From 24d66ad693eee6df6df37be8b64d594221a6221e Mon Sep 17 00:00:00 2001
From: Runxi Yu <me@runxiyu.org>
Date: Wed, 12 Feb 2025 01:42:38 +0800
Subject: [PATCH] repo_commit: Fix format_patch handling of root commits

---
 git_format_patch.go   | 13 ++-----------
 git_misc.go           | 30 ++++++++++++++++++++++++++++++
 handle_repo_commit.go | 29 ++---------------------------

diff --git a/git_format_patch.go b/git_format_patch.go
index 1f282fa440054efd54f958008f39b0960562bfd6..4f37e92e9fb01bccb0023ce828322fdfdc704bff 100644
--- a/git_format_patch.go
+++ b/git_format_patch.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -11,18 +10,10 @@ 	"github.com/go-git/go-git/v5/plumbing/object"
 	"go.lindenii.runxiyu.org/lindenii-common/misc"
 )
 
-var err_get_patch = errors.New("Failed to get patch from commit")
-
 func format_patch_from_commit(commit *object.Commit) (string, error) {
-	parent, err := commit.Parent(0)
+	_, patch, err := get_patch_from_commit(commit)
 	if err != nil {
-		return "", err
-	}
-
-	var patch *object.Patch
-	patch, err = parent.Patch(commit)
-	if err != nil {
-		return "", misc.Wrap_one_error(err_get_patch, err)
+		return "", misc.Wrap_one_error(err_getting_patch_of_commit, err)
 	}
 
 	var buf bytes.Buffer
diff --git a/git_misc.go b/git_misc.go
index 851fb683f03ed66ce924dea9170edfa7975994c8..c6ec9f9212154db252ac99ee2ecc32496ccde9b9 100644
--- a/git_misc.go
+++ b/git_misc.go
@@ -13,6 +13,9 @@ 	"go.lindenii.runxiyu.org/lindenii-common/misc"
 )
 
 var err_unsafe_path = errors.New("Unsafe path")
+var err_getting_commit_tree = errors.New("Error getting commit tree")
+var err_getting_patch_of_commit = errors.New("Error getting patch of commit")
+var err_getting_parent_commit_object = errors.New("Error getting parent commit object")
 
 func open_git_repo(group_name, repo_name string) (*git.Repository, error) {
 	group_name, group_name_ok := misc.Sanitize_path(group_name)
@@ -82,3 +85,30 @@ 		}
 	}
 	return recent_commits, err
 }
+
+func get_patch_from_commit(commit_object *object.Commit) (parent_commit_hash plumbing.Hash, patch *object.Patch, ret_err error) {
+	parent_commit_object, err := commit_object.Parent(0)
+	if errors.Is(err, object.ErrParentNotFound) {
+		commit_tree, err := commit_object.Tree()
+		if err != nil {
+			ret_err = misc.Wrap_one_error(err_getting_commit_tree, err)
+			return
+		}
+		patch, err = (&object.Tree{}).Patch(commit_tree)
+		if err != nil {
+			ret_err = misc.Wrap_one_error(err_getting_patch_of_commit, err)
+			return
+		}
+	} else if err != nil {
+		ret_err = misc.Wrap_one_error(err_getting_parent_commit_object, err)
+		return
+	} else {
+		parent_commit_hash = parent_commit_object.Hash
+		patch, err = parent_commit_object.Patch(commit_object)
+		if err != nil {
+			ret_err = misc.Wrap_one_error(err_getting_patch_of_commit, err)
+			return
+		}
+	}
+	return
+}
diff --git a/handle_repo_commit.go b/handle_repo_commit.go
index 03a7cd4b92dca385a2d5d10415451b6223bf0d8a..aeea380317c734f3b17f8d334c15465201141abc 100644
--- a/handle_repo_commit.go
+++ b/handle_repo_commit.go
@@ -1,14 +1,12 @@
 package main
 
 import (
-	"errors"
 	"net/http"
 	"strings"
 
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/filemode"
 	"github.com/go-git/go-git/v5/plumbing/format/diff"
-	"github.com/go-git/go-git/v5/plumbing/object"
 	"go.lindenii.runxiyu.org/lindenii-common/misc"
 )
 
@@ -53,31 +51,8 @@
 	data["commit_object"] = commit_object
 	data["commit_id"] = commit_id_string
 
-	var patch *object.Patch
-	parent_commit_object, err := commit_object.Parent(0)
-	if errors.Is(err, object.ErrParentNotFound) {
-		commit_tree, err := commit_object.Tree()
-		if err != nil {
-			_, _ = w.Write([]byte("Error getting commit tree (for comparing against an empty tree): " + err.Error()))
-			return
-		}
-		patch, err = (&object.Tree{}).Patch(commit_tree)
-		if err != nil {
-			_, _ = w.Write([]byte("Error getting patch of commit: " + err.Error()))
-			return
-		}
-	} else if err != nil {
-		_, _ = w.Write([]byte("Error getting parent commit object: " + err.Error()))
-		return
-	} else {
-		data["parent_commit_hash"] = parent_commit_object.Hash.String()
-
-		patch, err = parent_commit_object.Patch(commit_object)
-		if err != nil {
-			_, _ = w.Write([]byte("Error getting patch of commit: " + err.Error()))
-			return
-		}
-	}
+	parent_commit_hash, patch, err := get_patch_from_commit(commit_object)
+	data["parent_commit_hash"] = parent_commit_hash.String()
 	data["patch"] = patch
 
 	// TODO: Remove unnecessary context

-- 
2.48.1