mmap-ed memoryview support

[pyderasn.git] / pyderasn.py

diff --git a/pyderasn.py b/pyderasn.py
index 3533c6b9f18f46f28d9812b1dce8824b29ecfa44..002f0605c42e65b804ffc1d4907142a7000cd521 100755 (executable)
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -644,6 +644,7 @@ Various
 .. autofunction:: pyderasn.abs_decode_path
 .. autofunction:: pyderasn.colonize_hex
 .. autofunction:: pyderasn.encode_cer
+.. autofunction:: pyderasn.file_mmaped
 .. autofunction:: pyderasn.hexenc
 .. autofunction:: pyderasn.hexdec
 .. autofunction:: pyderasn.tag_encode
@@ -782,6 +783,8 @@ from datetime import datetime
 from datetime import timedelta
 from io import BytesIO
 from math import ceil
+from mmap import mmap
+from mmap import PROT_READ
 from operator import attrgetter
 from string import ascii_letters
 from string import digits
@@ -824,6 +827,7 @@ __all__ = (
     "encode_cer",
     "Enumerated",
     "ExceedingData",
+    "file_mmaped",
     "GeneralizedTime",
     "GeneralString",
     "GraphicString",
@@ -891,6 +895,14 @@ DECIMALS = frozenset(digits)
 DECIMAL_SIGNS = ".,"
 
 
+def file_mmaped(fd):
+    """Make mmap-ed memoryview for reading from file
+
+    :param fd: file object
+    :returns: memoryview over read-only mmap-ing of the whole file
+    """
+    return memoryview(mmap(fd.fileno(), 0, prot=PROT_READ))
+
 def pureint(value):
     if not set(value) <= DECIMALS:
         raise ValueError("non-pure integer")
@@ -6695,14 +6707,17 @@ def main():  # pragma: no cover
         help="Allow explicit tag out-of-bound",
     )
     parser.add_argument(
-        "DERFile",
+        "RAWFile",
         type=argparse.FileType("rb"),
-        help="Path to DER file you want to decode",
+        help="Path to BER/CER/DER file you want to decode",
     )
     args = parser.parse_args()
-    args.DERFile.seek(args.skip)
-    der = memoryview(args.DERFile.read())
-    args.DERFile.close()
+    if PY2:
+        args.RAWFile.seek(args.skip)
+        raw = memoryview(args.RAWFile.read())
+        args.RAWFile.close()
+    else:
+        raw = file_mmaped(args.RAWFile)[args.skip:]
     oid_maps = (
         [obj_by_path(_path) for _path in (args.oids or "").split(",")]
         if args.oids else ()
@@ -6719,7 +6734,7 @@ def main():  # pragma: no cover
     }
     if args.defines_by_path is not None:
         ctx["defines_by_path"] = obj_by_path(args.defines_by_path)
-    obj, tail = schema().decode(der, ctx=ctx)
+    obj, tail = schema().decode(raw, ctx=ctx)
     from os import environ
     print(pprinter(
         obj,