improved otg msd

kvmd/helpers/otgmsd/remount/__init__.py

@@ -21,44 +21,87 @@
 
 
 import sys
+import os
+import re
+import shutil
+import dataclasses
 import subprocess
 
 
 # ====
 _MOUNT_PATH = "/bin/mount"
 _FSTAB_PATH = "/etc/fstab"
-_OPTION = "X-kvmd.otg-msd"
 
 
 # =====
-def _find_mountpoint() -> str:
+@dataclasses.dataclass(frozen=True)
+class _Storage:
+    mount_path: str
+    root_path: str
+    user: str
+
+
+# =====
+def _log(msg: str) -> None:
+    print(msg, file=sys.stderr)
+
+
+def _find_storage() -> _Storage:
     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 = parts[3].split(",")
-                    if _OPTION in options:
-                        return parts[1]
-    raise SystemExit(f"Can't find {_OPTION!r} mountpoint in {_FSTAB_PATH}")
+                    options = dict(re.findall(r"X-kvmd\.otgmsd-(root|user)=([^,]+)", parts[3]))
+                    if options:
+                        return _Storage(
+                            mount_path=parts[1],
+                            root_path=options.get("root", ""),
+                            user=options.get("user", ""),
+                        )
+    raise RuntimeError(f"Can't find MSD mountpoint in {_FSTAB_PATH}")
 
 
-def _remount(path: str, ro: bool) -> None:
+def _remount(path: str, rw: bool) -> None:
+    mode = ("rw" if rw else "ro")
+    _log(f"Remouning {path} to {mode.upper()}-mode ...")
     try:
-        subprocess.check_call([
-            _MOUNT_PATH,
-            "--options",
-            f"remount,{'ro' if ro else 'rw'}",
-            path,
-        ])
+        subprocess.check_call([_MOUNT_PATH, "--options", f"remount,{mode}", path])
     except subprocess.CalledProcessError as err:
-        raise SystemExit(str(err)) from None
+        raise SystemExit(f"Can't remount: {err}")
+
+
+def _mkdir(path: str) -> None:
+    if not os.path.exists(path):
+        _log(f"MKDIR {path} ...")
+        try:
+            os.mkdir(path)
+        except Exception as err:
+            raise SystemExit(f"Can't create directory: {err}")
+
+
+def _chown(path: str, user: str) -> None:
+    _log(f"CHOWN {user} {path} ...")
+    try:
+        shutil.chown(path, user)
+    except Exception as err:
+        raise SystemExit(f"Can't change ownership: {err}")
 
 
 # =====
 def main() -> None:
     if len(sys.argv) != 2 or sys.argv[1] not in ["ro", "rw"]:
-        raise SystemExit(f"This program will remount a first volume marked by {_OPTION!r} option in {_FSTAB_PATH}\n\n"
-                         f"Usage: python -m kvmd.helpers.otgmsd.remount [-h|--help|ro|rw]")
-    _remount(_find_mountpoint(), (sys.argv[1] == "ro"))
+        raise SystemExit(f"Usage: {sys.argv[0]} [ro|rw]")
+
+    rw = (sys.argv[1] == "rw")
+
+    storage = _find_storage()
+    _remount(storage.mount_path, rw)
+    if rw:
+        if storage.root_path:
+            for name in ["images", "meta"]:
+                path = os.path.join(storage.root_path, name)
+                _mkdir(path)
+                if storage.user:
+                    _chown(path, storage.user)

kvmd/helpers/otgmsd/unlock/__init__.py

@@ -31,12 +31,17 @@ _PROCESS_NAME = "file-storage"
 
 
 # =====
+def _log(msg: str) -> None:
+    print(msg, file=sys.stderr)
+
+
 def _unlock() -> None:
     # https://github.com/torvalds/linux/blob/3039fad/drivers/usb/gadget/function/f_mass_storage.c#L2924
     found = False
     for proc in psutil.process_iter():
-        attrs = proc.as_dict(attrs=["name", "exe"])
+        attrs = proc.as_dict(attrs=["name", "exe", "pid"])
         if attrs.get("name") == _PROCESS_NAME and not attrs.get("exe"):
+            _log(f"Sending SIGUSR1 to MSD {_PROCESS_NAME!r} kernel thread with pid={attrs['pid']} ...")
             try:
                 proc.send_signal(signal.SIGUSR1)
                 found = True
@@ -49,6 +54,5 @@ def _unlock() -> None:
 # =====
 def main() -> None:
     if len(sys.argv) != 2 or sys.argv[1] != "unlock":
-        raise SystemExit(f"This program interrupts all IO operations performed by OTG MSD.\n\n"
-                         f"Usage: python -m kvmd.helpers.otgmsd.unlock [-h|--help|unlock]")
+        raise SystemExit(f"Usage: {sys.argv[0]} [unlock]")
     _unlock()