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mxml_write_node causing segfault #228

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stefanu21 opened this issue Aug 28, 2018 · 7 comments
Closed

mxml_write_node causing segfault #228

stefanu21 opened this issue Aug 28, 2018 · 7 comments
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@michaelrsweet
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@stefanu21
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when I'm writing a xml subchild as string I get an segfault in the function mxml_write_node

because current->parent in mxml-file.c:2984 is NULL!

I think the problem is here

while ((next = current->next) == NULL)
{
        if (current == node)
          break;

       /*
	* The ? and ! elements are special-cases and have no end tags...
	*/

	current = current->parent;
....
}

you should do current = current->parent; first and then do the check if we are now at the start node. In other case you have a problem when the start node has next elements. then you iterate trough all nodes until parent is zero...

When we print a subchild which has next elements you jump over the break condition....
@michaelrsweet
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What version of Mini-XML are you using?

Can you provide some sample code showing what you are doing?

@michaelrsweet michaelrsweet self-assigned this Aug 28, 2018
@stefanu21
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version is 2.11

void test()
{
  mxml_node_t *xml, *node;
  const char *dummy = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><note><to>Tove</to><from>Jani</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>";
  char *tmp;

  xml = mxmlLoadString(NULL, dummy, MXML_OPAQUE_CALLBACK);
  node = mxmlFindElement(xml, xml, "from", NULL, NULL, MXML_DESCEND);
  tmp = mxmlSaveAllocString(node, MXML_NO_CALLBACK);

  printf("tmp: %s\n",tmp);
  free(tmp);
  mxmlDelete(xml);
  return;
}

@michaelrsweet
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OK, thanks for the test code I've confirmed the issue, although I'm surprised that this hasn't cropped up before... Investigating...

@michaelrsweet michaelrsweet added the bug Something isn't working label Aug 31, 2018
@michaelrsweet michaelrsweet modified the milestones: Future, Stable Aug 31, 2018
michaelrsweet added a commit that referenced this issue Sep 30, 2018
@michaelrsweet
Fix crash bug in mxmlWrite functions (Issue #228)
d32a541
@michaelrsweet
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[master d32a541] Fix crash bug in mxmlWrite functions (Issue #228)

@stefanu21
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Hi,
your patch fixes the crash but the output is not correct. When you look at my example code I only want to print node "from". With your fix I print all nodes....

@michaelrsweet michaelrsweet reopened this Oct 1, 2018
@michaelrsweet
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Well, the function currently saves the specified node tree, which includes the siblings. That said, the typical usage is to print the root node (<?xml ... ?>) so I think I can safely change this to not also save sibling nodes.

michaelrsweet added a commit that referenced this issue Oct 1, 2018
@michaelrsweet
Do not write siblings of the passed node (Issue #228)
f86c267
@michaelrsweet
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[master f86c267] Do not write siblings of the passed node (Issue #228)

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