Fix an error in the ifupdown parser unparse function that doesn't handle allow-hotplug expressions

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What steps will reproduce the problem?
1. Parse an /etc/network/interfaces files that has allow-hotplug entries.
2. Using the dump operation works fine, but the unparse operation produces
(null)
3. Run the command llconf ifupdown -i /etc/network/interfaces -o - unparse

What is the expected output? What do you see instead?

The expected output is 

# Used by ifup(8) and ifdown(8). See the interfaces(5) manpage or
# /usr/share/doc/ifupdown/examples for more information.

auto lo eth0 eth1 eth2 eth3

iface lo inet loopback

allow-hotplug eth0
iface eth0 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

iface eth1 inet static
        address 192.168.0.1
        netmask 255.255.255.0
        pre-up touch /lib/init/rw/resolv.conf

allow-hotplug eth2
iface eth2 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

allow-hotplug eth3
iface eth3 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

allow-hotplug wlan0
iface wlan0 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf
        wpa-ssid ssid
    wpa-psk psk

BUT it actually is

# Used by ifup(8) and ifdown(8). See the interfaces(5) manpage or
# /usr/share/doc/ifupdown/examples for more information.

auto lo eth0 eth1 eth2 eth3

iface lo inet loopback

(null)
iface eth0 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

iface eth1 inet static
        address 192.168.0.1
        netmask 255.255.255.0
        pre-up touch /lib/init/rw/resolv.conf

(null)
iface eth2 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

(null)
iface eth3 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf

(null)
iface wlan0 inet dhcp
        pre-up touch /lib/init/rw/resolv.conf
        wpa-ssid ssid
    wpa-psk psk

What version of the product are you using? On what operating system?

Using 0.4.6.

Please provide any additional information below.

Applying the patch below fixes this:

--- ifupdown-old.c 2009-11-18 14:36:30.000000000 -0500
+++ ifupdown.c  2009-11-18 14:37:09.000000000 -0500
@@ -263,6 +263,16 @@
                        }
                        snprintf(b1, 255, "%s\n", b0);
                        cl_list = append_confline(cl_list, cl =
create_confline(b1));
+               }else if(strncmp(cn_top->name, "allow-", 6) == 0){
+                       char buf1[256], *b0 = buf, *b1 = buf1, *tmp;
+
+                       snprintf(b0, 255, "%s", cn_top->name);
+                       for(cn = cn_top->first_child; cn; cn = cn->next){
+                               snprintf(b1, 255, "%s %s", b0, cn->name);
+                               tmp = b0; b0 = b1; b1 = tmp;
+                       }
+                       snprintf(b1, 255, "%s\n", b0);
+                       cl_list = append_confline(cl_list, cl =
create_confline(b1));
                }else if(strcmp(cn_top->name, "mapping") == 0){
                        cn = cn_top->first_child;

Original issue reported on code.google.com by fomoj...@gmail.com on 18 Nov 2009 at 7:49