Fix a crasher in LoadFont() when non-standard font is used in XFA files

This CL includes the following changes:
1. Add return value for InitFont(). It can indicate a failure
   in the initialization of non-standard fonts.
2. Change NULL to nullptr.
3. Rewrite several pointer checking.

BUG=pdfium:279, pdfium:286
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1465423002 .

2 files changed, 33 insertions, 42 deletions

diff --git a/xfa/src/fgas/src/font/fx_gefont.cpp b/xfa/src/fgas/src/font/fx_gefont.cpp
index 280e0fb8cd..e3f04796de 100644
--- a/xfa/src/fgas/src/font/fx_gefont.cpp
+++ b/xfa/src/fgas/src/font/fx_gefont.cpp
@@ -189,7 +189,7 @@ IFX_Font* CFX_GEFont::Retain() {
 FX_BOOL CFX_GEFont::LoadFont(const FX_WCHAR* pszFontFamily,

                              FX_DWORD dwFontStyles,

                              FX_WORD wCodePage) {

-  if (m_pFont != NULL) {

+  if (m_pFont) {

     return FALSE;

   }

   Lock();

@@ -237,33 +237,27 @@ FX_BOOL CFX_GEFont::LoadFont(const FX_WCHAR* pszFontFamily,
   m_pFont->LoadSubst(csFontFamily, TRUE, dwFlags, iWeight, 0, wCodePage);

   FX_BOOL bRet = m_pFont->GetFace() != nullptr;

   if (bRet) {

-    InitFont();

+    bRet = InitFont();

   }

   Unlock();

   return bRet;

 }

 FX_BOOL CFX_GEFont::LoadFont(const uint8_t* pBuffer, int32_t length) {

-  if (m_pFont != NULL) {

+  if (m_pFont) {

     return FALSE;

   }

   Lock();

   m_pFont = new CFX_Font;

   FX_BOOL bRet = m_pFont->LoadEmbedded(pBuffer, length);

   if (bRet) {

-    InitFont();

+    bRet = InitFont();

   }

   m_wCharSet = 0xFFFF;

   Unlock();

   return bRet;

 }

 FX_BOOL CFX_GEFont::LoadFont(const FX_WCHAR* pszFileName) {

-  if (m_pFont != NULL) {

-    return FALSE;

-  }

-  if (m_pStream != NULL) {

-    return FALSE;

-  }

-  if (m_pFileRead != NULL) {

+  if (m_pFont || m_pStream || m_pFileRead) {

     return FALSE;

   }

   Lock();

@@ -271,14 +265,14 @@ FX_BOOL CFX_GEFont::LoadFont(const FX_WCHAR* pszFileName) {
       pszFileName, FX_STREAMACCESS_Binary | FX_STREAMACCESS_Read);

   m_pFileRead = FX_CreateFileRead(m_pStream);

   FX_BOOL bRet = FALSE;

-  if (m_pStream != NULL && m_pFileRead != NULL) {

+  if (m_pStream && m_pFileRead) {

     m_pFont = new CFX_Font;

     bRet = m_pFont->LoadFile(m_pFileRead);

-    if (!bRet) {

-      m_pFileRead->Release();

-      m_pFileRead = NULL;

+    if (bRet) {

+      bRet = InitFont();

     } else {

-      InitFont();

+      m_pFileRead->Release();

+      m_pFileRead = nullptr;

     }

   }

   m_wCharSet = 0xFFFF;

@@ -286,13 +280,7 @@ FX_BOOL CFX_GEFont::LoadFont(const FX_WCHAR* pszFileName) {
   return bRet;

 }

 FX_BOOL CFX_GEFont::LoadFont(IFX_Stream* pFontStream, FX_BOOL bSaveStream) {

-  if (m_pFont != NULL) {

-    return FALSE;

-  }

-  if (pFontStream == NULL || pFontStream->GetLength() < 1) {

-    return FALSE;

-  }

-  if (m_pFileRead != NULL) {

+  if (m_pFont || m_pFileRead || !pFontStream || pFontStream->GetLength() < 1) {

     return FALSE;

   }

   Lock();

@@ -302,50 +290,53 @@ FX_BOOL CFX_GEFont::LoadFont(IFX_Stream* pFontStream, FX_BOOL bSaveStream) {
   m_pFileRead = FX_CreateFileRead(pFontStream);

   m_pFont = new CFX_Font;

   FX_BOOL bRet = m_pFont->LoadFile(m_pFileRead);

-  if (!bRet) {

-    m_pFileRead->Release();

-    m_pFileRead = NULL;

+  if (bRet) {

+    bRet = InitFont();

   } else {

-    InitFont();

+    m_pFileRead->Release();

+    m_pFileRead = nullptr;

   }

   m_wCharSet = 0xFFFF;

   Unlock();

   return bRet;

 }

 FX_BOOL CFX_GEFont::LoadFont(CFX_Font* pExtFont, FX_BOOL bTakeOver) {

-  if (m_pFont != NULL) {

-    return FALSE;

-  }

-  if (pExtFont == NULL) {

+  if (m_pFont || !pExtFont) {

     return FALSE;

   }

   Lock();

-  if ((m_pFont = pExtFont) != NULL) {

+  m_pFont = pExtFont;

+  FX_BOOL bRet = !!m_pFont;

+  if (bRet) {

     m_bExtFont = !bTakeOver;

-    InitFont();

+    bRet = InitFont();

   } else {

     m_bExtFont = TRUE;

   }

   m_wCharSet = 0xFFFF;

   Unlock();

-  return m_pFont != NULL;

+  return bRet;

 }

-void CFX_GEFont::InitFont() {

-  if (m_pFont == NULL) {

-    return;

+FX_BOOL CFX_GEFont::InitFont() {

+  if (!m_pFont) {

+    return FALSE;

   }

-  if (m_pFontEncoding == NULL) {

+  if (!m_pFontEncoding) {

     m_pFontEncoding = FX_CreateFontEncodingEx(m_pFont);

+    if (!m_pFontEncoding) {

+      return FALSE;

+    }

   }

-  if (m_pCharWidthMap == NULL) {

+  if (!m_pCharWidthMap) {

     m_pCharWidthMap = new CFX_WordDiscreteArray(1024);

   }

-  if (m_pRectArray == NULL) {

+  if (!m_pRectArray) {

     m_pRectArray = new CFX_RectMassArray(16);

   }

-  if (m_pBBoxMap == NULL) {

+  if (!m_pBBoxMap) {

     m_pBBoxMap = new CFX_MapPtrToPtr(16);

   }

+  return TRUE;

 }

 IFX_Font* CFX_GEFont::Derive(FX_DWORD dwFontStyles, FX_WORD wCodePage) {

   if (GetFontStyles() == dwFontStyles) {

diff --git a/xfa/src/fgas/src/font/fx_gefont.h b/xfa/src/fgas/src/font/fx_gefont.h
index 5620f07bf2..a85cffa5e5 100644
--- a/xfa/src/fgas/src/font/fx_gefont.h
+++ b/xfa/src/fgas/src/font/fx_gefont.h
@@ -72,7 +72,7 @@ class CFX_GEFont : public IFX_Font, public CFX_ThreadLock {
   FX_WORD m_wCharSet;

   CFX_PtrArray m_SubstFonts;

   CFX_MapPtrToPtr m_FontMapper;

-  void InitFont();

+  FX_BOOL InitFont();

   FX_BOOL GetCharBBox(FX_WCHAR wUnicode,

                       CFX_Rect& bbox,

                       FX_BOOL bRecursive,