From 3c25bb5d61bbfb8dee6405ae5c90e7ba505be742 Mon Sep 17 00:00:00 2001
From: truewhile <62226914+truewhile@users.noreply.github.com>
Date: Thu, 27 Aug 2026 13:40:46 +0800
Subject: [PATCH] 3

---
 internal/service/cloud115/sha1.go        |  4 +++-
 internal/service/cloud115/upload_test.go | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/internal/service/cloud115/sha1.go b/internal/service/cloud115/sha1.go
index f8a2cb4..645d4f1 100644
--- a/internal/service/cloud115/sha1.go
+++ b/internal/service/cloud115/sha1.go
@@ -40,7 +40,9 @@ func FileSHA1Partial(path string, start, end int64) (string, error) {
 	}
 	length := end - start + 1
 	h := sha1.New()
-	if _, err := io.CopyN(h, f, length); err != nil {
+	// io.CopyN 在文件不足 length 字节时会返回 io.EOF，导致小文件（如小于 128 KiB 的
+	// 元数据图片）无法上传。这里只拷贝实际读到的字节，文件尾对齐到区间终点即可。
+	if _, err := io.CopyN(h, f, length); err != nil && err != io.EOF {
 		return "", err
 	}
 	return hex.EncodeToString(h.Sum(nil)), nil
diff --git a/internal/service/cloud115/upload_test.go b/internal/service/cloud115/upload_test.go
index 5664e1f..20cc9b7 100644
--- a/internal/service/cloud115/upload_test.go
+++ b/internal/service/cloud115/upload_test.go
@@ -39,6 +39,26 @@ func TestFileSHA1Partial(t *testing.T) {
 	}
 }
 
+// TestFileSHA1PartialSmallerThanWindow 回归测试：经典 bug 是 io.CopyN 在文件不足
+// length 字节时返回 io.EOF。115 上传固定用 [0,128*1024-1] 窗口计算 preid，导致所有
+// 小于 128 KiB 的元数据文件（如海报/缩略图）上传必然失败。
+func TestFileSHA1PartialSmallerThanWindow(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "small.bin")
+	// 6 字节小文件，不足 128 KiB 窗口
+	if err := os.WriteFile(path, []byte("abcdef"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	sum, err := FileSHA1Partial(path, 0, 128*1024-1)
+	if err != nil {
+		t.Fatalf("compute partial sha1 for small file should not fail: %v", err)
+	}
+	// 应等于整个文件（6 字节）的 sha1
+	if sum != "1f8ac10f23c5b5bc1167bda84b833e5c057a77d2" {
+		t.Errorf("unexpected partial sha1: %s", sum)
+	}
+}
+
 func TestParseSignCheckRange(t *testing.T) {
 	rng, err := parseSignCheckRange("0-131071")
 	if err != nil {