slist: constify Curl_slist_append_nodup() string argument

Although finally stored as a non-const pointer, the string is intended
to be left unchanged.

This change allows using the function without the need of a cast for
const pointers.

Closes #19692

diff --git a/lib/slist.c b/lib/slist.c
index 366b24760959bd0ce7c3037534d130e060f456fa..88fdd8a2bae2b191e5df8b5b2f2a6687b4c2db3e 100644 (file)
--- a/lib/slist.c
+++ b/lib/slist.c
@@ -58,7 +58,8 @@ static struct curl_slist *slist_get_last(struct curl_slist *list)
  * If an error occurs, NULL is returned and the string argument is NOT
  * released.
  */
-struct curl_slist *Curl_slist_append_nodup(struct curl_slist *list, char *data)
+struct curl_slist *Curl_slist_append_nodup(struct curl_slist *list,
+                                           const char *data)
 {
   struct curl_slist     *last;
   struct curl_slist     *new_item;
@@ -70,7 +71,7 @@ struct curl_slist *Curl_slist_append_nodup(struct curl_slist *list, char *data)
     return NULL;
 
   new_item->next = NULL;
-  new_item->data = data;
+  new_item->data = CURL_UNCONST(data);
 
   /* if this is the first item, then new_item *is* the list */
   if(!list)

diff --git a/lib/slist.h b/lib/slist.h
index 9561fd022686024191b4e61a418353120c14a635..47a30824db0116b29edc75460c26812ad0925719 100644 (file)
--- a/lib/slist.h
+++ b/lib/slist.h
@@ -36,6 +36,6 @@ struct curl_slist *Curl_slist_duplicate(struct curl_slist *inlist);
  * it to the list.
  */
 struct curl_slist *Curl_slist_append_nodup(struct curl_slist *list,
-                                           char *data);
+                                           const char *data);
 
 #endif /* HEADER_CURL_SLIST_H */