Re: [PATCH 5/6] virxml: Introduce parsing APIs that keep indentation

[Ján Tomko <jtomko@xxxxxxxxxx>]

On a Tuesday in 2023, Michal Privoznik wrote:
> When parsing an XML it may be important to keep indentation to
> produce a better looking result when formatting the XML back.
> Just look at all those xmlKeepBlanksDefault() calls just before
> virXMLParse() is called.
>
> Anyway, as of libxml2 commit v2.12.0~108 xmlKeepBlanksDefault()
> is deprecated. Therefore, introduce virXMLParse...WithIndent()
> variants which would do exactly xmlKeepBlanksDefault() did but
> with non-deprecated APIs.
>
> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
> ---
> src/util/virxml.c | 15 +++++++++++++--
> src/util/virxml.h | 29 +++++++++++++++++++++++++----
> 2 files changed, 38 insertions(+), 6 deletions(-)
>
> diff --git a/src/util/virxml.c b/src/util/virxml.c
> index 31685cddde..e94708448a 100644
> --- a/src/util/virxml.c
> +++ b/src/util/virxml.c
> @@ -1129,14 +1129,16 @@ virXMLParseHelper(int domcode,
>                   const char *rootelement,
>                   xmlXPathContextPtr *ctxt,
>                   const char *schemafile,
> -                  bool validate)
> +                  bool validate,
> +                  bool keepindent)
> {
>     struct virParserData private;
>     g_autoptr(xmlParserCtxt) pctxt = NULL;
>     g_autoptr(xmlDoc) xml = NULL;
>     xmlNodePtr rootnode;
>     const char *docname;
> -    const int parseFlags = XML_PARSE_NONET |
> +    int oldIndentTreeOutput = 0;
> +    int parseFlags = XML_PARSE_NONET |
>         XML_PARSE_NOWARNING;
>
>     if (filename)
> @@ -1155,12 +1157,21 @@ virXMLParseHelper(int domcode,
>     pctxt->_private = &private;
>     pctxt->sax->error = catchXMLError;
>
> +    if (keepindent) {
> +        parseFlags |= XML_PARSE_NOBLANKS;
> +        xmlIndentTreeOutput = 1;
> +    }
> +
>     if (filename) {
>         xml = xmlCtxtReadFile(pctxt, filename, NULL, parseFlags);
>     } else {
>         xml = xmlCtxtReadDoc(pctxt, BAD_CAST xmlStr, url, NULL, parseFlags);
>     }
>
> +    if (keepindent) {
> +        xmlIndentTreeOutput = oldIndentTreeOutput;
> +    }
> +

Touching xmlIndentTreeOutput is not necessary.
1) it does not affect parsing, which is what we're doing here
2) xmlIndentTreeOutput = 1 is the default

All we need here is the XML_PARSE_NOBLANKS flag.

(Also, we did revert to the original value of xmlKeepBlanksDefaultValue
by calling xmlKeepBlanksDefault, but xmlIndentTreeOutput is always set
to 1 by xmlKeepBlanksDefault and never reset)

>     if (!xml) {
>         if (virGetLastErrorCode() == VIR_ERR_OK) {
>             virGenericReportError(domcode, VIR_ERR_XML_ERROR,

Reviewed-by: Ján Tomko <jtomko@xxxxxxxxxx>

Jano

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