source: trunk/src/qt3support/other/q3process.cpp@ 134

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#include "q3process.h"

#ifndef QT_NO_PROCESS

#include "qapplication.h"
#include "private/q3membuf_p.h"

#include <stdio.h>
#include <stdlib.h>

QT_BEGIN_NAMESPACE

//#define QT_Q3PROCESS_DEBUG


/*!
    \class Q3Process

    \brief The Q3Process class is used to start external programs and
    to communicate with them.

    \compat

    You can write to the started program's standard input, and can
    read the program's standard output and standard error. You can
    pass command line arguments to the program either in the
    constructor or with setArguments() or addArgument(). The program's
    working directory can be set with setWorkingDirectory(). If you
    need to set up environment variables pass them to the start() or
    launch() functions (see below). The processExited() signal is
    emitted if the program exits. The program's exit status is
    available from exitStatus(), although you could simply call
    normalExit() to see if the program terminated normally.

    There are two different ways to start a process. If you just want
    to run a program, optionally passing data to its standard input at
    the beginning, use one of the launch() functions. If you want full
    control of the program's standard input (especially if you don't
    know all the data you want to send to standard input at the
    beginning), use the start() function.

    If you use start() you can write to the program's standard input
    using writeToStdin() and you can close the standard input with
    closeStdin(). The wroteToStdin() signal is emitted if the data
    sent to standard input has been written. You can read from the
    program's standard output using readStdout() or readLineStdout().
    These functions return an empty QByteArray if there is no data to
    read. The readyReadStdout() signal is emitted when there is data
    available to be read from standard output. Standard error has a
    set of functions that correspond to the standard output functions,
    i.e. readStderr(), readLineStderr() and readyReadStderr().

    If you use one of the launch() functions the data you pass will be
    sent to the program's standard input which will be closed once all
    the data has been written. You should \e not use writeToStdin() or
    closeStdin() if you use launch(). If you need to send data to the
    program's standard input after it has started running use start()
    instead of launch().

    Both start() and launch() can accept a string list of strings each
    of which has the format, key=value, where the keys are the names
    of environment variables.

    You can test to see if a program is running with isRunning(). The
    program's process identifier is available from
    processIdentifier(). If you want to terminate a running program
    use tryTerminate(), but note that the program may ignore this. If
    you \e really want to terminate the program, without it having any
    chance to clean up, you can use kill().

    Although you may need quotes for a file named on the command line
    (e.g. if it contains spaces) you shouldn't use extra quotes for
    arguments passed to addArgument() or setArguments().

    The readyReadStdout() signal is emitted when there is new data on
    standard output. This happens asynchronously: you don't know if
    more data will arrive later.

    In the above example you could connect the processExited() signal
    to the slot UicManager::readFromStdout() instead. If you do so,
    you will be certain that all the data is available when the slot
    is called. On the other hand, you must wait until the process has
    finished before doing any processing.

    Note that if you are expecting a lot of output from the process,
    you may hit platform-dependent limits to the pipe buffer size. The
    solution is to make sure you connect to the output, e.g. the
    readyReadStdout() and readyReadStderr() signals and read the data
    as soon as it becomes available.

    Please note that Q3Process does not emulate a shell. This means that
    Q3Process does not do any expansion of arguments: a '*' is passed as a '*'
    to the program and is \e not replaced by all the files, a '$HOME' is also
    passed literally and is \e not replaced by the environment variable HOME
    and the special characters for IO redirection ('>', '|', etc.) are also
    passed literally and do \e not have the special meaning as they have in a
    shell.

    Also note that Q3Process does not emulate a terminal. This means that
    certain programs which need direct terminal control, do not work as
    expected with Q3Process. Such programs include console email programs (like
    pine and mutt) but also programs which require the user to enter a password
    (like su and ssh).

    \section1 Notes for Windows users

    Some Windows commands, for example, \c dir, are not provided by
    separate applications, but by the command interpreter.
    If you attempt to use Q3Process to execute these commands directly
    it won't work. One possible solution is to execute the command
    interpreter itself (\c cmd.exe on some Windows systems), and ask
    the interpreter to execute the desired command.

    Under Windows there are certain problems starting 16-bit applications
    and capturing their output. Microsoft recommends using an intermediate
    application to start 16-bit applications.

    \sa Q3Socket
*/

/*!
    \enum Q3Process::Communication

    This enum type defines the communication channels connected to the
    process.

    \value Stdin  Data can be written to the process's standard input.

    \value Stdout  Data can be read from the process's standard
    output.

    \value Stderr  Data can be read from the process's standard error.

    \value DupStderr  Both the process's standard error output \e and
    its standard output are written to its standard output. (Like
    Unix's dup2().) This means that nothing is sent to the standard
    error output. This is especially useful if your application
    requires that the output on standard output and on standard error
    must be read in the same order that they are produced. This is a
    flag, so to activate it you must pass \c{Stdout|Stderr|DupStderr},
    or \c{Stdin|Stdout|Stderr|DupStderr} if you want to provide input,
    to the setCommunication() call.

    \sa setCommunication() communication()
*/