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Commit 1e4b0e54 authored by Adam Lesinski's avatar Adam Lesinski
Browse files

AAPT2: Workaround for findViewById with package ID > 0x7f 

The entire View code base checks IDs against View.NO_ID except
findViewById(), which checks to see if the ID is negative.

Any package ID > 0x7f is interpreted as a negative number in Java
(no unsigned ints), so this check prevents the use of IDs > 0x7f.

findViewById is final, so support library workarounds are not possible.

Instead, IDs (@id/foo) are just sentinels, their values don't matter.
If building for pre-O devices, rewrite any references to these IDs of
the for 0xPPTTEEEE, where PP > 7f, to 0x7fPPEEEE.

The symbol table will check for potential collisions against the base
APK, so this should be safe.

Bug: 37498913
Test: manual
Change-Id: Ife3bbd29db287757ef8a2ffd83053d97f1db2613
parent 0ddca920

tools/aapt2/Main.cpp

+1 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ namespace aapt { 
static const char* sMajorVersion = "2";



// Update minor version whenever a feature or flag is added.

static const char* sMinorVersion = "13";

static const char* sMinorVersion = "14";



int PrintVersion() {

  std::cerr << "Android Asset Packaging Tool (aapt) " << sMajorVersion << "."

tools/aapt2/cmd/Link.cpp

+69 −0
Original line number Diff line number Diff line
@@ -190,6 +190,62 @@ class LinkContext : public IAaptContext { 
  int min_sdk_version_ = 0;

};



// A custom delegate that generates compatible pre-O IDs for use with feature splits.

// Feature splits use package IDs > 7f, which in Java (since Java doesn't have unsigned ints)

// is interpreted as a negative number. Some verification was wrongly assuming negative values

// were invalid.

//

// This delegate will attempt to masquerade any '@id/' references with ID 0xPPTTEEEE,

// where PP > 7f, as 0x7fPPEEEE. Any potential overlapping is verified and an error occurs if such

// an overlap exists.

class FeatureSplitSymbolTableDelegate : public DefaultSymbolTableDelegate {

 public:

  FeatureSplitSymbolTableDelegate(IAaptContext* context) : context_(context) {

  }



  virtual ~FeatureSplitSymbolTableDelegate() = default;



  virtual std::unique_ptr<SymbolTable::Symbol> FindByName(

      const ResourceName& name,

      const std::vector<std::unique_ptr<ISymbolSource>>& sources) override {

    std::unique_ptr<SymbolTable::Symbol> symbol =

        DefaultSymbolTableDelegate::FindByName(name, sources);

    if (symbol == nullptr) {

      return {};

    }



    // Check to see if this is an 'id' with the target package.

    if (name.type == ResourceType::kId && symbol->id) {

      ResourceId* id = &symbol->id.value();

      if (id->package_id() > kAppPackageId) {

        // Rewrite the resource ID to be compatible pre-O.

        ResourceId rewritten_id(kAppPackageId, id->package_id(), id->entry_id());



        // Check that this doesn't overlap another resource.

        if (DefaultSymbolTableDelegate::FindById(rewritten_id, sources) != nullptr) {

          // The ID overlaps, so log a message (since this is a weird failure) and fail.

          context_->GetDiagnostics()->Error(DiagMessage() << "Failed to rewrite " << name

                                                          << " for pre-O feature split support");

          return {};

        }



        if (context_->IsVerbose()) {

          context_->GetDiagnostics()->Note(DiagMessage() << "rewriting " << name << " (" << *id

                                                         << ") -> (" << rewritten_id << ")");

        }



        *id = rewritten_id;

      }

    }

    return symbol;

  }



 private:

  DISALLOW_COPY_AND_ASSIGN(FeatureSplitSymbolTableDelegate);



  IAaptContext* context_;

};



static bool FlattenXml(xml::XmlResource* xml_res, const StringPiece& path,

                       Maybe<size_t> max_sdk_level, bool keep_raw_values, IArchiveWriter* writer,

                       IAaptContext* context) {
@@ -1463,6 +1519,19 @@ class LinkCommand { 
    context_->GetExternalSymbols()->PrependSource(

        util::make_unique<ResourceTableSymbolSource>(&final_table_));



    // Workaround for pre-O runtime that would treat negative resource IDs

    // (any ID with a package ID > 7f) as invalid. Intercept any ID (PPTTEEEE) with PP > 0x7f

    // and type == 'id', and return the ID 0x7fPPEEEE. IDs don't need to be real resources, they

    // are just identifiers.

    if (context_->GetMinSdkVersion() < SDK_O && context_->GetPackageType() == PackageType::kApp) {

      if (context_->IsVerbose()) {

        context_->GetDiagnostics()->Note(DiagMessage()

                                         << "enabling pre-O feature split ID rewriting");

      }

      context_->GetExternalSymbols()->SetDelegate(

          util::make_unique<FeatureSplitSymbolTableDelegate>(context_));

    }



    ReferenceLinker linker;

    if (!linker.Consume(context_, &final_table_)) {

      context_->GetDiagnostics()->Error(DiagMessage() << "failed linking references");

tools/aapt2/java/JavaClassGenerator.cpp

+9 −2
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include "Resource.h"

#include "ResourceTable.h"

#include "ResourceValues.h"

#include "SdkConstants.h"

#include "ValueVisitor.h"

#include "java/AnnotationProcessor.h"

#include "java/ClassDefinition.h"
@@ -430,9 +431,15 @@ void JavaClassGenerator::ProcessResource(const ResourceNameRef& name, const Reso 
                                         const ResourceEntry& entry, ClassDefinition* out_class_def,

                                         MethodDefinition* out_rewrite_method,

                                         std::ostream* out_r_txt) {

  ResourceId real_id = id;

  if (context_->GetMinSdkVersion() < SDK_O && name.type == ResourceType::kId &&

      id.package_id() > kAppPackageId) {

    real_id = ResourceId(kAppPackageId, id.package_id(), id.entry_id());

  }



  const std::string field_name = TransformToFieldName(name.entry);

  std::unique_ptr<ResourceMember> resource_member =

      util::make_unique<ResourceMember>(field_name, id);

      util::make_unique<ResourceMember>(field_name, real_id);



  // Build the comments and annotations for this entry.

  AnnotationProcessor* processor = resource_member->GetCommentBuilder();
@@ -458,7 +465,7 @@ void JavaClassGenerator::ProcessResource(const ResourceNameRef& name, const Reso 
  out_class_def->AddMember(std::move(resource_member));



  if (out_r_txt != nullptr) {

    *out_r_txt << "int " << name.type << " " << field_name << " " << id << "\n";

    *out_r_txt << "int " << name.type << " " << field_name << " " << real_id << "\n";

  }



  if (out_rewrite_method != nullptr) {

tools/aapt2/process/SymbolTable.cpp

+66 −31
Original line number Diff line number Diff line
@@ -34,6 +34,21 @@ using android::StringPiece; 


namespace aapt {



SymbolTable::SymbolTable(NameMangler* mangler)

    : mangler_(mangler),

      delegate_(util::make_unique<DefaultSymbolTableDelegate>()),

      cache_(200),

      id_cache_(200) {

}



void SymbolTable::SetDelegate(std::unique_ptr<ISymbolTableDelegate> delegate) {

  CHECK(delegate != nullptr) << "can't set a nullptr delegate";

  delegate_ = std::move(delegate);



  // Clear the cache in case this delegate changes the order of lookup.

  cache_.clear();

}



void SymbolTable::AppendSource(std::unique_ptr<ISymbolSource> source) {

  sources_.push_back(std::move(source));
@@ -75,9 +90,11 @@ const SymbolTable::Symbol* SymbolTable::FindByName(const ResourceName& name) { 
    mangled_name = &mangled_name_impl.value();

  }



  for (auto& symbolSource : sources_) {

    std::unique_ptr<Symbol> symbol = symbolSource->FindByName(*mangled_name);

    if (symbol) {

  std::unique_ptr<Symbol> symbol = delegate_->FindByName(*mangled_name, sources_);

  if (symbol == nullptr) {

    return nullptr;

  }



  // Take ownership of the symbol into a shared_ptr. We do this because

  // LruCache doesn't support unique_ptr.

  std::shared_ptr<Symbol> shared_symbol(std::move(symbol));
@@ -95,9 +112,6 @@ const SymbolTable::Symbol* SymbolTable::FindByName(const ResourceName& name) { 
  // between calls to Find*.

  return shared_symbol.get();

}

  }

  return nullptr;

}



const SymbolTable::Symbol* SymbolTable::FindById(const ResourceId& id) {

  if (const std::shared_ptr<Symbol>& s = id_cache_.get(id)) {
@@ -105,9 +119,11 @@ const SymbolTable::Symbol* SymbolTable::FindById(const ResourceId& id) { 
  }



  // We did not find it in the cache, so look through the sources.

  for (auto& symbolSource : sources_) {

    std::unique_ptr<Symbol> symbol = symbolSource->FindById(id);

    if (symbol) {

  std::unique_ptr<Symbol> symbol = delegate_->FindById(id, sources_);

  if (symbol == nullptr) {

    return nullptr;

  }



  // Take ownership of the symbol into a shared_ptr. We do this because LruCache

  // doesn't support unique_ptr.

  std::shared_ptr<Symbol> shared_symbol(std::move(symbol));
@@ -117,9 +133,6 @@ const SymbolTable::Symbol* SymbolTable::FindById(const ResourceId& id) { 
  // between calls to Find*.

  return shared_symbol.get();

}

  }

  return nullptr;

}



const SymbolTable::Symbol* SymbolTable::FindByReference(const Reference& ref) {

  // First try the ID. This is because when we lookup by ID, we only fill in the ID cache.
@@ -140,6 +153,28 @@ const SymbolTable::Symbol* SymbolTable::FindByReference(const Reference& ref) { 
  return symbol;

}



std::unique_ptr<SymbolTable::Symbol> DefaultSymbolTableDelegate::FindByName(

    const ResourceName& name, const std::vector<std::unique_ptr<ISymbolSource>>& sources) {

  for (auto& source : sources) {

    std::unique_ptr<SymbolTable::Symbol> symbol = source->FindByName(name);

    if (symbol) {

      return symbol;

    }

  }

  return {};

}



std::unique_ptr<SymbolTable::Symbol> DefaultSymbolTableDelegate::FindById(

    ResourceId id, const std::vector<std::unique_ptr<ISymbolSource>>& sources) {

  for (auto& source : sources) {

    std::unique_ptr<SymbolTable::Symbol> symbol = source->FindById(id);

    if (symbol) {

      return symbol;

    }

  }

  return {};

}



std::unique_ptr<SymbolTable::Symbol> ResourceTableSymbolSource::FindByName(

    const ResourceName& name) {

  Maybe<ResourceTable::SearchResult> result = table_->FindResource(name);

tools/aapt2/process/SymbolTable.h

+46 −14
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ inline android::hash_t hash_type(const ResourceId& id) { 
}



class ISymbolSource;

class ISymbolTableDelegate;

class NameMangler;



class SymbolTable {
@@ -73,7 +74,11 @@ class SymbolTable { 
    bool is_public = false;

  };



  SymbolTable(NameMangler* mangler) : mangler_(mangler), cache_(200), id_cache_(200) {}

  SymbolTable(NameMangler* mangler);



  // Overrides the default ISymbolTableDelegate, which allows a custom defined strategy for

  // looking up resources from a set of sources.

  void SetDelegate(std::unique_ptr<ISymbolTableDelegate> delegate);



  // Appends a symbol source. The cache is not cleared since entries that

  // have already been found would take precedence due to ordering.
@@ -99,6 +104,7 @@ class SymbolTable { 


 private:

  NameMangler* mangler_;

  std::unique_ptr<ISymbolTableDelegate> delegate_;

  std::vector<std::unique_ptr<ISymbolSource>> sources_;



  // We use shared_ptr because unique_ptr is not supported and
@@ -109,11 +115,41 @@ class SymbolTable { 
  DISALLOW_COPY_AND_ASSIGN(SymbolTable);

};



/**

 * An interface that a symbol source implements in order to surface symbol

 * information

 * to the symbol table.

 */

// Allows the customization of the lookup strategy/order of a symbol from a set of

// symbol sources.

class ISymbolTableDelegate {

 public:

  ISymbolTableDelegate() = default;

  virtual ~ISymbolTableDelegate() = default;



  // The name is already mangled and does not need further processing.

  virtual std::unique_ptr<SymbolTable::Symbol> FindByName(

      const ResourceName& name, const std::vector<std::unique_ptr<ISymbolSource>>& sources) = 0;



  virtual std::unique_ptr<SymbolTable::Symbol> FindById(

      ResourceId id, const std::vector<std::unique_ptr<ISymbolSource>>& sources) = 0;



 private:

  DISALLOW_COPY_AND_ASSIGN(ISymbolTableDelegate);

};



class DefaultSymbolTableDelegate : public ISymbolTableDelegate {

 public:

  DefaultSymbolTableDelegate() = default;

  virtual ~DefaultSymbolTableDelegate() = default;



  virtual std::unique_ptr<SymbolTable::Symbol> FindByName(

      const ResourceName& name,

      const std::vector<std::unique_ptr<ISymbolSource>>& sources) override;

  virtual std::unique_ptr<SymbolTable::Symbol> FindById(

      ResourceId id, const std::vector<std::unique_ptr<ISymbolSource>>& sources) override;



 private:

  DISALLOW_COPY_AND_ASSIGN(DefaultSymbolTableDelegate);

};



// An interface that a symbol source implements in order to surface symbol information

// to the symbol table.

class ISymbolSource {

 public:

  virtual ~ISymbolSource() = default;
@@ -122,9 +158,7 @@ class ISymbolSource { 
      const ResourceName& name) = 0;

  virtual std::unique_ptr<SymbolTable::Symbol> FindById(ResourceId id) = 0;



  /**

   * Default implementation tries the name if it exists, else the ID.

   */

  // Default implementation tries the name if it exists, else the ID.

  virtual std::unique_ptr<SymbolTable::Symbol> FindByReference(

      const Reference& ref) {

    if (ref.name) {
@@ -136,11 +170,9 @@ class ISymbolSource { 
  }

};



/**

 * Exposes the resources in a ResourceTable as symbols for SymbolTable.

 * Instances of this class must outlive the encompassed ResourceTable.

 * Lookups by ID are ignored.

 */

// Exposes the resources in a ResourceTable as symbols for SymbolTable.

// Instances of this class must outlive the encompassed ResourceTable.

// Lookups by ID are ignored.

class ResourceTableSymbolSource : public ISymbolSource {

 public:

  explicit ResourceTableSymbolSource(ResourceTable* table) : table_(table) {}