From ef4f74aa942f385f3a944edc11ceba9ebde0720b Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Thu, 22 Apr 2021 23:16:03 +0200
Subject: [PATCH] Gui: fix memory leak in SelectionParser::yyparse()

---
 src/Gui/SelectionFilter.cpp   | 26 ++++++++++++++++++++++++++
 src/Gui/SelectionFilter.h     |  4 +---
 src/Gui/SelectionFilter.l     |  2 +-
 src/Gui/SelectionFilter.tab.c |  2 +-
 src/Gui/SelectionFilter.y     | 22 +++++++++++-----------
 src/Gui/lex.SelectionFilter.c |  2 +-
 6 files changed, 41 insertions(+), 17 deletions(-)

diff --git a/src/Gui/SelectionFilter.cpp b/src/Gui/SelectionFilter.cpp
index dd4e2d89d91b..5c6d26a59028 100644
--- a/src/Gui/SelectionFilter.cpp
+++ b/src/Gui/SelectionFilter.cpp
@@ -363,6 +363,31 @@ int fileno(FILE *stream) {return _fileno(stream);}
 
 namespace SelectionParser {
 
+/*!
+ * \brief The StringFactory class
+ * Helper class to record the created strings used by the parser.
+ */
+class StringFactory {
+    std::list<std::unique_ptr<std::string>> data;
+    std::size_t max_elements = 20;
+public:
+    static StringFactory* instance() {
+        static StringFactory* inst = new StringFactory();
+        return inst;
+    }
+    std::string* make(const std::string& str) {
+        data.push_back(std::make_unique<std::string>(str));
+        return data.back().get();
+    }
+    static std::string* New(const std::string& str) {
+        return StringFactory::instance()->make(str);
+    }
+    void clear() {
+        if (data.size() > max_elements)
+            data.clear();
+    }
+};
+
 // show the parser the lexer method
 #define yylex SelectionFilterlex
 int SelectionFilterlex(void);
@@ -401,6 +426,7 @@ bool SelectionFilter::parse(void)
     Ast.reset(TopBlock);
     TopBlock = 0;
     SelectionParser::SelectionFilter_delete_buffer (my_string_buffer);
+    SelectionParser::StringFactory::instance()->clear();
 
     if (Errors.empty()) {
         return true;
diff --git a/src/Gui/SelectionFilter.h b/src/Gui/SelectionFilter.h
index 7f625f854ef6..505b0db9c4d9 100644
--- a/src/Gui/SelectionFilter.h
+++ b/src/Gui/SelectionFilter.h
@@ -207,10 +207,8 @@ struct Node_Object
         :Slice(slc)
     {
         ObjectType = Base::Type::fromName(type->c_str());
-        delete (type);
-        if(subname){
+        if (subname) {
             SubName = *subname;
-            delete subname;
         }
     }
     ~Node_Object(){
diff --git a/src/Gui/SelectionFilter.l b/src/Gui/SelectionFilter.l
index eda00025a775..fe96a20d6b87 100644
--- a/src/Gui/SelectionFilter.l
+++ b/src/Gui/SelectionFilter.l
@@ -58,7 +58,7 @@
 "::"					return TNAMESPACE;
 
 [a-zA-Z_][a-zA-Z0-9_]*  {
-       yylval.string = new std::string(yytext);
+       yylval.string = StringFactory::New(yytext);
        return TIDENTIFIER;
       }
 [0-9]+                  {
diff --git a/src/Gui/SelectionFilter.tab.c b/src/Gui/SelectionFilter.tab.c
index 5dabdbc950f4..9d136765b3f6 100644
--- a/src/Gui/SelectionFilter.tab.c
+++ b/src/Gui/SelectionFilter.tab.c
@@ -1345,7 +1345,7 @@ yyparse ()
 
 /* Line 1464 of yacc.c  */
 #line 40 "SelectionFilter.y"
-    { (yyval.string) = new std::string(*(yyvsp[(2) - (4)].string) + "::" + *(yyvsp[(4) - (4)].string)) ;}
+    { (yyval.string) = StringFactory::New(*(yyvsp[(2) - (4)].string) + "::" + *(yyvsp[(4) - (4)].string)) ;}
     break;
 
   case 4:
diff --git a/src/Gui/SelectionFilter.y b/src/Gui/SelectionFilter.y
index 051599e7ed6d..e82d4c109ba7 100644
--- a/src/Gui/SelectionFilter.y
+++ b/src/Gui/SelectionFilter.y
@@ -55,25 +55,25 @@
 
 
 
-type  : TSELECT TIDENTIFIER							{ $$ = $2 }
-       | TSELECT TIDENTIFIER TNAMESPACE TIDENTIFIER { $$ = new std::string(*$2 + "::" + *$4) }
+type  : TSELECT TIDENTIFIER							{ $$ = $2; }
+       | TSELECT TIDENTIFIER TNAMESPACE TIDENTIFIER { $$ = StringFactory::New(*$2 + "::" + *$4); }
 
-subname :								 { $$ = 0  }
-		 | TSUB TIDENTIFIER				 { $$ = $2 }
+subname :								 { $$ = 0;  }
+         | TSUB TIDENTIFIER				 { $$ = $2; }
 
-count :									 { $$ = 0                     }
-      | TCOUNT TNUMBER TSLICE TNUMBER    { $$ = new Node_Slice($2,$4) }
-      | TCOUNT TNUMBER TSLICE            { $$ = new Node_Slice($2)    }
-      | TCOUNT TNUMBER                   { $$ = new Node_Slice($2,$2) }
+count :									 { $$ = 0;                     }
+      | TCOUNT TNUMBER TSLICE TNUMBER    { $$ = new Node_Slice($2,$4); }
+      | TCOUNT TNUMBER TSLICE            { $$ = new Node_Slice($2);    }
+      | TCOUNT TNUMBER                   { $$ = new Node_Slice($2,$2); }
 
-matchline  : type subname count                { $$ = new Node_Object($1,$2,$3) }
+matchline  : type subname count                { $$ = new Node_Object($1,$2,$3); }
 
 matchlines : matchline            { $$ = new Node_Block($1);  }
            | matchlines matchline { $$ = $1 ; $$->Objects.emplace_back($2); }
 
-block : matchlines                { $$ = $1 }
+block : matchlines                { $$ = $1; }
 
-filter:   block					  { TopBlock = $1 }
+filter:   block					  { TopBlock = $1; }
 ;
 
 
diff --git a/src/Gui/lex.SelectionFilter.c b/src/Gui/lex.SelectionFilter.c
index 1518012aa4f8..4e0c03f462bd 100644
--- a/src/Gui/lex.SelectionFilter.c
+++ b/src/Gui/lex.SelectionFilter.c
@@ -856,7 +856,7 @@ case 8:
 YY_RULE_SETUP
 #line 41 "SelectionFilter.l"
 {
-       yylval.string = new std::string(SelectionFiltertext);
+       yylval.string = StringFactory::New(SelectionFiltertext);
        return TIDENTIFIER;
       }
 	YY_BREAK