Add an enum describing the return values from VSM_StillValid

Use the enum values where VSM_StillValid is used.

bin/varnishstat/varnishstat_curses.c

@@ -873,7 +873,7 @@ do_curses(struct VSM_data *vd, int delay)
 		}
 		VSC_C_mgt = VSC_Mgt(vd, &f_mgt);
 		VSC_C_main = VSC_Main(vd, &f_main);
-		if (VSM_StillValid(vd, &f_iter) != 1)
+		if (VSM_valid != VSM_StillValid(vd, &f_iter))
 			build_pt_list(vd, &f_iter);
 
 		now = VTIM_mono();

include/vapi/vsm.h

@@ -139,17 +139,23 @@ int VSM__itern(const struct VSM_data *vd, struct VSM_fantom *vf);
 	 * vd = "struct VSM_data *"
 	 */
 
-int VSM_StillValid(const struct VSM_data *vd, struct VSM_fantom *vf);
+enum VSM_valid_e {
+	VSM_invalid,
+	VSM_valid,
+	VSM_similar,
+};
+
+enum VSM_valid_e VSM_StillValid(const struct VSM_data *vd,
+    struct VSM_fantom *vf);
 	/*
 	 * This is a cheap syscall-less check to see if the fantom is still
 	 * valid.  Further checking with VSM_Abandoned() may be a good
 	 * idea.
 	 *
 	 * Return:
-	 *	0: fantom is not valid any more.
-	 *	1: fantom is still the same.
-	 *	2: a fantom with same dimensions exist in same position,
-	 *	   check class/type/ident
+	 *   VSM_invalid: fantom is not valid any more.
+	 *   VSM_valid:   fantom is still the same.
+	 *   VSM_similar: a fantom with same dimensions exist in same position.
 	 */
 
 int VSM_Get(const struct VSM_data *vd, struct VSM_fantom *vf,

lib/libvarnishapi/vsc.c

@@ -287,7 +287,7 @@ VSC_Get(struct VSM_data *vd, struct VSM_fantom *fantom, const char *type,
 
 	if (fantom == NULL)
 		fantom = &f2;
-	if (!VSM_StillValid(vd, fantom) &&
+	if (VSM_invalid == VSM_StillValid(vd, fantom) &&
 	    !VSM_Get(vd, fantom, VSC_CLASS, type, ident))
 		return (NULL);
 	return ((void*)fantom->b);
@@ -470,7 +470,7 @@ VSC_Iter(struct VSM_data *vd, struct VSM_fantom *fantom, VSC_iter_f *func,
 	struct vsc_pt *pt;
 	int i;
 
-	if (1 != VSM_StillValid(vd, &vsc->iter_fantom)) {
+	if (VSM_valid != VSM_StillValid(vd, &vsc->iter_fantom)) {
 		/* Tell app that list will be nuked */
 		(void)func(priv, NULL);
 		vsc_build_vf_list(vd);

lib/libvarnishapi/vsl_cursor.c

@@ -131,7 +131,7 @@ vslc_vsm_next(void *cursor)
 
 	/* Check VSL fantom and abandonment */
 	if (*(volatile const uint32_t *)c->next.ptr == VSL_ENDMARKER) {
-		if (!VSM_StillValid(c->vsm, &c->vf) ||
+		if (VSM_invalid == VSM_StillValid(c->vsm, &c->vf) ||
 		    VSM_Abandoned(c->vsm))
 			return (-2);
 	}

lib/libvarnishapi/vsm.c

@@ -367,7 +367,7 @@ VSM__itern(const struct VSM_data *vd, struct VSM_fantom *vf)
 
 /*--------------------------------------------------------------------*/
 
-int
+enum VSM_valid_e
 VSM_StillValid(const struct VSM_data *vd, struct VSM_fantom *vf)
 {
 	struct VSM_fantom f2;
@@ -375,11 +375,11 @@ VSM_StillValid(const struct VSM_data *vd, struct VSM_fantom *vf)
 	CHECK_OBJ_NOTNULL(vd, VSM_MAGIC);
 	AN(vf);
 	if (!vd->head)
-		return (0);
+		return (VSM_invalid);
 	if (!vd->head->alloc_seq)
-		return (0);
+		return (VSM_invalid);
 	if (vf->priv == vd->head->alloc_seq)
-		return (1);
+		return (VSM_valid);
 	VSM_FOREACH(&f2, vd) {
 		if (f2.chunk != vf->chunk || f2.b != vf->b || f2.e != vf->e)
 			continue;
@@ -390,9 +390,9 @@ VSM_StillValid(const struct VSM_data *vd, struct VSM_fantom *vf)
 		if (strcmp(f2.ident, vf->ident))
 			continue;
 		vf->priv = vd->head->alloc_seq;
-		return (2);
+		return (VSM_similar);
 	}
-	return (0);
+	return (VSM_invalid);
 }
 
 int