1 files changed, 103 insertions, 0 deletions
diff --git a/ioctl/__init__.py b/ioctl/__init__.py
new file mode 100644
index 0000000..820a4ba
--- /dev/null
+++ b/ioctl/__init__.py
@@ -0,0 +1,103 @@
+# SPDX-License-Identifier: MIT
+
+import array
+import fcntl
+
+from typing import BinaryIO, Optional, Union
+
+
+class IOCTL(object):
+    '''
+    Constructs and performs ioctl(s)
+    See include/asm-generic/ioctl.h
+    '''
+    NRBITS: int = 8
+    TYPEBITS: int = 8
+
+    SIZEBITS: int = 14
+    DIRBITS: int = 2
+
+    NRMASK: int = (1 << NRBITS) - 1
+    TYPEMASK: int = (1 << TYPEBITS) - 1
+    SIZEMASK: int = (1 << SIZEBITS) - 1
+    DIRMASK: int = (1 << DIRBITS) - 1
+
+    NRSHIFT: int = 0
+    TYPESHIFT: int = NRSHIFT + NRBITS
+    SIZESHIFT: int = TYPESHIFT + TYPEBITS
+    DIRSHIFT: int = SIZESHIFT + SIZEBITS
+
+    class Direction:
+        NONE = 0
+        WRITE = 1
+        READ = 2
+
+    def __init__(self, dir: int, ty: str, nr: int, size: int = 0, bad: bool = False) -> None:
+        assert self.Direction.NONE <= dir <= self.Direction.READ + self.Direction.WRITE
+
+        if dir == self.Direction.NONE:
+            size = 0
+        elif not bad:
+            assert size, size <= self.SIZEMASK
+
+        self.op = (
+            (dir << self.DIRSHIFT) |
+            (ord(ty) << self.TYPESHIFT) |
+            (nr << self.NRSHIFT) |
+            (size << self.SIZESHIFT)
+        )
+
+    def perform(self, fd: BinaryIO, buf: Optional[Union[str, bytes, 'array.array[int]']] = None) -> bytearray:
+        '''
+        Performs the ioctl
+        '''
+        size = self.unpack_size(self.op)
+
+        if buf is None:
+            buf = (size * '\x00').encode()
+
+        return bytearray(fcntl.ioctl(fd, self.op, buf))  # type: ignore
+
+    @classmethod
+    def unpack_dir(cls, nr: int) -> int:
+        return (nr >> cls.DIRSHIFT) & cls.DIRMASK
+
+    @classmethod
+    def unpack_type(cls, nr: int) -> int:
+        return (nr >> cls.TYPESHIFT) & cls.TYPEMASK
+
+    @classmethod
+    def unpack_nr(cls, nr: int) -> int:
+        return (nr >> cls.NRSHIFT) & cls.NRMASK
+
+    @classmethod
+    def unpack_size(cls, nr: int) -> int:
+        return (nr >> cls.SIZESHIFT) & cls.SIZEMASK
+
+    @classmethod
+    def IO(cls, ty: str, nr: int) -> 'IOCTL':
+        '''
+        Constructor for no direction
+        '''
+        return cls(cls.Direction.NONE, ty, nr)
+
+    @classmethod
+    def IOR(cls, ty: str, nr: int, size: int) -> 'IOCTL':
+        '''
+        Constructor for read
+        '''
+        return cls(cls.Direction.READ, ty, nr, size)
+
+    @classmethod
+    def IOW(cls, ty: str, nr: int, size: int) -> 'IOCTL':
+        '''
+        Constructor for write
+        '''
+        return cls(cls.Direction.WRITE, ty, nr, size)
+
+    @classmethod
+    def IORW(cls, ty: str, nr: int, size: int) -> 'IOCTL':
+        '''
+        Constructor for read & write
+        '''
+        return cls(cls.Direction.READ | cls.Direction.WRITE, ty, nr, size)