/* Copyright (C) 2004 J.F.Dockes
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _MH_EXECM_H_INCLUDED_
#define _MH_EXECM_H_INCLUDED_
#include "mh_exec.h"
#include "execmd.h"
/**
* Turn external document into internal one by executing an external filter.
*
* The command to execute, and its parameters, are stored in the "params"
* which is built in mimehandler.cpp out of data from the mimeconf file.
*
* This version uses persistent filters which can handle multiple requests
* without exiting (both multiple files and multiple documents per file),
* with a simple question/response protocol.
*
* The data is exchanged in TLV fashion, in a way that should be
* usable in most script languages. The basic unit of data has one line
* with a data type and a count (both ASCII), followed by the data. A
* 'message' is made of one or several units or tags and ends with one empty
* line.
*
* Example from recollindex (the message begins before 'Filename' and has
* 'Filename' and 'Ipath' tags):
*
Filename: 24
/my/home/mail/somefolderIpath: 2
22
<Message ends here: because of the empty line after '22'
*
* Example answer, with 'Mimetype' and 'Data' tags
*
Mimetype: 10
text/plainData: 10
0123456789
<Message ends here because of empty line
*
* This format is both extensible and reasonably easy to parse.
* While it's more fitted for python or perl on the script side, it
* should even be sort of usable from the shell (e.g.: use dd to read
* the counted data). Most alternatives would need data encoding in
* some cases.
*
* Higher level dialog:
* The C++ program is the master and sends request messages to the script.
* Both sides of the communication should be prepared to receive and discard
* unknown tags.
* The messages normally have the following tags:
* - Filename: the file to process. This can be empty meaning that we
* are requesting the next document in the current file.
* - Ipath: this will be present only if we are requesting a specific
* subdocument inside a container file (typically for preview, at query
* time). Absent during indexing (ipaths are generated and sent back from
* the script)
* - Mimetype: this is the mime type for the (possibly container) file.
* Can be useful to filters which handle multiple types, like rclaudio.
*
* The script answers with messages having the following fields:
* - Document: translated document data.
* - Ipath: ipath for the returned document. Can be used at query time to
* extract a specific subdocument for preview. Not present or empty for
* non-container files and for the "self" document of a container.
* - Mimetype: mime type for the returned data.
* This is optional. For multi-document filters, if mimetype is
* not present in the answer, the ipath must be a file-name-like
* string which will be used to divine the mime type (this is used
* typically with archives like Zip or Tar). If this fails,
* the document will be handled as unknown type and the contents won't
* be indexed. When neither ipath nor mimetype are present the default
* is to attempt to treat the document as HTML.
* - Charset: for document types for which it makes sense, and if the filter
* has the information.
* - Eofnow: empty field: no document is returned and we're at eof.
* - Eofnext: empty field: file ends after the doc returned by this message.
* - SubdocError: no subdoc returned by this request, but file goes on.
* - FileError: error, stop for this file.
*/
class MimeHandlerExecMultiple : public MimeHandlerExec {
/////////
// Things not reset by "clear()", additionally to those in MimeHandlerExec
ExecCmd m_cmd;
/////// End un-cleared stuff.
public:
MimeHandlerExecMultiple(RclConfig *cnf, const string& id)
: MimeHandlerExec(cnf, id)
{}
// No resources to clean up, the ExecCmd destructor does it.
virtual ~MimeHandlerExecMultiple() {}
virtual bool set_document_file(const string& mt, const string &file_path) {
m_filefirst = true;
return MimeHandlerExec::set_document_file(mt, file_path);
}
virtual bool next_document();
// skip_to and clear inherited from MimeHandlerExec
private:
bool startCmd();
bool readDataElement(string& name, string& data);
bool m_filefirst;
int m_maxmemberkb;
};
#endif /* _MH_EXECM_H_INCLUDED_ */