Remove use of GetBuffer()/ReleaseBuffer() when c_str() is sufficient.

Greatly simplify the code which was neither changing allocations nor
doing any actual work. Eventually GetBuffer() will return a span, and
this makes fewer places to change.

Comment AsFPDFWideString() as a place where we may want a redundant
copy, and make available outside the .cpp file.

Fix one "const" along the way.

Change-Id: I187758b69a0ba3501b3622f6c06280793cd5d464
Reviewed-on: https://pdfium-review.googlesource.com/30011
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

9 files changed, 47 insertions, 93 deletions

diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.cpp b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
index dd7d082312..c1846449cd 100644
--- a/fpdfsdk/cpdfsdk_formfillenvironment.cpp
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
@@ -20,17 +20,14 @@
 #include "fxjs/ijs_runtime.h"
 #include "third_party/base/ptr_util.h"
 
-namespace {
-
-// NOTE: |bsUTF16LE| must outlive the use of the result. Care must be taken
-// since modifying the result would impact |bsUTF16LE|.
 FPDF_WIDESTRING AsFPDFWideString(ByteString* bsUTF16LE) {
+  // Force a private version of the string, since we're about to hand it off
+  // to the embedder. Should the embedder modify it by accident, it won't
+  // corrupt other shares of the string beyond |bsUTF16LE|.
   return reinterpret_cast<FPDF_WIDESTRING>(
       bsUTF16LE->GetBuffer(bsUTF16LE->GetLength()));
 }
 
-}  // namespace
-
 CPDFSDK_FormFillEnvironment::CPDFSDK_FormFillEnvironment(
     UnderlyingDocumentType* pDoc,
     FPDF_FORMFILLINFO* pFFinfo)
@@ -374,9 +371,7 @@ void CPDFSDK_FormFillEnvironment::GotoURL(CPDFXFA_Context* document,
     return;
 
   ByteString bsTo = WideString(wsURL).UTF16LE_Encode();
-  FPDF_WIDESTRING pTo = (FPDF_WIDESTRING)bsTo.GetBuffer(wsURL.GetLength());
-  m_pInfo->FFI_GotoURL(m_pInfo, document, pTo);
-  bsTo.ReleaseBuffer(bsTo.GetStringLength());
+  m_pInfo->FFI_GotoURL(m_pInfo, document, AsFPDFWideString(&bsTo));
 }
 
 void CPDFSDK_FormFillEnvironment::GetPageViewRect(CPDFXFA_Page* page,
@@ -445,10 +440,9 @@ RetainPtr<IFX_SeekableReadStream> CPDFSDK_FormFillEnvironment::DownloadFromURL(
     return nullptr;
 
   ByteString bstrURL = WideString(url).UTF16LE_Encode();
-  FPDF_WIDESTRING wsURL =
-      (FPDF_WIDESTRING)bstrURL.GetBuffer(bstrURL.GetLength());
+  FPDF_LPFILEHANDLER fileHandler =
+      m_pInfo->FFI_DownloadFromURL(m_pInfo, AsFPDFWideString(&bstrURL));
 
-  FPDF_LPFILEHANDLER fileHandler = m_pInfo->FFI_DownloadFromURL(m_pInfo, wsURL);
   return MakeSeekableStream(fileHandler);
 }
 
@@ -462,32 +456,23 @@ WideString CPDFSDK_FormFillEnvironment::PostRequestURL(
     return L"";
 
   ByteString bsURL = WideString(wsURL).UTF16LE_Encode();
-  FPDF_WIDESTRING URL = (FPDF_WIDESTRING)bsURL.GetBuffer(bsURL.GetLength());
-
   ByteString bsData = WideString(wsData).UTF16LE_Encode();
-  FPDF_WIDESTRING data = (FPDF_WIDESTRING)bsData.GetBuffer(bsData.GetLength());
-
   ByteString bsContentType = WideString(wsContentType).UTF16LE_Encode();
-  FPDF_WIDESTRING contentType =
-      (FPDF_WIDESTRING)bsContentType.GetBuffer(bsContentType.GetLength());
-
   ByteString bsEncode = WideString(wsEncode).UTF16LE_Encode();
-  FPDF_WIDESTRING encode =
-      (FPDF_WIDESTRING)bsEncode.GetBuffer(bsEncode.GetLength());
-
   ByteString bsHeader = WideString(wsHeader).UTF16LE_Encode();
-  FPDF_WIDESTRING header =
-      (FPDF_WIDESTRING)bsHeader.GetBuffer(bsHeader.GetLength());
 
   FPDF_BSTR response;
   FPDF_BStr_Init(&response);
-  m_pInfo->FFI_PostRequestURL(m_pInfo, URL, data, contentType, encode, header,
-                              &response);
+  m_pInfo->FFI_PostRequestURL(
+      m_pInfo, AsFPDFWideString(&bsURL), AsFPDFWideString(&bsData),
+      AsFPDFWideString(&bsContentType), AsFPDFWideString(&bsEncode),
+      AsFPDFWideString(&bsHeader), &response);
 
-  WideString wsRet = WideString::FromUTF16LE(
-      (FPDF_WIDESTRING)response.str, response.len / sizeof(FPDF_WIDESTRING));
-  FPDF_BStr_Clear(&response);
+  WideString wsRet =
+      WideString::FromUTF16LE(reinterpret_cast<FPDF_WIDESTRING>(response.str),
+                              response.len / sizeof(FPDF_WIDESTRING));
 
+  FPDF_BStr_Clear(&response);
   return wsRet;
 }
 
@@ -498,16 +483,12 @@ FPDF_BOOL CPDFSDK_FormFillEnvironment::PutRequestURL(const wchar_t* wsURL,
     return false;
 
   ByteString bsURL = WideString(wsURL).UTF16LE_Encode();
-  FPDF_WIDESTRING URL = (FPDF_WIDESTRING)bsURL.GetBuffer(bsURL.GetLength());
-
   ByteString bsData = WideString(wsData).UTF16LE_Encode();
-  FPDF_WIDESTRING data = (FPDF_WIDESTRING)bsData.GetBuffer(bsData.GetLength());
-
   ByteString bsEncode = WideString(wsEncode).UTF16LE_Encode();
-  FPDF_WIDESTRING encode =
-      (FPDF_WIDESTRING)bsEncode.GetBuffer(bsEncode.GetLength());
 
-  return m_pInfo->FFI_PutRequestURL(m_pInfo, URL, data, encode);
+  return m_pInfo->FFI_PutRequestURL(m_pInfo, AsFPDFWideString(&bsURL),
+                                    AsFPDFWideString(&bsData),
+                                    AsFPDFWideString(&bsEncode));
 }
 
 WideString CPDFSDK_FormFillEnvironment::GetLanguage() {
diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.h b/fpdfsdk/cpdfsdk_formfillenvironment.h
index 3c14ac06ac..18626cfde3 100644
--- a/fpdfsdk/cpdfsdk_formfillenvironment.h
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.h
@@ -29,6 +29,10 @@ class CPDFSDK_InterForm;
 class CPDFSDK_PageView;
 class IJS_Runtime;
 
+// NOTE: |bsUTF16LE| must outlive the use of the result. Care must be taken
+// since modifying the result would impact |bsUTF16LE|.
+FPDF_WIDESTRING AsFPDFWideString(ByteString* bsUTF16LE);
+
 // The CPDFSDK_FormFillEnvironment is "owned" by the embedder across the
 // C API as a FPDF_FormHandle, and may pop out of existence at any time,
 // so long as the associated embedder-owned FPDF_Document outlives it.
diff --git a/fpdfsdk/cpdfsdk_interform.cpp b/fpdfsdk/cpdfsdk_interform.cpp
index 6d3e9cd848..e83e59938c 100644
--- a/fpdfsdk/cpdfsdk_interform.cpp
+++ b/fpdfsdk/cpdfsdk_interform.cpp
@@ -521,12 +521,7 @@ bool CPDFSDK_InterForm::FDFToURLEncodedData(uint8_t*& pBuf, size_t& nBufSize) {
     ByteString csBValue = pField->GetStringFor("V");
     WideString csWValue = PDF_DecodeText(csBValue);
     ByteString csValue_b = ByteString::FromUnicode(csWValue);
-
-    fdfEncodedData << name_b.GetBuffer(name_b.GetLength());
-    name_b.ReleaseBuffer(name_b.GetStringLength());
-    fdfEncodedData << "=";
-    fdfEncodedData << csValue_b.GetBuffer(csValue_b.GetLength());
-    csValue_b.ReleaseBuffer(csValue_b.GetStringLength());
+    fdfEncodedData << name_b.c_str() << "=" << csValue_b.c_str();
     if (i != pFields->GetCount() - 1)
       fdfEncodedData << "&";
   }
diff --git a/fpdfsdk/fpdf_text.cpp b/fpdfsdk/fpdf_text.cpp
index 7778696931..c5906acef0 100644
--- a/fpdfsdk/fpdf_text.cpp
+++ b/fpdfsdk/fpdf_text.cpp
@@ -193,7 +193,7 @@ FPDF_EXPORT int FPDF_CALLCONV FPDFText_GetText(FPDF_TEXTPAGE page,
   int ret_count = byte_str_len / kBytesPerCharacter;
 
   ASSERT(ret_count <= char_count + 1);  // +1 to account for the NUL terminator.
-  memcpy(result, byte_str.GetBuffer(byte_str_len), byte_str_len);
+  memcpy(result, byte_str.c_str(), byte_str_len);
   return ret_count;
 }
 
@@ -247,8 +247,7 @@ FPDF_EXPORT int FPDF_CALLCONV FPDFText_GetBoundedText(FPDF_TEXTPAGE text_page,
   ByteString cbUTF16Str = str.UTF16LE_Encode();
   int len = cbUTF16Str.GetLength() / sizeof(unsigned short);
   int size = buflen > len ? len : buflen;
-  memcpy(buffer, cbUTF16Str.GetBuffer(size * sizeof(unsigned short)),
-         size * sizeof(unsigned short));
+  memcpy(buffer, cbUTF16Str.c_str(), size * sizeof(unsigned short));
   cbUTF16Str.ReleaseBuffer(size * sizeof(unsigned short));
 
   return size;
@@ -352,7 +351,7 @@ FPDF_EXPORT int FPDF_CALLCONV FPDFLink_GetURL(FPDF_PAGELINK link_page,
   int size = std::min(required, buflen);
   if (size > 0) {
     int buf_size = size * sizeof(unsigned short);
-    memcpy(buffer, cbUTF16URL.GetBuffer(buf_size), buf_size);
+    memcpy(buffer, cbUTF16URL.c_str(), buf_size);
   }
   return size;
 }
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
index c9087e8a0b..1b503b3fca 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
@@ -404,8 +404,7 @@ void CPDFXFA_DocEnvironment::GetTitle(CXFA_FFDoc* hDoc, WideString& wsTitle) {
     return;
 
   ByteString csTitle = pInfoDict->GetStringFor("Title");
-  wsTitle = wsTitle.FromLocal(csTitle.GetBuffer(csTitle.GetLength()));
-  csTitle.ReleaseBuffer(csTitle.GetLength());
+  wsTitle = WideString::FromLocal(csTitle.c_str());
 }
 
 void CPDFXFA_DocEnvironment::SetTitle(CXFA_FFDoc* hDoc,
@@ -442,11 +441,8 @@ void CPDFXFA_DocEnvironment::ExportData(CXFA_FFDoc* hDoc,
     WideString filepath = pFormFillEnv->JS_fieldBrowse();
     bs = filepath.UTF16LE_Encode();
   }
-  int len = bs.GetLength();
-  FPDF_FILEHANDLER* pFileHandler =
-      pFormFillEnv->OpenFile(bXDP ? FXFA_SAVEAS_XDP : FXFA_SAVEAS_XML,
-                             (FPDF_WIDESTRING)bs.GetBuffer(len), "wb");
-  bs.ReleaseBuffer(len);
+  FPDF_FILEHANDLER* pFileHandler = pFormFillEnv->OpenFile(
+      bXDP ? FXFA_SAVEAS_XDP : FXFA_SAVEAS_XML, AsFPDFWideString(&bs), "wb");
   if (!pFileHandler)
     return;
 
@@ -662,16 +658,14 @@ bool CPDFXFA_DocEnvironment::OnBeforeNotifySubmit() {
 
       WideString ws = WideString::FromLocal(IDS_XFA_Validate_Input);
       ByteString bs = ws.UTF16LE_Encode();
-      int len = bs.GetLength();
-      pFormFillEnv->Alert((FPDF_WIDESTRING)bs.GetBuffer(len),
-                          (FPDF_WIDESTRING)L"", 0, 1);
-      bs.ReleaseBuffer(len);
+      pFormFillEnv->Alert(AsFPDFWideString(&bs),
+                          reinterpret_cast<FPDF_WIDESTRING>(L""), 0, 1);
       return false;
     }
     pNode = it->MoveToNext();
   }
-  docView->UpdateDocView();
 
+  docView->UpdateDocView();
   return true;
 }
 
@@ -719,10 +713,8 @@ RetainPtr<IFX_SeekableReadStream> CPDFXFA_DocEnvironment::OpenLinkedFile(
     return nullptr;
 
   ByteString bs = wsLink.UTF16LE_Encode();
-  int len = bs.GetLength();
   FPDF_FILEHANDLER* pFileHandler =
-      pFormFillEnv->OpenFile(0, (FPDF_WIDESTRING)bs.GetBuffer(len), "rb");
-  bs.ReleaseBuffer(len);
+      pFormFillEnv->OpenFile(0, AsFPDFWideString(&bs), "rb");
   if (!pFileHandler)
     return nullptr;
 
@@ -919,10 +911,8 @@ bool CPDFXFA_DocEnvironment::SubmitInternal(CXFA_FFDoc* hDoc,
   if (csURL.IsEmpty()) {
     WideString ws = WideString::FromLocal("Submit cancelled.");
     ByteString bs = ws.UTF16LE_Encode();
-    int len = bs.GetLength();
-    pFormFillEnv->Alert(reinterpret_cast<FPDF_WIDESTRING>(bs.GetBuffer(len)),
+    pFormFillEnv->Alert(AsFPDFWideString(&bs),
                         reinterpret_cast<FPDF_WIDESTRING>(L""), 0, 4);
-    bs.ReleaseBuffer(len);
     return false;
   }
 
@@ -978,27 +968,15 @@ bool CPDFXFA_DocEnvironment::SubmitInternal(CXFA_FFDoc* hDoc,
     ByteString bsBcc = WideString(csBCCAddress).UTF16LE_Encode();
     ByteString bsSubject = WideString(csSubject).UTF16LE_Encode();
     ByteString bsMsg = WideString(csMsg).UTF16LE_Encode();
-    FPDF_WIDESTRING pTo = (FPDF_WIDESTRING)bsTo.GetBuffer(bsTo.GetLength());
-    FPDF_WIDESTRING pCC = (FPDF_WIDESTRING)bsCC.GetBuffer(bsCC.GetLength());
-    FPDF_WIDESTRING pBcc = (FPDF_WIDESTRING)bsBcc.GetBuffer(bsBcc.GetLength());
-    FPDF_WIDESTRING pSubject =
-        (FPDF_WIDESTRING)bsSubject.GetBuffer(bsSubject.GetLength());
-    FPDF_WIDESTRING pMsg = (FPDF_WIDESTRING)bsMsg.GetBuffer(bsMsg.GetLength());
-    pFormFillEnv->EmailTo(pFileHandler, pTo, pSubject, pCC, pBcc, pMsg);
-    bsTo.ReleaseBuffer(bsTo.GetStringLength());
-    bsCC.ReleaseBuffer(bsCC.GetStringLength());
-    bsBcc.ReleaseBuffer(bsBcc.GetStringLength());
-    bsSubject.ReleaseBuffer(bsSubject.GetStringLength());
-    bsMsg.ReleaseBuffer(bsMsg.GetStringLength());
-  } else {
-    // HTTP or FTP
-    WideString ws;
-    ByteString bs = csURL.UTF16LE_Encode();
-    int len = bs.GetLength();
-    pFormFillEnv->UploadTo(pFileHandler, fileFlag,
-                           (FPDF_WIDESTRING)bs.GetBuffer(len));
-    bs.ReleaseBuffer(len);
+    pFormFillEnv->EmailTo(pFileHandler, AsFPDFWideString(&bsTo),
+                          AsFPDFWideString(&bsSubject), AsFPDFWideString(&bsCC),
+                          AsFPDFWideString(&bsBcc), AsFPDFWideString(&bsMsg));
+    return true;
   }
+
+  // HTTP or FTP
+  ByteString bs = csURL.UTF16LE_Encode();
+  pFormFillEnv->UploadTo(pFileHandler, fileFlag, AsFPDFWideString(&bs));
   return true;
 }
 
diff --git a/fxjs/cjs_document.cpp b/fxjs/cjs_document.cpp
index 83711e1b28..2a36b61a4a 100644
--- a/fxjs/cjs_document.cpp
+++ b/fxjs/cjs_document.cpp
@@ -942,11 +942,9 @@ CJS_Return CJS_Document::get_document_file_name(CJS_Runtime* pRuntime) {
     if (wsFilePath[i - 1] == L'\\' || wsFilePath[i - 1] == L'/')
       break;
   }
+  if (i > 0 && i < wsFilePath.GetLength())
+    return CJS_Return(pRuntime->NewString(wsFilePath.c_str() + i));
 
-  if (i > 0 && i < wsFilePath.GetLength()) {
-    return CJS_Return(
-        pRuntime->NewString(wsFilePath.GetBuffer(wsFilePath.GetLength()) + i));
-  }
   return CJS_Return(pRuntime->NewString(L""));
 }
 
diff --git a/xfa/fxfa/cxfa_linkuserdata.cpp b/xfa/fxfa/cxfa_linkuserdata.cpp
index c32b74664c..84cee352a7 100644
--- a/xfa/fxfa/cxfa_linkuserdata.cpp
+++ b/xfa/fxfa/cxfa_linkuserdata.cpp
@@ -6,7 +6,7 @@
 
 #include "xfa/fxfa/cxfa_linkuserdata.h"
 
-CXFA_LinkUserData::CXFA_LinkUserData(wchar_t* pszText)
+CXFA_LinkUserData::CXFA_LinkUserData(const wchar_t* pszText)
     : m_wsURLContent(pszText) {}
 
 CXFA_LinkUserData::~CXFA_LinkUserData() {}
diff --git a/xfa/fxfa/cxfa_linkuserdata.h b/xfa/fxfa/cxfa_linkuserdata.h
index 3d0f95e91c..f62bd3c044 100644
--- a/xfa/fxfa/cxfa_linkuserdata.h
+++ b/xfa/fxfa/cxfa_linkuserdata.h
@@ -19,7 +19,7 @@ class CXFA_LinkUserData : public Retainable {
   const wchar_t* GetLinkURL() const { return m_wsURLContent.c_str(); }
 
  private:
-  explicit CXFA_LinkUserData(wchar_t* pszText);
+  explicit CXFA_LinkUserData(const wchar_t* pszText);
   ~CXFA_LinkUserData() override;
 
   WideString m_wsURLContent;
diff --git a/xfa/fxfa/cxfa_textlayout.cpp b/xfa/fxfa/cxfa_textlayout.cpp
index 41d46f8824..e360c16dde 100644
--- a/xfa/fxfa/cxfa_textlayout.cpp
+++ b/xfa/fxfa/cxfa_textlayout.cpp
@@ -746,9 +746,8 @@ bool CXFA_TextLayout::LoadRichText(
           ASSERT(pElement);
           WideString wsLinkContent = pElement->GetString(L"href");
           if (!wsLinkContent.IsEmpty()) {
-            pLinkData = pdfium::MakeRetain<CXFA_LinkUserData>(
-                wsLinkContent.GetBuffer(wsLinkContent.GetLength()));
-            wsLinkContent.ReleaseBuffer(wsLinkContent.GetLength());
+            pLinkData =
+                pdfium::MakeRetain<CXFA_LinkUserData>(wsLinkContent.c_str());
           }
         }