Re: [PATCH 1/2] dhclient-script: let resolv.conf and resolv.conf.dhclient on the same direcotry

[Hongxu Jia <hongxu.jia@windriver.com>]

On 12/10/2013 12:41 PM, Saul Wold wrote:
> On 12/03/2013 05:46 AM, Hongxu Jia wrote:
>> Even though '/etc' is on the readonly partition, it's possible that
>> /etc/resolv.conf is on a separate writable partition.
>>
>> In this situation, we should make sure the temp file 
>> resolv.conf.dhclient
>> on the same direcotry.
>>
>> [YOCTO #5624]
>>
>> Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
>> ---
>>   meta/recipes-connectivity/dhcp/dhcp.inc            |  1 +
>>   ...ript-let-resolv.conf-and-resolv.conf.dhcl.patch | 74 
>> ++++++++++++++++++++++
>
> These new scripts are doing alot of out calling from the shell script, 
> and can cause additional fork/execs during the critical path of system 
> startup, is there any way to reduce this?
>

Do you mean the new script :readonly-dhclient-enter-hooks ?
If yes, we could just drop the [PATCH 2/2] patch and it could
work while read-only is enabled;

Because /etc/resolv.conf is a symlink to /var/run/ resolv.conf in
oe-core, and it's always writable:

#ls /etc/resolv.conf -al
lrwxrwxrwx 1 root root 29 Oct 22  2012 /etc/resolv.conf -> 
/var/run/resolv.conf

//Hongxu

> Sau!
>
>>   2 files changed, 75 insertions(+)
>>   create mode 100644 
>> meta/recipes-connectivity/dhcp/dhcp/dhclient-script-let-resolv.conf-and-resolv.conf.dhcl.patch
>>
>> diff --git a/meta/recipes-connectivity/dhcp/dhcp.inc 
>> b/meta/recipes-connectivity/dhcp/dhcp.inc
>> index ad82b57..d8376aa 100644
>> --- a/meta/recipes-connectivity/dhcp/dhcp.inc
>> +++ b/meta/recipes-connectivity/dhcp/dhcp.inc
>> @@ -16,6 +16,7 @@ SRC_URI = 
>> "ftp://ftp.isc.org/isc/dhcp/${PV}/dhcp-${PV}.tar.gz \
>>              file://site.h \
>>          file://init-relay file://default-relay \
>>          file://init-server file://default-server \
>> + file://dhclient-script-let-resolv.conf-and-resolv.conf.dhcl.patch \
>>          file://dhclient.conf file://dhcpd.conf"
>>
>>   inherit autotools
>> diff --git 
>> a/meta/recipes-connectivity/dhcp/dhcp/dhclient-script-let-resolv.conf-and-resolv.conf.dhcl.patch 
>> b/meta/recipes-connectivity/dhcp/dhcp/dhclient-script-let-resolv.conf-and-resolv.conf.dhcl.patch 
>>
>> new file mode 100644
>> index 0000000..db56f70
>> --- /dev/null
>> +++ 
>> b/meta/recipes-connectivity/dhcp/dhcp/dhclient-script-let-resolv.conf-and-resolv.conf.dhcl.patch
>> @@ -0,0 +1,74 @@
>> +dhclient-script: let resolv.conf and resolv.conf.dhclient on the 
>> same direcotry
>> +
>> +Even though '/etc' is on the readonly partition, it's possible that
>> +/etc/resolv.conf is on a separate writable partition.
>> +
>> +In this situation, we should make sure the temp file 
>> resolv.conf.dhclient
>> +on the same direcotry.
>> +
>> +Upstream-Status: Pending
>> +Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
>> +---
>> + client/scripts/linux |   24 +++++++++++++-----------
>> + 1 file changed, 13 insertions(+), 11 deletions(-)
>> +
>> +diff --git a/client/scripts/linux b/client/scripts/linux
>> +index 6f8ea4b..fbc6324 100755
>> +--- a/client/scripts/linux
>> ++++ b/client/scripts/linux
>> +@@ -27,27 +27,29 @@ ip=/sbin/ip
>> +
>> + make_resolv_conf() {
>> +   if [ x"$new_domain_name_servers" != x ]; then
>> +-    cat /dev/null > /etc/resolv.conf.dhclient
>> +-    chmod 644 /etc/resolv.conf.dhclient
>> ++    sysconfdir=`dirname $(readlink -f '/etc/resolv.conf')`
>> ++    cat /dev/null > $sysconfdir/resolv.conf.dhclient
>> ++    chmod 644 $sysconfdir/resolv.conf.dhclient
>> +     if [ x"$new_domain_search" != x ]; then
>> +-      echo search $new_domain_search >> /etc/resolv.conf.dhclient
>> ++      echo search $new_domain_search >> 
>> $sysconfdir/esolv.conf.dhclient
>> +     elif [ x"$new_domain_name" != x ]; then
>> +       # Note that the DHCP 'Domain Name Option' is really just a 
>> domain
>> +       # name, and that this practice of using the domain name 
>> option as
>> +       # a search path is both nonstandard and deprecated.
>> +-      echo search $new_domain_name >> /etc/resolv.conf.dhclient
>> ++      echo search $new_domain_name >> $sysconfdir/resolv.conf.dhclient
>> +     fi
>> +     for nameserver in $new_domain_name_servers; do
>> +-      echo nameserver $nameserver >>/etc/resolv.conf.dhclient
>> ++      echo nameserver $nameserver >>$sysconfdir/resolv.conf.dhclient
>> +     done
>> +
>> +-    mv /etc/resolv.conf.dhclient /etc/resolv.conf
>> ++    mv $sysconfdir/resolv.conf.dhclient $sysconfdir/resolv.conf
>> +   elif [ "x${new_dhcp6_name_servers}" != x ] ; then
>> +-    cat /dev/null > /etc/resolv.conf.dhclient6
>> +-    chmod 644 /etc/resolv.conf.dhclient6
>> ++    sysconfdir=`dirname $(readlink -f '/etc/resolv.conf')`
>> ++    cat /dev/null > $sysconfdir/resolv.conf.dhclient6
>> ++    chmod 644 $sysconfdir/resolv.conf.dhclient6
>> +
>> +     if [ "x${new_dhcp6_domain_search}" != x ] ; then
>> +-      echo search ${new_dhcp6_domain_search} >> 
>> /etc/resolv.conf.dhclient6
>> ++      echo search ${new_dhcp6_domain_search} >> 
>> $sysconfdir/resolv.conf.dhclient6
>> +     fi
>> +     shopt -s nocasematch
>> +     for nameserver in ${new_dhcp6_name_servers} ; do
>> +@@ -59,11 +61,11 @@ make_resolv_conf() {
>> +       else
>> +     zone_id=
>> +       fi
>> +-      echo nameserver ${nameserver}$zone_id >> 
>> /etc/resolv.conf.dhclient6
>> ++      echo nameserver ${nameserver}$zone_id >> 
>> $sysconfdir/resolv.conf.dhclient6
>> +     done
>> +     shopt -u nocasematch
>> +
>> +-    mv /etc/resolv.conf.dhclient6 /etc/resolv.conf
>> ++    mv $sysconfdir/resolv.conf.dhclient6 $sysconfdir/resolv.conf
>> +   fi
>> + }
>> +
>> +--
>> +1.7.9.5
>> +
>>
>