X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Flist.c;h=e341d45bd432e5cfe1178260eba1c276629f9b1f;hb=c5cf10598f8c9f4428291e9df3ecd72a05fb1ccf;hp=8aedd7573656cbc4beedd514019c42a855bdb686;hpb=34e63086edddcae06d7c1a4fa84fec0861e50758;p=sliver-openvswitch.git

diff --git a/lib/list.c b/lib/list.c
index 8aedd7573..e341d45bd 100644
--- a/lib/list.c
+++ b/lib/list.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,7 +15,6 @@
  */
 #include <config.h>
 #include "list.h"
-#include <assert.h>
 
 /* Initializes 'list' as an empty list. */
 void
@@ -24,14 +23,22 @@ list_init(struct list *list)
     list->next = list->prev = list;
 }
 
+/* Initializes 'list' with pointers that will (probably) cause segfaults if
+ * dereferenced and, better yet, show up clearly in a debugger. */
+void
+list_poison(struct list *list)
+{
+    memset(list, 0xcc, sizeof *list);
+}
+
 /* Inserts 'elem' just before 'before'. */
 void
 list_insert(struct list *before, struct list *elem)
 {
-  elem->prev = before->prev;
-  elem->next = before;
-  before->prev->next = elem;
-  before->prev = elem;
+    elem->prev = before->prev;
+    elem->next = before;
+    before->prev->next = elem;
+    before->prev = elem;
 }
 
 /* Removes elements 'first' though 'last' (exclusive) from their current list,
@@ -39,19 +46,20 @@ list_insert(struct list *before, struct list *elem)
 void
 list_splice(struct list *before, struct list *first, struct list *last)
 {
-  if (first == last)
-    return;
-  last = last->prev;
-
-  /* Cleanly remove 'first'...'last' from its current list. */
-  first->prev->next = last->next;
-  last->next->prev = first->prev;
-
-  /* Splice 'first'...'last' into new list. */
-  first->prev = before->prev;
-  last->next = before;
-  before->prev->next = first;
-  before->prev = last;
+    if (first == last) {
+        return;
+    }
+    last = last->prev;
+
+    /* Cleanly remove 'first'...'last' from its current list. */
+    first->prev->next = last->next;
+    last->next->prev = first->prev;
+
+    /* Splice 'first'...'last' into new list. */
+    first->prev = before->prev;
+    last->next = before;
+    before->prev->next = first;
+    before->prev = last;
 }
 
 /* Inserts 'elem' at the beginning of 'list', so that it becomes the front in
@@ -59,7 +67,7 @@ list_splice(struct list *before, struct list *first, struct list *last)
 void
 list_push_front(struct list *list, struct list *elem)
 {
-  list_insert(list->next, elem);
+    list_insert(list->next, elem);
 }
 
 /* Inserts 'elem' at the end of 'list', so that it becomes the back in
@@ -67,7 +75,7 @@ list_push_front(struct list *list, struct list *elem)
 void
 list_push_back(struct list *list, struct list *elem)
 {
-  list_insert(list, elem);
+    list_insert(list, elem);
 }
 
 /* Puts 'elem' in the position currently occupied by 'position'.
@@ -82,21 +90,39 @@ list_replace(struct list *element, const struct list *position)
 }
 
 /* Adjusts pointers around 'list' to compensate for 'list' having been moved
- * around in memory (e.g. as a consequence of realloc()). */
+ * around in memory (e.g. as a consequence of realloc()).
+ *
+ * This always works if 'list' is a member of a list, or if 'list' is the head
+ * of a non-empty list.  It fails badly, however, if 'list' is the head of an
+ * empty list; just use list_init() in that case. */
 void
 list_moved(struct list *list)
 {
     list->prev->next = list->next->prev = list;
 }
 
+/* Initializes 'dst' with the contents of 'src', compensating for moving it
+ * around in memory.  The effect is that, if 'src' was the head of a list, now
+ * 'dst' is the head of a list containing the same elements. */
+void
+list_move(struct list *dst, struct list *src)
+{
+    if (!list_is_empty(src)) {
+        *dst = *src;
+        list_moved(dst);
+    } else {
+        list_init(dst);
+    }
+}
+
 /* Removes 'elem' from its list and returns the element that followed it.
    Undefined behavior if 'elem' is not in a list. */
 struct list *
 list_remove(struct list *elem)
 {
-  elem->prev->next = elem->next;
-  elem->next->prev = elem->prev;
-  return elem->next;
+    elem->prev->next = elem->next;
+    elem->next->prev = elem->prev;
+    return elem->next;
 }
 
 /* Removes the front element from 'list' and returns it.  Undefined behavior if
@@ -104,9 +130,9 @@ list_remove(struct list *elem)
 struct list *
 list_pop_front(struct list *list)
 {
-  struct list *front = list->next;
-  list_remove(front);
-  return front;
+    struct list *front = list->next;
+    list_remove(front);
+    return front;
 }
 
 /* Removes the back element from 'list' and returns it.
@@ -114,27 +140,31 @@ list_pop_front(struct list *list)
 struct list *
 list_pop_back(struct list *list)
 {
-  struct list *back = list->prev;
-  list_remove(back);
-  return back;
+    struct list *back = list->prev;
+    list_remove(back);
+    return back;
 }
 
-/* Returns the front element in 'list'.
-   Undefined behavior if 'list' is empty. */
+/* Returns the front element in 'list_'.
+   Undefined behavior if 'list_' is empty. */
 struct list *
-list_front(struct list *list)
+list_front(const struct list *list_)
 {
-  assert(!list_is_empty(list));
-  return list->next;
+    struct list *list = CONST_CAST(struct list *, list_);
+
+    ovs_assert(!list_is_empty(list));
+    return list->next;
 }
 
-/* Returns the back element in 'list'.
-   Undefined behavior if 'list' is empty. */
+/* Returns the back element in 'list_'.
+   Undefined behavior if 'list_' is empty. */
 struct list *
-list_back(struct list *list)
+list_back(const struct list *list_)
 {
-  assert(!list_is_empty(list));
-  return list->prev;
+    struct list *list = CONST_CAST(struct list *, list_);
+
+    ovs_assert(!list_is_empty(list));
+    return list->prev;
 }
 
 /* Returns the number of elements in 'list'.
@@ -142,17 +172,32 @@ list_back(struct list *list)
 size_t
 list_size(const struct list *list)
 {
-  const struct list *e;
-  size_t cnt = 0;
+    const struct list *e;
+    size_t cnt = 0;
 
-  for (e = list->next; e != list; e = e->next)
-    cnt++;
-  return cnt;
+    for (e = list->next; e != list; e = e->next) {
+        cnt++;
+    }
+    return cnt;
 }
 
 /* Returns true if 'list' is empty, false otherwise. */
 bool
 list_is_empty(const struct list *list)
 {
-  return list->next == list;
+    return list->next == list;
+}
+
+/* Returns true if 'list' has exactly 1 element, false otherwise. */
+bool
+list_is_singleton(const struct list *list)
+{
+    return list_is_short(list) && !list_is_empty(list);
+}
+
+/* Returns true if 'list' has 0 or 1 elements, false otherwise. */
+bool
+list_is_short(const struct list *list)
+{
+    return list->next == list->prev;
 }