Detect integer overflow/underflow

include/qpdf/QUtil.hh

@@ -29,8 +29,12 @@ namespace QUtil
     QPDF_DLL
     std::string double_to_string(double, int decimal_places = 0);
 
+    // These string to number methods throw std::runtime_error on
+    // underflow/overflow.
     QPDF_DLL
     long long string_to_ll(char const* str);
+    QPDF_DLL
+    int string_to_int(char const* str);
 
     // Pipeline's write method wants unsigned char*, but we often have
     // some other type of string.  These methods do combinations of

libqpdf/QUtil.cc

@@ -81,11 +81,40 @@ QUtil::double_to_string(double num, int decimal_places)
 long long
 QUtil::string_to_ll(char const* str)
 {
+    errno = 0;
 #ifdef _MSC_VER
-    return _strtoi64(str, 0, 10);
+    long long result = _strtoi64(str, 0, 10);
 #else
-    return strtoll(str, 0, 10);
+    long long result = strtoll(str, 0, 10);
 #endif
+    if (errno == ERANGE)
+    {
+        throw std::runtime_error(
+            std::string("overflow/underflow converting ") + str
+            + " to 64-bit integer");
+    }
+    return result;
+}
+
+int
+QUtil::string_to_int(char const* str)
+{
+    errno = 0;
+    long long_val = strtol(str, 0, 10);
+    if (errno == ERANGE)
+    {
+        throw std::runtime_error(
+            std::string("overflow/underflow converting ") + str
+            + " to long integer");
+    }
+    int result = static_cast<int>(long_val);
+    if (static_cast<long>(result) != long_val)
+    {
+        throw std::runtime_error(
+            std::string("overflow/underflow converting ") + str
+            + " to integer");
+    }
+    return result;
 }
 
 unsigned char*

libtests/qtest/qutil/qutil.out

@@ -14,6 +14,14 @@
 one
 7
 compare okay
+-2147483648 to int: PASSED
+2147483647 to int: PASSED
+2147483648 to int threw: PASSED
+-2147483649 to int threw: PASSED
+9999999999999999999999999 to int threw: PASSED
+2147483648 to int: PASSED
+-2147483649 to int: PASSED
+99999999999999999999999999999999999999999999999999 to int threw: PASSED
 ----
 before remove
 exception: remove file: No such file or directory

libtests/qutil.cc

@@ -6,6 +6,7 @@
 #include <qpdf/QUtil.hh>
 #include <qpdf/PointerHolder.hh>
 #include <string.h>
+#include <limits.h>
 
 #ifdef _WIN32
 # include <io.h>
@@ -13,6 +14,57 @@
 # include <unistd.h>
 #endif
 
+template <class int_T>
+void test_to_number(char const* str, int_T wanted, bool error,
+                    int_T (*fn)(char const*))
+{
+    bool threw = false;
+    bool worked = false;
+    int_T result = 0;
+    try
+    {
+        result = fn(str);
+        worked = (wanted == result);
+    }
+    catch (std::runtime_error)
+    {
+        threw = true;
+    }
+    if (threw)
+    {
+        if (error)
+        {
+            std::cout << str << " to int threw: PASSED" << std::endl;
+        }
+        else
+        {
+            std::cout << str << " to int threw but wanted "
+                      << wanted << std::endl;
+        }
+    }
+    else
+    {
+        if (worked)
+        {
+            std::cout << str << " to int: PASSED" << std::endl;
+        }
+        else
+        {
+            std::cout << str << " to int failed; got " << result << std::endl;
+        }
+    }
+}
+
+void test_to_int(char const* str, int wanted, bool error)
+{
+    test_to_number(str, wanted, error, QUtil::string_to_int);
+}
+
+void test_to_ll(char const* str, long long wanted, bool error)
+{
+    test_to_number(str, wanted, error, QUtil::string_to_ll);
+}
+
 void string_conversion_test()
 {
     std::cout << QUtil::int_to_string(16059) << std::endl
@@ -44,6 +96,21 @@ void string_conversion_test()
 	std::cout << "compare failed" << std::endl;
     }
     delete [] tmp;
+
+    std::string int_max_str = QUtil::int_to_string(INT_MAX);
+    std::string int_min_str = QUtil::int_to_string(INT_MIN);
+    long long int_max_plus_1 = static_cast<long long>(INT_MAX) + 1;
+    long long int_min_minus_1 = static_cast<long long>(INT_MIN) - 1;
+    std::string int_max_plus_1_str = QUtil::int_to_string(int_max_plus_1);
+    std::string int_min_minus_1_str = QUtil::int_to_string(int_min_minus_1);
+    test_to_int(int_min_str.c_str(), INT_MIN, false);
+    test_to_int(int_max_str.c_str(), INT_MAX, false);
+    test_to_int(int_max_plus_1_str.c_str(), 0, true);
+    test_to_int(int_min_minus_1_str.c_str(), 0, true);
+    test_to_int("9999999999999999999999999", 0, true);
+    test_to_ll(int_max_plus_1_str.c_str(), int_max_plus_1, false);
+    test_to_ll(int_min_minus_1_str.c_str(), int_min_minus_1, false);
+    test_to_ll("99999999999999999999999999999999999999999999999999", 0, true);
 }
 
 void os_wrapper_test()