diff options
| author | Etienne Perot <eperot@google.com> | 2020-12-03 06:18:03 -0800 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2020-12-03 06:20:29 -0800 |
| commit | 6f60a2b0a27a742690aa6acd5df1912ccb5fc8d3 (patch) | |
| tree | b706a5e534592d9aaa7fb4dc6237b4ab3686af13 /pkg/sentry/vfs/file_description.go | |
| parent | 80552b936d06e43ea77df09a6b6c5ce2600a6f6a (diff) | |
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
Diffstat (limited to 'pkg/sentry/vfs/file_description.go')
| -rw-r--r-- | pkg/sentry/vfs/file_description.go | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index 51fddbaff..2153382e9 100644 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -43,7 +43,7 @@ import ( type FileDescription struct { FileDescriptionRefs - // flagsMu protects statusFlags and asyncHandler below. + // flagsMu protects `statusFlags`, `saved`, and `asyncHandler` below. flagsMu sync.Mutex `state:"nosave"` // statusFlags contains status flags, "initialized by open(2) and possibly @@ -52,6 +52,11 @@ type FileDescription struct { // access to asyncHandler. statusFlags uint32 + // saved is true after beforeSave is called. This is used to prevent + // double-unregistration of asyncHandler. This does not work properly for + // save-resume, which is not currently supported in gVisor (see b/26588733). + saved bool `state:"nosave"` + // asyncHandler handles O_ASYNC signal generation. It is set with the // F_SETOWN or F_SETOWN_EX fcntls. For asyncHandler to be used, O_ASYNC must // also be set by fcntl(2). @@ -184,7 +189,7 @@ func (fd *FileDescription) DecRef(ctx context.Context) { } fd.vd.DecRef(ctx) fd.flagsMu.Lock() - if fd.statusFlags&linux.O_ASYNC != 0 && fd.asyncHandler != nil { + if !fd.saved && fd.statusFlags&linux.O_ASYNC != 0 && fd.asyncHandler != nil { fd.asyncHandler.Unregister(fd) } fd.asyncHandler = nil |