Remove CFX_BufferSeekableReadStream.

Replace it with CFX_ReadOnlyMemoryStream, which does the same thing.
Take some checks from CFX_BufferSeekableReadStream and add them
CFX_ReadOnlyMemoryStream.

Change-Id: I25554c3aec3ec96967f8df16ca68a64dba121b6f
Reviewed-on: https://pdfium-review.googlesource.com/40070
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

12 files changed, 42 insertions, 83 deletions

diff --git a/core/fpdfapi/parser/cpdf_cross_ref_avail_unittest.cpp b/core/fpdfapi/parser/cpdf_cross_ref_avail_unittest.cpp
index eab7330cf6..6cdc3f1817 100644
--- a/core/fpdfapi/parser/cpdf_cross_ref_avail_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_cross_ref_avail_unittest.cpp
@@ -8,7 +8,7 @@
 #include <string>
 
 #include "core/fpdfapi/parser/cpdf_syntax_parser.h"
-#include "testing/fx_string_testhelpers.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/base/ptr_util.h"
 
@@ -17,7 +17,7 @@ namespace {
 std::unique_ptr<CPDF_SyntaxParser> MakeParserForBuffer(
     pdfium::span<const uint8_t> buffer) {
   return pdfium::MakeUnique<CPDF_SyntaxParser>(
-      pdfium::MakeRetain<CFX_BufferSeekableReadStream>(buffer));
+      pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(buffer));
 }
 
 }  // namespace
diff --git a/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp b/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
index 97ba434768..c372d74a00 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_hint_tables_unittest.cpp
@@ -16,8 +16,8 @@
 #include "core/fpdfapi/parser/cpdf_read_validator.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_syntax_parser.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxcrt/fx_stream.h"
-#include "testing/fx_string_testhelpers.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/utils/path_service.h"
@@ -48,7 +48,7 @@ class TestLinearizedHeader : public CPDF_LinearizedHeader {
 
   static std::unique_ptr<CPDF_LinearizedHeader> MakeHeader(
       const std::string& inline_data) {
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::as_bytes(pdfium::make_span(inline_data))));
     std::unique_ptr<CPDF_Dictionary> dict =
         ToDictionary(parser.GetObjectBody(nullptr));
diff --git a/core/fpdfapi/parser/cpdf_parser_unittest.cpp b/core/fpdfapi/parser/cpdf_parser_unittest.cpp
index d5166fbdf0..00f3770e87 100644
--- a/core/fpdfapi/parser/cpdf_parser_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_parser_unittest.cpp
@@ -11,10 +11,10 @@
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
 #include "core/fpdfapi/parser/cpdf_syntax_parser.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/utils/path_service.h"
 
@@ -50,8 +50,7 @@ class CPDF_TestParser : public CPDF_Parser {
   bool InitTestFromBufferWithOffset(pdfium::span<const uint8_t> buffer,
                                     FX_FILESIZE header_offset) {
     m_pSyntax = CPDF_SyntaxParser::CreateForTesting(
-        pdfium::MakeRetain<CFX_BufferSeekableReadStream>(buffer),
-        header_offset);
+        pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(buffer), header_offset);
     return true;
   }
 
diff --git a/core/fpdfapi/parser/cpdf_read_validator_unittest.cpp b/core/fpdfapi/parser/cpdf_read_validator_unittest.cpp
index ccfb451dd8..640269884d 100644
--- a/core/fpdfapi/parser/cpdf_read_validator_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_read_validator_unittest.cpp
@@ -8,6 +8,7 @@
 #include <utility>
 #include <vector>
 
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -65,7 +66,7 @@ class MockDownloadHints : public CPDF_DataAvail::DownloadHints {
 
 TEST(CPDF_ReadValidatorTest, UnavailableData) {
   std::vector<uint8_t> test_data(kTestDataSize);
-  auto file = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(test_data);
+  auto file = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(test_data);
   MockFileAvail file_avail;
   auto validator = pdfium::MakeRetain<CPDF_ReadValidator>(file, &file_avail);
 
@@ -88,7 +89,7 @@ TEST(CPDF_ReadValidatorTest, UnavailableData) {
 
 TEST(CPDF_ReadValidatorTest, UnavailableDataWithHints) {
   std::vector<uint8_t> test_data(kTestDataSize);
-  auto file = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(test_data);
+  auto file = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(test_data);
   MockFileAvail file_avail;
   auto validator = pdfium::MakeRetain<CPDF_ReadValidator>(file, &file_avail);
 
@@ -143,7 +144,7 @@ TEST(CPDF_ReadValidatorTest, ReadError) {
 
 TEST(CPDF_ReadValidatorTest, IntOverflow) {
   std::vector<uint8_t> test_data(kTestDataSize);
-  auto file = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(test_data);
+  auto file = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(test_data);
   MockFileAvail file_avail;
   auto validator = pdfium::MakeRetain<CPDF_ReadValidator>(file, &file_avail);
 
@@ -241,7 +242,7 @@ TEST(CPDF_ReadValidatorTest, SessionReset) {
 
 TEST(CPDF_ReadValidatorTest, CheckDataRangeAndRequestIfUnavailable) {
   std::vector<uint8_t> test_data(kTestDataSize);
-  auto file = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(test_data);
+  auto file = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(test_data);
   MockFileAvail file_avail;
   auto validator = pdfium::MakeRetain<CPDF_ReadValidator>(file, &file_avail);
 
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser_unittest.cpp b/core/fpdfapi/parser/cpdf_syntax_parser_unittest.cpp
index 498eddf12b..5b06d33d4b 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_syntax_parser_unittest.cpp
@@ -8,8 +8,8 @@
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
 #include "core/fpdfapi/parser/cpdf_syntax_parser.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxcrt/fx_extension.h"
-#include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/utils/path_service.h"
 
@@ -17,7 +17,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Empty string.
     static const uint8_t data[] = "";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 0)));
     EXPECT_EQ("", parser.ReadHexString());
     EXPECT_EQ(0, parser.GetPos());
@@ -26,7 +26,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Blank string.
     static const uint8_t data[] = "  ";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 2)));
     EXPECT_EQ("", parser.ReadHexString());
     EXPECT_EQ(2, parser.GetPos());
@@ -35,7 +35,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Skips unknown characters.
     static const uint8_t data[] = "z12b";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 4)));
     EXPECT_EQ("\x12\xb0", parser.ReadHexString());
     EXPECT_EQ(4, parser.GetPos());
@@ -44,7 +44,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Skips unknown characters.
     static const uint8_t data[] = "*<&*#$^&@1";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 10)));
     EXPECT_EQ("\x10", parser.ReadHexString());
     EXPECT_EQ(10, parser.GetPos());
@@ -53,7 +53,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Skips unknown characters.
     static const uint8_t data[] = "\x80zab";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 4)));
     EXPECT_EQ("\xab", parser.ReadHexString());
     EXPECT_EQ(4, parser.GetPos());
@@ -62,7 +62,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Skips unknown characters.
     static const uint8_t data[] = "\xffzab";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 4)));
     EXPECT_EQ("\xab", parser.ReadHexString());
     EXPECT_EQ(4, parser.GetPos());
@@ -71,7 +71,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Regular conversion.
     static const uint8_t data[] = "1A2b>abcd";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 9)));
     EXPECT_EQ("\x1a\x2b", parser.ReadHexString());
     EXPECT_EQ(5, parser.GetPos());
@@ -80,7 +80,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Position out of bounds.
     static const uint8_t data[] = "12ab>";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 5)));
     parser.SetPos(5);
     EXPECT_EQ("", parser.ReadHexString());
@@ -102,7 +102,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Missing ending >.
     static const uint8_t data[] = "1A2b";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 4)));
     EXPECT_EQ("\x1a\x2b", parser.ReadHexString());
     EXPECT_EQ(4, parser.GetPos());
@@ -111,7 +111,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Missing ending >.
     static const uint8_t data[] = "12abz";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 5)));
     EXPECT_EQ("\x12\xab", parser.ReadHexString());
     EXPECT_EQ(5, parser.GetPos());
@@ -120,7 +120,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Uneven number of bytes.
     static const uint8_t data[] = "1A2>asdf";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 8)));
     EXPECT_EQ("\x1a\x20", parser.ReadHexString());
     EXPECT_EQ(4, parser.GetPos());
@@ -129,7 +129,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Uneven number of bytes.
     static const uint8_t data[] = "1A2zasdf";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 8)));
     EXPECT_EQ("\x1a\x2a\xdf", parser.ReadHexString());
     EXPECT_EQ(8, parser.GetPos());
@@ -138,7 +138,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
   {
     // Just ending character.
     static const uint8_t data[] = ">";
-    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, 1)));
     EXPECT_EQ("", parser.ReadHexString());
     EXPECT_EQ(1, parser.GetPos());
@@ -148,7 +148,7 @@ TEST(cpdf_syntax_parser, ReadHexString) {
 TEST(cpdf_syntax_parser, GetInvalidReference) {
   // Data with a reference with number CPDF_Object::kInvalidObjNum
   static const uint8_t data[] = "4294967295 0 R";
-  CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::make_span(data, 14)));
   std::unique_ptr<CPDF_Object> ref = parser.GetObjectBody(nullptr);
   EXPECT_FALSE(ref);
@@ -156,8 +156,7 @@ TEST(cpdf_syntax_parser, GetInvalidReference) {
 
 TEST(cpdf_syntax_parser, PeekNextWord) {
   static const uint8_t data[] = "    WORD ";
-  CPDF_SyntaxParser parser(
-      pdfium::MakeRetain<CFX_BufferSeekableReadStream>(data));
+  CPDF_SyntaxParser parser(pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(data));
   EXPECT_EQ("WORD", parser.PeekNextWord(nullptr));
   EXPECT_EQ("WORD", parser.GetNextWord(nullptr));
 }
diff --git a/core/fxcrt/cfx_readonlymemorystream.cpp b/core/fxcrt/cfx_readonlymemorystream.cpp
index a01ed2e474..0a1a53a456 100644
--- a/core/fxcrt/cfx_readonlymemorystream.cpp
+++ b/core/fxcrt/cfx_readonlymemorystream.cpp
@@ -21,7 +21,7 @@ FX_FILESIZE CFX_ReadOnlyMemoryStream::GetSize() {
 bool CFX_ReadOnlyMemoryStream::ReadBlock(void* buffer,
                                          FX_FILESIZE offset,
                                          size_t size) {
-  if (offset < 0)
+  if (!buffer || offset < 0 || size == 0)
     return false;
 
   FX_SAFE_SIZE_T pos = size;
diff --git a/core/fxcrt/xml/cfx_xmlinstruction_unittest.cpp b/core/fxcrt/xml/cfx_xmlinstruction_unittest.cpp
index 0109ab2985..c1fbad5f0f 100644
--- a/core/fxcrt/xml/cfx_xmlinstruction_unittest.cpp
+++ b/core/fxcrt/xml/cfx_xmlinstruction_unittest.cpp
@@ -4,10 +4,10 @@
 
 #include "core/fxcrt/xml/cfx_xmlinstruction.h"
 
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmlparser.h"
-#include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/string_write_stream.h"
 #include "testing/test_support.h"
@@ -86,7 +86,7 @@ TEST(CFX_XMLInstructionTest, ParseAndReSave) {
       "<?acrobat http://www.xfa.org/schema/xfa-template/3.3/ Display:1 ?>\n"
       "<node></node>";
 
-  auto in_stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto in_stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
 
   CFX_XMLParser parser(in_stream);
@@ -119,7 +119,7 @@ TEST(CFX_XMLInstructionTest, ParseAndReSaveInnerInstruction) {
       "<?acrobat http://www.xfa.org/schema/xfa-template/3.3/ Display:1 ?>\n"
       "</node>";
 
-  auto in_stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto in_stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
 
   CFX_XMLParser parser(in_stream);
diff --git a/core/fxcrt/xml/cfx_xmlparser_unittest.cpp b/core/fxcrt/xml/cfx_xmlparser_unittest.cpp
index c1236ce182..86d340ea83 100644
--- a/core/fxcrt/xml/cfx_xmlparser_unittest.cpp
+++ b/core/fxcrt/xml/cfx_xmlparser_unittest.cpp
@@ -6,11 +6,11 @@
 
 #include <memory>
 
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmlinstruction.h"
-#include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
 #include "third_party/base/ptr_util.h"
@@ -18,8 +18,8 @@
 class CFX_XMLParserTest : public testing::Test {
  public:
   std::unique_ptr<CFX_XMLDocument> Parse(pdfium::span<const char> input) {
-    CFX_XMLParser parser(pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
-        pdfium::as_bytes(input)));
+    CFX_XMLParser parser(
+        pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(pdfium::as_bytes(input)));
     return parser.Parse();
   }
 };
diff --git a/testing/fuzzers/xfa_codec_fuzzer.h b/testing/fuzzers/xfa_codec_fuzzer.h
index bc40f653af..fe9e72b89d 100644
--- a/testing/fuzzers/xfa_codec_fuzzer.h
+++ b/testing/fuzzers/xfa_codec_fuzzer.h
@@ -9,8 +9,8 @@
 
 #include "core/fxcodec/codec/ccodec_progressivedecoder.h"
 #include "core/fxcodec/fx_codec.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
-#include "testing/fx_string_testhelpers.h"
 #include "third_party/base/ptr_util.h"
 #include "third_party/base/span.h"
 
@@ -53,7 +53,7 @@ class XFACodecFuzzer {
 
     std::unique_ptr<CCodec_ProgressiveDecoder> decoder =
         mgr->CreateProgressiveDecoder();
-    auto source = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+    auto source = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
         pdfium::make_span(data, size));
     FXCODEC_STATUS status = decoder->LoadImageInfo(source, type, nullptr, true);
     if (status != FXCODEC_STATUS_FRAME_READY)
diff --git a/testing/fx_string_testhelpers.cpp b/testing/fx_string_testhelpers.cpp
index e3c443ac4e..96f2c64535 100644
--- a/testing/fx_string_testhelpers.cpp
+++ b/testing/fx_string_testhelpers.cpp
@@ -22,24 +22,3 @@ CFX_InvalidSeekableReadStream::CFX_InvalidSeekableReadStream(
     : data_size_(data_size) {}
 
 CFX_InvalidSeekableReadStream::~CFX_InvalidSeekableReadStream() = default;
-
-CFX_BufferSeekableReadStream::CFX_BufferSeekableReadStream(
-    pdfium::span<const uint8_t> data)
-    : data_(data) {}
-
-CFX_BufferSeekableReadStream::~CFX_BufferSeekableReadStream() = default;
-
-bool CFX_BufferSeekableReadStream::ReadBlock(void* buffer,
-                                             FX_FILESIZE offset,
-                                             size_t size) {
-  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;
-}
diff --git a/testing/fx_string_testhelpers.h b/testing/fx_string_testhelpers.h
index 4cddefab0a..a828d825ab 100644
--- a/testing/fx_string_testhelpers.h
+++ b/testing/fx_string_testhelpers.h
@@ -32,23 +32,4 @@ class CFX_InvalidSeekableReadStream : public IFX_SeekableReadStream {
   const 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;
-
-  FX_FILESIZE GetSize() override {
-    return static_cast<FX_FILESIZE>(data_.size());
-  }
-
- private:
-  explicit CFX_BufferSeekableReadStream(pdfium::span<const uint8_t> data);
-  ~CFX_BufferSeekableReadStream() override;
-
-  pdfium::span<const uint8_t> data_;
-};
-
 #endif  // TESTING_FX_STRING_TESTHELPERS_H_
diff --git a/xfa/fxfa/parser/cxfa_document_parser_unittest.cpp b/xfa/fxfa/parser/cxfa_document_parser_unittest.cpp
index 62bd380326..7ce2efe954 100644
--- a/xfa/fxfa/parser/cxfa_document_parser_unittest.cpp
+++ b/xfa/fxfa/parser/cxfa_document_parser_unittest.cpp
@@ -4,7 +4,7 @@
 
 #include "xfa/fxfa/parser/cxfa_document_parser.h"
 
-#include "testing/fx_string_testhelpers.h"
+#include "core/fxcrt/cfx_readonlymemorystream.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
@@ -39,7 +39,7 @@ TEST_F(CXFA_DocumentParserTest, XMLInstructionsScriptOff) {
       "</config>";
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_Scripting));
 
-  auto stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
   ASSERT_TRUE(GetParser()->Parse(stream, XFA_PacketType::Config));
 
@@ -57,7 +57,7 @@ TEST_F(CXFA_DocumentParserTest, XMLInstructionsScriptOn) {
 
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_Scripting));
 
-  auto stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
   ASSERT_TRUE(GetParser()->Parse(stream, XFA_PacketType::Config));
 
@@ -74,7 +74,7 @@ TEST_F(CXFA_DocumentParserTest, XMLInstructionsStrictScope) {
 
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_StrictScoping));
 
-  auto stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
   ASSERT_TRUE(GetParser()->Parse(stream, XFA_PacketType::Config));
 
@@ -91,7 +91,7 @@ TEST_F(CXFA_DocumentParserTest, XMLInstructionsStrictScopeBad) {
 
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_StrictScoping));
 
-  auto stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
   ASSERT_TRUE(GetParser()->Parse(stream, XFA_PacketType::Config));
 
@@ -111,7 +111,7 @@ TEST_F(CXFA_DocumentParserTest, MultipleXMLInstructions) {
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_Scripting));
   EXPECT_FALSE(GetDoc()->HasFlag(XFA_DOCFLAG_StrictScoping));
 
-  auto stream = pdfium::MakeRetain<CFX_BufferSeekableReadStream>(
+  auto stream = pdfium::MakeRetain<CFX_ReadOnlyMemoryStream>(
       pdfium::as_bytes(pdfium::make_span(input)));
   ASSERT_TRUE(GetParser()->Parse(stream, XFA_PacketType::Config));