Change VCL_Check signature to return enum vcl_check

include/vapi/vsl.h

@@ -312,7 +312,15 @@ int VSL_ResetCursor(const struct VSL_cursor *c);
 	 *    -1: Operation not supported
 	 */
 
-int VSL_Check(const struct VSL_cursor *c, const struct VSLC_ptr *ptr);
+enum vsl_check {
+	vsl_check_e_notsupp	= -1,
+	vsl_check_e_inval	=  0,
+	vsl_check_warn		=  1,
+	vsl_check_valid	=  2
+};
+
+enum vsl_check
+VSL_Check(const struct VSL_cursor *c, const struct VSLC_ptr *ptr);
 	/*
 	 * Check if the VSLC_ptr structure points to a value that is still
 	 * valid:

lib/libvarnishapi/vsl_api.h

@@ -39,7 +39,8 @@ void vsl_vbm_bitclr(int bit, void *priv);
 typedef void vslc_delete_f(const struct VSL_cursor *);
 typedef int vslc_next_f(const struct VSL_cursor *);
 typedef int vslc_reset_f(const struct VSL_cursor *);
-typedef int vslc_check_f(const struct VSL_cursor *, const struct VSLC_ptr *);
+typedef enum vsl_check vslc_check_f(const struct VSL_cursor *,
+    const struct VSLC_ptr *);
 
 struct vslc_tbl {
 	unsigned			magic;

lib/libvarnishapi/vsl_cursor.c

@@ -91,7 +91,7 @@ vslc_vsm_delete(const struct VSL_cursor *cursor)
  * written
  */
 
-static int
+static enum vsl_check v_matchproto_(vslc_check_f)
 vslc_vsm_check(const struct VSL_cursor *cursor, const struct VSLC_ptr *ptr)
 {
 	const struct vslc_vsm *c;
@@ -101,25 +101,25 @@ vslc_vsm_check(const struct VSL_cursor *cursor, const struct VSLC_ptr *ptr)
 	assert(&c->cursor == cursor);
 
 	if (ptr->ptr == NULL)
-		return (0);
+		return (vsl_check_e_inval);
 
 	dist = c->head->segment_n - ptr->priv;
 
 	if (dist >= VSL_SEGMENTS - 2)
 		/* Too close to continue */
-		return (0);
+		return (vsl_check_e_inval);
 	if (dist >= VSL_SEGMENTS - 4)
 		/* Warning level */
-		return (1);
+		return (vsl_check_warn);
 	/* Safe */
-	return (2);
+	return (vsl_check_valid);
 }
 
 static int
 vslc_vsm_next(const struct VSL_cursor *cursor)
 {
 	struct vslc_vsm *c;
-	int i;
+	enum vsl_check i;
 	uint32_t t;
 
 	CAST_OBJ_NOTNULL(c, cursor->priv_data, VSLC_VSM_MAGIC);
@@ -127,7 +127,7 @@ vslc_vsm_next(const struct VSL_cursor *cursor)
 
 	while (1) {
 		i = vslc_vsm_check(&c->cursor, &c->next);
-		if (i <= 0) {
+		if (i < vsl_check_warn) {
 			if (VSM_StillValid(c->vsm, &c->vf) != VSM_valid)
 				return (-2); /* VSL abandoned */
 			else
@@ -489,13 +489,13 @@ VSL_Next(const struct VSL_cursor *cursor)
 	return ((tbl->next)(cursor));
 }
 
-int
+enum vsl_check
 VSL_Check(const struct VSL_cursor *cursor, const struct VSLC_ptr *ptr)
 {
 	const struct vslc_tbl *tbl;
 
 	CAST_OBJ_NOTNULL(tbl, cursor->priv_tbl, VSLC_TBL_MAGIC);
 	if (tbl->check == NULL)
-		return (-1);
+		return (vsl_check_e_notsupp);
 	return ((tbl->check)(cursor, ptr));
 }

lib/libvarnishapi/vsl_dispatch.c

@@ -435,7 +435,7 @@ vtx_append(struct VSLQ *vslq, struct vtx *vtx, const struct VSLC_ptr *start,
 		return;
 	AN(start);
 
-	if (VSL_Check(vslq->c, start) == 2 &&
+	if (VSL_Check(vslq->c, start) == vsl_check_valid &&
 	    !VTAILQ_EMPTY(&vtx->shmchunks_free)) {
 		/* Shmref it */
 		chunk = VTAILQ_FIRST(&vtx->shmchunks_free);