Description of problem:
The way libguestfs handle "mode" in "mknod-b" "mknod-c" "mkfifo" have some bugs.

The source code are:

int
do_mkfifo (int mode, const char *path)
{
  return do_mknod (mode | S_IFIFO, 0, 0, path);
}

int
do_mknod_b (int mode, int devmajor, int devminor, const char *path)
{
  return do_mknod (mode | S_IFBLK, devmajor, devminor, path);
}

int
do_mknod_c (int mode, int devmajor, int devminor, const char *path)
{
  return do_mknod (mode | S_IFCHR, devmajor, devminor, path);
}

/usr/include/bits/stat.h
#define __S_IFCHR   0020000 /* Character device.  */
#define __S_IFBLK   0060000 /* Block device.  */
#define __S_IFIFO   0010000 /* FIFO.  */

"mknod-c 0060XXX" == "mknod 0060XXX", In this case, "mknod-c" will create a block device.
"mkfifo 0000XXX" == "mkfifo 0010XXX", In this case, returning an error would be better.

Version-Release number of selected component (if applicable):
libguestfs-tools-c-1.28.1-1.17.el7.x86_64

How reproducible:
100%


Steps to Reproduce:
1. create a img, and add the img
# guestfish -N fs:ext3

2. use mknod, mknod-b, mknod-c to create device
><fs> mknod-c 0060777 8 1 /test_mknod_c
><fs> mkfifo 0000777 /test_mkfifo
><fs> ll /
total 17
drwxr-xr-x  3 root root  1024 Jan 15 04:29 .
drwxr-xr-x 19 root root  4096 Jan 15 03:40 ..
drwx------  2 root root 12288 Jan 15 03:41 lost+found
prwxr-xr-x  1 root root     0 Jan 15 04:29 test_mkfifo
brwxr-xr-x  1 root root  8, 1 Jan 15 04:28 test_mknod_c


Actual results:
mknod-c create a block device, and mkfifo create a fifo device when given a wrong mode.


Expected results:
If the mode doesn't match the device mode, libguestfs returns an "Invalid argument" error.


Additional info:
...