pdf/pdfium/pdfium_api_string_buffer_adapter.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef PDF_PDFIUM_PDFIUM_API_STRING_BUFFER_ADAPTER_H_
   6 #define PDF_PDFIUM_PDFIUM_API_STRING_BUFFER_ADAPTER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/numerics/safe_math.h"
  10
  11 namespace chrome_pdf {
  12
  13 // Helper to deal with the fact that many PDFium APIs write the null-terminator
  14 // into string buffers that are passed to them, but the PDF plugin likes to pass
  15 // in std::strings / base::string16s, where one should not count on the internal
  16 // string buffers to be null-terminated.
  17
  18 template <class StringType>
  19 class PDFiumAPIStringBufferAdapter {
  20  public:
  21   // |str| is the string to write into.
  22   // |expected_size| is the number of characters the PDFium API will write,
  23   // including the null-terminator. It should be at least 1.
  24   // |check_expected_size| whether to check the actual number of characters
  25   // written into |str| against |expected_size| when calling Close().
  26   PDFiumAPIStringBufferAdapter(StringType* str,
  27                                size_t expected_size,
  28                                bool check_expected_size);
  29   ~PDFiumAPIStringBufferAdapter();
  30
  31   // Returns a pointer to |str_|'s buffer. The buffer's size is large enough to
  32   // hold |expected_size_| + 1 characters, so the PDFium API that uses the
  33   // pointer has space to write a null-terminator.
  34   void* GetData();
  35
  36   // Resizes |str_| to |actual_size| - 1 characters, thereby removing the extra
  37   // null-terminator. This must be called prior to the adapter's destruction.
  38   // The pointer returned by GetData() should be considered invalid.
  39   void Close(size_t actual_size);
  40
  41   template <typename IntType>
  42   void Close(IntType actual_size) {
  43     base::CheckedNumeric<size_t> unsigned_size = actual_size;
  44     Close(unsigned_size.ValueOrDie());
  45   }
  46
  47  private:
  48   StringType* const str_;
  49   void* const data_;
  50   const size_t expected_size_;
  51   const bool check_expected_size_;
  52   bool is_closed_;
  53
  54   DISALLOW_COPY_AND_ASSIGN(PDFiumAPIStringBufferAdapter);
  55 };
  56
  57 // Helper to deal with the fact that many PDFium APIs write the null-terminator
  58 // into string buffers that are passed to them, but the PDF plugin likes to pass
  59 // in std::strings / base::string16s, where one should not count on the internal
  60 // string buffers to be null-terminated. This version is suitable for APIs that
  61 // work in terms of number of bytes instead of the number of characters.
  62 template <class StringType>
  63 class PDFiumAPIStringBufferSizeInBytesAdapter {
  64  public:
  65   // |str| is the string to write into.
  66   // |expected_size| is the number of bytes the PDFium API will write,
  67   // including the null-terminator. It should be at least the size of a
  68   // character in bytes.
  69   // |check_expected_size| whether to check the actual number of bytes
  70   // written into |str| against |expected_size| when calling Close().
  71   PDFiumAPIStringBufferSizeInBytesAdapter(StringType* str,
  72                                           size_t expected_size,
  73                                           bool check_expected_size);
  74   ~PDFiumAPIStringBufferSizeInBytesAdapter();
  75
  76   // Returns a pointer to |str_|'s buffer. The buffer's size is large enough to
  77   // hold |expected_size_| + sizeof(StringType::value_type) bytes, so the PDFium
  78   // API that uses the pointer has space to write a null-terminator.
  79   void* GetData();
  80
  81   // Resizes |str_| to |actual_size| - sizeof(StringType::value_type) bytes,
  82   // thereby removing the extra null-terminator. This must be called prior to
  83   // the adapter's destruction. The pointer returned by GetData() should be
  84   // considered invalid.
  85   void Close(size_t actual_size);
  86
  87   template <typename IntType>
  88   void Close(IntType actual_size) {
  89     base::CheckedNumeric<size_t> unsigned_size = actual_size;
  90     Close(unsigned_size.ValueOrDie());
  91   }
  92
  93  private:
  94   PDFiumAPIStringBufferAdapter<StringType> adapter_;
  95 };
  96
  97 }  // namespace chrome_pdf
  98
  99 #endif  // PDF_PDFIUM_PDFIUM_API_STRING_BUFFER_ADAPTER_H_