143 lines
4.9 KiB
C++
143 lines
4.9 KiB
C++
/*
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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 _EXECMD_H_INCLUDED_
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#define _EXECMD_H_INCLUDED_
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/* @(#$Id: execmd.h,v 1.12 2007-05-21 13:30:22 dockes Exp $ (C) 2004 J.F.Dockes */
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#include <string>
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#include <list>
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#include <vector>
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#ifndef NO_NAMESPACES
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using std::list;
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using std::string;
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using std::vector;
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#endif
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/** Callback function object to advise of new data arrival (or just heartbeat) * if cnt is 0 */
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class ExecCmdAdvise {
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public:
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virtual ~ExecCmdAdvise() {}
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virtual void newData(int cnt) = 0;
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};
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/** Callback function object to get more input data. Data has to be provided
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* in the initial input string, set it to empty to signify eof
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*/
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class ExecCmdProvide {
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public:
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virtual ~ExecCmdProvide() {}
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virtual void newData() = 0;
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};
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/**
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* Execute command possibly taking both input and output (will do
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* asynchronous io as appropriate for things to work).
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*
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* Input to the command can be provided either once in a parameter to doexec
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* or provided in chunks by setting a callback which will be called to
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* request new data. In this case, the 'input' parameter to doexec may be
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* empty (but not null)
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*
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* Output from the command is normally returned in a single string, but a
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* callback can be set to be called whenever new data arrives, in which case
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* it is permissible to consume the data and erase the string.
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*
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* Note that SIGPIPE should be ignored and SIGCLD blocked when calling doexec,
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* else things might fail randomly. (This is not done inside the class because
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* of concerns with multithreaded programs).
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*
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*/
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class ExecCmd {
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public:
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/**
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* Execute command.
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*
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* Both input and output can be specified, and asynchronous
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* io (select-based) is used to prevent blocking. This will not
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* work if input and output need to be synchronized (ie: Q/A), but
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* works ok for filtering.
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* The function is exception-safe. In case an exception occurs in the
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* advise callback, fds and pids will be cleaned-up properly.
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*
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* @param cmd the program to execute. This must be an absolute file name
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* or exist in the PATH.
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* @param args the argument list (NOT including argv[0]).
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* @param input Input to send TO the command.
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* @param output Output FROM the command.
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* @return the exec ouput status (0 if ok).
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*/
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int doexec(const string &cmd, const list<string>& args,
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const string *input = 0,
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string *output = 0);
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/**
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* Add/replace environment variable before executing command. This must
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* be called before doexec to have an effect (possibly multiple
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* times for several variables).
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* @param envassign an environment assignment string (name=value)
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*/
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void putenv(const string &envassign);
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/**
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* Set function objects to call whenever new data is available or on
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* select timeout / whenever new data is needed to send.
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*/
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void setAdvise(ExecCmdAdvise *adv) {m_advise = adv;}
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void setProvide(ExecCmdProvide *p) {m_provide = p;}
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/**
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* Set select timeout in milliseconds. The default is 1 S.
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*/
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void setTimeout(int mS) {if (mS > 30) m_timeoutMs = mS;}
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/**
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* Set destination for stderr data. The default is to let it alone (will
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* usually go to the terminal or to wherever the desktop messages go).
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* There is currently no option to put stderr data into a program variable
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* If the parameter can't be opened for writing, the command's
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* stderr will be closed.
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*/
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void setStderr(const string &stderrFile) {m_stderrFile = stderrFile;}
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/**
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* Cancel/kill command. This can be called from another thread or
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* from the advise callback, which could also raise an exception to
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* accomplish the same thing
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*/
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void setCancel() {m_cancelRequest = true;}
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ExecCmd()
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: m_advise(0), m_provide(0), m_cancelRequest(false), m_timeoutMs(1000)
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{}
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/**
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* Utility routine: check if/where a command is found according to the
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* current PATH
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*/
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static bool which(const string& cmd, string& path);
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private:
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vector<string> m_env;
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ExecCmdAdvise *m_advise;
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ExecCmdProvide *m_provide;
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bool m_cancelRequest;
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int m_timeoutMs;
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string m_stderrFile;
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};
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#endif /* _EXECMD_H_INCLUDED_ */
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