Rewrite LL_* (link list) macros

kernel/util/util.h

@@ -8,35 +8,45 @@
 
 #define LL_APPEND(head, new) \
   do { \
-    if ((head) != NULL) { \
-      typeof((head)) __tmp; \
-      (new)->next = NULL; \
-      __tmp = (head); \
-      while (__tmp->next != NULL) { \
-        __tmp = __tmp->next; \
+    if ((new) != NULL) { \
+      if ((head) != NULL) { \
+        typeof((head)) __tmp; \
+        (new)->next = NULL; \
+        __tmp = (head); \
+        while (__tmp->next != NULL) { \
+          __tmp = __tmp->next; \
+        } \
+        __tmp->next = (new); \
+      } else { \
+        (new)->next = NULL; \
+        (head) = (new); \
       } \
-      __tmp->next = (new); \
-    } else { \
-      (new)->next = NULL; \
-      (head) = (new); \
     } \
   } while(0)
 
 #define LL_REMOVE(head, ele) \
   do { \
-    typeof((head)) __cur = (head); \
-    typeof((head)) __prev = NULL; \
-    while (__cur != (ele)) { \
-      __prev = __cur; \
-      __cur = __cur->next; \
-    } \
-    if (__prev != NULL) { \
-      __prev->next = __cur->next; \
+    if ((head) != NULL && (ele) != NULL) { \
+      typeof((head)) __cur = (head); \
+      typeof((head)) __prev = NULL; \
+      while (__cur != NULL && __cur != (ele)) { \
+        __prev = __cur; \
+        __cur = __cur->next; \
+      } \
+      if (__cur == (ele)) { \
+        if (__prev != NULL) { \
+          __prev->next = __cur->next; \
+        } else { \
+          (head) = __cur->next; \
+        } \
+        (ele)->next = NULL; \
+      } \
     } \
   } while(0)
 
 #define LL_FINDPROP(head, out, propname, propvalue) \
   do { \
+    (out) = NULL; \
     typeof((head)) __tmp = (head); \
     while (__tmp) { \
       if (__tmp->propname == (propvalue)) { \
@@ -47,6 +57,22 @@
     } \
   } while(0)
 
+#define LL_FOREACH_SAFE(head, var, tmp) \
+  for (typeof(head) var = (head), tmp = (var ? var->next : NULL); \
+      var != NULL; \
+      var = tmp, tmp = (var ? var->next : NULL) \
+      )
+
+#define LL_FOREACH_SAFE_IDX(head, var, tmp, idx) \
+  for (typeof(head) var = (head), tmp = (var ? var->next : NULL); \
+       var != NULL && ((idx) = 0, 1); \
+       var = tmp, tmp = (var ? var->next : NULL), (idx)++)
+
+#define LL_FOREACH_SAFE_IDX_LIMIT(head, var, tmp, idx, max) \
+  for ((idx) = 0, var = (head), tmp = (var ? var->next : NULL); \
+       var != NULL && (idx) < (max); \
+       var = tmp, tmp = (var ? var->next : NULL), (idx)++)
+
 char *util_get_filename(char *path);
 
 #endif // UTIL_UTIL_H_