Make CFX_WideString::LockBuffer() completely unused.

Then remove CFX_{Wide,Byte}String::LockBuffer().  Prelude to a vast
simplification. There's an additional copy now in one place, so
shoot me.

BUG=pdfium:144
R=thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/ee7412f5aef353e5c6f1a64d0e1708ed926869d9

Committed: https://pdfium.googlesource.com/pdfium/+/5a256ad29483eb2b13e6e2c89fe0f77a9103f68f

Review URL: https://codereview.chromium.org/1053613004

4 files changed, 13 insertions, 28 deletions

diff --git a/core/include/fxcrt/fx_string.h b/core/include/fxcrt/fx_string.h
index 1efb814b08..a7cf2e1c16 100644
--- a/core/include/fxcrt/fx_string.h
+++ b/core/include/fxcrt/fx_string.h
@@ -320,8 +320,6 @@ public:
 
     FX_LPSTR				GetBuffer(FX_STRSIZE len);
 
-    FX_LPSTR				LockBuffer();
-
     void					ReleaseBuffer(FX_STRSIZE len = -1);
 
     CFX_ByteString			Mid(FX_STRSIZE first) const;
@@ -730,8 +728,6 @@ public:
 
     FX_LPWSTR				GetBuffer(FX_STRSIZE len);
 
-    FX_LPWSTR				LockBuffer();
-
     void					ReleaseBuffer(FX_STRSIZE len = -1);
 
     int						GetInteger() const;
diff --git a/core/src/fpdfdoc/doc_bookmark.cpp b/core/src/fpdfdoc/doc_bookmark.cpp
index 9814de61bf..6ba98e655d 100644
--- a/core/src/fpdfdoc/doc_bookmark.cpp
+++ b/core/src/fpdfdoc/doc_bookmark.cpp
@@ -4,7 +4,11 @@
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
+#include <vector>
+
+#include "../../../third_party/base/nonstd_unique_ptr.h"
 #include "../../include/fpdfdoc/fpdf_doc.h"
+
 CPDF_Bookmark CPDF_BookmarkTree::GetFirstChild(const CPDF_Bookmark& parent) const
 {
     if (!parent.m_pDict) {
@@ -55,15 +59,18 @@ CFX_WideString CPDF_Bookmark::GetTitle() const
         return CFX_WideString();
     }
     CFX_WideString title = pString->GetUnicodeText();
-    FX_LPWSTR buf = title.LockBuffer();
     int len = title.GetLength();
+    if (!len) {
+        return CFX_WideString();
+    }
+    nonstd::unique_ptr<std::vector<FX_WCHAR> > vec;
+    vec.reset(new std::vector<FX_WCHAR>(len));
+    FX_WCHAR* buf = &vec->front();
     for (int i = 0; i < len; i++) {
-        if (buf[i] < 0x20) {
-            buf[i] = 0x20;
-        }
+        FX_WCHAR w = title[i];
+        buf[i] = w > 0x20 ? w : 0x20;
     }
-    title.ReleaseBuffer(len);
-    return title;
+    return CFX_WideString(buf, len);
 }
 CPDF_Dest CPDF_Bookmark::GetDest(CPDF_Document* pDocument) const
 {
diff --git a/core/src/fxcrt/fx_basic_bstring.cpp b/core/src/fxcrt/fx_basic_bstring.cpp
index cda7d1fdd7..961aebe69c 100644
--- a/core/src/fxcrt/fx_basic_bstring.cpp
+++ b/core/src/fxcrt/fx_basic_bstring.cpp
@@ -341,15 +341,6 @@ void CFX_ByteString::ReleaseBuffer(FX_STRSIZE nNewLength)
     m_pData->m_nDataLength = nNewLength;
     m_pData->m_String[nNewLength] = 0;
 }
-FX_LPSTR CFX_ByteString::LockBuffer()
-{
-    if (m_pData == NULL) {
-        return NULL;
-    }
-    FX_LPSTR lpsz = GetBuffer(0);
-    m_pData->m_nRefs = -1;
-    return lpsz;
-}
 void CFX_ByteString::Reserve(FX_STRSIZE len)
 {
     GetBuffer(len);
diff --git a/core/src/fxcrt/fx_basic_wstring.cpp b/core/src/fxcrt/fx_basic_wstring.cpp
index e255aa0779..2ea23e4f19 100644
--- a/core/src/fxcrt/fx_basic_wstring.cpp
+++ b/core/src/fxcrt/fx_basic_wstring.cpp
@@ -535,15 +535,6 @@ int CFX_WideString::Compare(const CFX_WideString& str) const
     }
     return 0;
 }
-FX_LPWSTR CFX_WideString::LockBuffer()
-{
-    if (m_pData == NULL) {
-        return NULL;
-    }
-    FX_LPWSTR lpsz = GetBuffer(0);
-    m_pData->m_nRefs = -1;
-    return lpsz;
-}
 void CFX_WideString::SetAt(FX_STRSIZE nIndex, FX_WCHAR ch)
 {
     if (m_pData == NULL) {