docs/188214: Manpage for fsck(8) doesn't say what happens when no -t or -T

[Tom Rhodes]

The following reply was made to PR docs/188214; it has been noted by GNATS.

From: Tom Rhodes <trhodes at FreeBSD.org>
To: Benjamin Kaduk <bjk at freebsd.org>
Cc: trhodes at freebsd.org, allanjude at freebsd.org, bug-followup at freebsd.org
Subject: Re: docs/188214: Manpage for fsck(8) doesn't say what happens
 when no -t or -T
Date: Sun, 25 May 2014 01:16:52 -0400

 Hi Benjamin,
 
 On Sat, 24 May 2014 17:42:47 -0400 (EDT)
 Benjamin Kaduk <bjk at freebsd.org> wrote:
 
 > On Sat, 24 May 2014, Tom Rhodes wrote:
 > 
 > > So, in theory, an attempt to parse /etc/fstab would be
 > > an attempt to detect the type; however, my quick glance
 > > at the code showed no real parsing of fstab.  But in
 > > my case, I followed to both the T and t flags, and just
 > > glanced at what was done would they not be specified.
 > > That was really as far as I got, and I attempted to use
 > > very generic language in case it only does one, or the
 > > other, or both.  :)
 > 
 > When passed no device or path arguments, fsck just checks everything from 
 > the fstab; that's not very interesting for this question.
 > 
 > Given a path argument and no type argument to use, fstab is parsed using 
 > getfsfile() or getfsspec() around line 204 of fsck.c.  This will fail 
 > (well, barring special circumstances) if the argument is instead a device 
 > name.
 > 
 > Given a device name argument and no type argument to use, after the fstab 
 > check above, fsck opens the device and uses ioctl() to get the disklabel 
 > and does some magic to grab the fstype from it.  (See getfslab(), in 
 > fsck.c)
 > 
 > 
 > So, I think there is a fair bit of autodetection that is attempted.
 
 Thanks for the deep dive - I was going to revisit this later
 (i.e.: actually step through the code more) if there was a real
 issue.  Thanks for saving me the time!  :)
 
 -- 
 Tom Rhodes