From 734a3394faffd042b99c520963f78d3084f2e56e Mon Sep 17 00:00:00 2001
From: Yifan Hong
Date: Wed, 23 Aug 2017 15:14:02 -0700
Subject: Do not allow first <kernel> version to have non-empty <condition>.

Stating <condition> on a <kernel> tag in fwk compat mat means
the fragment is conditionally used. Older libvintf (libvintf on
O devices) use the first <kernel> tag with a match version
unconditionally. Disable this to allow old libvintf to parse
the requirements more correctly. In detail:

* O libvintf may still falsely accept incompatible fwk comp mat, because
it only looks at the first <kernel> element. The conditional
requirements are not checked.

* O libvintf does not falsely reject a compatible fwk comp mat.
Conditional requirements are never the first <kernel> element and hence
are not checked by O libvintf.

This is a workaround solution for backwards compatibility, since
O has been released.

Test: libvintf_test
Bug: 64124223
Change-Id: I20a9bb768720fc83ac5cdf293a976cb279cb6eab
Merged-In: I20a9bb768720fc83ac5cdf293a976cb279cb6eab
---
 parse_xml.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/parse_xml.cpp b/parse_xml.cpp
index f524fb8..3e495fd 100644
--- a/parse_xml.cpp
+++ b/parse_xml.cpp
@@ -887,6 +887,21 @@ struct CompatibilityMatrixConverter : public XmlNodeConverter<CompatibilityMatri
                 !parseOptionalChild(root, avbConverter, {}, &object->framework.mAvbMetaVersion)) {
                 return false;
             }
+
+            std::set<Version> seenKernelVersions;
+            for (const auto& kernel : object->framework.mKernels) {
+                Version minLts(kernel.minLts().version, kernel.minLts().majorRev);
+                if (seenKernelVersions.find(minLts) != seenKernelVersions.end()) {
+                    continue;
+                }
+                if (!kernel.conditions().empty()) {
+                    this->mLastError = "First <kernel> for version " + to_string(minLts) +
+                                       " must have empty <conditions> for backwards compatibility.";
+                    return false;
+                }
+                seenKernelVersions.insert(minLts);
+            }
+
         } else if (object->mType == SchemaType::DEVICE) {
             // <vndk> can be missing because it can be determined at build time, not hard-coded
             // in the XML file.
-- 
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