common fstab and libc funcs

kvmd/fstab.py

@@ -0,0 +1,50 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main PiKVM daemon.                                           #
+#                                                                            #
+#    Copyright (C) 2018-2022  Maxim Devaev <mdevaev@gmail.com>               #
+#                                                                            #
+#    This program is free software: you can redistribute it and/or modify    #
+#    it under the terms of the GNU General Public License as published by    #
+#    the Free Software Foundation, either version 3 of the License, or       #
+#    (at your option) any later version.                                     #
+#                                                                            #
+#    This program is distributed in the hope that it will be useful,         #
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
+#    GNU General Public License for more details.                            #
+#                                                                            #
+#    You should have received a copy of the GNU General Public License       #
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#                                                                            #
+# ========================================================================== #
+
+
+import re
+import dataclasses
+
+
+# =====
+@dataclasses.dataclass(frozen=True)
+class FstabStorage:
+    mount_path: str
+    root_path: str
+    user: str
+
+
+def find_storage(target: str) -> FstabStorage:
+    fstab_path = "/etc/fstab"
+    with open(fstab_path) as file:
+        for line in file.read().split("\n"):
+            line = line.strip()
+            if line and not line.startswith("#"):
+                parts = line.split()
+                if len(parts) == 6:
+                    options = dict(re.findall(r"X-kvmd\.%s-(root|user)(?:=([^,]+))?" % (target), parts[3]))
+                    if options:
+                        return FstabStorage(
+                            mount_path=parts[1],
+                            root_path=(options.get("root", "") or parts[1]),
+                            user=options.get("user", ""),
+                        )
+    raise RuntimeError(f"Can't find {target!r} mountpoint in {fstab_path}")

kvmd/helpers/remount/__init__.py

@@ -22,23 +22,10 @@
 
 import sys
 import os
-import re
 import shutil
-import dataclasses
 import subprocess
 
-
+from ... import fstab
-# ====
-_MOUNT_PATH = "/bin/mount"
-_FSTAB_PATH = "/etc/fstab"
-
-
-# =====
-@dataclasses.dataclass(frozen=True)
-class _Storage:
-    mount_path: str
-    root_path: str
-    user: str
 
 
 # =====
@@ -46,29 +33,11 @@ def _log(msg: str) -> None:
     print(msg, file=sys.stderr)
 
 
-def _find_storage(target: str) -> _Storage:
-    assert target
-    with open(_FSTAB_PATH) as fstab_file:
-        for line in fstab_file.read().split("\n"):
-            line = line.strip()
-            if line and not line.startswith("#"):
-                parts = line.split()
-                if len(parts) == 6:
-                    options = dict(re.findall(r"X-kvmd\.%s-(root|user)(?:=([^,]+))?" % (target), parts[3]))
-                    if options:
-                        return _Storage(
-                            mount_path=parts[1],
-                            root_path=(options.get("root", "") or parts[1]),
-                            user=options.get("user", ""),
-                        )
-    raise SystemExit(f"Can't find {target!r} mountpoint in {_FSTAB_PATH}")
-
-
 def _remount(path: str, rw: bool) -> None:
     mode = ("rw" if rw else "ro")
     _log(f"Remounting {path} to {mode.upper()}-mode ...")
     try:
-        subprocess.check_call([_MOUNT_PATH, "--options", f"remount,{mode}", path])
+        subprocess.check_call(["/bin/mount", "--options", f"remount,{mode}", path])
     except subprocess.CalledProcessError as err:
         raise SystemExit(f"Can't remount: {err}")
 
@@ -109,7 +78,8 @@ def main() -> None:
 
     rw = (sys.argv[1] == "rw")
 
-    storage = _find_storage(target)
+    assert target
+    storage = fstab.find_storage(target)
     _remount(storage.mount_path, rw)
     if rw and storage.root_path:
         for name in dirs:

kvmd/helpers/swapfiles/__init__.py

@@ -22,12 +22,8 @@
 
 import sys
 import os
-import ctypes
-import ctypes.util
 
-from ctypes import c_int
+from ... import libc
-from ctypes import c_uint
-from ctypes import c_char_p
 
 
 # =====
@@ -35,14 +31,6 @@ def main() -> None:
     if len(sys.argv) != 3:
         raise SystemExit(f"Usage: {sys.argv[0]} <file1> <file2>")
 
-    path = ctypes.util.find_library("c")
-    if not path:
-        raise SystemExit("Where is libc?")
-    assert path
-    libc = ctypes.CDLL(path)
-    libc.renameat2.restype = c_int
-    libc.renameat2.argtypes = [c_int, c_char_p, c_int, c_char_p, c_uint]
-
     result = libc.renameat2(
         -100,  # AT_FDCWD
         os.fsencode(sys.argv[1]),
@@ -52,4 +40,4 @@ def main() -> None:
     )
 
     if result != 0:
-        raise SystemExit(f"{sys.argv[0]}: {os.strerror(ctypes.get_errno())}")
+        raise SystemExit(f"{sys.argv[0]}: {os.strerror(libc.get_errno())}")

kvmd/inotify.py

@@ -25,7 +25,6 @@
 import sys
 import os
 import asyncio
-import ctypes
 import struct
 import dataclasses
 import types
@@ -64,7 +63,7 @@ def _inotify_parsed_buffer(data: bytes) -> Generator[tuple[int, int, int, bytes]
 
 def _inotify_check(retval: int) -> int:
     if retval < 0:
-        c_errno = ctypes.get_errno()
+        c_errno = libc.get_errno()
         if c_errno == errno.ENOSPC:  # pylint: disable=no-else-raise
             raise OSError(c_errno, "Inotify watch limit reached")
         elif c_errno == errno.EMFILE:

kvmd/libc.py

@@ -26,6 +26,7 @@ import ctypes
 import ctypes.util
 
 from ctypes import c_int
+from ctypes import c_uint
 from ctypes import c_uint32
 from ctypes import c_char_p
 from ctypes import c_void_p
@@ -42,6 +43,7 @@ def _load_libc() -> ctypes.CDLL:
         ("inotify_init", c_int, []),
         ("inotify_add_watch", c_int, [c_int, c_char_p, c_uint32]),
         ("inotify_rm_watch", c_int, [c_int, c_uint32]),
+        ("renameat2", c_int, [c_int, c_char_p, c_int, c_char_p, c_uint]),
         ("free", c_int, [c_void_p]),
     ]:
         func = getattr(lib, name)
@@ -56,7 +58,10 @@ _libc = _load_libc()
 
 
 # =====
+get_errno = ctypes.get_errno
+
 inotify_init = _libc.inotify_init
 inotify_add_watch = _libc.inotify_add_watch
 inotify_rm_watch = _libc.inotify_rm_watch
+renameat2 = _libc.renameat2
 free = _libc.free

kvmd/plugins/msd/otg/__init__.py

@@ -38,12 +38,12 @@ from ....yamlconf import Option
 
 from ....validators.basic import valid_bool
 from ....validators.basic import valid_number
-from ....validators.os import valid_abs_dir
 from ....validators.os import valid_printable_filename
 from ....validators.os import valid_command
 
 from .... import aiotools
 from .... import aiohelpers
+from .... import fstab
 
 from .. import MsdError
 from .. import MsdIsBusyError
@@ -143,8 +143,6 @@ class Plugin(BaseMsd):  # pylint: disable=too-many-instance-attributes
         write_chunk_size: int,
         sync_chunk_size: int,
 
-        storage_path: str,
-
         remount_cmd: list[str],
 
         initial: dict,
@@ -162,7 +160,7 @@ class Plugin(BaseMsd):  # pylint: disable=too-many-instance-attributes
         self.__initial_cdrom: bool = initial["cdrom"]
 
         self.__drive = Drive(gadget, instance=0, lun=0)
-        self.__storage = Storage(storage_path)
+        self.__storage = Storage(fstab.find_storage("otgmsd").root_path)
 
         self.__reader: (MsdFileReader | None) = None
         self.__writer: (MsdFileWriter | None) = None
@@ -181,8 +179,6 @@ class Plugin(BaseMsd):  # pylint: disable=too-many-instance-attributes
             "write_chunk_size":  Option(65536,   type=functools.partial(valid_number, min=1024)),
             "sync_chunk_size":   Option(4194304, type=functools.partial(valid_number, min=1024)),
 
-            "storage": Option("/var/lib/kvmd/msd", type=valid_abs_dir, unpack_as="storage_path"),
-
             "remount_cmd": Option([
                 "/usr/bin/sudo", "--non-interactive",
                 "/usr/bin/kvmd-helper-otgmsd-remount", "{mode}",