cr_checker: Add remove offset as option

The new option enables the removal of outdated copyright headers
from source files. This functionality is potentially destructive
and should be used with extreme caution.

tools/cr_checker/tool/cr_checker.py

@@ -19,6 +19,7 @@
 import tempfile
 import mmap
 import json
+import shutil
 from datetime import datetime
 from pathlib import Path
 
@@ -354,6 +355,24 @@ def create_temp_file(path, encoding):
                 temp.write(chunk)
     return temp.name
 
+def remove_old_header(file_path, encoding, num_of_chars):
+    """
+    Removes the first `num_of_chars` characters from a file and updates it in-place.
+
+    Args:
+        file_path (str): Path to the file to be modified.
+        encoding (str): Encoding used to read and write the file.
+        num_of_chars (int): Number of characters to remove from the beginning of the file.
+
+    Raises:
+        IOError: If there is an issue reading or writing the file.
+        ValueError: If `num_of_chars` is negative.
+    """
+    with open(file_path, 'r', encoding=encoding) as file:
+        file.seek(num_of_chars)
+        with tempfile.NamedTemporaryFile('w', delete=False, encoding=encoding) as temp_file:
+            shutil.copyfileobj(file, temp_file)
+    shutil.move(temp_file.name, file_path)
 
 def fix_copyright(path, copyright_text, encoding, offset):
     """
@@ -393,8 +412,8 @@ def fix_copyright(path, copyright_text, encoding, offset):
 
 
 def process_files(
-    files, templates, fix, config, use_mmap=False, encoding="utf-8", offset=0
-):  # pylint: disable=too-many-arguments
+    files, templates, fix, config, use_mmap=False, encoding="utf-8", offset=0,
+    remove_offset=0):  # pylint: disable=too-many-arguments
     """
     Processes a list of files to check for the presence of copyright text.
 
@@ -411,6 +430,8 @@ def process_files(
         offset (int): Additional number of characters to read beyond the length
                       of `copyright_text`, used to account for extra content
                       (such as a shebang) before the copyright text.
+        remove_offset(int): Flag for removing old header from source files
+                             (before applying the new one) in number of chars.
 
     Returns:
         int: The number of files that do not contain the required copyright text.
@@ -426,6 +447,8 @@ def process_files(
             continue
         if not has_copyright(item, templates[key], use_mmap, encoding, offset, config):
             if fix:
+                if remove_offset:
+                    remove_old_header(item, encoding, remove_offset)
                 fix_copyright(item, templates[key], encoding, offset)
                 results["no_copyright"] += 1
                 results["fixed"] += 1
@@ -515,6 +538,15 @@ def parse_arguments(argv):
         help="Additional length offset to account for characters like a shebang (default is 0)",
     )
 
+    parser.add_argument(
+        "--remove-offset",
+        dest="remove_offset",
+        type=int,
+        default=0,
+        help="Offset to remove old header from begining of the file \
+             (supported only with --fix mode)",
+    )
+
     parser.add_argument(
         "inputs",
         nargs="+",
@@ -558,6 +590,14 @@ def main(argv=None):
 
     LOGGER.debug("Running check on files: %s", files)
 
+    if args.fix and args.remove_offset:
+        LOGGER.info("%s!------DANGER ZONE------!%s",
+                    COLORS["RED"], COLORS["ENDC"])
+        LOGGER.info("Remove offset set! This can REMOVE parts of source files!")
+        LOGGER.info("Use ONLY if invalid copyright header is present that needs to be removed!")
+        LOGGER.info("%s!-----------------------!%s",
+                    COLORS["RED"], COLORS["ENDC"])
+
     results = process_files(
         files,
         templates,
@@ -566,6 +606,7 @@ def main(argv=None):
         args.use_memory_map,
         args.encoding,
         args.offset,
+        args.remove_offset,
     )
     total_no = results["no_copyright"]
     total_fixes = results["fixed"]