kern/163076: It is not possible to read in chunks from linprocfs and procfs.

[Petr Salinger]

>Number:         163076
>Category:       kern
>Synopsis:       It is not possible to read in chunks from linprocfs  and procfs.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Dec 05 08:10:08 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Petr Salinger
>Release:        9.0-RC2
>Organization:
>Environment:
>Description:
It is not possible to read in chunks from linprocfs and procfs.
It is a regression against stable-8.
I suspect it is due to changes of sbuf implementation between 8 and 9.

Some files are rather big (over 4KB) and it is really standard to read them in blocks.
>How-To-Repeat:
"dd if=$FILE bs=1", with FILE any file in procfs or linprocfs
The result is empty output.

Tried with FILE /proc/version from linprocfs 
and /proc/curproc/map from procfs. 

For more details see Debian GNU/kFreeBSD bug report 
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=650667

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: