rom/utility/clonetagitems.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: CloneTagItems()
   6     Lang: english
   7 */
   8 #include "intern.h"
   9
  10 /*****************************************************************************
  11
  12     NAME */
  13 #include <utility/tagitem.h>
  14 #include <proto/utility.h>
  15
  16         AROS_LH1(struct TagItem *, CloneTagItems,
  17
  18 /*  SYNOPSIS */
  19         AROS_LHA(const struct TagItem *, tagList, A0),
  20
  21 /*  LOCATION */
  22         struct UtilityBase *, UtilityBase, 12, Utility)
  23
  24 /*  FUNCTION
  25         Duplicates a TagList. The input TagList can be NULL, in which
  26         case an empty TagList will be returned.
  27
  28     INPUTS
  29         tagList     -   The TagList that you want to clone
  30
  31     RESULT
  32         A TagList which contains a copy of the TagItems contained in the
  33         original list. The list is cloned so that calling FindTagItem()
  34         on a tag in the clone will return the same value as that in the
  35         original list (assuming the original has not been modified).
  36
  37     NOTES
  38
  39     EXAMPLE
  40         struct TagItem *tagList, *tagListClone;
  41
  42         \* Set up the original taglist tagList *\
  43
  44         tagListClone = CloneTagItems( tagList );
  45
  46         \* Do what you want with your TagList here *\
  47
  48         FreeTagItems( tagListClone );
  49
  50     BUGS
  51
  52     SEE ALSO
  53         AllocateTagItems(), FreeTagItems(), RefreshTagItemClones()
  54
  55     INTERNALS
  56
  57 *****************************************************************************/
  58 {
  59     AROS_LIBFUNC_INIT
  60
  61     struct TagItem *newList;
  62     LONG numTags = 1;
  63
  64     /*
  65         This is rather strange, if we have a NULL input, then we still
  66         have to allocate a list. This is to circumvent a bug in SID v2,
  67         which for some unknown reason is the only program I have seen
  68         that has this problem.
  69
  70         Had to alter RefreshTagItemClones as well.
  71         However, that is also what the autodoc says...
  72     */
  73     if (tagList)
  74     {
  75         const struct TagItem *tmp;
  76         /*
  77             We start the counter at 1 since this count will not include the
  78             TAG_DONE TagItem
  79
  80             newList is used here to save a variable. We don't need to do
  81             anything to the value of newList afterwards, since AllocateTagItems()
  82             will take care of setting it to NULL if the allocation fails.
  83         */
  84         tmp = tagList;
  85         while (NextTagItem (&tmp) != NULL)
  86             numTags++;
  87     }
  88
  89     /*
  90         Then we shall allocate the TagList.
  91         If we can actually allocate a clone tag list, then we shall copy
  92         the tag values from one tag to another, the function
  93         "RefreshTagItemClones()" is used here to help re-use code.
  94
  95         Of course we don't have to worry about the if and only if
  96         statement, since the original is guaranteed to have not
  97         been changed since CloneTagItems() :)
  98     */
  99
 100     if ((newList = AllocateTagItems(numTags)))
 101         RefreshTagItemClones(newList, tagList);
 102
 103     /* newList == 0 when allocation failed - AllocateTagItems handles this*/
 104     return newList;
 105
 106     AROS_LIBFUNC_EXIT
 107 } /* CloneTagItems */