Use rev-parse to check if commit exists

Signed-off-by: Gary Kim <gary@garykim.dev>

modules/markup/html.go

@@ -647,6 +647,9 @@ func fullSha1PatternProcessor(ctx *postProcessCtx, node *html.Node) {
 // sha1CurrentPatternProcessor renders SHA1 strings to corresponding links that
 // are assumed to be in the same repository.
 func sha1CurrentPatternProcessor(ctx *postProcessCtx, node *html.Node) {
+	if ctx.metas == nil || ctx.metas["user"] == "" || ctx.metas["repo"] == "" || ctx.metas["repoPath"] == "" {
+		return
+	}
 	m := sha1CurrentPattern.FindStringSubmatchIndex(node.Data)
 	if m == nil {
 		return
@@ -660,11 +663,8 @@ func sha1CurrentPatternProcessor(ctx *postProcessCtx, node *html.Node) {
 	// as used by git and github for linking and thus we have to do similar.
 	// Because of this, we check to make sure that a matched hash is actually
 	// a commit in the repository before making it a link.
-	if ctx.metas["repoPath"] != "" {
-		repo, err := git.OpenRepository(ctx.metas["repoPath"])
-		if err != nil || !repo.IsCommitExist(hash) {
-			return
-		}
+	if _, err := git.NewCommand("rev-parse", "--verify", hash).RunInDirBytes(ctx.metas["repoPath"]); err != nil {
+		return
 	}
 
 	replaceContent(node, m[2], m[3],