Base: Fixed segfault on destructing cached string (#20563)

* Base: Fixed segfault on destructing cached string

Xerces default memory manager is deleted before destructing static local
variable and segfault.

---------

Co-authored-by: Chris Hennes <chennes@pioneerlibrarysystem.org>

src/Base/PreCompiled.h

@@ -67,6 +67,7 @@
 #include <map>
 #include <memory>
 #include <mutex>
+#include <new>
 #include <numbers>
 #include <queue>
 #include <set>
@@ -82,6 +83,7 @@
 #include <sstream>
 
 // Xerces
+#include <xercesc/util/OutOfMemoryException.hpp>
 #include <xercesc/util/PlatformUtils.hpp>
 #include <xercesc/util/XercesVersion.hpp>
 #include <xercesc/dom/DOM.hpp>
@@ -95,6 +97,7 @@
 #include <xercesc/framework/LocalFileInputSource.hpp>
 #include <xercesc/framework/MemBufFormatTarget.hpp>
 #include <xercesc/framework/MemBufInputSource.hpp>
+#include <xercesc/framework/MemoryManager.hpp>
 #include <xercesc/parsers/XercesDOMParser.hpp>
 #include <xercesc/util/XMLUni.hpp>
 #include <xercesc/util/XMLUniDefs.hpp>

src/Base/XMLTools.cpp

@@ -23,6 +23,11 @@
 
 #include "PreCompiled.h"
 
+#ifndef _PreComp_
+#include <xercesc/framework/MemoryManager.hpp>
+#include <xercesc/util/OutOfMemoryException.hpp>
+#endif
+
 #include "Exception.h"
 #include "XMLTools.h"
 
@@ -128,3 +133,19 @@ void XMLTools::terminate()
 {
     transcoder.reset();
 }
+
+void* XStrMemoryManager::allocate(XMLSize_t size)
+{
+    auto ptr = ::operator new(static_cast<size_t>(size),
+                              static_cast<std::align_val_t>(alignof(XMLCh)),
+                              std::nothrow);
+    if (ptr == nullptr && size != 0) {
+        throw XERCES_CPP_NAMESPACE::OutOfMemoryException();
+    }
+    return ptr;
+}
+
+void XStrMemoryManager::deallocate(void* p)
+{
+    ::operator delete(p);
+}

src/Base/XMLTools.h

@@ -28,6 +28,7 @@
 #include <memory>
 #include <ostream>
 #include <xercesc/util/TransService.hpp>
+#include <xercesc/framework/MemoryManager.hpp>
 
 #ifndef XERCES_CPP_NAMESPACE_BEGIN
 #define XERCES_CPP_NAMESPACE_QUALIFIER
@@ -58,6 +59,23 @@ private:
     static std::unique_ptr<XERCES_CPP_NAMESPACE::XMLTranscoder> transcoder;  // NOLINT
 };
 
+// Helper class for XStrLiteral macro
+// This implementation is almost same as Xerces default memory manager.
+class BaseExport XStrMemoryManager final: public XERCES_CPP_NAMESPACE::MemoryManager
+{
+public:
+    XStrMemoryManager() = default;
+    ~XStrMemoryManager() = default;
+
+    MemoryManager* getExceptionMemoryManager() override
+    {
+        return this;
+    }
+
+    void* allocate(XMLSize_t size) override;
+    void deallocate(void* p) override;
+};
+
 //**************************************************************************
 //**************************************************************************
 // StrXLocal
@@ -149,6 +167,8 @@ class XStr
 public:
     ///  Constructors and Destructor
     explicit XStr(const char* const toTranscode);
+    explicit XStr(const char* const toTranscode,
+                  XERCES_CPP_NAMESPACE_QUALIFIER MemoryManager* memMgr);
     ~XStr();
 
 
@@ -159,24 +179,35 @@ public:
 private:
     /// This is the Unicode XMLCh format of the string.
     XMLCh* fUnicodeForm;
+    XERCES_CPP_NAMESPACE_QUALIFIER MemoryManager* memMgr;
 };
 
 
 inline XStr::XStr(const char* const toTranscode)
-    : fUnicodeForm(XERCES_CPP_NAMESPACE_QUALIFIER XMLString::transcode(toTranscode))
+    : XStr(toTranscode, XERCES_CPP_NAMESPACE_QUALIFIER XMLPlatformUtils::fgMemoryManager)
+{}
+
+inline XStr::XStr(const char* const toTranscode,
+                  XERCES_CPP_NAMESPACE_QUALIFIER MemoryManager* memMgr)
+    : fUnicodeForm(XERCES_CPP_NAMESPACE_QUALIFIER XMLString::transcode(toTranscode, memMgr))
+    , memMgr(memMgr)
 {}
 
 inline XStr::~XStr()
 {
-    XERCES_CPP_NAMESPACE_QUALIFIER XMLString::release(&fUnicodeForm);
+    XERCES_CPP_NAMESPACE_QUALIFIER XMLString::release(&fUnicodeForm, memMgr);
 }
 
 // Uses the compiler to create a cache of transcoded string literals so that each subsequent call
 // can reuse the data from the lambda's initial creation. Permits the same usage as
 // XStr("literal").unicodeForm()
+// XStrLiteral macro use local memory manager instance to prevent segfault on releasing cached
+// string because xerces default memory manager is already deleted when destructing local static
+// variable.
 #define XStrLiteral(literal)                                                                       \
     ([]() -> const XStr& {                                                                         \
-        static const XStr str {literal};                                                           \
+        static XStrMemoryManager memMgr;                                                           \
+        static const XStr str {literal, &memMgr};                                                  \
         return str;                                                                                \
     }())