Re: One more anomaly after 5.99.17 upgrade

[Alan Barrett <apb%cequrux.com@localhost>]

On Sun, 13 Sep 2009, Paul Goyette wrote:
> >I think we need a way of distinguishing between
> >"critical_filesystems_remote=/usr because that's the default" and
> >"critical_filesystems_remote=/usr because the admin said so", with
> >no error in the first case even if /usr doesn't exist.  I have two
> >simple ideas:
> >
> >A) Set critical_filesystems_remote="DEFAULT" [...]
> >B) Set critical_filesystems_remote="NOERROR:/var" [...]

> I prefer B.  Option A requires embedding the "real" default value in
> some unexpected location.  Even if there were a comment telling
> people where to go to find the "real" default, it's an extra step...

I agree.  Here's an implementation using "OPTIONAL:foo",
which I have tested only a little.

--apb (Alan Barrett)

Index: etc/defaults/rc.conf
===================================================================
--- etc/defaults/rc.conf        11 Sep 2009 18:17:04 -0000      1.105
+++ etc/defaults/rc.conf        13 Sep 2009 17:41:39 -0000
@@ -87,10 +87,11 @@ domainname=""
 # Note that `/var' is needed in $critical_filesystems_local (or
 # implied as part of `/') as certain services that need /var (such as
 # dhclient) may be needed to get the network operational enough to mount
-# the $critical_filesystems_remote.
+# the $critical_filesystems_remote.  Prepending "OPTIONAL:"  means it
+# will not be an error if that file system is not present in fstab(5).
 #
-critical_filesystems_local="/var"
-critical_filesystems_remote="/usr"
+critical_filesystems_local="OPTIONAL:/var"
+critical_filesystems_remote="OPTIONAL:/usr"
 
 # Swap device controls.
 #
Index: etc/rc.subr
===================================================================
--- etc/rc.subr 11 Sep 2009 18:17:04 -0000      1.78
+++ etc/rc.subr 13 Sep 2009 17:41:41 -0000
@@ -115,25 +115,61 @@ stop_boot()
 #      Go through the list of critical filesystems as provided in
 #      the rc.conf(5) variable $critical_filesystems_${type}, checking
 #      each one to see if it is mounted, and if it is not, mounting it.
+#      It's not an error if file systems prefixed with "OPTIONAL:"
+#      are not mentioned in /etc/fstab.
 #
 mount_critical_filesystems()
 {
        eval _fslist=\$critical_filesystems_${1}
+       _mountcrit_es=0
        for _fs in $_fslist; do
-               mount | (
-                       _ismounted=false
-                       while read what _on on _type type; do
-                               if [ $on = $_fs ]; then
-                                       _ismounted=true
+               _optional=false
+               case "$_fs" in
+               OPTIONAL:*)
+                       _optional=true
+                       _fs="${_fs#*:}"
+                       ;;
+               esac
+               _ismounted=false
+               # look for a line like "${fs} on * type *"
+               # or "* on ${fs} type *" in the output from mount.
+               case "${nl}$( mount )${nl}" in
+               *" on ${_fs} type "*)
+                       _ismounted=true
+                       ;;
+               *"${nl}${_fs} on "*)
+                       _ismounted=true
+                       ;;
+               esac
+               if $_ismounted; then
+                       :
+               else
+                       _mount_output=$( mount $_fs 2>&1 )
+                       _mount_es=$?
+                       case "$_mount_output" in
+                       *"${nl}"*)
+                               # multiple lines can't be good,
+                               # not even if $_optional is true
+                               ;;
+                       *'unknown special file or file system'*)
+                               if $_optional; then
+                                       # ignore this error
+                                       print_rc_metadata \
+                       "note:Ignored error for optional file system ${_fs}"
+                                       _mount_es=0
+                                       _mount_output=""
                                fi
-                       done
-                       if $_ismounted; then
-                               :
-                       else
-                               mount $_fs >/dev/null 2>&1
+                               ;;
+                       esac
+                       if [ -n "$_mount_output" ]; then
+                               printf "%s\n" "$_mount_output"
                        fi
-               )
+                       if [ "$_mount_es" != 0 ]; then
+                               _es="$_mount_es"
+                       fi
+               fi
        done
+       return $_mountcrit_es
 }
 
 #
Index: share/man/man5/rc.conf.5
===================================================================
--- share/man/man5/rc.conf.5    11 Sep 2009 19:47:27 -0000      1.134
+++ share/man/man5/rc.conf.5    13 Sep 2009 17:41:42 -0000
@@ -279,12 +279,26 @@ Usually
 is part of this, because it is needed by services such as
 .Xr dhclient 8
 which may be required to get the network operational.
+The default is
+.Dq "OPTIONAL:/var" ,
+where the
+.Dq OPTIONAL:
+prefix means that it's not an error if the file system is not
+present in
+.Xr fstab 5.
 .It Sy critical_filesystems_remote
 A string.
 File systems such as
 .Pa /usr
 that may require network services to be available to mount,
 that must be available early in the system boot for general services to use.
+The default is
+.Dq "OPTIONAL:/usr" ,
+where the
+.Dq OPTIONAL:
+prefix means that it's not an error if the file system is not
+present in
+.Xr fstab 5.
 .It Sy fsck_flags
 A string.
 A file system is checked with