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include/llvm/Bitcode/NaCl/NaClBitcodeHeader.h

 //===-- llvm/Bitcode/NaCl/NaClBitcodeHeader.h - ----------------*- C++ -*-===//
 //      NaCl Bitcode header reader.
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This header defines interfaces to read and write NaCl bitcode wire format
 // file headers.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_BITCODE_NACL_NACLBITCODEHEADER_H
 #define LLVM_BITCODE_NACL_NACLBITCODEHEADER_H
 
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
 #include <string>
 #include <vector>
 
 namespace llvm {
 class StreamableMemoryObject;
 
 // Class representing a variable-size metadata field in the bitcode header.
 // Also contains the list of known (typed) Tag IDs.
@@ skipping 112 matching lines @@
   // Defines the PNaCl version defined by the header file.
   uint32_t PNaClVersion;
 
 public:
   static const int WordSize = NaClBitcodeHeaderField::WordSize;
 
   NaClBitcodeHeader();
   ~NaClBitcodeHeader();
 
   /// \brief Installs the fields of the header, defining if the header
-  /// is readable and supported.
+  /// is readable and supported. Sets UnsupportedMessage on failure.
   void InstallFields();
 
   /// \brief Adds a field to the list of fields in a header. Takes ownership
   /// of fields added.
   void push_back(NaClBitcodeHeaderField *Field) {
     Fields.push_back(Field);
   }
 
   /// \brief Read the PNaCl bitcode header, The format of the header is:
   ///
@@ skipping 40 matching lines @@
   /// (0 if no such field).
   NaClBitcodeHeaderField *GetField(size_t index) const;
 
   /// \brief Returns the PNaClVersion, as defined by the header.
   uint32_t GetPNaClVersion() const { return PNaClVersion; }
 
 private:
   // Reads and verifies the first 8 bytes of the header, consisting
   // of the magic number 'PEXE', and the value defining the number
   // of fields and number of bytes used to hold fields.
-  // Returns false if successful.
+  // Returns false if successful, sets UnsupportedMessage otherwise.
   bool ReadPrefix(const unsigned char *BufPtr, const unsigned char *BufEnd,
                   unsigned &NumFields, unsigned &NumBytes);
 
   // Reads and verifies the fields in the header.
-  // Returns false if successful.
+  // Returns false if successful, sets UnsupportedMessage otherwise.
   bool ReadFields(const unsigned char *BufPtr, const unsigned char *BufEnd,
                   unsigned NumFields, unsigned NumBytes);
 
+  // Sets the Unsupported error message and returns true.
+  bool UnsupportedError(StringRef Message) {
+    UnsupportedMessage = Message.str();
+    return true;
+  }
+
 };
 
 } // namespace llvm
 
 #endif