Hello, There's an effort inside of Google to make builds more hermetic across the board. One of the challenges we ran into was supporting the transitive dependencies of generate_test_list.pl, namely XML::LibXML. Since this isn't in the perl standard library, we have to add what amounts to an entire sysroot with a bunch of dependencies just to support this one library. Not impossible (and to be clear, this is the route that we went with), but not ideal either.
Another approach that we explored was rewriting generate_test_list.pl in python. XML parsing is in python's standard library and many of our engineers are more familiar with it, so we thought this would be a reasonable choice. We wrote the script, and it seems to work (with some caveats that I'll discuss below). However, we don't want to diverge from upstream, hence why I'm here :).
The script is approximately the same length as the original script and supports all of the same features and checking, with one catch. The standard library's XML parsing module doesn't support entity expansion, which is a feature used in many places within TFTF (see, for example, tests-standard.xml). This is done for security reasons and I haven't found a way around it without resorting to xml parsers outside of the standard library (which kinda defeats the purpose). To resolve this, we use xincludes instead, meaning that tests-standard.xml (for example) would have to be rewritten to use the new syntax.
For example, tests-standard.xml would look like the following: <document> <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="tests-tftf-validation.xml"/> ... rest of includes here... </document>
Any thoughts on this? If you're okay with this approach we can put our CL up for review.
We also experimented with doing some hand-parsing to support entity expansion and I suspect that there's *some* way to convince entity expansion to occur within the standard library, but wanted to take your temperature on the above changes before pursuing those further.
Thanks, Jim
Hi Jim,
This sounds like a good idea to me!
I don't see any particular problem with using xincludes instead of entities, if it's doing the exact same job. The syntax is not very appealing to me, but neither was the entity syntax!
Best regards, Sandrine
On 4/19/23 04:06, Jim Ray via TF-A-Tests wrote:
Hello, There's an effort inside of Google to make builds more hermetic across the board. One of the challenges we ran into was supporting the transitive dependencies of generate_test_list.pl, namely XML::LibXML. Since this isn't in the perl standard library, we have to add what amounts to an entire sysroot with a bunch of dependencies just to support this one library. Not impossible (and to be clear, this is the route that we went with), but not ideal either.
Another approach that we explored was rewriting generate_test_list.pl in python. XML parsing is in python's standard library and many of our engineers are more familiar with it, so we thought this would be a reasonable choice. We wrote the script, and it seems to work (with some caveats that I'll discuss below). However, we don't want to diverge from upstream, hence why I'm here :).
The script is approximately the same length as the original script and supports all of the same features and checking, with one catch. The standard library's XML parsing module doesn't support entity expansion, which is a feature used in many places within TFTF (see, for example, tests-standard.xml). This is done for security reasons and I haven't found a way around it without resorting to xml parsers outside of the standard library (which kinda defeats the purpose). To resolve this, we use xincludes instead, meaning that tests-standard.xml (for example) would have to be rewritten to use the new syntax.
For example, tests-standard.xml would look like the following:
<document> <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="tests-tftf-validation.xml"/> ... rest of includes here... </document>
Any thoughts on this? If you're okay with this approach we can put our CL up for review.
We also experimented with doing some hand-parsing to support entity expansion and I suspect that there's *some* way to convince entity expansion to occur within the standard library, but wanted to take your temperature on the above changes before pursuing those further.
Thanks, Jim
Hi Jim,
You have done the right thing, raise the issue on the Mailing List and I think we would be happy to consider your patch(es) for review. If the review cannot be handled by normal patch review processes and if there is a further wider discussion required that cannot be handled by the Mailing List we can schedule some time in a Tech Forum (Zoom call) of interested TF-A community members to have a live discussion.
Thanks
Joanna
From: Sandrine Bailleux via TF-A-Tests tf-a-tests@lists.trustedfirmware.org Date: Friday, 21 April 2023 at 07:10 To: Jim Ray jimray@google.com, tf-a-tests@lists.trustedfirmware.org tf-a-tests@lists.trustedfirmware.org Subject: [Tf-a-tests] Re: Standalone python version of generate_test_list.pl? Hi Jim,
This sounds like a good idea to me!
I don't see any particular problem with using xincludes instead of entities, if it's doing the exact same job. The syntax is not very appealing to me, but neither was the entity syntax!
Best regards, Sandrine
On 4/19/23 04:06, Jim Ray via TF-A-Tests wrote:
Hello, There's an effort inside of Google to make builds more hermetic across the board. One of the challenges we ran into was supporting the transitive dependencies of generate_test_list.pl, namely XML::LibXML. Since this isn't in the perl standard library, we have to add what amounts to an entire sysroot with a bunch of dependencies just to support this one library. Not impossible (and to be clear, this is the route that we went with), but not ideal either.
Another approach that we explored was rewriting generate_test_list.pl in python. XML parsing is in python's standard library and many of our engineers are more familiar with it, so we thought this would be a reasonable choice. We wrote the script, and it seems to work (with some caveats that I'll discuss below). However, we don't want to diverge from upstream, hence why I'm here :).
The script is approximately the same length as the original script and supports all of the same features and checking, with one catch. The standard library's XML parsing module doesn't support entity expansion, which is a feature used in many places within TFTF (see, for example, tests-standard.xml). This is done for security reasons and I haven't found a way around it without resorting to xml parsers outside of the standard library (which kinda defeats the purpose). To resolve this, we use xincludes instead, meaning that tests-standard.xml (for example) would have to be rewritten to use the new syntax.
For example, tests-standard.xml would look like the following:
<document> <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="tests-tftf-validation.xml"/> ... rest of includes here... </document>
Any thoughts on this? If you're okay with this approach we can put our CL up for review.
We also experimented with doing some hand-parsing to support entity expansion and I suspect that there's *some* way to convince entity expansion to occur within the standard library, but wanted to take your temperature on the above changes before pursuing those further.
Thanks, Jim
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Thanks all for your feedback. I'll fool around a little more with the python parsers to see if I can come up with something better. If not, I'll get this code through internal review then post it here. This may take some time to get back to since I have other priorities at the moment. Will let you know.
On Fri, Apr 21, 2023 at 2:16 AM Joanna Farley Joanna.Farley@arm.com wrote:
Hi Jim,
You have done the right thing, raise the issue on the Mailing List and I think we would be happy to consider your patch(es) for review. If the review cannot be handled by normal patch review processes and if there is a further wider discussion required that cannot be handled by the Mailing List we can schedule some time in a Tech Forum (Zoom call) of interested TF-A community members to have a live discussion.
Thanks
Joanna
*From: *Sandrine Bailleux via TF-A-Tests < tf-a-tests@lists.trustedfirmware.org> *Date: *Friday, 21 April 2023 at 07:10 *To: *Jim Ray jimray@google.com, tf-a-tests@lists.trustedfirmware.org < tf-a-tests@lists.trustedfirmware.org> *Subject: *[Tf-a-tests] Re: Standalone python version of generate_test_list.pl?
Hi Jim,
This sounds like a good idea to me!
I don't see any particular problem with using xincludes instead of entities, if it's doing the exact same job. The syntax is not very appealing to me, but neither was the entity syntax!
Best regards, Sandrine
On 4/19/23 04:06, Jim Ray via TF-A-Tests wrote:
Hello, There's an effort inside of Google to make builds more hermetic across
the board. One of the challenges we ran into was supporting the transitive dependencies of generate_test_list.pl, namely XML::LibXML. Since this isn't in the perl standard library, we have to add what amounts to an entire sysroot with a bunch of dependencies just to support this one library. Not impossible (and to be clear, this is the route that we went with), but not ideal either.
Another approach that we explored was rewriting generate_test_list.pl
in python. XML parsing is in python's standard library and many of our engineers are more familiar with it, so we thought this would be a reasonable choice. We wrote the script, and it seems to work (with some caveats that I'll discuss below). However, we don't want to diverge from upstream, hence why I'm here :).
The script is approximately the same length as the original script and
supports all of the same features and checking, with one catch. The standard library's XML parsing module doesn't support entity expansion, which is a feature used in many places within TFTF (see, for example, tests-standard.xml). This is done for security reasons and I haven't found a way around it without resorting to xml parsers outside of the standard library (which kinda defeats the purpose). To resolve this, we use xincludes instead, meaning that tests-standard.xml (for example) would have to be rewritten to use the new syntax.
For example, tests-standard.xml would look like the following:
<document> <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
href="tests-tftf-validation.xml"/>
... rest of includes here...
</document>
Any thoughts on this? If you're okay with this approach we can put our
CL up for review.
We also experimented with doing some hand-parsing to support entity
expansion and I suspect that there's *some* way to convince entity expansion to occur within the standard library, but wanted to take your temperature on the above changes before pursuing those further.
Thanks, Jim
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I was able to spend some time on this. Eventually I figured out a way to get the standard library to do external entity expansion without too much headache, so switching out all of the upstream tests to use XIncludes is no longer necessary.
Review is here: https://review.trustedfirmware.org/c/TF-A/tf-a-tests/+/21135
tf-a-tests@lists.trustedfirmware.org
-
Jim Ray -
Joanna Farley -
Sandrine Bailleux