Description of problem:
when running chmod and umask command with an invalid number(negative or number >07777), there is no error message and the mode is set with the wrong value.
I believe other commands like mkdir-mode have same issue.

Version-Release number of selected component (if applicable):
libguestfs-1.0.85-1.fc12.3.x86_64, latest git version 1.3.3

How reproducible:
100%

Steps to Reproduce:
run umask or chmod with an invalid mode, such as 022222 or -1
  
Actual results:
wrong mode is set

Expected results:
should be error message say "out of range" etc

Additional info:


logs:
><fs> version
version
major: 1
minor: 3
release: 3
extra: 
><fs> umask 0000
umask 0
147
><fs> umask 0000
umask 0
0
><fs> umask 0002
umask 2
0
><fs> umask 0002
umask 2
2
><fs> umask -1
umask -1
2
><fs> umask 0000
umask 0
511
><fs> umask 08888
umask: mask: invalid integer parameter (xstrtoll returned 2)
><fs> umask 022222
umask 9362
0
><fs> umask 0000
umask 0
146
><fs> umask 022222
umask 9362
0
><fs> umask 022222
umask 9362
146
><fs> umask 022221
umask 9361
146
><fs> umask 0000
umask 0
145