Handle more pathological branch and tag names (#11843) (#11863)

Backport #11843

It's possible to push quite pathological appearing branch names to gitea
using git push gitea reasonable-branch:refs/heads/-- at which point
large parts of the UI will break. Similarly you can git push origin
reasonable-tag:refs/tags/-- which wil return an error.

This PR fixes the problems these cause. It also changes the code from
creating branches to pushing to ensure that branch restoration has to
pass hooks.

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

3 files changed, 24 insertions, 10 deletions

diff --git a/routers/repo/branch.go b/routers/repo/branch.go
index e7eac04bce..4d8b9158fe 100644
--- a/routers/repo/branch.go
+++ b/routers/repo/branch.go
@@ -6,6 +6,7 @@
 package repo
 
 import (
+	"fmt"
 	"strings"
 
 	"code.gitea.io/gitea/models"
@@ -102,7 +103,11 @@ func RestoreBranchPost(ctx *context.Context) {
 		return
 	}
 
-	if err := ctx.Repo.GitRepo.CreateBranch(deletedBranch.Name, deletedBranch.Commit); err != nil {
+	if err := git.Push(ctx.Repo.Repository.RepoPath(), git.PushOptions{
+		Remote: ctx.Repo.Repository.RepoPath(),
+		Branch: fmt.Sprintf("%s:%s%s", deletedBranch.Commit, git.BranchPrefix, deletedBranch.Name),
+		Env:    models.PushingEnvironment(ctx.User, ctx.Repo.Repository),
+	}); err != nil {
 		if strings.Contains(err.Error(), "already exists") {
 			ctx.Flash.Error(ctx.Tr("repo.branch.already_exists", deletedBranch.Name))
 			return
@@ -112,12 +117,6 @@ func RestoreBranchPost(ctx *context.Context) {
 		return
 	}
 
-	if err := ctx.Repo.Repository.RemoveDeletedBranch(deletedBranch.ID); err != nil {
-		log.Error("RemoveDeletedBranch: %v", err)
-		ctx.Flash.Error(ctx.Tr("repo.branch.restore_failed", deletedBranch.Name))
-		return
-	}
-
 	// Don't return error below this
 	if err := repofiles.PushUpdate(
 		ctx.Repo.Repository,
@@ -216,7 +215,7 @@ func loadBranches(ctx *context.Context) []*Branch {
 			}
 		}
 
-		divergence, divergenceError := repofiles.CountDivergingCommits(ctx.Repo.Repository, branchName)
+		divergence, divergenceError := repofiles.CountDivergingCommits(ctx.Repo.Repository, git.BranchPrefix+branchName)
 		if divergenceError != nil {
 			ctx.ServerError("CountDivergingCommits", divergenceError)
 			return nil
@@ -331,6 +330,8 @@ func CreateBranch(ctx *context.Context, form auth.NewBranchForm) {
 	var err error
 	if ctx.Repo.IsViewBranch {
 		err = repo_module.CreateNewBranch(ctx.User, ctx.Repo.Repository, ctx.Repo.BranchName, form.NewBranchName)
+	} else if ctx.Repo.IsViewTag {
+		err = repo_module.CreateNewBranchFromCommit(ctx.User, ctx.Repo.Repository, ctx.Repo.CommitID, form.NewBranchName)
 	} else {
 		err = repo_module.CreateNewBranchFromCommit(ctx.User, ctx.Repo.Repository, ctx.Repo.BranchName, form.NewBranchName)
 	}
diff --git a/routers/repo/compare.go b/routers/repo/compare.go
index 97bb5e6b18..3ffabc14a1 100644
--- a/routers/repo/compare.go
+++ b/routers/repo/compare.go
@@ -381,7 +381,20 @@ func ParseCompareInfo(ctx *context.Context) (*models.User, *models.Repository, *
 		return nil, nil, nil, nil, "", ""
 	}
 
-	compareInfo, err := headGitRepo.GetCompareInfo(baseRepo.RepoPath(), baseBranch, headBranch)
+	baseBranchRef := baseBranch
+	if baseIsBranch {
+		baseBranchRef = git.BranchPrefix + baseBranch
+	} else if baseIsTag {
+		baseBranchRef = git.TagPrefix + baseBranch
+	}
+	headBranchRef := headBranch
+	if headIsBranch {
+		headBranchRef = git.BranchPrefix + headBranch
+	} else if headIsTag {
+		headBranchRef = git.TagPrefix + headBranch
+	}
+
+	compareInfo, err := headGitRepo.GetCompareInfo(baseRepo.RepoPath(), baseBranchRef, headBranchRef)
 	if err != nil {
 		ctx.ServerError("GetCompareInfo", err)
 		return nil, nil, nil, nil, "", ""
diff --git a/routers/repo/pull.go b/routers/repo/pull.go
index ec82d14f18..da826026b3 100644
--- a/routers/repo/pull.go
+++ b/routers/repo/pull.go
@@ -484,7 +484,7 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 	}
 
 	compareInfo, err := baseGitRepo.GetCompareInfo(pull.BaseRepo.RepoPath(),
-		pull.BaseBranch, pull.GetGitRefName())
+		git.BranchPrefix+pull.BaseBranch, pull.GetGitRefName())
 	if err != nil {
 		if strings.Contains(err.Error(), "fatal: Not a valid object name") {
 			ctx.Data["IsPullRequestBroken"] = true