Bug Description

[Impact]

* The cache refresh is blocked on a strdup on a non-NULL-terminated string in some very rare occasions (very rare because this bug is present for almost 3y without a single report).

* Fixing this bug resolves the issue for people who might experience it.

* See https:/ /github. com/ximion/ appstream/ issues/ 35 for details.

[Test Case 1]

* Run `sudo appstreamcli refresh --force`

* The AppStream cache should be updated, no change in behavior should be seen.

[Test Case 2]

* In case you were experiencing the almost-infinite hang when running `sudo appstreamcli refresh --force`, this issue should be fixed with the SRU.

[Regression Potential]

* Very low, since this only fixes the decompression code. There should be no sideeffects of that (given that the patch itself doesn't break anything, which it shouldn't, since it has been tested upstream for a while)

[Other Info]

* This fix has been applied upstream: https:/ /github. com/ximion/ appstream/ commit/ f33c520c37e2ba5 1d92402220250b8 d501a2bf43

* A smaller version of the patch (one-liner) is available, at the expense of not having reduced memory usage: https:/ /github. com/ximion/ appstream/ commit/ 378941787d3584b 3eb31a6ebe40e0a acc10e180a

####

/!\ Installing the bugfix from xenial-proposed, without going through APT:

To install the fixed packages manually, please execute the following commands (for amd64, adjust URLs for other architectures):

```

cd /tmp && mkdir asfix

cd asfix

wget https:/ /launchpad. net/ubuntu/ +archive/ primary/ +files/ appstream_ 0.9.4-1ubuntu1_ amd64.deb

wget https:/ /launchpad. net/ubuntu/ +archive/ primary/ +files/ libappstream3_ 0.9.4-1ubuntu1_ amd64.deb

sudo dpkg -i libappstream3*.deb

sudo dpkg -i appstream*.deb

```