Re: [xml] PATCH: implement xmlSaveToBuffer()

[Geert Jansen <geert boskant nl>]

Hi Daniel,

thanks for your reply. I've checked my code and was actually passing in 
an xmlOutputBufferPtr, not an xmlBufferPtr! That's why it worked in my 
tests. See the (Pyrex/lxml) code below:

           buffer = tree.xmlAllocOutputBuffer(encoder)
           ctxt = tree.xmlSaveToBuffer(buffer, encoding, options)
           tree.xmlSaveDoc(ctxt, self._c_doc)
           tree.xmlSaveFlush(ctxt)
           s = dumpOutputBuffer(buffer, encoding)
           file.write(s)
           tree.xmlSaveClose(ctxt)

Can we just change the xmlSaveToBuffer() prototype to accept an 
xmlOutputBuffer as per the updated patch attached? Or is there something 
which makes it better to have an interface with an xmlBuffer?

The attached patch also comments in and updates the prototype in xmlsave.h.

Regards,
Geert


Daniel Veillard wrote:
> On Sun, Nov 06, 2005 at 06:07:52PM +0100, Geert Jansen wrote:
>   
> > Hi,
> >
> > the attached patch implement the function xmlSaveToBuffer() which was 
> > documented but not implemented.
> >
> > Can the patch be applied?
> >     
>
>   Sounds wrong. You are using an xmlBufferPtr while ret->buf is expected
> to be an xmlOutputBufferPtr. As a result if someone tries to free the returned
> value with the xmlFreeSaveCtxt() call it will crash or corrupt memory.
> If you compile with gcc you get a warning about this:
>     xmlsave.c: In function `xmlSaveToBuffer':
>     xmlsave.c:1489: warning: assignment from incompatible pointer type
> That patch really can't be applied as-is, I really can't see how it would
> have worked in any test either. Instead generate an xmlOutputBufferPtr
> from the passed xmlBufferPtr and check that the passed buffer is not freed
> when xmlFreeSaveCtxt is called, that should work correctly.
>
>   Sorry, no, but thanks !
>
> Daniel
>
>   

diff -ur libxml2-2.6.22.orig/include/libxml/xmlsave.h libxml2-2.6.22/include/libxml/xmlsave.h
--- libxml2-2.6.22.orig/include/libxml/xmlsave.h        2005-09-12 17:34:25.000000000 +0200
+++ libxml2-2.6.22/include/libxml/xmlsave.h     2005-11-06 20:10:42.000000000 +0100
@@ -45,14 +45,12 @@
                xmlSaveToFilename       (const char *filename,
                                         const char *encoding,
                                         int options);
-/******
-  Not yet implemented.
 
 XMLPUBFUN xmlSaveCtxtPtr XMLCALL
-               xmlSaveToBuffer         (xmlBufferPtr buffer,
+               xmlSaveToBuffer         (xmlOutputBufferPtr buffer,
                                         const char *encoding,
                                         int options);
- ******/
+
 XMLPUBFUN xmlSaveCtxtPtr XMLCALL
                xmlSaveToIO             (xmlOutputWriteCallback iowrite,
                                         xmlOutputCloseCallback ioclose,
diff -ur libxml2-2.6.22.orig/xmlsave.c libxml2-2.6.22/xmlsave.c
--- libxml2-2.6.22.orig/xmlsave.c       2005-09-12 17:35:07.000000000 +0200
+++ libxml2-2.6.22/xmlsave.c    2005-11-06 20:01:21.000000000 +0100
@@ -1473,13 +1473,18 @@
  * with the encoding and the options given
  *
  * Returns a new serialization context or NULL in case of error.
+ */
+
 xmlSaveCtxtPtr
-xmlSaveToBuffer(xmlBufferPtr buffer, const char *encoding, int options)
+xmlSaveToBuffer(xmlOutputBufferPtr buffer, const char *encoding, int options)
 {
-    TODO
-    return(NULL);
+    xmlSaveCtxtPtr ret;
+
+    ret = xmlNewSaveCtxt(encoding, options);
+    if (ret == NULL) return(NULL);
+    ret->buf = buffer;
+    return(ret);
 }
- */
 
 /**
  * xmlSaveToIO: