fatfsparse.py: enable automatic WL detection

components/fatfs/fatfsparse.py

@@ -83,6 +83,25 @@ def traverse_folder_tree(directory_bytes_: bytes,
                                  binary_array_=binary_array_)
 
 
+def remove_wear_levelling_if_exists(fs_: bytes) -> bytes:
+    """
+    Detection of the wear levelling layer is performed in two steps:
+    1) check if the first sector is a valid boot sector
+    2) check if the size defined in the boot sector is the same as the partition size:
+        - if it is, there is no wear levelling layer
+        - otherwise, we need to remove wl for further processing
+    """
+    try:
+        boot_sector__ = BootSector()
+        boot_sector__.parse_boot_sector(fs_)
+        if boot_sector__.boot_sector_state.size == len(fs_):
+            return fs_
+    except construct.core.ConstError:
+        pass
+    plain_fs: bytes = remove_wl(fs_)
+    return plain_fs
+
+
 if __name__ == '__main__':
     desc = 'Tool for parsing fatfs image and extracting directory structure on host.'
     argument_parser: argparse.ArgumentParser = argparse.ArgumentParser(description=desc)
@@ -92,12 +111,29 @@ if __name__ == '__main__':
                                  action='store_true',
                                  help=argparse.SUPPRESS)
 
+    # ensures backward compatibility
     argument_parser.add_argument('--wear-leveling',
                                  action='store_true',
-                                 help='Set flag to parse an image encoded using wear levelling.')
+                                 help=argparse.SUPPRESS)
+    argument_parser.add_argument('--wl-layer',
+                                 choices=['detect', 'enabled', 'disabled'],
+                                 default=None,
+                                 help="If detection doesn't work correctly, "
+                                      'you can force analyzer to or not to assume WL.')
 
     args = argument_parser.parse_args()
 
+    # if wear levelling is detected or user explicitly sets the parameter `--wl_layer enabled`
+    # the partition with wear levelling is transformed to partition without WL for convenient parsing
+    # in some cases the partitions with and without wear levelling can be 100% equivalent
+    # and only user can break this tie by explicitly setting
+    # the parameter --wl-layer to enabled, respectively disabled
+    if args.wear_leveling and args.wl_layer:
+        raise NotImplementedError('Argument --wear-leveling cannot be combined with --wl-layer!')
+    if args.wear_leveling:
+        args.wl_layer = 'enabled'
+    args.wl_layer = args.wl_layer or 'detect'
+
     fs = read_filesystem(args.input_image)
 
     # An algorithm for removing wear levelling:
@@ -109,8 +145,12 @@ if __name__ == '__main__':
     # 2. remove state sectors (trivial)
     # 3. remove cfg sector (trivial)
     # 4. valid fs is then old_fs[-mc:] + old_fs[:-mc]
-    if args.wear_leveling:
+    if args.wl_layer == 'enabled':
         fs = remove_wl(fs)
+    elif args.wl_layer != 'disabled':
+        # wear levelling is removed to enable parsing using common algorithm
+        fs = remove_wear_levelling_if_exists(fs)
+
     boot_sector_ = BootSector()
     boot_sector_.parse_boot_sector(fs)
     fat = FAT(boot_sector_.boot_sector_state, init_=False)

components/fatfs/test_fatfsgen/test_fatfsparse.py

@@ -146,7 +146,7 @@ class FatFSGen(unittest.TestCase):
             f'{os.path.join(os.path.dirname(__file__), "..", "wl_fatfsgen.py")}',
             'testf'
         ], stderr=STDOUT)
-        run(['python', '../fatfsparse.py', '--wear-leveling', 'fatfs_image.img'], stderr=STDOUT)
+        run(['python', '../fatfsparse.py', 'fatfs_image.img'], stderr=STDOUT)
         assert compare_folders('testf', 'Espressif')
 
     def test_e2e_deeper(self) -> None:
@@ -185,7 +185,7 @@ class FatFSGen(unittest.TestCase):
             f'{os.path.join(os.path.dirname(__file__), "..", "wl_fatfsgen.py")}',
             'testf'
         ], stderr=STDOUT)
-        run(['python', '../fatfsparse.py', '--wear-leveling', 'fatfs_image.img'], stderr=STDOUT)
+        run(['python', '../fatfsparse.py', 'fatfs_image.img'], stderr=STDOUT)
         assert compare_folders('testf', 'Espressif')
 
     def test_e2e_deeper_large(self) -> None:
@@ -241,7 +241,7 @@ class FatFSGen(unittest.TestCase):
             f'{os.path.join(os.path.dirname(__file__), "..", "wl_fatfsgen.py")}',
             'testf'
         ], stderr=STDOUT)
-        run(['python', '../fatfsparse.py', '--wear-leveling', 'fatfs_image.img'], stderr=STDOUT)
+        run(['python', '../fatfsparse.py', 'fatfs_image.img'], stderr=STDOUT)
         assert compare_folders('testf', 'Espressif')
 
     def test_e2e_very_deep(self) -> None:

docs/en/api-reference/storage/fatfs.rst

@@ -144,4 +144,4 @@ It is a reverse tool of (:component_file:`fatfsgen.py<fatfs/fatfsgen.py>`), i.e.
 
 Usage::
 
-    ./fatfsparse.py [-h] [--wear-leveling] fatfs_image.img
+    ./fatfsparse.py [-h] [--wl-layer {detect,enabled,disabled}] fatfs_image.img

docs/zh_CN/api-reference/storage/fatfs.rst

@@ -144,4 +144,4 @@ FatFs 分区分析器
 
 您可以使用::
 
-    ./fatfsparse.py [-h] [--wear-leveling] fatfs_image.img
+    ./fatfsparse.py [-h] [--wl-layer {detect,enabled,disabled}] fatfs_image.img