Add ability to make StringCs from std::vector<>s.

Pre-cursor to using more std::vector<uint8_t> as byte buffers.

The widestring test case is more complicated, where we're not sure
of having any particular uint*_t type to match wchar_t.

Change-Id: Ic27980f16cdbc61fac7c11f39a85eea58d19bacb
Reviewed-on: https://pdfium-review.googlesource.com/4153
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

4 files changed, 38 insertions, 3 deletions

diff --git a/core/fxcrt/cfx_bytestring_unittest.cpp b/core/fxcrt/cfx_bytestring_unittest.cpp
index 3b679a086c..9cfc773fad 100644
--- a/core/fxcrt/cfx_bytestring_unittest.cpp
+++ b/core/fxcrt/cfx_bytestring_unittest.cpp
@@ -4,6 +4,8 @@
 
 #include "core/fxcrt/cfx_bytestring.h"
 
+#include <vector>
+
 #include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -773,6 +775,17 @@ TEST(fxcrt, ByteStringCFromChar) {
   EXPECT_NE(longer_string, lower_a_string_from_char);
 }
 
+TEST(fxcrt, ByteStringCFromVector) {
+  std::vector<uint8_t> null_vec;
+  CFX_ByteStringC null_string(null_vec);
+  EXPECT_EQ(0, null_string.GetLength());
+
+  std::vector<uint8_t> lower_a_vec(10, static_cast<uint8_t>('a'));
+  CFX_ByteStringC lower_a_string(lower_a_vec);
+  EXPECT_EQ(10, lower_a_string.GetLength());
+  EXPECT_EQ("aaaaaaaaaa", lower_a_string);
+}
+
 TEST(fxcrt, ByteStringCGetID) {
   CFX_ByteStringC null_string;
   EXPECT_EQ(0u, null_string.GetID());
diff --git a/core/fxcrt/cfx_string_c_template.h b/core/fxcrt/cfx_string_c_template.h
index b52817d790..4aba2cd4b9 100644
--- a/core/fxcrt/cfx_string_c_template.h
+++ b/core/fxcrt/cfx_string_c_template.h
@@ -9,8 +9,10 @@
 
 #include <algorithm>
 #include <type_traits>
+#include <vector>
 
 #include "core/fxcrt/fx_system.h"
+#include "third_party/base/stl_util.h"
 
 // An immutable string with caller-provided storage which must outlive the
 // string itself. These are not necessarily nul-terminated, so that substring
@@ -53,6 +55,12 @@ class CFX_StringCTemplate {
     m_Length = src.m_Length;
   }
 
+  // Any changes to |vec| invalidate the string.
+  explicit CFX_StringCTemplate(const std::vector<UnsignedType>& vec) {
+    m_Ptr = vec.data();
+    m_Length = pdfium::CollectionSize<FX_STRSIZE>(vec);
+  }
+
   CFX_StringCTemplate& operator=(const CharType* src) {
     m_Ptr = reinterpret_cast<const UnsignedType*>(src);
     m_Length = src ? FXSYS_len(src) : 0;
diff --git a/core/fxcrt/cfx_widestring_unittest.cpp b/core/fxcrt/cfx_widestring_unittest.cpp
index dd44cb70af..498b4f0b6a 100644
--- a/core/fxcrt/cfx_widestring_unittest.cpp
+++ b/core/fxcrt/cfx_widestring_unittest.cpp
@@ -4,6 +4,8 @@
 
 #include "core/fxcrt/cfx_widestring.h"
 
+#include <vector>
+
 #include "testing/fx_string_testhelpers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -689,6 +691,18 @@ TEST(fxcrt, WideStringUTF16LE_Encode) {
   }
 }
 
+TEST(fxcrt, WideStringCFromVector) {
+  std::vector<CFX_WideStringC::UnsignedType> null_vec;
+  CFX_WideStringC null_string(null_vec);
+  EXPECT_EQ(0, null_string.GetLength());
+
+  std::vector<CFX_WideStringC::UnsignedType> lower_a_vec(
+      10, static_cast<CFX_WideStringC::UnsignedType>(L'a'));
+  CFX_WideStringC lower_a_string(lower_a_vec);
+  EXPECT_EQ(10, lower_a_string.GetLength());
+  EXPECT_EQ(L"aaaaaaaaaa", lower_a_string);
+}
+
 TEST(fxcrt, WideStringCOperatorSubscript) {
   // CFX_WideStringC includes the NUL terminator for non-empty strings.
   CFX_WideStringC abc(L"abc");
diff --git a/xfa/fxfa/fm2js/xfa_fm2jscontext.cpp b/xfa/fxfa/fm2js/xfa_fm2jscontext.cpp
index 56a99157d3..ead2a7dbe3 100644
--- a/xfa/fxfa/fm2js/xfa_fm2jscontext.cpp
+++ b/xfa/fxfa/fm2js/xfa_fm2jscontext.cpp
@@ -4642,9 +4642,9 @@ void CXFA_FM2JSContext::Get(CFXJSE_Value* pThis,
     return;
 
   int32_t size = pFile->GetSize();
-  std::vector<uint8_t> pData(size);
-  pFile->ReadBlock(pData.data(), size);
-  args.GetReturnValue()->SetString(CFX_ByteStringC(pData.data(), size));
+  std::vector<uint8_t> dataBuf(size);
+  pFile->ReadBlock(dataBuf.data(), size);
+  args.GetReturnValue()->SetString(CFX_ByteStringC(dataBuf));
 }
 
 // static