wumb0/delta_patch.py

## delta_patch.py
from ctypes import (windll, wintypes, c_uint64, cast, POINTER, Union, c_ubyte,
                    LittleEndianStructure, byref, c_size_t)
import zlib


# types and flags
DELTA_FLAG_TYPE             = c_uint64
DELTA_FLAG_NONE             = 0x00000000
DELTA_APPLY_FLAG_ALLOW_PA19 = 0x00000001


# structures
class DELTA_INPUT(LittleEndianStructure):
    class U1(Union):
        _fields_ = [('lpcStart', wintypes.LPVOID),
                    ('lpStart', wintypes.LPVOID)]
    _anonymous_ = ('u1',)
    _fields_ = [('u1', U1),
                ('uSize', c_size_t),
                ('Editable', wintypes.BOOL)]


class DELTA_OUTPUT(LittleEndianStructure):
    _fields_ = [('lpStart', wintypes.LPVOID),
                ('uSize', c_size_t)]


# functions
ApplyDeltaB = windll.msdelta.ApplyDeltaB
ApplyDeltaB.argtypes = [DELTA_FLAG_TYPE, DELTA_INPUT, DELTA_INPUT,
                        POINTER(DELTA_OUTPUT)]
ApplyDeltaB.rettype = wintypes.BOOL
DeltaFree = windll.msdelta.DeltaFree
DeltaFree.argtypes = [wintypes.LPVOID]
DeltaFree.rettype = wintypes.BOOL
gle = windll.kernel32.GetLastError


def apply_patchfile_to_buffer(buf, buflen, patchpath, legacy):
    with open(patchpath, 'rb') as patch:
        patch_contents = patch.read()

    # most (all?) patches (Windows Update MSU) come with a CRC32 prepended to the file
    # we don't really care if it is valid or not, we just need to remove it if it is there
    # we only need to calculate if the file starts with PA30 or PA19 and then has PA30 or PA19 after it
    magic = [b"PA30"]
    if legacy:
        magic.append(b"PA19")
    if patch_contents[:4] in magic and patch_contents[4:][:4] in magic:
        # we have to validate and strip the crc instead of just stripping it
        crc = int.from_bytes(patch_contents[:4], 'little')
        if zlib.crc32(patch_contents[4:]) == crc:
            # crc is valid, strip it, else don't
            patch_contents = patch_contents[4:]
    elif patch_contents[4:][:4] in magic:
        # validate the header strip the CRC, we don't care about it
        patch_contents = patch_contents[4:]
    # check if there is just no CRC at all
    elif patch_contents[:4] not in magic:
        # this just isn't valid
        raise Exception("Patch file is invalid")

    applyflags = DELTA_APPLY_FLAG_ALLOW_PA19 if legacy else DELTA_FLAG_NONE

    dd = DELTA_INPUT()
    ds = DELTA_INPUT()
    dout = DELTA_OUTPUT()

    ds.lpcStart = buf
    ds.uSize = buflen
    ds.Editable = False

    dd.lpcStart = cast(patch_contents, wintypes.LPVOID)
    dd.uSize = len(patch_contents)
    dd.Editable = False

    status = ApplyDeltaB(applyflags, ds, dd, byref(dout))
    if status == 0:
        raise Exception("Patch {} failed with error {}".format(patchpath, gle()))

    return (dout.lpStart, dout.uSize)


if __name__ == '__main__':
    import sys
    import base64
    import hashlib
    import argparse

    ap = argparse.ArgumentParser()
    mode = ap.add_mutually_exclusive_group(required=True)
    output = ap.add_mutually_exclusive_group(required=True)
    mode.add_argument("-i", "--input-file",
                      help="File to patch (forward or reverse)")
    mode.add_argument("-n", "--null", action="store_true", default=False,
                      help="Create the output file from a null diff "
                           "(null diff must be the first one specified)")
    output.add_argument("-o", "--output-file",
                        help="Destination to write patched file to")
    output.add_argument("-d", "--dry-run", action="store_true",
                        help="Don't write patch, just see if it would patch"
                             "correctly and get the resulting hash")
    ap.add_argument("-l", "--legacy", action='store_true', default=False,
                    help="Let the API use the PA19 legacy API (if required)")
    ap.add_argument("patches", nargs='+', help="Patches to apply")
    args = ap.parse_args()

    if not args.dry_run and not args.output_file:
        print("Either specify -d or -o", file=sys.stderr)
        ap.print_help()
        sys.exit(1)

    if args.null:
        inbuf = b""
    else:
        with open(args.input_file, 'rb') as r:
            inbuf = r.read()

    buf = cast(inbuf, wintypes.LPVOID)
    n = len(inbuf)
    to_free = []
    try:
        for patch in args.patches:
            buf, n = apply_patchfile_to_buffer(buf, n, patch, args.legacy)
            to_free.append(buf)

        outbuf = bytes((c_ubyte*n).from_address(buf))
        if not args.dry_run:
            with open(args.output_file, 'wb') as w:
                w.write(outbuf)
    finally:
        for buf in to_free:
            DeltaFree(buf)

    finalhash = hashlib.sha256(outbuf)
    print("Applied {} patch{} successfully"
          .format(len(args.patches), "es" if len(args.patches) > 1 else ""))
    print("Final hash: {}"
          .format(base64.b64encode(finalhash.digest()).decode()))
	from ctypes import (windll, wintypes, c_uint64, cast, POINTER, Union, c_ubyte,
	LittleEndianStructure, byref, c_size_t)
	import zlib


	# types and flags
	DELTA_FLAG_TYPE = c_uint64
	DELTA_FLAG_NONE = 0x00000000
	DELTA_APPLY_FLAG_ALLOW_PA19 = 0x00000001


	# structures
	class DELTA_INPUT(LittleEndianStructure):
	class U1(Union):
	_fields_ = [('lpcStart', wintypes.LPVOID),
	('lpStart', wintypes.LPVOID)]
	_anonymous_ = ('u1',)
	_fields_ = [('u1', U1),
	('uSize', c_size_t),
	('Editable', wintypes.BOOL)]


	class DELTA_OUTPUT(LittleEndianStructure):
	_fields_ = [('lpStart', wintypes.LPVOID),
	('uSize', c_size_t)]


	# functions
	ApplyDeltaB = windll.msdelta.ApplyDeltaB
	ApplyDeltaB.argtypes = [DELTA_FLAG_TYPE, DELTA_INPUT, DELTA_INPUT,
	POINTER(DELTA_OUTPUT)]
	ApplyDeltaB.rettype = wintypes.BOOL
	DeltaFree = windll.msdelta.DeltaFree
	DeltaFree.argtypes = [wintypes.LPVOID]
	DeltaFree.rettype = wintypes.BOOL
	gle = windll.kernel32.GetLastError


	def apply_patchfile_to_buffer(buf, buflen, patchpath, legacy):
	with open(patchpath, 'rb') as patch:
	patch_contents = patch.read()

	# most (all?) patches (Windows Update MSU) come with a CRC32 prepended to the file
	# we don't really care if it is valid or not, we just need to remove it if it is there
	# we only need to calculate if the file starts with PA30 or PA19 and then has PA30 or PA19 after it
	magic = [b"PA30"]
	if legacy:
	magic.append(b"PA19")
	if patch_contents[:4] in magic and patch_contents[4:][:4] in magic:
	# we have to validate and strip the crc instead of just stripping it
	crc = int.from_bytes(patch_contents[:4], 'little')
	if zlib.crc32(patch_contents[4:]) == crc:
	# crc is valid, strip it, else don't
	patch_contents = patch_contents[4:]
	elif patch_contents[4:][:4] in magic:
	# validate the header strip the CRC, we don't care about it
	patch_contents = patch_contents[4:]
	# check if there is just no CRC at all
	elif patch_contents[:4] not in magic:
	# this just isn't valid
	raise Exception("Patch file is invalid")

	applyflags = DELTA_APPLY_FLAG_ALLOW_PA19 if legacy else DELTA_FLAG_NONE

	dd = DELTA_INPUT()
	ds = DELTA_INPUT()
	dout = DELTA_OUTPUT()

	ds.lpcStart = buf
	ds.uSize = buflen
	ds.Editable = False

	dd.lpcStart = cast(patch_contents, wintypes.LPVOID)
	dd.uSize = len(patch_contents)
	dd.Editable = False

	status = ApplyDeltaB(applyflags, ds, dd, byref(dout))
	if status == 0:
	raise Exception("Patch {} failed with error {}".format(patchpath, gle()))

	return (dout.lpStart, dout.uSize)


	if __name__ == '__main__':
	import sys
	import base64
	import hashlib
	import argparse

	ap = argparse.ArgumentParser()
	mode = ap.add_mutually_exclusive_group(required=True)
	output = ap.add_mutually_exclusive_group(required=True)
	mode.add_argument("-i", "--input-file",
	help="File to patch (forward or reverse)")
	mode.add_argument("-n", "--null", action="store_true", default=False,
	help="Create the output file from a null diff "
	"(null diff must be the first one specified)")
	output.add_argument("-o", "--output-file",
	help="Destination to write patched file to")
	output.add_argument("-d", "--dry-run", action="store_true",
	help="Don't write patch, just see if it would patch"
	"correctly and get the resulting hash")
	ap.add_argument("-l", "--legacy", action='store_true', default=False,
	help="Let the API use the PA19 legacy API (if required)")
	ap.add_argument("patches", nargs='+', help="Patches to apply")
	args = ap.parse_args()

	if not args.dry_run and not args.output_file:
	print("Either specify -d or -o", file=sys.stderr)
	ap.print_help()
	sys.exit(1)

	if args.null:
	inbuf = b""
	else:
	with open(args.input_file, 'rb') as r:
	inbuf = r.read()

	buf = cast(inbuf, wintypes.LPVOID)
	n = len(inbuf)
	to_free = []
	try:
	for patch in args.patches:
	buf, n = apply_patchfile_to_buffer(buf, n, patch, args.legacy)
	to_free.append(buf)

	outbuf = bytes((c_ubyte*n).from_address(buf))
	if not args.dry_run:
	with open(args.output_file, 'wb') as w:
	w.write(outbuf)
	finally:
	for buf in to_free:
	DeltaFree(buf)

	finalhash = hashlib.sha256(outbuf)
	print("Applied {} patch{} successfully"
	.format(len(args.patches), "es" if len(args.patches) > 1 else ""))
	print("Final hash: {}"
	.format(base64.b64encode(finalhash.digest()).decode()))