fix cgo pointer runtime error in TestLogistic

linear_models/liblinear.go

@@ -47,12 +47,16 @@ func NewProblem(X [][]float64, y []float64, bias float64) *Problem {
 	prob.c_prob.l = C.int(len(X))
 	prob.c_prob.n = C.int(len(X[0]) + 1)
 
-	prob.c_prob.x = convert_features(X, bias)
-	c_y := make([]C.double, len(y))
+
+	prob.c_prob.x = convert_features_optim(X, bias)
+
+	var c_y *C.double = C.mallocDouble(C.int(len(y)))
 	for i := 0; i < len(y); i++ {
-		c_y[i] = C.double(y[i])
+		tmp_next := uintptr(unsafe.Pointer(c_y)) + unsafe.Sizeof(*c_y) * uintptr(i)
+		tmp_next_p := (*C.double)(unsafe.Pointer(tmp_next))
+		*tmp_next_p = C.double(y[i])
 	}
-	prob.c_prob.y = &c_y[0]
+	prob.c_prob.y = c_y
 	prob.c_prob.bias = C.double(-1)
 
 	return &prob
@@ -150,6 +154,35 @@ func convert_features(X [][]float64, bias float64) **C.struct_feature_node {
 		x_space[cursor].index = C.int(-1)
 		cursor++
 	}
+
 	c_x = &x[0]
 	return c_x
 }
+
+
+func convert_features_optim(X [][]float64, bias float64) **C.struct_feature_node {
+	n_samples := len(X)
+	n_elements := 0
+	n_features := 0
+
+	if n_samples > 0 {
+		n_features = len(X[0])
+	}
+
+	var X_data *C.double = C.mallocDouble(C.int(n_samples * n_features))
+	for i := 0; i < n_samples; i++ {
+		for j := 0; j < len(X[i]); j++ {
+			if X[i][j] != 0.0 {
+				n_elements++
+			}
+			tmp := uintptr(unsafe.Pointer(X_data)) + unsafe.Sizeof(*X_data) * uintptr(i * len(X[i]) + j)
+			tmp_p := (*C.double)(unsafe.Pointer(tmp))
+			*tmp_p = C.double(X[i][j])
+			n_elements++ //for bias
+		}
+	}
+
+	var x **C.struct_feature_node = C.convert_features_helper(X_data,
+		C.int(n_samples), C.int(n_features), C.int(n_elements), C.double(bias))
+	return x
+}

linear_models/linear.cpp

@@ -2291,7 +2291,7 @@ static void train_one(const problem *prob, const parameter *param, double *w, do
 // Interface functions
 //
 model* train(const problem *prob, const parameter *param)
-{	
+{
 	int i,j;
 	int l = prob->l;
 	int n = prob->n;
@@ -2835,3 +2835,54 @@ void set_print_string_function(void (*print_func)(const char*))
 		liblinear_print_string = print_func;
 }
 
+double* mallocDouble(int size) {
+    return Malloc(double, (size_t)size);
+}
+
+feature_node* mallocSingleDimensionFeatureNode(int size) {
+    feature_node* f_node_s_p = (feature_node*)Malloc(feature_node, (size_t)size);
+    memset(f_node_s_p, 0, sizeof(feature_node) * (size_t)size);
+    return f_node_s_p;
+}
+
+feature_node** mallocDoubleDimensionFeatureNodePointer(int size) {
+    feature_node** f_node_d_p;
+    f_node_d_p = (feature_node**)Malloc(feature_node*, (size_t)size);
+    return f_node_d_p;
+}
+
+feature_node** convert_features_helper(double* data, int samples, int features, int elements, double bias) {
+
+	feature_node* x_space = mallocSingleDimensionFeatureNode(elements + samples);
+
+	int cursor = 0;
+
+	feature_node** x = mallocDoubleDimensionFeatureNodePointer(samples);
+
+	for (int i = 0; i < samples; i++) {
+
+		x[i] = &x_space[cursor];
+
+		for (int j = 0; j < features; j++) {
+
+			if (data[i * features +j] != 0.0) {
+                x_space[cursor].index = j + 1;
+                x_space[cursor].value = data[i * features +j];
+				cursor++;
+			}
+			if (bias > 0) {
+                x_space[cursor].index = 0;
+                x_space[cursor].value = bias;
+				cursor++;
+			}
+		}
+
+        x_space[cursor].index = -1;
+        x_space[cursor].value = 0.0;
+		cursor++;
+	}
+
+	return x;
+}
+
+

linear_models/linear.h

@@ -66,6 +66,11 @@ const char *check_parameter(const struct problem *prob, const struct parameter *
 int check_probability_model(const struct model *model);
 void set_print_string_function(void (*print_func) (const char*));
 
+double* mallocDouble(int size);
+struct feature_node* mallocSingleDimensionFeatureNode(int size);
+struct feature_node** mallocDoubleDimensionFeatureNodePointer(int size);
+struct feature_node** convert_features_helper(double* data, int samples, int features, int elements, double bias);
+
 #ifdef __cplusplus
 }
 #endif