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

1 files changed, 21 insertions, 6 deletions

diff --git a/tools/aapt/ResourceTable.cpp b/tools/aapt/ResourceTable.cpp
index 76c59dd57068..661409e3d4bc 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()));
                     }