otg msd and big refactoring

kvmd/plugins/msd/otg/drive.py

@@ -0,0 +1,80 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main Pi-KVM daemon.                                          #
+#                                                                            #
+#    Copyright (C) 2018  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 os
+import errno
+
+from .. import MsdOperationError
+
+
+# =====
+class MsdDriveLockedError(MsdOperationError):
+    def __init__(self) -> None:
+        super().__init__("MSD drive is locked on IO operation")
+
+
+# =====
+class Drive:
+    def __init__(self, gadget: str, instance: int, lun: int) -> None:
+        self.__path = os.path.join(
+            "/sys/kernel/config/usb_gadget",
+            gadget,
+            f"functions/mass_storage.usb{instance}/lun.{lun}",
+        )
+
+    def get_sysfs_path(self) -> str:
+        return self.__path
+
+    # =====
+
+    def set_image_path(self, path: str) -> None:
+        self.__set_param("file", path)
+
+    def get_image_path(self) -> str:
+        return self.__get_param("file")
+
+    def set_cdrom_flag(self, flag: bool) -> None:
+        self.__set_param("cdrom", str(int(flag)))
+
+    def get_cdrom_flag(self) -> bool:
+        return bool(int(self.__get_param("cdrom")))
+
+    def set_rw_flag(self, flag: bool) -> None:
+        self.__set_param("ro", str(int(not flag)))
+
+    def get_rw_flag(self) -> bool:
+        return (not int(self.__get_param("ro")))
+
+    # =====
+
+    def __get_param(self, param: str) -> str:
+        with open(os.path.join(self.__path, param)) as param_file:
+            return param_file.read().strip()
+
+    def __set_param(self, param: str, value: str) -> None:
+        try:
+            with open(os.path.join(self.__path, param), "w") as param_file:
+                param_file.write(value + "\n")
+        except OSError as err:
+            if err.errno == errno.EBUSY:
+                raise MsdDriveLockedError()
+            raise