xref: /curl/lib/slist.c (revision 2bc1d775)
1 /***************************************************************************
2  *                                  _   _ ____  _
3  *  Project                     ___| | | |  _ \| |
4  *                             / __| | | | |_) | |
5  *                            | (__| |_| |  _ <| |___
6  *                             \___|\___/|_| \_\_____|
7  *
8  * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9  *
10  * This software is licensed as described in the file COPYING, which
11  * you should have received as part of this distribution. The terms
12  * are also available at https://curl.se/docs/copyright.html.
13  *
14  * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15  * copies of the Software, and permit persons to whom the Software is
16  * furnished to do so, under the terms of the COPYING file.
17  *
18  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19  * KIND, either express or implied.
20  *
21  * SPDX-License-Identifier: curl
22  *
23  ***************************************************************************/
24 
25 #include "curl_setup.h"
26 
27 #include <curl/curl.h>
28 
29 #include "slist.h"
30 
31 /* The last #include files should be: */
32 #include "curl_memory.h"
33 #include "memdebug.h"
34 
35 /* returns last node in linked list */
slist_get_last(struct curl_slist * list)36 static struct curl_slist *slist_get_last(struct curl_slist *list)
37 {
38   struct curl_slist     *item;
39 
40   /* if caller passed us a NULL, return now */
41   if(!list)
42     return NULL;
43 
44   /* loop through to find the last item */
45   item = list;
46   while(item->next) {
47     item = item->next;
48   }
49   return item;
50 }
51 
52 /*
53  * Curl_slist_append_nodup() appends a string to the linked list. Rather than
54  * copying the string in dynamic storage, it takes its ownership. The string
55  * should have been malloc()ated. Curl_slist_append_nodup always returns
56  * the address of the first record, so that you can use this function as an
57  * initialization function as well as an append function.
58  * If an error occurs, NULL is returned and the string argument is NOT
59  * released.
60  */
Curl_slist_append_nodup(struct curl_slist * list,char * data)61 struct curl_slist *Curl_slist_append_nodup(struct curl_slist *list, char *data)
62 {
63   struct curl_slist     *last;
64   struct curl_slist     *new_item;
65 
66   DEBUGASSERT(data);
67 
68   new_item = malloc(sizeof(struct curl_slist));
69   if(!new_item)
70     return NULL;
71 
72   new_item->next = NULL;
73   new_item->data = data;
74 
75   /* if this is the first item, then new_item *is* the list */
76   if(!list)
77     return new_item;
78 
79   last = slist_get_last(list);
80   last->next = new_item;
81   return list;
82 }
83 
84 /*
85  * curl_slist_append() appends a string to the linked list. It always returns
86  * the address of the first record, so that you can use this function as an
87  * initialization function as well as an append function. If you find this
88  * bothersome, then simply create a separate _init function and call it
89  * appropriately from within the program.
90  */
curl_slist_append(struct curl_slist * list,const char * data)91 struct curl_slist *curl_slist_append(struct curl_slist *list,
92                                      const char *data)
93 {
94   char *dupdata = strdup(data);
95 
96   if(!dupdata)
97     return NULL;
98 
99   list = Curl_slist_append_nodup(list, dupdata);
100   if(!list)
101     free(dupdata);
102 
103   return list;
104 }
105 
106 /*
107  * Curl_slist_duplicate() duplicates a linked list. It always returns the
108  * address of the first record of the cloned list or NULL in case of an
109  * error (or if the input list was NULL).
110  */
Curl_slist_duplicate(struct curl_slist * inlist)111 struct curl_slist *Curl_slist_duplicate(struct curl_slist *inlist)
112 {
113   struct curl_slist *outlist = NULL;
114   struct curl_slist *tmp;
115 
116   while(inlist) {
117     tmp = curl_slist_append(outlist, inlist->data);
118 
119     if(!tmp) {
120       curl_slist_free_all(outlist);
121       return NULL;
122     }
123 
124     outlist = tmp;
125     inlist = inlist->next;
126   }
127   return outlist;
128 }
129 
130 /* be nice and clean up resources */
curl_slist_free_all(struct curl_slist * list)131 void curl_slist_free_all(struct curl_slist *list)
132 {
133   struct curl_slist     *next;
134   struct curl_slist     *item;
135 
136   if(!list)
137     return;
138 
139   item = list;
140   do {
141     next = item->next;
142     Curl_safefree(item->data);
143     free(item);
144     item = next;
145   } while(next);
146 }
147