Developers writing code for accessing /dev/smb may use this base utility
as an example. Now that SMB_READB, SMB_READW, SMB_PCALL behave as
documented, wwe can use them in a more convenient way than before.
MFC after: 4 weeks
X-MFC after: r308527
. forward declare all static functions
. add a couple of redundant parens in return statements where they've
been missing
. remove the space after exit since it's a function
