removing unsafe sscanf from parse function of double-double

stillwater-sc · Aug 5, 2024 · fe434b9 · fe434b9
1 parent 790f889
commit fe434b9
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Showing 3 changed files with 64 additions and 18 deletions.
diff --git a/include/universal/number/dd/dd_impl.hpp b/include/universal/number/dd/dd_impl.hpp
@@ -550,7 +550,7 @@ class dd {
 				}
 			}
 
-			if (scientific && !isinf()) {
+			if (!fixed && !isinf()) {
 				// construct the exponent
 				s += uppercase ? 'E' : 'e';
 				append_expn(s, e);
@@ -1055,16 +1055,23 @@ bool parse(const std::string& number, dd& value) {
 	dd r{ 0.0 };
 	int nrDigits{ 0 };
 	int decimalPoint{ -1 };
-	int sign{ 0 };
+	int sign{ 0 }, eSign{ 1 };
 	int e{ 0 };
-	bool done = false;
+	bool done{ false }, parsingMantissa{ true };
 	char ch;
 	while (!done && (ch = *p) != '\0') {
 		if (std::isdigit(ch)) {
-			int digit = ch - '0';
-			r *= 10.0;
-			r += static_cast<double>(digit);
-			++nrDigits;
+			if (parsingMantissa) {
+				int digit = ch - '0';
+				r *= 10.0;
+				r += static_cast<double>(digit);
+				++nrDigits;
+			}
+			else { // parsing exponent section
+				int digit = ch - '0';
+				e *= 10;
+				e += digit;
+			}
 		}
 		else {
 			switch (ch) {
@@ -1075,26 +1082,28 @@ bool parse(const std::string& number, dd& value) {
 
 			case '-':
 			case '+':
-				if (sign != 0 || nrDigits > 0) return false;
-				sign = (ch == '-') ? -1 : 1;
+				if (parsingMantissa) {
+					if (sign != 0 || nrDigits > 0) return false;
+					sign = (ch == '-' ? -1 : 1);
+				}
+				else {
+					eSign = (ch == '-' ? -1 : 1);
+				}
 				break;
 
 			case 'E':
 			case 'e':
-			{
-				int nread = std::sscanf(p + 1, "%d", &e);
-				done = true;
-				if (nread != 1)
-					return false;
+				parsingMantissa = false;
 				break;
-			}
+
 			default:
 				return false;
 			}
 		}
 
 		++p;
 	}
+	e *= eSign;
 
 	if (decimalPoint >= 0) e -= (nrDigits - decimalPoint);
 	dd _ten(10.0, 0.0);

diff --git a/static/dd/api/api.cpp b/static/dd/api/api.cpp
@@ -25,7 +25,7 @@ namespace sw {
 		void Progression(Real v) {
 			using namespace sw::universal;
 
-			int oldPrec = std::cout.precision();
+			auto oldPrec = std::cout.precision();
 			float f{ float(v) };
 			std::cout << std::setprecision(7);
 			std::cout << to_binary(f, true) << " : " << f << '\n';

diff --git a/static/dd/api/constants.cpp b/static/dd/api/constants.cpp
@@ -64,6 +64,19 @@ namespace sw {
 			dd _inv_sqrt2("0.707106781186547524400844362104849039"); report(_inv_sqrt2);
 		}
 
+		int VerifyParse(const std::string& str) {
+			int nrFailedTestCases{ 0 };
+			dd v{};
+			if (!parse(str, v)) {
+				std::cerr << "failed to parse " << str << '\n';
+				++nrFailedTestCases;
+			}
+			else {
+				ReportValue(v, str);
+				std::cout << "PASS\n";
+			}
+			return nrFailedTestCases;
+		}
 	}
 }
 
@@ -87,8 +100,8 @@ int main()
 try {
 	using namespace sw::universal;
 
-	std::string test_suite         = "doubledouble conversion validation";
-	std::string test_tag           = "doubledouble conversion";
+	std::string test_suite         = "doubledouble constants";
+	std::string test_tag           = "dd constants";
 	bool reportTestCases           = false;
 	int nrOfFailedTestCases        = 0;
 
@@ -124,6 +137,30 @@ try {
 	std::cout << to_pair(f) << '\n';
 
 
+	// parsing scientific formats
+	VerifyParse("12.5e-2");
+	VerifyParse("12.5e-1");
+	VerifyParse("12.5e-0");
+	VerifyParse("12.5e+1");
+	VerifyParse("12.5e2");
+	VerifyParse("12.5e-02");
+	VerifyParse("12.5e-01");
+	VerifyParse("12.5e00");
+	VerifyParse("12.5e+01");
+	VerifyParse("12.5e02");
+	VerifyParse("12.5e-002");
+	VerifyParse("12.5e-001");
+	VerifyParse("12.5e000");
+	VerifyParse("12.5e+001");
+	VerifyParse("12.5e002");
+	VerifyParse("12.5e-200");
+	VerifyParse("12.5e-100");
+	VerifyParse("12.5e000");
+	VerifyParse("12.5e+100");
+	VerifyParse("12.5e200");
+
+	d = 12.5e200;
+	std::cout << d << '\n';
 
 	ReportTestSuiteResults(test_suite, nrOfFailedTestCases);
 	return EXIT_SUCCESS; // ignore failures