Always initialize the result.

c/include/prima/prima.h

@@ -245,6 +245,9 @@ int prima_init_options(prima_options_t *const options);
 
 
 // Structure to hold the result
+// prima_minimize will allocate the memory for x and nlconstr (if needed),
+// and as such the user is expected to free the memory using prima_free_result
+// once they are done using the contents of the result (or have saved the contents).
 typedef struct {
 
     // x: returned point
@@ -277,11 +280,14 @@ int prima_free_result(prima_result_t *const result);
 
 
 /*
- * The function that does the minimization using a PRIMA solver
- * algorithm : optimization algorithm (see prima_algorithm)
- * problem   : optimization problem (see prima_problem)
- * options   : optimization options (see prima_options)
- * result    : optimization result (see prima_result)
+ * The function that does the minimization using a PRIMA solver.
+ * After using (or saving) the result, the user is expected to call
+ * prima_free_result, regardless of the return value of prima_minimize,
+ * in order to avoid memory leaks.
+ * algorithm : optimization algorithm (see prima_algorithm_t)
+ * problem   : optimization problem (see prima_problem_t)
+ * options   : optimization options (see prima_options_t)
+ * result    : optimization result (see prima_result_t)
  * return    : see prima_rc_t enum for return codes
  */
 PRIMAC_API

c/prima.c

@@ -93,32 +93,12 @@ int prima_init_result(prima_result_t *const result, const prima_problem_t proble
 
     memset(result, 0, sizeof(prima_result_t));
 
-    // x: returned point
-    result->x = (double*)malloc(problem.n * sizeof(double));
-    if (!result->x)
-        return PRIMA_MEMORY_ALLOCATION_FAILS;
-    for (int i = 0; i < problem.n; i++)
-        result->x[i] = problem.x0[i];
-
     // f: objective function value at the returned point
     result->f = NAN;
 
     // cstrv: constraint violation at the returned point (COBYLA and LINCOA only)
     result->cstrv = NAN;
 
-    // nlconstr: nonlinear constraint values at the returned point, of size m_nlcon (COBYLA only)
-    if (problem.m_nlcon <= 0)
-        result->nlconstr = NULL;
-    else {
-        result->nlconstr = (double*)malloc(problem.m_nlcon * sizeof(double));
-        if (!result->nlconstr) {
-            free(result->x);
-            return PRIMA_MEMORY_ALLOCATION_FAILS;
-        }
-        for (int i = 0; i < problem.m_nlcon; i++)
-            result->nlconstr[i] = NAN;
-    }
-
     // nf: number of function evaluations
     result->nf = INT_MIN;
 
@@ -128,6 +108,22 @@ int prima_init_result(prima_result_t *const result, const prima_problem_t proble
     // message: exit message
     result->message = NULL;
 
+    // x: returned point
+    result->x = (double*)malloc(problem.n * sizeof(double));
+    if (!result->x)
+        return PRIMA_MEMORY_ALLOCATION_FAILS;
+    for (int i = 0; i < problem.n; i++)
+        result->x[i] = NAN;
+
+    // nlconstr: nonlinear constraint values at the returned point, of size m_nlcon (COBYLA only)
+    result->nlconstr = (double*)malloc(problem.m_nlcon * sizeof(double));
+    if (!result->nlconstr) {
+        free(result->x);
+        return PRIMA_MEMORY_ALLOCATION_FAILS;
+    }
+    for (int i = 0; i < problem.m_nlcon; i++)
+        result->nlconstr[i] = NAN;
+
     return 0;
 }
 
@@ -238,12 +234,19 @@ int prima_minimize(const prima_algorithm_t algorithm, const prima_problem_t prob
 {
     int use_constr = (algorithm == PRIMA_COBYLA);
 
-    int info = prima_check_problem(problem, use_constr, algorithm);
+    int info = prima_init_result(result, problem);
 
     if (info == 0)
-        info = prima_init_result(result, problem);
+        info = prima_check_problem(problem, use_constr, algorithm);
 
     if (info == 0) {
+        // We copy x0 into result->x only after prima_check_problem has succeeded,
+        // so that if prima_check_problem failed, result->x will not contained a
+        // seemingly valid value.
+        for (int i = 0; i < problem.n; i++) {
+            result->x[i] = problem.x0[i];
+        }
+
         switch (algorithm) {
             case PRIMA_BOBYQA:
                 bobyqa_c(problem.calfun, options.data, problem.n, result->x, &(result->f), problem.xl, problem.xu, &(result->nf), options.rhobeg, options.rhoend, options.ftarget, options.maxfun, options.npt, options.iprint, options.callback, &info);
@@ -275,10 +278,10 @@ int prima_minimize(const prima_algorithm_t algorithm, const prima_problem_t prob
             default:
                 return PRIMA_INVALID_INPUT;
         }
-
-        result->status = info;
-        result->message = prima_get_rc_string(info);
     }
 
+    result->status = info;
+    result->message = prima_get_rc_string(info);
+
     return info;
 }