otg service and helper

1 files changed, 71 insertions, 0 deletions

diff --git a/kvmd/apps/otgmsd/__init__.py b/kvmd/apps/otgmsd/__init__.py
new file mode 100644
index 00000000..ef341dec
--- /dev/null
+++ b/kvmd/apps/otgmsd/__init__.py
@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main Pi-KVM daemon.                                          #
+#                                                                            #
+#    Copyright (C) 2018  Maxim Devaev <[email protected]>                    #
+#                                                                            #
+#    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 signal
+import errno
+import argparse
+
+import psutil
+
+
+# =====
+def _set_msd_image(gadget: str, path: str) -> None:
+    lun_file_path = os.path.join("/sys/kernel/config/usb_gadget", gadget, "functions/mass_storage.usb0/lun.0/file")
+    try:
+        with open(lun_file_path, "w") as lun_file:
+            lun_file.write(path + "\n")
+    except OSError as err:
+        if err.errno == errno.EBUSY:
+            raise SystemExit(f"Can't change image because device is locked: {str(err)}")
+        raise
+
+
+def _reset_msd() -> None:
+    # https://github.com/torvalds/linux/blob/3039fadf2bfdc104dc963820c305778c7c1a6229/drivers/usb/gadget/function/f_mass_storage.c#L2924
+    found = False
+    for proc in psutil.process_iter():
+        attrs = proc.as_dict(attrs=["name", "exe", "pid"])
+        if attrs.get("name") == "file-storage" and not attrs.get("exe"):
+            try:
+                proc.send_signal(signal.SIGUSR1)
+                found = True
+            except Exception as err:
+                SystemExit(f"Can't send SIGUSR1 to MSD kernel thread with pid={attrs['pid']}: {str(err)}")
+    if not found:
+        raise SystemExit("Can't find MSD kernel thread")
+
+
+# =====
+def main() -> None:
+    parser = argparse.ArgumentParser(description="KVMD OTG MSD Helper")
+    parser.add_argument("--reset", action="store_true", help="Send SIGUSR1 to MSD kernel thread")
+    parser.add_argument("--set-image", dest="image_path", default=None, help="Change active image path")
+    parser.add_argument("--gadget", default="pikvm", help="USB gadget name")
+    options = parser.parse_args()
+
+    if options.reset:
+        _reset_msd()
+
+    if options.image_path is not None:
+        _set_msd_image(options.gadget, options.image_path)