eina/convert: init endptr in failure case of eina_convert_strtod_c

Summary:
there is not any way to determine that this function has failed other
than to check this pointer, so ensure that it always has a value which
is meaningful in failure cases

Reviewers: cedric

Reviewed By: cedric

Subscribers: #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D10445

src/lib/eina/eina_convert.c

@@ -476,6 +476,7 @@ eina_convert_strtod_c(const char *nptr, char **endptr)
    unsigned long long integer_part;
    int minus;
 
+   if (endptr) *endptr = (char*)nptr;
    EINA_SAFETY_ON_NULL_RETURN_VAL(nptr, 0.0);
 
    a = iter = nptr;

src/lib/eina/eina_convert.h

@@ -337,9 +337,9 @@ EAPI Eina_Bool eina_convert_atofp(const char  *src,
  * @brief Converts a string to a floating point number.
  *
  * @param[in] nptr a string to convert. It shouldn't be NULL.
- * @param[out] endptr If endptr is not NULL, a pointer to the character after the last
+ * @param[out] endptr If @p endptr is not NULL, a pointer to the character after the last
  *                    character used in the conversion is stored in the location referenced
- *                    by endptr.
+ *                    by endptr. If @p nptr is NULL, this will also be set to NULL.
  * @return a double type floating point number.
  *
  * This function returns converted floating point number with locale-independency.