AAPT: Handle gaps in resources when building splits

Due to public ID assignment, gaps in resource type and entry
IDs can occur. This can lead to null pointer dereferencing
if not careful. This happened in ResourceTable::getDensityVaryingResources()
which is called when building Splits.

Bug:30879690
Change-Id: I588e4dcd2e042fccfcb2e87967b5cbd0d23b4497
(cherry picked from commit 081d1b4cf602fdd7302b597e6bf902cb415bc3a8)

1 files changed, 21 insertions, 6 deletions

diff --git a/tools/aapt/ResourceTable.cpp b/tools/aapt/ResourceTable.cpp
index 4d5bb312aaf1..9cae00f778b4 100644
--- a/tools/aapt/ResourceTable.cpp
+++ b/tools/aapt/ResourceTable.cpp
@@ -4860,24 +4860,39 @@ void ResourceTable::getDensityVaryingResources(
         const Vector<sp<Type> >& types = mOrderedPackages[p]->getOrderedTypes();
         const size_t typeCount = types.size();
         for (size_t t = 0; t < typeCount; t++) {
-            const Vector<sp<ConfigList> >& configs = types[t]->getOrderedConfigs();
+            const sp<Type>& type = types[t];
+            if (type == NULL) {
+                continue;
+            }
+
+            const Vector<sp<ConfigList> >& configs = type->getOrderedConfigs();
             const size_t configCount = configs.size();
             for (size_t c = 0; c < configCount; c++) {
+                const sp<ConfigList>& configList = configs[c];
+                if (configList == NULL) {
+                    continue;
+                }
+
                 const DefaultKeyedVector<ConfigDescription, sp<Entry> >& configEntries
-                        = configs[c]->getEntries();
+                        = configList->getEntries();
                 const size_t configEntryCount = configEntries.size();
                 for (size_t ce = 0; ce < configEntryCount; ce++) {
+                    const sp<Entry>& entry = configEntries.valueAt(ce);
+                    if (entry == NULL) {
+                        continue;
+                    }
+
                     const ConfigDescription& config = configEntries.keyAt(ce);
                     if (AaptConfig::isDensityOnly(config)) {
                         // This configuration only varies with regards to density.
                         const Symbol symbol(
                                 mOrderedPackages[p]->getName(),
-                                types[t]->getName(),
-                                configs[c]->getName(),
+                                type->getName(),
+                                configList->getName(),
                                 getResId(mOrderedPackages[p], types[t],
-                                         configs[c]->getEntryIndex()));
+                                         configList->getEntryIndex()));
+
 
-                        const sp<Entry>& entry = configEntries.valueAt(ce);
                         AaptUtil::appendValue(resources, symbol,
                                               SymbolDefinition(symbol, config, entry->getPos()));
                     }