil, nil, "", ""
-	}
-
-	// Check if head branch is valid.
-	if !headGitRepo.IsBranchExist(headBranch) && !headGitRepo.IsTagExist(headBranch) {
-		headGitRepo.Close()
-		ctx.NotFound()
-		return nil, nil, nil, "", ""
-	}
-
-	compareInfo, err := headGitRepo.GetCompareInfo(repo_model.RepoPath(baseRepo.Owner.Name, baseRepo.Name), baseBranch, headBranch, false, false)
-	if err != nil {
-		headGitRepo.Close()
-		ctx.Error(http.StatusInternalServerError, "GetCompareInfo", err)
-		return nil, nil, nil, "", ""
-	}
-
-	return headRepo, headGitRepo, compareInfo, baseBranch, headBranch
-}
-
 // UpdatePullRequest merge PR's baseBranch into headBranch
 func UpdatePullRequest(ctx *context.APIContext) {
 	// swagger:operation POST /repos/{owner}/{repo}/pulls/{index}/update repository repoUpdatePullRequest

routers/common/compare.go

@@ -4,18 +4,198 @@
 package common
 
 import (
+	"context"
+	"strings"
+
+	git_model "code.gitea.io/gitea/models/git"
 	repo_model "code.gitea.io/gitea/models/repo"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/gitrepo"
+	"code.gitea.io/gitea/modules/util"
 )
 
+type CompareRouter struct {
+	BaseOriRef    string
+	BaseFullRef   git.RefName
+	HeadOwnerName string
+	HeadRepoName  string
+	HeadOriRef    string
+	HeadFullRef   git.RefName
+	CaretTimes    int // ^ times after base ref
+	DotTimes      int // 2(..) or 3(...)
+}
+
+func (cr *CompareRouter) IsSameRepo() bool {
+	return cr.HeadOwnerName == "" && cr.HeadRepoName == ""
+}
+
+func (cr *CompareRouter) IsSameRef() bool {
+	return cr.IsSameRepo() && cr.BaseOriRef == cr.HeadOriRef
+}
+
+func (cr *CompareRouter) DirectComparison() bool {
+	return cr.DotTimes == 2
+}
+
+func parseBase(base string) (string, int) {
+	parts := strings.SplitN(base, "^", 2)
+	if len(parts) == 1 {
+		return base, 0
+	}
+	return parts[0], len(parts[1]) + 1
+}
+
+func parseHead(head string) (string, string, string) {
+	paths := strings.SplitN(head, ":", 2)
+	if len(paths) == 1 {
+		return "", "", paths[0]
+	}
+	ownerRepo := strings.SplitN(paths[0], "/", 2)
+	if len(ownerRepo) == 1 {
+		return "", paths[0], paths[1]
+	}
+	return ownerRepo[0], ownerRepo[1], paths[1]
+}
+
+func parseCompareRouter(router string) (*CompareRouter, error) {
+	var basePart, headPart string
+	dotTimes := 3
+	parts := strings.Split(router, "...")
+	if len(parts) > 2 {
+		return nil, util.NewSilentWrapErrorf(util.ErrInvalidArgument, "invalid compare router: %s", router)
+	}
+	if len(parts) != 2 {
+		parts = strings.Split(router, "..")
+		if len(parts) == 1 {
+			headOwnerName, headRepoName, headRef := parseHead(router)
+			return &CompareRouter{
+				HeadOriRef:    headRef,
+				HeadOwnerName: headOwnerName,
+				HeadRepoName:  headRepoName,
+			}, nil
+		} else if len(parts) > 2 {
+			return nil, util.NewSilentWrapErrorf(util.ErrInvalidArgument, "invalid compare router: %s", router)
+		}
+		dotTimes = 2
+	}
+	basePart, headPart = parts[0], parts[1]
+
+	baseRef, caretTimes := parseBase(basePart)
+	headOwnerName, headRepoName, headRef := parseHead(headPart)
+
+	return &CompareRouter{
+		BaseOriRef:    baseRef,
+		HeadOriRef:    headRef,
+		HeadOwnerName: headOwnerName,
+		HeadRepoName:  headRepoName,
+		CaretTimes:    caretTimes,
+		DotTimes:      dotTimes,
+	}, nil
+}
+
 // CompareInfo represents the collected results from ParseCompareInfo
 type CompareInfo struct {
+	*CompareRouter
 	HeadUser     *user_model.User
 	HeadRepo     *repo_model.Repository
 	HeadGitRepo  *git.Repository
 	CompareInfo  *git.CompareInfo
-	BaseBranch       string
+	close        func()
-	HeadBranch       string
+	IsBaseCommit bool
-	DirectComparison bool
+	IsHeadCommit bool
+}
+
+// display pull related information or not
+func (ci *CompareInfo) IsPull() bool {
+	return ci.CaretTimes == 0 && !ci.DirectComparison() &&
+		ci.BaseFullRef.IsBranch() && ci.HeadFullRef.IsBranch()
+}
+
+func (ci *CompareInfo) Close() {
+	if ci.close != nil {
+		ci.close()
+	}
+}
+
+func detectFullRef(ctx context.Context, repoID int64, gitRepo *git.Repository, oriRef string) (git.RefName, bool, error) {
+	b, err := git_model.GetBranch(ctx, repoID, oriRef)
+	if err != nil {
+		return "", false, err
+	}
+	if !b.IsDeleted {
+		return git.RefNameFromBranch(oriRef), false, nil
+	}
+
+	rel, err := repo_model.GetRelease(ctx, repoID, oriRef)
+	if err != nil && !repo_model.IsErrReleaseNotExist(err) {
+		return "", false, err
+	}
+	if rel != nil && rel.Sha1 != "" {
+		return git.RefNameFromTag(oriRef), false, nil
+	}
+
+	commitObjectID, err := gitRepo.ConvertToGitID(oriRef)
+	if err != nil {
+		return "", false, err
+	}
+	return git.RefName(commitObjectID.String()), true, nil
+}
+
+func ParseComparePathParams(ctx context.Context, pathParam string, baseRepo *repo_model.Repository, baseGitRepo *git.Repository) (*CompareInfo, error) {
+	ci := &CompareInfo{}
+	var err error
+
+	if pathParam == "" {
+		ci.HeadOriRef = baseRepo.DefaultBranch
+	} else {
+		ci.CompareRouter, err = parseCompareRouter(pathParam)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if ci.BaseOriRef == "" {
+		ci.BaseOriRef = baseRepo.DefaultBranch
+	}
+
+	if ci.IsSameRepo() {
+		ci.HeadUser = baseRepo.Owner
+		ci.HeadRepo = baseRepo
+		ci.HeadGitRepo = baseGitRepo
+	} else {
+		if ci.HeadOwnerName == baseRepo.Owner.Name {
+			ci.HeadUser = baseRepo.Owner
+		} else {
+			ci.HeadUser, err = user_model.GetUserByName(ctx, ci.HeadOwnerName)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		ci.HeadRepo, err = repo_model.GetRepositoryByOwnerAndName(ctx, ci.HeadOwnerName, ci.HeadRepoName)
+		if err != nil {
+			return nil, err
+		}
+		ci.HeadRepo.Owner = ci.HeadUser
+		ci.HeadGitRepo, err = gitrepo.OpenRepository(ctx, ci.HeadRepo)
+		if err != nil {
+			return nil, err
+		}
+		ci.close = func() {
+			if ci.HeadGitRepo != nil {
+				ci.HeadGitRepo.Close()
+			}
+		}
+	}
+
+	ci.BaseFullRef, ci.IsBaseCommit, err = detectFullRef(ctx, baseRepo.ID, baseGitRepo, ci.BaseOriRef)
+	if err != nil {
+		return nil, err
+	}
+
+	ci.HeadFullRef, ci.IsHeadCommit, err = detectFullRef(ctx, ci.HeadRepo.ID, ci.HeadGitRepo, ci.HeadOriRef)
+	if err != nil {
+		return nil, err
+	}
+	return ci, nil
 }

routers/common/compare_test.go

@@ -0,0 +1,120 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package common
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCompareRouters(t *testing.T) {
+	kases := []struct {
+		router        string
+		compareRouter *CompareRouter
+	}{
+		{
+			router: "main...develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "main",
+				HeadOriRef: "develop",
+				DotTimes:   3,
+			},
+		},
+		{
+			router: "main..develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "main",
+				HeadOriRef: "develop",
+				DotTimes:   2,
+			},
+		},
+		{
+			router: "main^...develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "main",
+				HeadOriRef: "develop",
+				CaretTimes: 1,
+				DotTimes:   3,
+			},
+		},
+		{
+			router: "main^^^^^...develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "main",
+				HeadOriRef: "develop",
+				CaretTimes: 5,
+				DotTimes:   3,
+			},
+		},
+		{
+			router: "develop",
+			compareRouter: &CompareRouter{
+				HeadOriRef: "develop",
+			},
+		},
+		{
+			router: "lunny/forked_repo:develop",
+			compareRouter: &CompareRouter{
+				HeadOwnerName: "lunny",
+				HeadRepoName:  "forked_repo",
+				HeadOriRef:    "develop",
+			},
+		},
+		{
+			router: "main...lunny/forked_repo:develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef:    "main",
+				HeadOwnerName: "lunny",
+				HeadRepoName:  "forked_repo",
+				HeadOriRef:    "develop",
+				DotTimes:      3,
+			},
+		},
+		{
+			router: "main...lunny/forked_repo:develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef:    "main",
+				HeadOwnerName: "lunny",
+				HeadRepoName:  "forked_repo",
+				HeadOriRef:    "develop",
+				DotTimes:      3,
+			},
+		},
+		{
+			router: "main^...lunny/forked_repo:develop",
+			compareRouter: &CompareRouter{
+				BaseOriRef:    "main",
+				HeadOwnerName: "lunny",
+				HeadRepoName:  "forked_repo",
+				HeadOriRef:    "develop",
+				DotTimes:      3,
+				CaretTimes:    1,
+			},
+		},
+		{
+			router: "v1.0...v1.1",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "v1.0",
+				HeadOriRef: "v1.1",
+				DotTimes:   3,
+			},
+		},
+		{
+			router: "8eb19a5ae19abae15c0666d4ab98906139a7f439...283c030497b455ecfa759d4649f9f8b45158742e",
+			compareRouter: &CompareRouter{
+				BaseOriRef: "8eb19a5ae19abae15c0666d4ab98906139a7f439",
+				HeadOriRef: "283c030497b455ecfa759d4649f9f8b45158742e",
+				DotTimes:   3,
+			},
+		},
+	}
+	for _, kase := range kases {
+		t.Run(kase.router, func(t *testing.T) {
+			r, err := parseCompareRouter(kase.router)
+			assert.NoError(t, err)
+			assert.EqualValues(t, kase.compareRouter, r)
+		})
+	}
+}

routers/web/repo/compare.go

@@ -187,12 +187,8 @@ func setCsvCompareContext(ctx *context.Context) {
 }
 
 // ParseCompareInfo parse compare info between two commit for preparing comparing references
+// Permission check for base repository's code read should be checked before invoking this function
 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:
 	//
@@ -219,111 +215,51 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 	// base<-head: master...head:feature
 	// same repo: master...feature
 
-	var (
+	fileOnly := ctx.FormBool("file-only")
-		isSameRepo bool
+	pathParam := ctx.PathParam("*")
-		infoPath   string
+	baseRepo := ctx.Repo.Repository
-		err        error
-	)
 
-	infoPath = ctx.PathParam("*")
+	ci, err := common.ParseComparePathParams(ctx, pathParam, baseRepo, ctx.Repo.GitRepo)
-	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) {
+		switch {
+		case user_model.IsErrUserNotExist(err):
 			ctx.NotFound("GetUserByName", nil)
-				} else {
+		case repo_model.IsErrRepoNotExist(err):
-					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 {
+		case errors.Is(err, util.ErrInvalidArgument):
+			ctx.NotFound("ParseComparePathParams", nil)
+		default:
 			ctx.ServerError("GetRepositoryByOwnerAndName", err)
 		}
 		return nil
 	}
-			if err := ci.HeadRepo.LoadOwner(ctx); err != nil {
+	defer ci.Close()
-				if user_model.IsErrUserNotExist(err) {
+
-					ctx.NotFound("GetUserByName", nil)
+	// remove the check when we support compare with carets
+	if ci.CaretTimes > 0 {
+		ctx.NotFound("Unsupported compare", nil)
+		return nil
+	}
+
+	if ci.BaseOriRef == ctx.Repo.GetObjectFormat().EmptyObjectID().String() {
+		if ci.IsSameRepo() {
+			ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadOriRef))
 		} else {
-					ctx.ServerError("GetUserByName", err)
+			ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadRepo.FullName()) + ":" + util.PathEscapeSegments(ci.HeadOriRef))
 		}
 		return nil
 	}
-			ci.HeadBranch = headInfos[1]
+
-			ci.HeadUser = ci.HeadRepo.Owner
+	ctx.Data["PageIsComparePull"] = ci.IsPull() && ctx.Repo.CanReadIssuesOrPulls(true)
-			isSameRepo = ci.HeadRepo.ID == ctx.Repo.Repository.ID
+	ctx.Data["BaseName"] = baseRepo.OwnerName
-		}
+	ctx.Data["BaseBranch"] = ci.BaseOriRef
-	} else {
-		ctx.NotFound("CompareAndPullRequest", nil)
-		return nil
-	}
 	ctx.Data["HeadUser"] = ci.HeadUser
-	ctx.Data["HeadBranch"] = ci.HeadBranch
+	ctx.Data["HeadBranch"] = ci.HeadOriRef
-	ctx.Repo.PullRequest.SameRepo = isSameRepo
+	ctx.Repo.PullRequest.SameRepo = ci.IsSameRepo()
 
-	// Check if base branch is valid.
+	ctx.Data["BaseIsCommit"] = ci.IsBaseCommit
-	baseIsCommit := ctx.Repo.GitRepo.IsCommitExist(ci.BaseBranch)
+	ctx.Data["BaseIsBranch"] = ci.BaseFullRef.IsBranch()
-	baseIsBranch := ctx.Repo.GitRepo.IsBranchExist(ci.BaseBranch)
+	ctx.Data["BaseIsTag"] = ci.BaseFullRef.IsTag()
-	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
@@ -391,50 +327,15 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 	}
 
 	// 7. Otherwise if we're not the same repo and haven't found a repo give up
-	if !isSameRepo && !has {
+	if !ci.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 {
+	if !ci.IsSameRepo() {
 		// Assert ctx.Doer has permission to read headRepo's codes
 		permHead, err := access_model.GetUserRepoPermission(ctx, ci.HeadRepo, ctx.Doer)
 		if err != nil {
@@ -501,60 +402,16 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 		}
 	}
 
-	// Check if head branch is valid.
+	ctx.Data["HeadIsCommit"] = ci.IsHeadCommit
-	headIsCommit := ci.HeadGitRepo.IsCommitExist(ci.HeadBranch)
+	ctx.Data["HeadIsBranch"] = ci.HeadFullRef.IsBranch()
-	headIsBranch := ci.HeadGitRepo.IsBranchExist(ci.HeadBranch)
+	ctx.Data["HeadIsTag"] = ci.HeadFullRef.IsTag()
-	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
+	ci.CompareInfo, err = ci.HeadGitRepo.GetCompareInfo(baseRepo.RepoPath(), ci.BaseFullRef.String(), ci.HeadFullRef.String(), ci.DirectComparison(), fileOnly)
-	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 {
+	if ci.DirectComparison() {
 		ctx.Data["BeforeCommitID"] = ci.CompareInfo.BaseCommitID
 	} else {
 		ctx.Data["BeforeCommitID"] = ci.CompareInfo.MergeBase
@@ -582,14 +439,14 @@ func PrepareCompareDiff(
 
 	ctx.Data["AfterCommitID"] = headCommitID
 
-	if (headCommitID == ci.CompareInfo.MergeBase && !ci.DirectComparison) ||
+	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)
+				allowEmptyPr := !(ci.BaseOriRef == ci.HeadOriRef && ctx.Repo.Repository.Name == ci.HeadRepo.Name)
 				ctx.Data["AllowEmptyPr"] = allowEmptyPr
 
 				return !allowEmptyPr
@@ -601,7 +458,7 @@ func PrepareCompareDiff(
 	}
 
 	beforeCommitID := ci.CompareInfo.MergeBase
-	if ci.DirectComparison {
+	if ci.DirectComparison() {
 		beforeCommitID = ci.CompareInfo.BaseCommitID
 	}
 
@@ -622,7 +479,7 @@ func PrepareCompareDiff(
 			MaxLineCharacters:  setting.Git.MaxGitDiffLineCharacters,
 			MaxFiles:           maxFiles,
 			WhitespaceBehavior: whitespaceBehavior,
-			DirectComparison:   ci.DirectComparison,
+			DirectComparison:   ci.DirectComparison(),
 			FileOnly:           fileOnly,
 		}, ctx.FormStrings("files")...)
 	if err != nil {
@@ -659,7 +516,7 @@ func PrepareCompareDiff(
 			ctx.Data["content"] = strings.Join(body[1:], "\n")
 		}
 	} else {
-		title = ci.HeadBranch
+		title = ci.HeadOriRef
 	}
 	if len(title) > 255 {
 		var trailer string
@@ -720,7 +577,7 @@ func CompareDiff(ctx *context.Context) {
 	ctx.Data["DirectComparison"] = ci.DirectComparison
 	ctx.Data["OtherCompareSeparator"] = ".."
 	ctx.Data["CompareSeparator"] = "..."
-	if ci.DirectComparison {
+	if ci.DirectComparison() {
 		ctx.Data["CompareSeparator"] = ".."
 		ctx.Data["OtherCompareSeparator"] = "..."
 	}
@@ -769,7 +626,7 @@ func CompareDiff(ctx *context.Context) {
 	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)
+		pr, err := issues_model.GetUnmergedPullRequest(ctx, ci.HeadRepo.ID, ctx.Repo.Repository.ID, ci.HeadOriRef, ci.BaseOriRef, issues_model.PullRequestFlowGithub)
 		if err != nil {
 			if !issues_model.IsErrPullRequestNotExist(err) {
 				ctx.ServerError("GetUnmergedPullRequest", err)
@@ -802,7 +659,7 @@ func CompareDiff(ctx *context.Context) {
 	afterCommitID := ctx.Data["AfterCommitID"].(string)
 
 	separator := "..."
-	if ci.DirectComparison {
+	if ci.DirectComparison() {
 		separator = ".."
 	}
 	ctx.Data["Title"] = "Comparing " + base.ShortSha(beforeCommitID) + separator + base.ShortSha(afterCommitID)

routers/web/repo/pull.go

@@ -1315,8 +1315,8 @@ func CompareAndPullRequestPost(ctx *context.Context) {
 	pullRequest := &issues_model.PullRequest{
 		HeadRepoID:          ci.HeadRepo.ID,
 		BaseRepoID:          repo.ID,
-		HeadBranch:          ci.HeadBranch,
+		HeadBranch:          ci.HeadOriRef,
-		BaseBranch:          ci.BaseBranch,
+		BaseBranch:          ci.BaseOriRef,
 		HeadRepo:            ci.HeadRepo,
 		BaseRepo:            repo,
 		MergeBase:           ci.CompareInfo.MergeBase,