In order to support features that differ from PPD to PPD, the ppd-cache version of a printer now includes a series of mappings that are used to determine what options are passed to the filters. What _ppdConvertOptions expects to find is as follows:
The (cupsd_printer_t*)p->ppd_attrs should contain an ipp collection called “option-mappings”. It is expect that this collection will contain subcollections which indicate how IPP attributes found in a print job are to be converted into filter options. The name of these subcollections should be the name of the IPP attribute that should be translated:
ipp_t *option_mappings = ippFindAttribute(p->ppd_attrs, "option-mappings", IPP_TAG_BEGIN_COLLECTION); ipp_t *ipp_attr = ippNew(); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_TEXT, "setting", NULL, "True"); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_TEXT, "foo", NULL, "%s"); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_TEXT, "bar", NULL, "Custom.%s"); ippAddCollection(option_mappings, IPP_TAG_ZERO, "ipp-attr", ipp_attr);
If a job comes in whose job->attrs contains an “ipp-attr” whose value is baz@Domain.com, then this mapping will result in the following three options being passed to the filter:
setting=True foo=baz@Domain.com bar=Custom.baz@Domain.com
The only substitutions allowed currently are “%s” for the transformed value of the attribute. Non-string values will be converted to strings.
Sometimes IPP values cannot be converted directly into PPD values, so transformations can also be added to the collection. The name of a transformation must begin with “_”, and the transformation should be in the same collection which contains the mappings for the specified ippAttribute:
ipp_t *option_mappings = ippFindAttribute(p->ppd_attrs, "option-mappings", IPP_TAG_BEGIN_COLLECTION); ipp_t *ipp_attr = ippNew(); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_TEXT, "bar", NULL, "Custom.%s"); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "_delimiters", NULL, "@"); ippAddCollection(option_mappings, IPP_TAG_ZERO, "ipp-attr", ipp_attr);
Transformations are applied to the ipp value before it is added to the option strings. And they are applied in the order they are found in the collection. So in this case, if a job comes in whose job_attrs contains the “ipp-attr=baz@Domain.com”, then the following options would be output:
bar=Custom.baz
The currently available transformations are:
Delimiters must always be a IPP_TAG_KEYWORD, and the string is the list of characters that terminate the value. So for example:
ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "_delimiters", NULL, "@");
Means that only characters before the first ‘@’ in a ipp attribute value will be passed as an option value.
Valid Chars must always be an IPP_TAG_KEYWORD, and the string is the list of characters that are allowed in as an option value. Any invalid character is replace with the character found in the _replacement-char transformation. So if the following transformations were in place:
ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "_valid-chars", NULL, "abcdefghijklmnopqrstuvwxyz"); ippAddString(ipp_attr, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "_replacement-char", NULL, "-");
And the value of the specified ipp attribute was “ipp-attr=baz@Domain.com”, the transformed value used for the options would be:
baz--omain-com
Constraint must always be an IPP_TAG_RANGE attribute, and it contains the minimum and maximum allowed characters for a filter option. If the value is shorter than the minimum, then the mapping is aborted and no options are passed to the filter for this transformation. If the value is longer than the maximum, then the string is truncated to that length. So if this transformation was in place:
ippAddRange(ipp_attr, IPP_TAG_ZERO, "_constraint", 2, 8);
And the value of the specified ipp attribute was “ipp-attr=baz@Domain.com”, the transformed value used for the options would be:
baz@Doma
Mapping is always an ippCollection that consists of a series of IPP_TAG_KEYWORDs whose name is the IPP value and whose value is the PPD filter option value. If the ipp value can be found in the collection, then it is exchanged for the value of that keyword. If not, then the ipp attribute is discard and not converted into filter options. So if the following keywords existed in the mapping:
ipp_t *mapping = ippNew(); ippAddString(mapping, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "baz", NULL, "bottle"); ippAddString(mapping, IPP_TAG_ZERO, IPP_TAG_KEYWORD, "bat", NULL, "ball"); ippAddCollection(ipp_attr, IPP_TAG_ZERO, "_mapping", mapping);
And the value of the specified ipp attribute was “ipp-attr=baz”, the transformed value used for the options would be:
bottle