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a/src/cdplugins/cmdtalk.h |
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b/src/cdplugins/cmdtalk.h |
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/home/dockes/projets/docklib/cmdtalk/cmdtalk.h |
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/* Copyright (C) 2016 J.F.Dockes
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the
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* Free Software Foundation, Inc.,
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifndef _CMDTALK_H_INCLUDED_
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#define _CMDTALK_H_INCLUDED_
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/**
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* Execute commands and exchange messages with it.
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*
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* A simple stream protocol is used for the dialog. HTTP or some kind
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* of full-blown RPC could have been used, but there was also good
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* reason to keep it simple (yet powerful), given the limited context
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* of dialog through a pipe.
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*
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* The data is exchanged in TLV fashion, in a way that should be
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* usable in most script languages. The basic unit of data has one line
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* with a data type and a count (both ASCII), followed by the data. A
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* 'message' is made of one or several units or tags and ends with one empty
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* line.
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*
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* Example:(the message begins before 'Filename' and has 'Filename' and
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* 'Ipath' tags):
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*
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Filename: 24
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/my/home/mail/somefolderIpath: 2
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22
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<Message ends here: because of the empty line after '22'
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*
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* Example answer, with 'Mimetype' and 'Data' tags
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*
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Mimetype: 10
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text/plainData: 10
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0123456789
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<Message ends here because of empty line
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*
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* This format is both extensible and reasonably easy to parse.
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* While it's more fitted for python or perl on the script side, it
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* should even be sort of usable from the shell (e.g.: use dd to read
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* the counted data). Most alternatives would need data encoding in
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* some cases.
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*
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* Higher level dialog:
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* The C++ program is the master and sends request messages to the script.
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* Both sides of the communication should be prepared to receive and discard
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* unknown tags.
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*/
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#include <string>
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#include <vector>
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#include <unordered_map>
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class CmdTalk {
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public:
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CmdTalk();
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virtual ~CmdTalk();
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// @param env each entry should be of the form name=value. They
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// augment the subprocess environnement.
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// @param path replaces the PATH variable when looking for the command.
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virtual bool startCmd(const std::string& cmdname,
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const std::vector<std::string>& args =
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std::vector<std::string>(),
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const std::vector<std::string>& env =
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std::vector<std::string>(),
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const std::vector<std::string>& path =
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std::vector<std::string>()
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);
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virtual bool running();
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// Single exchange: send and receive data.
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virtual bool talk(const std::unordered_map<std::string, std::string>& args,
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std::unordered_map<std::string, std::string>& rep);
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// Specialized version with special argument used by dispatcher to call
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// designated method
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virtual bool callproc(
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const std::string& proc,
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const std::unordered_map<std::string, std::string>& args,
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std::unordered_map<std::string, std::string>& rep);
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private:
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class Internal;
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Internal *m;
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};
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#endif /* _CMDTALK_H_INCLUDED_ */
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