[GiNaC-devel] [PATCH] Constructing expression from a string does not leak memory any more.

[Alexei Sheplyakov]

Thanks to valgrind for spotting this.

---
 check/parser_memleak.cpp |   36 ++++++++++++++++++++++++++++++++++++
 ginac/input_lexer.ll     |    4 +++-
 2 files changed, 39 insertions(+), 1 deletions(-)
 create mode 100644 check/parser_memleak.cpp

diff --git a/check/parser_memleak.cpp b/check/parser_memleak.cpp
new file mode 100644
index 0000000..f347ce9
--- /dev/null
+++ b/check/parser_memleak.cpp
@@ -0,0 +1,36 @@
+/**
+ * This small program exhibits the memory leak in the ginac_yylex().
+ * Run it as
+ *
+ * valgrind --leak-check=yes  ./parser_memleak
+ *
+ * or simply
+ *
+ * ulimit -v `expr 64 \* 1024` ./parser_memleak
+ */
+#include <iostream>
+#include <stdexcept>
+#include <ginac/ginac.h>
+using namespace std;
+using namespace GiNaC;
+
+int main(int argc, char** argv) {
+	const symbol x("x"), y("y");
+	const lst syms(x, y);
+	// parser-generated symbol => memory leak.
+	static const char* str[] = { "x^2+2*x*y + cos(x)", "Li2(x/y) + log(y/x)" };
+	
+	// depends on the amount of the available VM, compiler options, etc.
+	const unsigned N_max = 500000;
+	unsigned N=0;
+	ex e;
+	try {
+		for (; N < N_max; N++) {
+			e = ex(str[N & 1], syms);
+		}
+	} catch (std::bad_alloc) {
+		cerr << "N = " << N << endl;
+		return 1;
+	}
+	return 0;
+}
diff --git a/ginac/input_lexer.ll b/ginac/input_lexer.ll
index f931394..bc568ce 100644
--- a/ginac/input_lexer.ll
+++ b/ginac/input_lexer.ll
@@ -119,7 +119,9 @@ Digits			ginac_yylval = (long)Digits; return T_DIGITS;
 {A}{AN}*		{
 				sym_tab::const_iterator i = syms.find(yytext);
 				if (i == syms.end()) {
-					syms[yytext] = sym_def(ginac_yylval = *(new symbol(yytext)), false);
+					symbol tmp(yytext);
+					ginac_yylval = tmp;
+					syms[yytext] = sym_def(tmp, false);
 				} else
 					ginac_yylval = (*i).second.sym;
 				return T_SYMBOL;
-- 
1.5.3.2

Best regards,
	Alexei

-- 
All science is either physics or stamp collecting.

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