Extract test subclasses of IFX_SeekableReadStream

There are multiple instances of subclasses that either act as an
invalid stream or one backed by a memory buffer. Merging all of these
into two shared stream classes and removing the others.

BUG=pdfium:911

Change-Id: I264602808c6dc0e5c878da462a5e00883fe43e51
Reviewed-on: https://pdfium-review.googlesource.com/15093
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>

2 files changed, 52 insertions, 27 deletions

diff --git a/testing/fx_string_testhelpers.h b/testing/fx_string_testhelpers.h
index 34ac69dab4..5a269a3cf6 100644
--- a/testing/fx_string_testhelpers.h
+++ b/testing/fx_string_testhelpers.h
@@ -8,8 +8,58 @@
 #include <ostream>
 
 #include "core/fxcrt/cfx_datetime.h"
+#include "core/fxcrt/fx_stream.h"
 
 // Output stream operator so GTEST macros work with CFX_DateTime objects.
 std::ostream& operator<<(std::ostream& os, const CFX_DateTime& dt);
 
+class CFX_InvalidSeekableReadStream : public IFX_SeekableReadStream {
+ public:
+  template <typename T, typename... Args>
+  friend RetainPtr<T> pdfium::MakeRetain(Args&&... args);
+
+  // IFX_SeekableReadStream overrides:
+  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override {
+    return false;
+  }
+  FX_FILESIZE GetSize() override { return data_size_; }
+
+ private:
+  explicit CFX_InvalidSeekableReadStream(FX_FILESIZE data_size)
+      : data_size_(data_size) {}
+
+  FX_FILESIZE data_size_;
+};
+
+class CFX_BufferSeekableReadStream : public IFX_SeekableReadStream {
+ public:
+  template <typename T, typename... Args>
+  friend RetainPtr<T> pdfium::MakeRetain(Args&&... args);
+
+  // IFX_SeekableReadStream:
+  bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override {
+    if (offset < 0 || static_cast<size_t>(offset) >= data_size_)
+      return false;
+
+    if (static_cast<size_t>(offset) + size > data_size_)
+      size = data_size_ - static_cast<size_t>(offset);
+    if (size == 0)
+      return false;
+
+    memcpy(buffer, data_ + offset, size);
+    return true;
+  }
+
+  FX_FILESIZE GetSize() override {
+    return static_cast<FX_FILESIZE>(data_size_);
+  }
+
+ private:
+  CFX_BufferSeekableReadStream(const unsigned char* src, size_t src_size)
+      : data_(src), data_size_(src_size) {}
+
+  const unsigned char* data_;
+  size_t data_size_;
+};
+
 #endif  // TESTING_FX_STRING_TESTHELPERS_H_
diff --git a/testing/libfuzzer/xfa_codec_fuzzer.h b/testing/libfuzzer/xfa_codec_fuzzer.h
index 5193a8930f..a590596dcf 100644
--- a/testing/libfuzzer/xfa_codec_fuzzer.h
+++ b/testing/libfuzzer/xfa_codec_fuzzer.h
@@ -13,8 +13,8 @@
 #include "core/fxcodec/codec/ccodec_progressivedecoder.h"
 #include "core/fxcodec/codec/ccodec_tiffmodule.h"
 #include "core/fxcodec/fx_codec.h"
-#include "core/fxcrt/fx_stream.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
+#include "testing/fx_string_testhelpers.h"
 #include "third_party/base/ptr_util.h"
 
 class XFACodecFuzzer {
@@ -28,7 +28,7 @@ class XFACodecFuzzer {
 
     std::unique_ptr<CCodec_ProgressiveDecoder> decoder =
         mgr->CreateProgressiveDecoder();
-    auto source = pdfium::MakeRetain<Reader>(data, size);
+    auto source = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(data, size);
     FXCODEC_STATUS status = decoder->LoadImageInfo(source, type, nullptr, true);
     if (status != FXCODEC_STATUS_FRAME_READY)
       return 0;
@@ -49,31 +49,6 @@ class XFACodecFuzzer {
 
     return 0;
   }
-
- private:
-  class Reader : public IFX_SeekableReadStream {
-   public:
-    Reader(const uint8_t* data, size_t size) : m_data(data), m_size(size) {}
-    ~Reader() {}
-
-    bool ReadBlock(void* buffer, FX_FILESIZE offset, size_t size) override {
-      if (offset < 0 || static_cast<size_t>(offset) >= m_size)
-        return false;
-      if (offset + size > m_size)
-        size = m_size - offset;
-      if (size == 0)
-        return false;
-
-      memcpy(buffer, m_data + offset, size);
-      return true;
-    }
-
-    FX_FILESIZE GetSize() override { return static_cast<FX_FILESIZE>(m_size); }
-
-   private:
-    const uint8_t* const m_data;
-    const size_t m_size;
-  };
 };
 
 #endif  // TESTING_LIBFUZZER_XFA_CODEC_FUZZER_H_