Read `previous` info from git blame (#28306)

Fixes #28280

Reads the `previous` info from the `git blame` output instead of
calculating it afterwards.

1 files changed, 8 insertions, 30 deletions

diff --git a/routers/web/repo/blame.go b/routers/web/repo/blame.go
index 1f1cca897e..52d350ff66 100644
--- a/routers/web/repo/blame.go
+++ b/routers/web/repo/blame.go
@@ -114,12 +114,12 @@ func RefBlame(ctx *context.Context) {
 		return
 	}
 
-	commitNames, previousCommits := processBlameParts(ctx, result.Parts)
+	commitNames := processBlameParts(ctx, result.Parts)
 	if ctx.Written() {
 		return
 	}
 
-	renderBlame(ctx, result.Parts, commitNames, previousCommits)
+	renderBlame(ctx, result.Parts, commitNames)
 
 	ctx.HTML(http.StatusOK, tplRepoHome)
 }
@@ -185,12 +185,9 @@ func fillBlameResult(br *git.BlameReader, r *blameResult) error {
 	return nil
 }
 
-func processBlameParts(ctx *context.Context, blameParts []git.BlamePart) (map[string]*user_model.UserCommit, map[string]string) {
+func processBlameParts(ctx *context.Context, blameParts []git.BlamePart) map[string]*user_model.UserCommit {
 	// store commit data by SHA to look up avatar info etc
 	commitNames := make(map[string]*user_model.UserCommit)
-	// previousCommits contains links from SHA to parent SHA,
-	// if parent also contains the current TreePath.
-	previousCommits := make(map[string]string)
 	// and as blameParts can reference the same commits multiple
 	// times, we cache the lookup work locally
 	commits := make([]*git.Commit, 0, len(blameParts))
@@ -214,29 +211,11 @@ func processBlameParts(ctx *context.Context, blameParts []git.BlamePart) (map[st
 				} else {
 					ctx.ServerError("Repo.GitRepo.GetCommit", err)
 				}
-				return nil, nil
+				return nil
 			}
 			commitCache[sha] = commit
 		}
 
-		// find parent commit
-		if commit.ParentCount() > 0 {
-			psha := commit.Parents[0]
-			previousCommit, ok := commitCache[psha.String()]
-			if !ok {
-				previousCommit, _ = commit.Parent(0)
-				if previousCommit != nil {
-					commitCache[psha.String()] = previousCommit
-				}
-			}
-			// only store parent commit ONCE, if it has the file
-			if previousCommit != nil {
-				if haz1, _ := previousCommit.HasFile(ctx.Repo.TreePath); haz1 {
-					previousCommits[commit.ID.String()] = previousCommit.ID.String()
-				}
-			}
-		}
-
 		commits = append(commits, commit)
 	}
 
@@ -245,10 +224,10 @@ func processBlameParts(ctx *context.Context, blameParts []git.BlamePart) (map[st
 		commitNames[c.ID.String()] = c
 	}
 
-	return commitNames, previousCommits
+	return commitNames
 }
 
-func renderBlame(ctx *context.Context, blameParts []git.BlamePart, commitNames map[string]*user_model.UserCommit, previousCommits map[string]string) {
+func renderBlame(ctx *context.Context, blameParts []git.BlamePart, commitNames map[string]*user_model.UserCommit) {
 	repoLink := ctx.Repo.RepoLink
 
 	language := ""
@@ -295,7 +274,6 @@ func renderBlame(ctx *context.Context, blameParts []git.BlamePart, commitNames m
 			}
 
 			commit := commitNames[part.Sha]
-			previousSha := previousCommits[part.Sha]
 			if index == 0 {
 				// Count commit number
 				commitCnt++
@@ -313,8 +291,8 @@ func renderBlame(ctx *context.Context, blameParts []git.BlamePart, commitNames m
 				br.Avatar = gotemplate.HTML(avatar)
 				br.RepoLink = repoLink
 				br.PartSha = part.Sha
-				br.PreviousSha = previousSha
-				br.PreviousShaURL = fmt.Sprintf("%s/blame/commit/%s/%s", repoLink, url.PathEscape(previousSha), util.PathEscapeSegments(ctx.Repo.TreePath))
+				br.PreviousSha = part.PreviousSha
+				br.PreviousShaURL = fmt.Sprintf("%s/blame/commit/%s/%s", repoLink, url.PathEscape(part.PreviousSha), util.PathEscapeSegments(part.PreviousPath))
 				br.CommitURL = fmt.Sprintf("%s/commit/%s", repoLink, url.PathEscape(part.Sha))
 				br.CommitMessage = commit.CommitMessage
 				br.CommitSince = commitSince