/*
                            This file is part of the Opie Project
                            Copyright (C) 2003-2004 Holger Freyther <zecke@handhelds.org>
                            Copyright (C) The Opie Team <opie-devel@handhelds.org>
             =.             Based on KProcess (C) 1997 Christian Czezatke (e9025461@student.tuwien.ac.at)
           .=l.
          .>+-=
_;:,     .>    :=|.         This program is free software; you can
.> <`_,   >  .   <=         redistribute it and/or  modify it under
:`=1 )Y*s>-.--   :          the terms of the GNU Library General Public
.="- .-=="i,     .._        License as published by the Free Software
- .   .-<_>     .<>         Foundation; either version 2 of the License,
    ._= =}       :          or (at your option) any later version.
   .%`+i>       _;_.
   .i_,=:_.      -<s.       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
..}^=.=       =       ;     Library General Public License for more
++=   -.     .`     .:      details.
:     =  ...= . :.=-
-.   .:....=;==+<;          You should have received a copy of the GNU
 -_. . .   )=.  =           Library General Public License along with
   --        :-=`           this library; see the file COPYING.LIB.
                            If not, write to the Free Software Foundation,
                            Inc., 59 Temple Place - Suite 330,
                            Boston, MA 02111-1307, USA.
*/

#ifndef OPROCESS_H
#define OPROCESS_H

/* QT */
#include <qcstring.h>
#include <qobject.h>
#include <qvaluelist.h>

/* STD */
#include <sys/types.h> // for pid_t
#include <sys/wait.h>
#include <signal.h>
#include <unistd.h>

class QSocketNotifier;

namespace Opie {
namespace Core {
namespace Internal {
class OProcessController;
class OProcessPrivate;
}

/**
 * Child process invocation, monitoring and control.
 *
 * @par General usage and features
 *
 *This class allows a KDE and OPIE application to start child processes without having
 *to worry about UN*X signal handling issues and zombie process reaping.
 *
 *@see KProcIO
 *
 *Basically, this class distinguishes three different ways of running
 *child processes:
 *
 *@li  OProcess::DontCare -- The child process is invoked and both the child
 *process and the parent process continue concurrently.
 *
 *Starting a  DontCare child process means that the application is
 *not interested in any notification to determine whether the
 *child process has already exited or not.
 *
 *@li  OProcess::NotifyOnExit -- The child process is invoked and both the
 *child and the parent process run concurrently.
 *
 *When the child process exits, the OProcess instance
 *corresponding to it emits the Qt signal @ref processExited().
 *
 *Since this signal is @em not emitted from within a UN*X
 *signal handler, arbitrary function calls can be made.
 *
 *Be aware: When the OProcess objects gets destructed, the child
 *process will be killed if it is still running!
 *This means in particular, that you cannot use a OProcess on the stack
 *with OProcess::NotifyOnExit.
 *
 *@li  OProcess::Block -- The child process starts and the parent process
 *is suspended until the child process exits. (@em Really not recommended
 *for programs with a GUI.)
 *
 *OProcess also provides several functions for determining the exit status
 *and the pid of the child process it represents.
 *
 *Furthermore it is possible to supply command-line arguments to the process
 *in a clean fashion (no null -- terminated stringlists and such...)
 *
 *A small usage example:
 *<pre>
 *OProcess *proc = new OProcess;
 *
 **proc << "my_executable";
 **proc << "These" << "are" << "the" << "command" << "line" << "args";
 *QObject::connect(proc, SIGNAL(processExited(Opie::Core::OProcess *)),
 *                 pointer_to_my_object, SLOT(my_objects_slot(Opie::Core::OProcess *)));
 *proc->start();
 *</pre>
 *
 *This will start "my_executable" with the commandline arguments "These"...
 *
 *When the child process exits, the respective Qt signal will be emitted.
 *
 *@par Communication with the child process
 *
 *OProcess supports communication with the child process through
 *stdin/stdout/stderr.
 *
 *The following functions are provided for getting data from the child
 *process or sending data to the child's stdin (For more information,
 *have a look at the documentation of each function):
 *
 *@li bool @ref writeStdin(char  *buffer, int  buflen);
 *@li  -- Transmit data to the child process's stdin.
 *
 *@li bool @ref closeStdin();
 *@li -- Closes the child process's stdin (which causes it to see an  feof(stdin)).
 *Returns false if you try to close stdin for a process that has been started
 *without a communication channel to stdin.
 *
 *@li bool @ref closeStdout();
 *@li -- Closes the child process's stdout.
 *Returns false if you try to close stdout for a process that has been started
 *without a communication channel to stdout.
 *
 *@li bool @ref closeStderr();
 *@li -- Closes the child process's stderr.
 *Returns false if you try to close stderr for a process that has been started
 *without a communication channel to stderr.
 *
 *
 *@par QT signals:
 *
 *@li void @ref receivedStdout(OProcess  *proc, char  *buffer, int  buflen);
 *@li  void @ref receivedStderr(OProcess  *proc, char  *buffer, int  buflen);
 *@li  -- Indicates that new data has arrived from either the
 *child process's stdout or stderr.
 *
 *@li  void @ref wroteStdin(OProcess  *proc);
 *@li  -- Indicates that all data that has been sent to the child process
 *by a prior call to @ref writeStdin() has actually been transmitted to the
 *client .
 *
 *@author Christian Czezakte e9025461@student.tuwien.ac.at
 *@author Holger Freyther (Opie Port)
 *
 **/
class OProcess : public QObject
{
    Q_OBJECT

public:

    /**
     * Modes in which the communication channel can be opened.
     *
     * If communication for more than one channel is required,
     * the values have to be or'ed together, for example to get
     * communication with stdout as well as with stdin, you would
     * specify @p Stdin @p | @p Stdout
     *
     * If @p NoRead is specified in conjunction with @p Stdout,
     * no data is actually read from @p Stdout but only
     * the signal @ref childOutput(int fd) is emitted.
     */
    enum Communication { NoCommunication = 0, Stdin = 1, Stdout = 2, Stderr = 4,
                         AllOutput = 6, All = 7,
                         NoRead };

    /**
     * Run-modes for a child process.
     */
    enum RunMode {
        /**
         * The application does not receive notifications from the subprocess when
         * it is finished or aborted.
         */
        DontCare,
        /**
         * The application is notified when the subprocess dies.
         */
        NotifyOnExit,
        /**
         * The application is suspended until the started process is finished.
         */
        Block };

    /**
     * Constructor
     */
    OProcess( QObject *parent = 0, const char *name = 0 );
    /**
     * Constructor
     */
    OProcess( const QString &arg0, QObject *parent = 0, const char *name = 0 );
    /**
     * Constructor
     */
    OProcess( const QStringList &args, QObject *parent = 0, const char *name = 0 );

    /**
     *Destructor:
     *
     *  If the process is running when the destructor for this class
     *  is called, the child process is killed with a SIGKILL, but
     *  only if the run mode is not of type @p DontCare.
     *  Processes started as @p DontCare keep running anyway.
    */
    virtual ~OProcess();

    /**
     @deprecated

           The use of this function is now deprecated. -- Please use the
    "operator<<" instead of "setExecutable".

    Sets the executable to be started with this OProcess object.
    Returns false if the process is currently running (in that
    case the executable remains unchanged.)

    @see operator<<

    */
    bool setExecutable( const QString& proc );


    /**
     * Sets the executable and the command line argument list for this process.
     *
     * For example, doing an "ls -l /usr/local/bin" can be achieved by:
     *  <pre>
     *  OProcess p;
     *  ...
     *  p << "ls" << "-l" << "/usr/local/bin"
     *  </pre>
     *
     **/
    OProcess &operator<<( const QString& arg );
    /**
     * Similar to previous method, takes a char *, supposed to be in locale 8 bit already.
     */
    OProcess &operator<<( const char * arg );
    /**
     * Similar to previous method, takes a QCString, supposed to be in locale 8 bit already.
     */
    OProcess &operator<<( const QCString & arg );

    /**
     * Sets the executable and the command line argument list for this process,
     * in a single method call, or add a list of arguments.
     **/
    OProcess &operator<<( const QStringList& args );

    /**
     * Clear a command line argument list that has been set by using
     * the "operator<<".
    */
    void clearArguments();

    /**
     *  Starts the process.
     *  For a detailed description of the
     *  various run modes and communication semantics, have a look at the
     *  general description of the OProcess class.
     *
     *  The following problems could cause this function to
     *    return false:
     *
     *  @li The process is already running.
     *  @li The command line argument list is empty.
     *  @li The starting of the process failed (could not fork).
     *  @li The executable was not found.
     *
     *  @param comm  Specifies which communication links should be
     *  established to the child process (stdin/stdout/stderr). By default,
     *  no communication takes place and the respective communication
     *  signals will never get emitted.
     *
     *  @return true on success, false on error
     *  (see above for error conditions)
     **/
    virtual bool start( RunMode runmode = NotifyOnExit,
                        Communication comm = NoCommunication );

    /**
     * Stop the process (by sending it a signal).
     *
     * @param signo	The signal to send. The default is SIGTERM.
     * @return @p true if the signal was delivered successfully.
    */
    virtual bool kill( int signo = SIGTERM );

    /**
       @return @p true if the process is (still) considered to be running
    */
    bool isRunning() const;

    /** Returns the process id of the process.
     *
     * If it is called after
     * the process has exited, it returns the process id of the last
     *  child process that was created by this instance of OProcess.
     *
     *  Calling it before any child process has been started by this
     *  OProcess instance causes pid() to return 0.
     **/
    pid_t pid() const;

    /**
     * Suspend processing of data from stdout of the child process.
     */
    void suspend();

    /**
     * Resume processing of data from stdout of the child process.
     */
    void resume();

    /**
     * @return @p true if the process has already finished and has exited
     *  "voluntarily", ie: it has not been killed by a signal.
     *
     * Note that you should check @ref OProcess::exitStatus() to determine
     * whether the process completed its task successful or not.
     */
    bool normalExit() const;

    /**
     * Returns the exit status of the process.
     *
     * Please use
     * @ref OProcess::normalExit() to check whether the process has exited
     * cleanly (i.e., @ref OProcess::normalExit() returns @p true) before calling
     * this function because if the process did not exit normally,
     * it does not have a valid exit status.
    */
    int exitStatus() const;


    /**
     *	 Transmit data to the child process's stdin.
     *
     * OProcess::writeStdin may return false in the following cases:
     *
     *     @li The process is not currently running.
     *
     *     @li Communication to stdin has not been requested in the @ref start() call.
     *
     *     @li Transmission of data to the child process by a previous call to
     * @ref writeStdin() is still in progress.
     *
     * Please note that the data is sent to the client asynchronously,
     * so when this function returns, the data might not have been
     * processed by the child process.
     *
     * If all the data has been sent to the client, the signal
     * @ref wroteStdin() will be emitted.
     *
     * Please note that you must not free "buffer" or call @ref writeStdin()
     * again until either a @ref wroteStdin() signal indicates that the
     * data has been sent or a @ref processHasExited() signal shows that
     * the child process is no longer alive...
     **/
    bool writeStdin( const char *buffer, int buflen );

    void flushStdin();

    /**
     * This causes the stdin file descriptor of the child process to be
     * closed indicating an "EOF" to the child.
     *
     * @return @p false if no communication to the process's stdin
     *  had been specified in the call to @ref start().
    */
    bool closeStdin();

    /**
     * This causes the stdout file descriptor of the child process to be
     * closed.
     *
     * @return @p false if no communication to the process's stdout
     *  had been specified in the call to @ref start().
    */
    bool closeStdout();

    /**
     * This causes the stderr file descriptor of the child process to be
     * closed.
     *
     * @return @p false if no communication to the process's stderr
     *  had been specified in the call to @ref start().
    */
    bool closeStderr();

    /**
     * Lets you see what your arguments are for debugging.
     * \todo make const
     */

    const QValueList<QCString> &args()
    {
        return arguments;
    }

    /**
     * Controls whether the started process should drop any
     * setuid/segid privileges or whether it should keep them
     *
     * The default is @p false : drop privileges
     */
    void setRunPrivileged( bool keepPrivileges );

    /**
     * Returns whether the started process will drop any
     * setuid/segid privileges or whether it will keep them
     */
    bool runPrivileged() const;

    /**
     * Modifies the environment of the process to be started.
     * This function must be called before starting the process.
     */
    void setEnvironment( const QString &name, const QString &value );

    /**
     * Changes the current working directory (CWD) of the process
     * to be started.
     * This function must be called before starting the process.
     */
    void setWorkingDirectory( const QString &dir );

    /**
     * Specify whether to start the command via a shell or directly.
     * The default is to start the command directly.
     * If @p useShell is true @p shell will be used as shell, or
     * if shell is empty, the standard shell is used.
     * @p quote A flag indicating whether to quote the arguments.
     *
     * When using a shell, the caller should make sure that all filenames etc.
     * are properly quoted when passed as argument.
     * @see quote()
     */
    void setUseShell( bool useShell, const char *shell = 0 );

    /**
     * This function can be used to quote an argument string such that
     * the shell processes it properly. This is e. g. necessary for
     * user-provided file names which may contain spaces or quotes.
     * It also prevents expansion of wild cards and environment variables.
     */
    static QString quote( const QString &arg );

    /**
     * Detaches OProcess from child process. All communication is closed.
     * No exit notification is emitted any more for the child process.
     * Deleting the OProcess will no longer kill the child process.
     * Note that the current process remains the parent process of the
     * child process.
     */
    void detach();

    /**
     * @return the PID of @a process, or -1 if the process is not running
     */
    static int processPID( const QString& process );

signals:

    /**
     * Emitted after the process has terminated when
     * the process was run in the @p NotifyOnExit  (==default option to
     * @ref start()) or the @ref Block mode.
     **/
    void processExited( Opie::Core::OProcess *proc );


    /**
     * Emitted, when output from the child process has
     * been received on stdout.
     *
     *  To actually get
     * these signals, the respective communication link (stdout/stderr)
     * has to be turned on in @ref start().
     *
     * @param proc The process
     * @param buffer The data received.
     * @param buflen The number of bytes that are available.
     *
     * You should copy the information contained in @p buffer to your private
     * data structures before returning from this slot.
     **/
    void receivedStdout( Opie::Core::OProcess *proc, char *buffer, int buflen );

    /**
     * Emitted when output from the child process has
     * been received on stdout.
     *
     * To actually get these signals, the respective communications link
     * (stdout/stderr) has to be turned on in @ref start() and the
     * @p NoRead flag should have been passed.
     *
     * You will need to explicitly call resume() after your call to start()
     * to begin processing data from the child process's stdout.  This is
     * to ensure that this signal is not emitted when no one is connected
     * to it, otherwise this signal will not be emitted.
     *
     * The data still has to be read from file descriptor @p fd.
     **/
    void receivedStdout( int fd, int &len );


    /**
     * Emitted, when output from the child process has
     * been received on stderr.
     * To actually get
     * these signals, the respective communication link (stdout/stderr)
     * has to be turned on in @ref start().
     *
     * @param proc The process
     * @param buffer The data received.
     * @param buflen The number of bytes that are available.
     *
     * You should copy the information contained in @p buffer to your private
     * data structures before returning from this slot.
    */
    void receivedStderr( Opie::Core::OProcess *proc, char *buffer, int buflen );

    /**
     * Emitted after all the data that has been
     * specified by a prior call to @ref writeStdin() has actually been
     * written to the child process.
     **/
    void wroteStdin( Opie::Core::OProcess *proc );

protected slots:

    /**
     * This slot gets activated when data from the child's stdout arrives.
     * It usually calls "childOutput"
     */
    void slotChildOutput( int fdno );

    /**
     * This slot gets activated when data from the child's stderr arrives.
     * It usually calls "childError"
     */
    void slotChildError( int fdno );
    /*
    Slot functions for capturing stdout and stderr of the child
    */

    /**
     * Called when another bulk of data can be sent to the child's
     * stdin. If there is no more data to be sent to stdin currently
     * available, this function must disable the QSocketNotifier "innot".
     */
    void slotSendData( int dummy );

protected:

    /**
     * Sets up the environment according to the data passed via
     * setEnvironment(...)
     */
    void setupEnvironment();

    /**
     * The list of the process' command line arguments. The first entry
     * in this list is the executable itself.
     */
    QValueList<QCString> arguments;
    /**
     * How to run the process (Block, NotifyOnExit, DontCare). You should
     *  not modify this data member directly from derived classes.
     */
    RunMode run_mode;
    /**
     * true if the process is currently running. You should not
     * modify this data member directly from derived classes. For
     * reading the value of this data member, please use "isRunning()"
     * since "runs" will probably be made private in later versions
     * of OProcess.
     */
    bool runs;

    /**
     * The PID of the currently running process (see "getPid()").
     * You should not modify this data member in derived classes.
     * Please use "getPid()" instead of directly accessing this
     * member function since it will probably be made private in
     * later versions of OProcess.
     */
    pid_t pid_;

    /**
     * The process' exit status as returned by "waitpid". You should not
     * modify the value of this data member from derived classes. You should
     * rather use @ref exitStatus than accessing this data member directly
     * since it will probably be made private in further versions of
     * OProcess.
     */
    int status;


    /**
     * See setRunPrivileged()
     */
    bool keepPrivs;

    /*
    Functions for setting up the sockets for communication.
    setupCommunication
    -- is called from "start" before "fork"ing.
    commSetupDoneP
    -- completes communication socket setup in the parent
    commSetupDoneC
    -- completes communication setup in the child process
    commClose
    -- frees all allocated communication resources in the parent
    after the process has exited
    */

    /**
     * This function is called from "OProcess::start" right before a "fork" takes
     * place. According to
     * the "comm" parameter this function has to initialize the "in", "out" and
     * "err" data member of OProcess.
     *
     * This function should return 0 if setting the needed communication channels
     * was successful.
     *
     * The default implementation is to create UNIX STREAM sockets for the communication,
     * but you could overload this function and establish a TCP/IP communication for
     * network communication, for example.
     */
    virtual int setupCommunication( Communication comm );

    /**
     * Called right after a (successful) fork on the parent side. This function
     * will usually do some communications cleanup, like closing the reading end
     * of the "stdin" communication channel.
     *
     * Furthermore, it must also create the QSocketNotifiers "innot", "outnot" and
     * "errnot" and connect their Qt slots to the respective OProcess member functions.
     *
     * For a more detailed explanation, it is best to have a look at the default
     * implementation of "setupCommunication" in kprocess.cpp.
     */
    virtual int commSetupDoneP();

    /**
     * Called right after a (successful) fork, but before an "exec" on the child
     * process' side. It usually just closes the unused communication ends of
     * "in", "out" and "err" (like the writing end of the "in" communication
     * channel.
     */
    virtual int commSetupDoneC();


    /**
     * Immediately called after a process has exited. This function normally
     * calls commClose to close all open communication channels to this
     * process and emits the "processExited" signal (if the process was
     * not running in the "DontCare" mode).
     */
    virtual void processHasExited( int state );

    /**
     * Should clean up the communication links to the child after it has
     * exited. Should be called from "processHasExited".
     */
    virtual void commClose();


    /**
     * the socket descriptors for stdin/stdout/stderr.
     */
    int out[ 2 ];
    int in[ 2 ];
    int err[ 2 ];

    /**
     * The socket notifiers for the above socket descriptors.
     */
    QSocketNotifier *innot;
    QSocketNotifier *outnot;
    QSocketNotifier *errnot;

    /**
     * Lists the communication links that are activated for the child
     * process.  Should not be modified from derived classes.
     */
    Communication communication;

    /**
     * Called by "slotChildOutput" this function copies data arriving from the
     * child process's stdout to the respective buffer and emits the signal
     * "@ref receivedStderr".
     */
    int childOutput( int fdno );

    /**
     * Called by "slotChildOutput" this function copies data arriving from the
     * child process's stdout to the respective buffer and emits the signal
     * "@ref receivedStderr"
     */
    int childError( int fdno );

    // information about the data that has to be sent to the child:

    const char *input_data;  // the buffer holding the data
    int input_sent;    // # of bytes already transmitted
    int input_total;   // total length of input_data

    /**
     * @ref OProcessController is a friend of OProcess because it has to have
     * access to various data members.
     */
    friend class Internal::OProcessController;

private:
    /**
     * Searches for a valid shell.
     * Here is the algorithm used for finding an executable shell:
     *
     *    @li Try the executable pointed to by the "SHELL" environment
     *    variable with white spaces stripped off
     *
     *    @li If your process runs with uid != euid or gid != egid, a shell
     *    not listed in /etc/shells will not used.
     *
     *    @li If no valid shell could be found, "/bin/sh" is used as a last resort.
     */
    QCString searchShell();

    /**
     * Used by @ref searchShell in order to find out whether the shell found
     * is actually executable at all.
     */
    bool isExecutable( const QCString &filename );

    // Disallow assignment and copy-construction
    OProcess( const OProcess& );
    OProcess& operator= ( const OProcess& );

private:
    void init ( );
    Internal::OProcessPrivate *d;
};
}
}

#endif