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path: root/lib/libalpm/alpm_list.c
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Diffstat (limited to 'lib/libalpm/alpm_list.c')
-rw-r--r--lib/libalpm/alpm_list.c121
1 files changed, 63 insertions, 58 deletions
diff --git a/lib/libalpm/alpm_list.c b/lib/libalpm/alpm_list.c
index 57c8376a..bdf9b5f5 100644
--- a/lib/libalpm/alpm_list.c
+++ b/lib/libalpm/alpm_list.c
@@ -40,20 +40,15 @@
/* Allocation */
/**
- * @brief Allocate a new alpm_list_t.
+ * @brief Allocate a new node for alpm_list_t (with empty ->data)
*
- * @return a new alpm_list_t item, or NULL on failure
+ * @return a new node item, or NULL on failure
*/
-alpm_list_t SYMEXPORT *alpm_list_new()
+static alpm_list_t *node_new()
{
alpm_list_t *list = NULL;
- list = malloc(sizeof(alpm_list_t));
- if(list) {
- list->data = NULL;
- list->prev = list; /* maintain a back reference to the tail pointer */
- list->next = NULL;
- }
+ list = calloc(1, sizeof(alpm_list_t));
return(list);
}
@@ -107,30 +102,26 @@ alpm_list_t SYMEXPORT *alpm_list_add(alpm_list_t *list, void *data)
{
alpm_list_t *ptr, *lp;
- ptr = list;
+ ptr = node_new();
if(ptr == NULL) {
- ptr = alpm_list_new();
- if(ptr == NULL) {
- return(NULL);
- }
+ return(list);
}
- lp = alpm_list_last(ptr);
- if(lp == ptr && lp->data == NULL) {
- /* nada */
- } else {
- lp->next = alpm_list_new();
- if(lp->next == NULL) {
- return(NULL);
- }
- lp->next->prev = lp;
- lp = lp->next;
- list->prev = lp;
+ ptr->data = data;
+ ptr->next = NULL;
+
+ /* Special case: the input list is empty */
+ if(list == NULL) {
+ ptr->prev = ptr;
+ return(ptr);
}
- lp->data = data;
+ lp = alpm_list_last(list);
+ lp->next = ptr;
+ ptr->prev = lp;
+ list->prev = ptr;
- return(ptr);
+ return(list);
}
/**
@@ -144,12 +135,15 @@ alpm_list_t SYMEXPORT *alpm_list_add(alpm_list_t *list, void *data)
*/
alpm_list_t SYMEXPORT *alpm_list_add_sorted(alpm_list_t *list, void *data, alpm_list_fn_cmp fn)
{
- if(!fn) {
- return alpm_list_add(list, data);
+ if(!fn || !list) {
+ return(alpm_list_add(list, data));
} else {
alpm_list_t *add = NULL, *prev = NULL, *next = list;
- add = alpm_list_new();
+ add = node_new();
+ if(add == NULL) {
+ return(list);
+ }
add->data = data;
/* Find insertion point. */
@@ -159,26 +153,25 @@ alpm_list_t SYMEXPORT *alpm_list_add_sorted(alpm_list_t *list, void *data, alpm_
next = next->next;
}
- /* Insert node before insertion point. */
- add->prev = prev;
- add->next = next;
-
- if(next != NULL) {
- next->prev = add; /* Not at end. */
- }
-
- if(prev != NULL) {
- prev->next = add; /* In middle. */
- } else {
- list = add; /* At beginning, or new list */
- }
-
- if(next == NULL) {
- /* At end, adjust tail pointer on head node */
+ /* Insert the add node to the list */
+ if(prev == NULL) { /* special case: we insert add as the first element */
+ add->prev = list->prev; /* list != NULL */
+ add->next = list;
list->prev = add;
+ return(add);
+ } else if(next == NULL) { /* another special case: add last element */
+ add->prev = prev;
+ add->next = NULL;
+ prev->next = add;
+ list->prev = add;
+ return(list);
+ } else {
+ add->prev = prev;
+ add->next = next;
+ next->prev = add;
+ prev->next = add;
+ return(list);
}
-
- return(list);
}
}
@@ -198,10 +191,10 @@ alpm_list_t SYMEXPORT *alpm_list_join(alpm_list_t *first, alpm_list_t *second)
alpm_list_t *tmp;
if (first == NULL) {
- return second;
+ return(second);
}
if (second == NULL) {
- return first;
+ return(first);
}
/* tmp is the last element of the first list */
tmp = first->prev;
@@ -464,18 +457,22 @@ alpm_list_t SYMEXPORT *alpm_list_copy_data(const alpm_list_t *list,
alpm_list_t SYMEXPORT *alpm_list_reverse(alpm_list_t *list)
{
const alpm_list_t *lp;
- alpm_list_t *newlist = NULL;
+ alpm_list_t *newlist = NULL, *backup;
- lp = alpm_list_last(list);
- if(list) {
- /* break our reverse circular list */
- list->prev = NULL;
+ if(list == NULL) {
+ return(NULL);
}
+ lp = alpm_list_last(list);
+ /* break our reverse circular list */
+ backup = list->prev;
+ list->prev = NULL;
+
while(lp) {
newlist = alpm_list_add(newlist, lp->data);
lp = lp->prev;
}
+ list->prev = backup; /* restore tail pointer */
return(newlist);
}
@@ -490,14 +487,18 @@ alpm_list_t SYMEXPORT *alpm_list_reverse(alpm_list_t *list)
*/
inline alpm_list_t SYMEXPORT *alpm_list_first(const alpm_list_t *list)
{
- return((alpm_list_t*)list);
+ if(list) {
+ return((alpm_list_t*)list);
+ } else {
+ return(NULL);
+ }
}
/**
* @brief Return nth element from list (starting from 0).
*
* @param list the list
- * @param n the index of the item to find
+ * @param n the index of the item to find (n < alpm_list_count(list) IS needed)
*
* @return an alpm_list_t node for index `n`
*/
@@ -519,7 +520,11 @@ alpm_list_t SYMEXPORT *alpm_list_nth(const alpm_list_t *list, int n)
*/
inline alpm_list_t SYMEXPORT *alpm_list_next(const alpm_list_t *node)
{
- return(node->next);
+ if(node) {
+ return(node->next);
+ } else {
+ return(NULL);
+ }
}
/**