Port fadvise64 to vfs2.

Like vfs1, we have a trivial implementation that ignores all valid advice.

Updates #2923.

PiperOrigin-RevId: 317349505

2 files changed, 39 insertions, 1 deletions

diff --git a/pkg/sentry/syscalls/linux/vfs2/fd.go b/pkg/sentry/syscalls/linux/vfs2/fd.go
index f5eaa076b..e68b20bed 100644
--- a/pkg/sentry/syscalls/linux/vfs2/fd.go
+++ b/pkg/sentry/syscalls/linux/vfs2/fd.go
@@ -210,3 +210,41 @@ func posixLock(t *kernel.Task, args arch.SyscallArguments, file *vfs.FileDescrip
 		return syserror.EINVAL
 	}
 }
+
+// Fadvise64 implements fadvise64(2).
+// This implementation currently ignores the provided advice.
+func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	length := args[2].Int64()
+	advice := args[3].Int()
+
+	// Note: offset is allowed to be negative.
+	if length < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	file := t.GetFileVFS2(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// If the FD refers to a pipe or FIFO, return error.
+	if _, isPipe := file.Impl().(*pipe.VFSPipeFD); isPipe {
+		return 0, nil, syserror.ESPIPE
+	}
+
+	switch advice {
+	case linux.POSIX_FADV_NORMAL:
+	case linux.POSIX_FADV_RANDOM:
+	case linux.POSIX_FADV_SEQUENTIAL:
+	case linux.POSIX_FADV_WILLNEED:
+	case linux.POSIX_FADV_DONTNEED:
+	case linux.POSIX_FADV_NOREUSE:
+	default:
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Sure, whatever.
+	return 0, nil, nil
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/vfs2.go b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
index caa6a98ff..b463edf2a 100644
--- a/pkg/sentry/syscalls/linux/vfs2/vfs2.go
+++ b/pkg/sentry/syscalls/linux/vfs2/vfs2.go
@@ -108,7 +108,7 @@ func Override() {
 	s.Table[209] = syscalls.PartiallySupported("io_submit", IoSubmit, "Generally supported with exceptions. User ring optimizations are not implemented.", []string{"gvisor.dev/issue/204"})
 	s.Table[213] = syscalls.Supported("epoll_create", EpollCreate)
 	s.Table[217] = syscalls.Supported("getdents64", Getdents64)
-	delete(s.Table, 221) // fdavise64
+	s.Table[221] = syscalls.PartiallySupported("fadvise64", Fadvise64, "The syscall is 'supported', but ignores all provided advice.", nil)
 	s.Table[232] = syscalls.Supported("epoll_wait", EpollWait)
 	s.Table[233] = syscalls.Supported("epoll_ctl", EpollCtl)
 	s.Table[235] = syscalls.Supported("utimes", Utimes)