From 30a111639ce6a7ad54f77a091451bd5354afaae9 Mon Sep 17 00:00:00 2001
From: Helmut Grohne <helmut@subdivi.de>
Date: Wed, 21 May 2025 21:24:28 +0200
Subject: expand use of FileDescriptor and add FileDescriptorLike type alias

When accepting file descriptors, non-int objects with a fileno method
are now generally accepted. When returning a file descriptor, a
FileDescriptor instance is now returned.
---
 linuxnamespaces/syscalls.py | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

(limited to 'linuxnamespaces/syscalls.py')

diff --git a/linuxnamespaces/syscalls.py b/linuxnamespaces/syscalls.py
index f6af348..be0a5f7 100644
--- a/linuxnamespaces/syscalls.py
+++ b/linuxnamespaces/syscalls.py
@@ -15,6 +15,7 @@ import os
 import signal
 import typing
 
+from .filedescriptor import FileDescriptor, FileDescriptorLike
 from .atlocation import AtFlags, AtLocation, AtLocationLike, PathConvertible
 
 
@@ -498,7 +499,7 @@ class EventFD:
     ) -> None:
         if flags & ~EventFDFlags.ALL_FLAGS:
             raise ValueError("invalid flags for eventfd")
-        self.fd = os.eventfd(initval, int(flags))
+        self.fd = FileDescriptor(os.eventfd(initval, int(flags)))
 
     def read(self) -> int:
         """Decrease the value of the eventfd using eventfd_read."""
@@ -541,7 +542,7 @@ class EventFD:
             raise ValueError("attempt to read from closed eventfd")
         os.eventfd_write(self.fd, value)
 
-    def fileno(self) -> int:
+    def fileno(self) -> FileDescriptor:
         """Return the underlying file descriptor."""
         return self.fd
 
@@ -551,7 +552,7 @@ class EventFD:
             try:
                 os.close(self.fd)
             finally:
-                self.fd = -1
+                self.fd = FileDescriptor(-1)
 
     __del__ = close
 
@@ -610,7 +611,7 @@ def mount_setattr(
     attr_set: MountAttrFlags = MountAttrFlags.NONE,
     attr_clr: MountAttrFlags = MountAttrFlags.NONE,
     propagation: int = 0,
-    userns_fd: int = -1,
+    userns_fd: FileDescriptorLike = -1,
 ) -> None:
     """Python wrapper for mount_setattr(2)."""
     filesystem = AtLocation(filesystem)
@@ -619,6 +620,8 @@ def mount_setattr(
         flags |= MountSetattrFlags.AT_RECURSIVE
     if attr_clr & MountAttrFlags.IDMAP:
         raise ValueError("cannot clear the MOUNT_ATTR_IDMAP flag")
+    if not isinstance(userns_fd, int):
+        userns_fd = userns_fd.fileno()
     attr = MountAttr(attr_set, attr_clr, propagation, userns_fd)
     call_libc(
         "mount_setattr",
@@ -764,12 +767,14 @@ class SignalFD:
         sigmask: typing.Iterable[signal.Signals],
         flags: SignalFDFlags = SignalFDFlags.NONE,
     ):
-        self.fd = SignalFD.__signalfd(-1, sigmask, flags)
+        self.fd = SignalFD.__signalfd(FileDescriptor(-1), sigmask, flags)
 
     @staticmethod
     def __signalfd(
-        fd: int, sigmask: typing.Iterable[signal.Signals], flags: SignalFDFlags
-    ) -> int:
+        fd: FileDescriptor,
+        sigmask: typing.Iterable[signal.Signals],
+        flags: SignalFDFlags,
+    ) -> FileDescriptor:
         """Python wrapper for signalfd(2)."""
         bitsperlong = 8 * ctypes.sizeof(ctypes.c_ulong)
         nval = 64 // bitsperlong
@@ -778,7 +783,7 @@ class SignalFD:
             sigval = int(sig) - 1
             mask[sigval // bitsperlong] |= 1 << (sigval % bitsperlong)
         csigmask = (ctypes.c_ulong * nval)(*mask)
-        return call_libc("signalfd", fd, csigmask, int(flags))
+        return FileDescriptor(call_libc("signalfd", fd, csigmask, int(flags)))
 
     def readv(self, count: int) -> list[SignalFDSigInfo]:
         """Read up to count signals from the signalfd."""
@@ -824,7 +829,7 @@ class SignalFD:
         loop.add_reader(self.fd, self.__handle_readable, self.fd, fut)
         return fut
 
-    def fileno(self) -> int:
+    def fileno(self) -> FileDescriptor:
         """Return the underlying file descriptor."""
         return self.fd
 
@@ -834,7 +839,7 @@ class SignalFD:
             try:
                 os.close(self.fd)
             finally:
-                self.fd = -1
+                self.fd = FileDescriptor(-1)
 
     __del__ = close
 
-- 
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