--- a
+++ b/src/execmd.h
@@ -0,0 +1,276 @@
+/* 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 _EXECMD_H_INCLUDED_
+#define _EXECMD_H_INCLUDED_
+
+#include <signal.h>
+
+#include <string>
+#include <vector>
+#include <stack>
+
+#include "netcon.h"
+
+/** 
+ * Callback function object to advise of new data arrival, or just periodic 
+ * heartbeat if cnt is 0. 
+ *
+ * To interrupt the command, the code using ExecCmd should either
+ * raise an exception inside newData() (and catch it in doexec's caller), or 
+ * call ExecCmd::setKill() 
+ * 
+ */
+class ExecCmdAdvise {
+ public:
+    virtual ~ExecCmdAdvise() {}
+    virtual void newData(int cnt) = 0;
+};
+
+/** 
+ * Callback function object to get more input data. Data has to be provided
+ * in the initial input string, set it to empty to signify eof.
+ */
+class ExecCmdProvide {
+ public:
+    virtual ~ExecCmdProvide() {}
+    virtual void newData() = 0;
+};
+
+/**
+ * Execute command possibly taking both input and output (will do
+ * asynchronous io as appropriate for things to work).
+ *
+ * Input to the command can be provided either once in a parameter to doexec
+ * or provided in chunks by setting a callback which will be called to 
+ * request new data. In this case, the 'input' parameter to doexec may be
+ * empty (but not null)
+ *
+ * Output from the command is normally returned in a single string, but a
+ * callback can be set to be called whenever new data arrives, in which case
+ * it is permissible to consume the data and erase the string.
+ * 
+ * Note that SIGPIPE should be ignored and SIGCLD blocked when calling doexec,
+ * else things might fail randomly. (This is not done inside the class because
+ * of concerns with multithreaded programs).
+ *
+ */
+class ExecCmd {
+ public:
+    // Use vfork instead of fork. This must not be called in a multithreaded 
+    // program.
+    static void useVfork(bool on)
+    {
+	o_useVfork  = on;
+    }
+    /** 
+     * Add/replace environment variable before executing command. This must
+     * be called before doexec() to have an effect (possibly multiple
+     * times for several variables).
+     * @param envassign an environment assignment string ("name=value")
+     */
+    void putenv(const std::string &envassign);
+    void putenv(const std::string &name, const std::string& value);
+
+    /** 
+     * Set function objects to call whenever new data is available or on
+     * select timeout / whenever new data is needed to send. Must be called
+     * before doexec()
+     */
+    void setAdvise(ExecCmdAdvise *adv) {m_advise = adv;}
+    void setProvide(ExecCmdProvide *p) {m_provide = p;}
+
+    /**
+     * Set select timeout in milliseconds. The default is 1 S. 
+     * This is NOT a time after which an error will occur, but the period of
+     * the calls to the cancellation check routine.
+     */
+    void setTimeout(int mS) {if (mS > 30) m_timeoutMs = mS;}
+
+    /** 
+     * Set destination for stderr data. The default is to let it alone (will 
+     * usually go to the terminal or to wherever the desktop messages go).
+     * There is currently no option to put stderr data into a program variable
+     * If the parameter can't be opened for writing, the command's
+     * stderr will be closed.
+     */
+    void setStderr(const std::string &stderrFile) {m_stderrFile = stderrFile;}
+
+    /**
+     * Execute command. 
+     *
+     * Both input and output can be specified, and asynchronous 
+     * io (select-based) is used to prevent blocking. This will not
+     * work if input and output need to be synchronized (ie: Q/A), but
+     * works ok for filtering.
+     * The function is exception-safe. In case an exception occurs in the 
+     * advise callback, fds and pids will be cleaned-up properly.
+     *
+     * @param cmd the program to execute. This must be an absolute file name 
+     *   or exist in the PATH.
+     * @param args the argument vector (NOT including argv[0]).
+     * @param input Input to send TO the command.
+     * @param output Output FROM the command.
+     * @return the exec ouput status (0 if ok), or -1
+     */
+    int doexec(const std::string &cmd, const std::vector<std::string>& args, 
+	       const std::string *input = 0, 
+	       std::string *output = 0);
+
+    /*
+     * The next four methods can be used when a Q/A dialog needs to be 
+     * performed with the command
+     */
+    int startExec(const std::string &cmd, const std::vector<std::string>& args, 
+		  bool has_input, bool has_output);
+    int send(const std::string& data);
+    int receive(std::string& data, int cnt = -1);
+    int getline(std::string& data);
+    int wait();
+    /** Wait with WNOHANG set. 
+	@return true if process exited, false else.
+	@param O: status, the wait(2) call's status value */
+    bool maybereap(int *status);
+
+    pid_t getChildPid() {return m_pid;}
+
+    /** 
+     * Cancel/kill command. This can be called from another thread or
+     * from the advise callback, which could also raise an exception to 
+     * accomplish the same thing
+     */
+    void setKill() {m_killRequest = true;}
+
+    /**
+     * Get rid of current process (become ready for start). 
+     */
+    void zapChild() {setKill(); (void)wait();}
+
+    ExecCmd()
+	: m_advise(0), m_provide(0), m_timeoutMs(1000)
+    {
+	reset();
+    }
+    ~ExecCmd();
+
+    /**
+     * Utility routine: check if/where a command is found according to the
+     * current PATH (or the specified one
+     * @param cmd command name
+     * @param exe on return, executable path name if found
+     * @param path exec seach path to use instead of getenv(PATH)
+     * @return true if found
+     */
+    static bool which(const std::string& cmd, std::string& exe, const char* path = 0);
+
+    /**
+     * Execute command and return stdout output in a string
+     * @param cmd input: command and args
+     * @param out output: what the command printed
+     * @return true if exec status was 0
+     */
+    static bool backtick(const std::vector<std::string> cmd, std::string& out);
+
+    friend class ExecCmdRsrc;
+ private:
+    static bool      o_useVfork;
+
+    std::vector<std::string>   m_env;
+    ExecCmdAdvise   *m_advise;
+    ExecCmdProvide  *m_provide;
+    bool             m_killRequest;
+    int              m_timeoutMs;
+    std::string           m_stderrFile;
+    // Pipe for data going to the command
+    int              m_pipein[2];
+    NetconP          m_tocmd;
+    // Pipe for data coming out
+    int              m_pipeout[2];
+    NetconP          m_fromcmd;
+    // Subprocess id
+    pid_t            m_pid;
+    // Saved sigmask
+    sigset_t         m_blkcld;
+
+    // Reset internal state indicators. Any resources should have been
+    // previously freed
+    void reset() {
+	m_killRequest = false;
+	m_pipein[0] = m_pipein[1] = m_pipeout[0] = m_pipeout[1] = -1;
+	m_pid = -1;
+	sigemptyset(&m_blkcld);
+    }
+    // Child process code
+    inline void dochild(const std::string &cmd, const char **argv, 
+			const char **envv, bool has_input, bool has_output);
+    /* Copyconst and assignment private and forbidden */
+    ExecCmd(const ExecCmd &) {}
+    ExecCmd& operator=(const ExecCmd &) {return *this;};
+};
+
+
+/** 
+ * Rexecute self process with the same arguments. 
+ *
+ * Note that there are some limitations:
+ *  - argv[0] has to be valid: an executable name which will be found in 
+ *    the path when exec is called in the initial working directory. This is 
+ *    by no means guaranteed. The shells do this, but argv[0] could be an
+ *    arbitrary string.
+ *  - The initial working directory must be found and remain valid.
+ *  - We don't try to do anything with fd 0,1,2. If they were changed by the
+ *    program, their initial meaning won't be the same as at the moment of the 
+ *    initial invocation.
+ *  - We don't restore the signals. Signals set to be blocked 
+ *    or ignored by the program will remain ignored even if this was not their
+ *    initial state.
+ *  - The environment is also not restored.
+ *  - Others system aspects ?
+ *  - Other program state: application-dependant. Any external cleanup 
+ *    (temp files etc.) must be performed by the application. ReExec() 
+ *    duplicates the atexit() function to make this easier, but the 
+ *    ReExec().atexit() calls must be done explicitely, this is not automatic
+ * 
+ * In short, this is usable in reasonably controlled situations and if there 
+ * are no security issues involved, but this does not perform miracles.
+ */
+class ReExec {
+public:
+    ReExec() {}
+    ReExec(int argc, char *argv[]);
+    void init(int argc, char *argv[]);
+    int atexit(void (*function)(void))
+    {
+	m_atexitfuncs.push(function);
+	return 0;
+    }
+    void reexec();
+    const std::string& getreason() {return m_reason;}
+    // Insert new args into the initial argv. idx designates the place
+    // before which the new args are inserted (the default of 1
+    // inserts after argv[0] which would probably be an appropriate
+    // place for additional options)
+    void insertArgs(const std::vector<std::string>& args, int idx = 1);
+    void removeArg(const std::string& arg);
+private:
+    std::vector<std::string> m_argv;
+    std::string m_curdir;
+    int    m_cfd;
+    std::string m_reason;
+    std::stack<void (*)(void)> m_atexitfuncs;
+};
+
+#endif /* _EXECMD_H_INCLUDED_ */