finish fragment files copy

files_utils/files_save.py

@@ -1,7 +1,7 @@
 import os
 
 
-def extract_drive_letter(path: str) -> str:
+def ExtractVolumeLetter(path: str) -> str:
     """从绝对路径中提取盘符"""
     drive = os.path.splitdrive(path)[0]
     if not drive:
@@ -9,7 +9,7 @@ def extract_drive_letter(path: str) -> str:
     return drive[0].upper()  # 返回 'Y'
 
 
-def CopyFileFromBytes(source_data_dict, target_path):
+def CopySingleFragmentFiles(source_data_dict, target_path):
     """
     根据起始字节和长度，从磁盘中读取数据并保存为目标文件
 
@@ -29,7 +29,7 @@ def CopyFileFromBytes(source_data_dict, target_path):
         print("错误：缺少必要的文件信息")
         return
 
-    source_disk_path = extract_drive_letter(absolute_path)
+    source_disk_path = ExtractVolumeLetter(absolute_path)
     target_file_path = os.path.join(target_path, file_name)
 
     try:
@@ -60,14 +60,75 @@ def CopyFileFromBytes(source_data_dict, target_path):
         print(f"发生错误: {str(e)}")
 
 
-if __name__ == "__main__":
-    test_dict = {
-        'absolute_path': 'Y:\\CloudMusic\\Aaron Zigman - Main Title.mp3',
-        'filename': 'Aaron Zigman - Main Title.mp3',
-        'extent_count': 1,
-        'start_byte': 687685632,
-        'length': 7163904,
-        'fragment_index': 1
-    }
+def ReadDiskBytes(volume_letter: str, start_byte: int, length: int) -> bytes:
+    """
+    从指定磁盘的指定起始位置读取指定长度的字节。
 
-    CopyFileFromBytes(test_dict, target_path=r"Z:\RecoveredFiles")
+    :param volume_letter: 盘符（如 "Y"）
+    :param start_byte: 起始字节位置（整数）
+    :param length: 要读取的字节数（整数）
+    :return: 读取到的原始字节数据（bytes）
+    """
+    if not isinstance(volume_letter, str) or len(volume_letter.strip()) != 1:
+        raise ValueError("drive_letter 必须是单个字母，如 'Y'")
+
+    # 构建 Windows 设备路径格式：\\.\Y:
+    disk_path = f"\\\\.\\{volume_letter.strip().upper()}:"
+
+    try:
+        with open(disk_path, "rb") as disk:
+            disk.seek(start_byte)
+            data = disk.read(length)
+            return data
+    except PermissionError:
+        raise PermissionError("权限不足，请以管理员身份运行程序")
+    except Exception as e:
+        raise RuntimeError(f"读取磁盘失败：{e}")
+
+
+def CopyMultiFragmentFiles(
+        item: dict,
+        fragment_lists: dict,
+        target_path: str
+):
+    """
+    处理具有多个分片的文件，读取并按顺序拼接内容，最终写入磁盘。
+
+    :param item: 包含文件分片信息的字典
+    :param fragment_lists: 存储各文件分片内容的字典
+    :param target_path: 恢复文件的目标保存路径
+    :return: None
+    """
+    file_name = item['filename']
+    extent_count = item['extent_count']
+    fragment_index = item['fragment_index']
+    start_byte = item['start_byte']
+    length_byte = item['length']
+
+    volume_letter = ExtractVolumeLetter(item['absolute_path'])
+
+    # 读取分片内容
+    fragment_content = ReadDiskBytes(volume_letter, start_byte, length_byte)
+
+    # 如果还没有为这个文件创建列表，则初始化
+    if file_name not in fragment_lists:
+        fragment_lists[file_name] = [None] * extent_count
+
+    # 将内容插入到指定位置
+    if fragment_index <= extent_count:
+        fragment_lists[file_name][fragment_index - 1] = fragment_content
+        print(f"已写入 {file_name} 的第 {fragment_index} 个片段。")
+    else:
+        print(f"警告：{file_name} 的 fragment_index 超出范围：{fragment_index} / {extent_count}")
+
+    # 检查是否所有分片都已加载
+    fragments = fragment_lists[file_name]
+    if None not in fragments:
+        full_content = b''.join(fragments)
+        target_file_path = os.path.join(target_path, file_name)
+        try:
+            with open(target_file_path, 'wb') as f:
+                f.write(full_content)
+            print(f"已成功恢复文件：{file_name}")
+        except Exception as e:
+            print(f"写入文件失败：{file_name}，错误：{e}")