From 6f60a2b0a27a742690aa6acd5df1912ccb5fc8d3 Mon Sep 17 00:00:00 2001 From: Etienne Perot Date: Thu, 3 Dec 2020 06:18:03 -0800 Subject: Implement `fcntl` options `F_GETSIG` and `F_SETSIG`. These options allow overriding the signal that gets sent to the process when I/O operations are available on the file descriptor, rather than the default `SIGIO` signal. Doing so also populates `siginfo` to contain extra information about which file descriptor caused the event (`si_fd`) and what events happened on it (`si_band`). The logic around which FD is populated within `si_fd` matches Linux's, which means it has some weird edge cases where that value may not actually refer to a file descriptor that is still valid. This CL also ports extra S/R logic regarding async handler in VFS2. Without this, async I/O handlers aren't properly re-registered after S/R. PiperOrigin-RevId: 345436598 --- pkg/sentry/arch/signal.go | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'pkg/sentry/arch/signal.go') diff --git a/pkg/sentry/arch/signal.go b/pkg/sentry/arch/signal.go index c9fb55d00..5138f3bf5 100644 --- a/pkg/sentry/arch/signal.go +++ b/pkg/sentry/arch/signal.go @@ -251,3 +251,26 @@ func (s *SignalInfo) Arch() uint32 { func (s *SignalInfo) SetArch(val uint32) { usermem.ByteOrder.PutUint32(s.Fields[12:16], val) } + +// Band returns the si_band field. +func (s *SignalInfo) Band() int64 { + return int64(usermem.ByteOrder.Uint64(s.Fields[0:8])) +} + +// SetBand mutates the si_band field. +func (s *SignalInfo) SetBand(val int64) { + // Note: this assumes the platform uses `long` as `__ARCH_SI_BAND_T`. + // On some platforms, which gVisor doesn't support, `__ARCH_SI_BAND_T` is + // `int`. See siginfo.h. + usermem.ByteOrder.PutUint64(s.Fields[0:8], uint64(val)) +} + +// FD returns the si_fd field. +func (s *SignalInfo) FD() uint32 { + return usermem.ByteOrder.Uint32(s.Fields[8:12]) +} + +// SetFD mutates the si_fd field. +func (s *SignalInfo) SetFD(val uint32) { + usermem.ByteOrder.PutUint32(s.Fields[8:12], val) +} -- cgit v1.2.3