prevent delete pull request head ref

fix go-gitea#18174

Signed-off-by: a1012112796 <[email protected]>

Author: a1012112796

modules/git/repo_branch.go

@@ -16,9 +16,9 @@ const BranchPrefix = "refs/heads/"
 
 // AGit Flow
 
-// PullRequestPrefix sepcial ref to create a pull request: refs/for/<targe-branch>/<topic-branch>
+// AgitPullPrefix sepcial ref to create a pull request: refs/for/<targe-branch>/<topic-branch>
 // or refs/for/<targe-branch> -o topic='<topic-branch>'
-const PullRequestPrefix = "refs/for/"
+const AgitPullPrefix = "refs/for/"
 
 // TODO: /refs/for-review for suggest change interface
 

routers/private/hook_pre_receive.go

@@ -124,8 +124,13 @@ func HookPreReceive(ctx *gitea_context.PrivateContext) {
 			preReceiveBranch(ourCtx, oldCommitID, newCommitID, refFullName)
 		case strings.HasPrefix(refFullName, git.TagPrefix):
 			preReceiveTag(ourCtx, oldCommitID, newCommitID, refFullName)
-		case git.SupportProcReceive && strings.HasPrefix(refFullName, git.PullRequestPrefix):
+		case git.SupportProcReceive && strings.HasPrefix(refFullName, git.AgitPullPrefix):
 			preReceivePullRequest(ourCtx, oldCommitID, newCommitID, refFullName)
+		case strings.HasPrefix(refFullName, git.PullPrefix) && newCommitID == git.EmptySHA:
+			ctx.JSON(http.StatusForbidden, private.Response{
+				Err: "delete head ref of pull request is not allowed",
+			})
+			return
 		default:
 			ourCtx.AssertCanWriteCode()
 		}
@@ -409,7 +414,7 @@ func preReceivePullRequest(ctx *preReceiveContext, oldCommitID, newCommitID, ref
 		return
 	}
 
-	baseBranchName := refFullName[len(git.PullRequestPrefix):]
+	baseBranchName := refFullName[len(git.AgitPullPrefix):]
 
 	baseBranchExist := false
 	if ctx.Repo.GitRepo.IsBranchExist(baseBranchName) {

services/agit/agit.go

@@ -50,15 +50,15 @@ func ProcRecive(ctx *context.PrivateContext, opts *private.HookOptions) []privat
 			continue
 		}
 
-		if !strings.HasPrefix(opts.RefFullNames[i], git.PullRequestPrefix) {
+		if !strings.HasPrefix(opts.RefFullNames[i], git.AgitPullPrefix) {
 			results = append(results, private.HookProcReceiveRefResult{
 				IsNotMatched: true,
 				OriginalRef:  opts.RefFullNames[i],
 			})
 			continue
 		}
 
-		baseBranchName := opts.RefFullNames[i][len(git.PullRequestPrefix):]
+		baseBranchName := opts.RefFullNames[i][len(git.AgitPullPrefix):]
 		curentTopicBranch := ""
 		if !gitRepo.IsBranchExist(baseBranchName) {
 			// try match refs/for/<target-branch>/<topic-branch>