Change length type, and let fadvise64 return ESPIPE if file is a pipe

Kernel before 2.6.16 return EINVAL, but later return ESPIPE for this case.
Also change type of "length" from Uint(uint32) to Int64.
Because C header uses type "size_t" (unsigned long) or "off_t" (long) for length.
And it makes more sense to check length < 0 with Int64 because Uint cannot be negative.

Change-Id: Ifd7fea2dcded7577a30760558d0d31f479f074c4
PiperOrigin-RevId: 197616743

pkg/sentry/syscalls/linux/sys_file.go

@@ -871,7 +871,7 @@ const (
 func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
 	fd := kdefs.FD(args[0].Int())
 	offset := args[1].Int64()
-	length := args[2].Uint()
+	length := args[2].Int64()
 	advice := args[3].Int()
 
 	if offset < 0 || length < 0 {
@@ -884,6 +884,11 @@ func Fadvise64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sys
 	}
 	defer file.DecRef()
 
+	// If the FD refers to a pipe or FIFO, return error.
+	if fs.IsPipe(file.Dirent.Inode.StableAttr) {
+		return 0, nil, syserror.ESPIPE
+	}
+
 	switch advice {
 	case _FADV_NORMAL:
 	case _FADV_RANDOM: