diff options
| -rw-r--r-- | core/src/fxcrt/fx_basic_bstring.cpp | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/core/src/fxcrt/fx_basic_bstring.cpp b/core/src/fxcrt/fx_basic_bstring.cpp index 961aebe69c..2c8f7a766b 100644 --- a/core/src/fxcrt/fx_basic_bstring.cpp +++ b/core/src/fxcrt/fx_basic_bstring.cpp @@ -52,13 +52,25 @@ static CFX_StringData* FX_AllocString(int nLen) if (nLen == 0 || nLen < 0) { return NULL; } + + int overhead = sizeof(long) * 3 + 1; // 3 longs in header plus 1 for NUL. pdfium::base::CheckedNumeric<int> nSize = nLen; - nSize += sizeof(long) * 3 + 1; - CFX_StringData* pData = (CFX_StringData*)FX_Alloc(FX_BYTE, nSize.ValueOrDie()); + nSize += overhead; + + // Now round to an 8-byte boundary. We'd expect that this is the minimum + // granularity of any of the underlying allocators, so there may be cases + // where we can save a re-alloc when adding a few characters to a string + // by using this otherwise wasted space. + nSize += 7; + int totalSize = nSize.ValueOrDie() & ~7; + int usableSize = totalSize - overhead; + FXSYS_assert(usableSize >= nLen); + + CFX_StringData* pData = (CFX_StringData*)FX_Alloc(FX_BYTE, totalSize); if (!pData) { return NULL; } - pData->m_nAllocLength = nLen; + pData->m_nAllocLength = usableSize; pData->m_nDataLength = nLen; pData->m_nRefs = 1; pData->m_String[nLen] = 0; |