Merge lp:~yuningdodo/usb-creator/usb-creator.lp1325801v3-use-source-syslinux into lp:usb-creator

[Yu Ning]

Find and use the syslinux from the source squashfs. (LP: #1325801)

This patch can fix the bug in below cases (not a full list, only what I've tested):
* host: ubuntu 14.04; target: ubuntu 14.04;
* host: ubuntu 14.04; target: ubuntu 14.10;
* host: ubuntu 14.04; target: ubuntu 13.10;
* host: ubuntu 14.10; target: ubuntu 14.10;
* host: ubuntu 14.10; target: ubuntu 14.04;
* host: ubuntu 14.10; target: ubuntu 13.10;

This patch won't work in below cases, but at least it won't make things worse, it just keep the original behavior:
* target: debian-7.7.0-amd64-netinst.iso: no squashfs at all
* target: xubuntu 14.10: syslinux not pre-installed into squashfs

As long as there is syslinux pre-installed in the ISO this patch will take effect; and when there is no syslinux pre-installed, it won't change anything.

One thing to mention is that the patch adds one parameter to the dbus method InstallBootloader(), so it will break API compatibility. However it maybe possible to do the job w/o this parameter. I'll keep working on it.

[lp:~yuningdodo/usb-creator/usb-creator.lp1325801v3-use-source-syslinux]

462. By Yu Ning on 2015-02-25

Mount the squashfs from the usbstick instead of the CDROM/ISO, so we don't need to break the API compability.

[Yu Ning (yuningdodo)]

Updated, now we'll mount the squashfs on the usbstick instead of the CDROM/ISO, so we don't need to break the API compatibility.

[Mathieu Trudel-Lapierre (cyphermox)]

Looks good, approve.

review: Approve

=== modified file 'bin/usb-creator-helper'
--- bin/usb-creator-helper	2014-09-02 20:12:12 +0000
+++ bin/usb-creator-helper	2015-02-25 07:51:13 +0000
@@ -190,17 +190,45 @@
                    'bs=512', 'count=62', 'seek=1', 'conv=sync'])
         else:
             if syslinux_legacy and find_on_path('syslinux-legacy'):
+                syslinux_var = "syslinux-legacy"
                 syslinux_exe = "syslinux-legacy"
                 syslinux_bin = "/usr/lib/syslinux-legacy/mbr.bin"
             else:
+                syslinux_var = "syslinux"
                 syslinux_exe = "syslinux"
                 syslinux_bin = "/usr/lib/syslinux/mbr/mbr.bin"
                 if not os.path.exists(syslinux_bin):
                     syslinux_bin = "/usr/lib/syslinux/mbr.bin"
+            squashfs_mnt = ''
+            target_mounts = obj.get_filesystem().get_cached_property('MountPoints').get_bytestring_array()
+            if len(target_mounts) > 0:
+                target_mnt = target_mounts[0]
+                squashfs_img = os.path.join(target_mnt, 'casper',
+                                            'filesystem.squashfs')
+                if os.path.exists(squashfs_img):
+                    # Mount the squashfs so we are possible to install
+                    # syslinux & mbr.bin from it.
+                    squashfs_mnt = self.MountISO(squashfs_img)
+            if squashfs_mnt:
+                for mbrbin in [
+                        os.path.join(squashfs_mnt, 'usr', 'lib',
+                                     syslinux_var, 'mbr.bin'),
+                        os.path.join(squashfs_mnt, 'usr', 'lib',
+                                     syslinux_var, 'mbr', 'mbr.bin'),
+                        os.path.join(squashfs_mnt, 'usr', 'lib',
+                                     syslinux_var.upper(), 'mbr.bin'),
+                        ]:
+                    if os.path.exists(mbrbin):
+                        syslinux_exe = os.path.join(squashfs_mnt, 'usr',
+                                                    'bin', syslinux_var)
+                        syslinux_bin = mbrbin
+                        break
             popen([syslinux_exe, '-f', device])
             # Write the syslinux MBR.
             popen(['dd', 'if=%s' % syslinux_bin, 'of=%s' % parent_file,
                    'bs=446', 'count=1', 'conv=sync'])
+            if squashfs_mnt:
+                self.UnmountFile(squashfs_mnt)
 
         part = obj.get_partition()
         if part: