path: root/src/kernel/qprocess.cpp

/****************************************************************************
**
** Implementation of QProcess class
**
** Created : 20000905
**
** Copyright (C) 1992-2008 Trolltech ASA.  All rights reserved.
**
** This file is part of the kernel module of the Qt GUI Toolkit.
**
** This file may be used under the terms of the GNU General
** Public License versions 2.0 or 3.0 as published by the Free
** Software Foundation and appearing in the files LICENSE.GPL2
** and LICENSE.GPL3 included in the packaging of this file.
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** publicly approved by Trolltech ASA (or its successors, if any)
** and the KDE Free Qt Foundation.
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**********************************************************************/

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

#include "qprocess.h"

#ifndef QT_NO_PROCESS

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


//#define QT_QPROCESS_DEBUG


/*!
    \class QProcess qprocess.h

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

    \ingroup io
    \ingroup misc
    \mainclass

    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().

    As an example, suppose we want to start the \c uic command (a Qt
    command line tool used with \e{Qt Designer}) and perform some
    operations on the output (the \c uic outputs the code it generates
    to standard output by default). Suppose further that we want to
    run the program on the file "small_dialog.ui" with the command
    line options "-tr i18n". On the command line we would write:
    \code
    uic -tr i18n small_dialog.ui
    \endcode

    \quotefile process/process.cpp

    A code snippet for this with the QProcess class might look like
    this:

    \skipto UicManager::UicManager()
    \printline UicManager::UicManager()
    \printline {
    \skipto proc = new QProcess( this );
    \printline proc = new QProcess( this );
    \skipto proc->addArgument( "uic" );
    \printuntil this, SLOT(readFromStdout()) );
    \skipto if ( !proc->start() ) {
    \printuntil // error handling
    \skipto }
    \printline }
    \printline }

    \skipto void UicManager::readFromStdout()
    \printuntil // Bear in mind that the data might be output in chunks.
    \skipto }
    \printline }

    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 QProcess does not emulate a shell. This means that
    QProcess 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 QProcess does not emulate a terminal. This means that
    certain programs which need direct terminal control, do not work as
    expected with QProcess. 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 QProcess 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 QSocket
*/

/*!
    \enum QProcess::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()
*/

/*!
    Constructs a QProcess object. The \a parent and \a name parameters
    are passed to the QObject constructor.

    \sa setArguments() addArgument() start()
*/
QProcess::QProcess( QObject *parent, const char *name )
    : QObject( parent, name ), ioRedirection( FALSE ), notifyOnExit( FALSE ),
    wroteToStdinConnected( FALSE ),
    readStdoutCalled( FALSE ), readStderrCalled( FALSE ),
    comms( Stdin|Stdout|Stderr )
{
    init();
}

/*!
    Constructs a QProcess with \a arg0 as the command to be executed.
    The \a parent and \a name parameters are passed to the QObject
    constructor.

    The process is not started. You must call start() or launch() to
    start the process.

    \sa setArguments() addArgument() start()
*/
QProcess::QProcess( const QString& arg0, QObject *parent, const char *name )
    : QObject( parent, name ), ioRedirection( FALSE ), notifyOnExit( FALSE ),
    wroteToStdinConnected( FALSE ),
    readStdoutCalled( FALSE ), readStderrCalled( FALSE ),
    comms( Stdin|Stdout|Stderr )
{
    init();
    addArgument( arg0 );
}

/*!
    Constructs a QProcess with \a args as the arguments of the
    process. The first element in the list is the command to be
    executed. The other elements in the list are the arguments to this
    command. The \a parent and \a name parameters are passed to the
    QObject constructor.

    The process is not started. You must call start() or launch() to
    start the process.

    \sa setArguments() addArgument() start()
*/
QProcess::QProcess( const QStringList& args, QObject *parent, const char *name )
    : QObject( parent, name ), ioRedirection( FALSE ), notifyOnExit( FALSE ),
    wroteToStdinConnected( FALSE ),
    readStdoutCalled( FALSE ), readStderrCalled( FALSE ),
    comms( Stdin|Stdout|Stderr )
{
    init();
    setArguments( args );
}


/*!
    Returns the list of arguments that are set for the process.
    Arguments can be specified with the constructor or with the
    functions setArguments() and addArgument().

    Note that if you want to iterate over the list, you should iterate
    over a copy, e.g.
    \code
    QStringList list = myProcess.arguments();
    QStringList::Iterator it = list.begin();
    while( it != list.end() ) {
	myProcessing( *it );
	++it;
    }
    \endcode

    \sa setArguments() addArgument()
*/
QStringList QProcess::arguments() const
{
    return _arguments;
}

/*!
    Clears the list of arguments that are set for the process.

    \sa setArguments() addArgument()
*/
void QProcess::clearArguments()
{
    _arguments.clear();
}

/*!
    Sets \a args as the arguments for the process. The first element
    in the list is the command to be executed. The other elements in
    the list are the arguments to the command. Any previous arguments
    are deleted.

    QProcess does not perform argument substitutions; for example, if you
    specify "*" or "$DISPLAY", these values are passed to the process
    literally. If you want to have the same behavior as the shell
    provides, you must do the substitutions yourself; i.e. instead of
    specifying a "*" you must specify the list of all the filenames in
    the current directory, and instead of "$DISPLAY" you must specify
    the value of the environment variable \c DISPLAY.

    Note for Windows users. The standard Windows shells, e.g. \c
    command.com and \c cmd.exe, do not perform file globbing, i.e.
    they do not convert a "*" on the command line into a list of files
    in the current directory. For this reason most Windows
    applications implement their own file globbing, and as a result of
    this, specifying an argument of "*" for a Windows application is
    likely to result in the application performing a file glob and
    ending up with a list of filenames.

    \sa arguments() addArgument()
*/
void QProcess::setArguments( const QStringList& args )
{
    _arguments = args;
}

/*!
    Adds \a arg to the end of the list of arguments.

    The first element in the list of arguments is the command to be
    executed; the following elements are the command's arguments.

    \sa arguments() setArguments()
*/
void QProcess::addArgument( const QString& arg )
{
    _arguments.append( arg );
}

#ifndef QT_NO_DIR
/*!
    Returns the working directory that was set with
    setWorkingDirectory(), or the current directory if none has been
    explicitly set.

    \sa setWorkingDirectory() QDir::current()
*/
QDir QProcess::workingDirectory() const
{
    return workingDir;
}

/*!
    Sets \a dir as the working directory for processes. This does not
    affect running processes; only processes that are started
    afterwards are affected.

    Setting the working directory is especially useful for processes
    that try to access files with relative paths.

    \sa workingDirectory() start()
*/
void QProcess::setWorkingDirectory( const QDir& dir )
{
    workingDir = dir;
}
#endif //QT_NO_DIR

/*!
    Returns the communication required with the process, i.e. some
    combination of the \c Communication flags.

    \sa setCommunication()
*/
int QProcess::communication() const
{
    return comms;
}

/*!
    Sets \a commFlags as the communication required with the process.

    \a commFlags is a bitwise OR of the flags defined by the \c
    Communication enum.

    The default is \c{Stdin|Stdout|Stderr}.

    \sa communication()
*/
void QProcess::setCommunication( int commFlags )
{
    comms = commFlags;
}

/*!
    Returns TRUE if the process has exited normally; otherwise returns
    FALSE. This implies that this function returns FALSE if the
    process is still running.

    \sa isRunning() exitStatus() processExited()
*/
bool QProcess::normalExit() const
{
    // isRunning() has the side effect that it determines the exit status!
    if ( isRunning() )
	return FALSE;
    else
	return exitNormal;
}

/*!
    Returns the exit status of the process or 0 if the process is
    still running. This function returns immediately and does not wait
    until the process is finished.

    If normalExit() is FALSE (e.g. if the program was killed or
    crashed), this function returns 0, so you should check the return
    value of normalExit() before relying on this value.

    \sa normalExit() processExited()
*/
int QProcess::exitStatus() const
{
    // isRunning() has the side effect that it determines the exit status!
    if ( isRunning() )
	return 0;
    else
	return exitStat;
}


/*!
    Reads the data that the process has written to standard output.
    When new data is written to standard output, the class emits the
    signal readyReadStdout().

    If there is no data to read, this function returns a QByteArray of
    size 0: it does not wait until there is something to read.

    \sa readyReadStdout() readLineStdout() readStderr() writeToStdin()
*/
QByteArray QProcess::readStdout()
{
    if ( readStdoutCalled ) {
	return QByteArray();
    }
    readStdoutCalled = TRUE;
    QMembuf *buf = membufStdout();
    readStdoutCalled = FALSE;

    return buf->readAll();
}

/*!
    Reads the data that the process has written to standard error.
    When new data is written to standard error, the class emits the
    signal readyReadStderr().

    If there is no data to read, this function returns a QByteArray of
    size 0: it does not wait until there is something to read.

    \sa readyReadStderr() readLineStderr() readStdout() writeToStdin()
*/
QByteArray QProcess::readStderr()
{
    if ( readStderrCalled ) {
	return QByteArray();
    }
    readStderrCalled = TRUE;
    QMembuf *buf = membufStderr();
    readStderrCalled = FALSE;

    return buf->readAll();
}

/*!
    Reads a line of text from standard output, excluding any trailing
    newline or carriage return characters, and returns it. Returns
    QString::null if canReadLineStdout() returns FALSE.

    By default, the text is interpreted to be in Latin-1 encoding. If you need
    other codecs, you can set a different codec with
    QTextCodec::setCodecForCStrings().

    \sa canReadLineStdout() readyReadStdout() readStdout() readLineStderr()
*/
QString QProcess::readLineStdout()
{
    QByteArray a( 256 );
    QMembuf *buf = membufStdout();
    if ( !buf->scanNewline( &a ) ) {
      if ( !canReadLineStdout() )
	return QString::null;

      if ( !buf->scanNewline( &a ) )
	return QString( buf->readAll() );
    }

    uint size = a.size();
    buf->consumeBytes( size, 0 );

    // get rid of terminating \n or \r\n
    if ( size>0 && a.at( size - 1 ) == '\n' ) {
      if ( size>1 && a.at( size - 2 ) == '\r' )
	a.at( size - 2 ) = '\0';
      else
	a.at( size - 1 ) = '\0';
    }
    return QString( a );
}

/*!
    Reads a line of text from standard error, excluding any trailing
    newline or carriage return characters and returns it. Returns
    QString::null if canReadLineStderr() returns FALSE.

    By default, the text is interpreted to be in Latin-1 encoding. If you need
    other codecs, you can set a different codec with
    QTextCodec::setCodecForCStrings().

    \sa canReadLineStderr() readyReadStderr() readStderr() readLineStdout()
*/
QString QProcess::readLineStderr()
{
    QByteArray a( 256 );
    QMembuf *buf = membufStderr();
    if ( !buf->scanNewline( &a ) ) {
      if ( !canReadLineStderr() )
	return QString::null;

      if ( !buf->scanNewline( &a ) )
	return QString( buf->readAll() );
    }

    uint size = a.size();
    buf->consumeBytes( size, 0 );

    // get rid of terminating \n or \r\n
    if ( size>0 && a.at( size - 1 ) == '\n' ) {
      if ( size>1 && a.at( size - 2 ) == '\r' )
	a.at( size - 2 ) = '\0';
      else
	a.at( size - 1 ) = '\0';
    }
    return QString( a );
}

/*!
    \fn void QProcess::launchFinished()

    This signal is emitted when the process was started with launch().
    If the start was successful, this signal is emitted after all the
    data has been written to standard input. If the start failed, then
    this signal is emitted immediately.

    This signal is especially useful if you want to know when you can
    safely delete the QProcess object when you are not interested in
    reading from standard output or standard error.

    \sa launch() QObject::deleteLater()
*/

/*!
    Runs the process and writes the data \a buf to the process's
    standard input. If all the data is written to standard input,
    standard input is closed. The command is searched for in the path
    for executable programs; you can also use an absolute path in the
    command itself.

    If \a env is null, then the process is started with the same
    environment as the starting process. If \a env is non-null, then
    the values in the string list are interpreted as environment
    setttings of the form \c {key=value} and the process is started
    with these environment settings. For convenience, there is a small
    exception to this rule under Unix: if \a env does not contain any
    settings for the environment variable \c LD_LIBRARY_PATH, then
    this variable is inherited from the starting process.

    Returns TRUE if the process could be started; otherwise returns
    FALSE.

    Note that you should not use the slots writeToStdin() and
    closeStdin() on processes started with launch(), since the result
    is not well-defined. If you need these slots, use start() instead.

    The process may or may not read the \a buf data sent to its
    standard input.

    You can call this function even when a process that was started
    with this instance is still running. Be aware that if you do this
    the standard input of the process that was launched first will be
    closed, with any pending data being deleted, and the process will
    be left to run out of your control. Similarly, if the process
    could not be started the standard input will be closed and the
    pending data deleted. (On operating systems that have zombie
    processes, Qt will also wait() on the old process.)

    The object emits the signal launchFinished() when this function
    call is finished. If the start was successful, this signal is
    emitted after all the data has been written to standard input. If
    the start failed, then this signal is emitted immediately.

    \sa start() launchFinished();
*/
bool QProcess::launch( const QByteArray& buf, QStringList *env )
{
    if ( start( env ) ) {
	if ( !buf.isEmpty() ) {
	    connect( this, SIGNAL(wroteToStdin()),
		    this, SLOT(closeStdinLaunch()) );
	    writeToStdin( buf );
	} else {
	    closeStdin();
	    emit launchFinished();
	}
	return TRUE;
    } else {
	emit launchFinished();
	return FALSE;
    }
}

/*!
    \overload

    The data \a buf is written to standard input with writeToStdin()
    using the QString::local8Bit() representation of the strings.
*/
bool QProcess::launch( const QString& buf, QStringList *env )
{
    if ( start( env ) ) {
	if ( !buf.isEmpty() ) {
	    connect( this, SIGNAL(wroteToStdin()),
		    this, SLOT(closeStdinLaunch()) );
	    writeToStdin( buf );
	} else {
	    closeStdin();
	    emit launchFinished();
	}
	return TRUE;
    } else {
	emit launchFinished();
	return FALSE;
    }
}

/*
  This private slot is used by the launch() functions to close standard input.
*/
void QProcess::closeStdinLaunch()
{
    disconnect( this, SIGNAL(wroteToStdin()),
	    this, SLOT(closeStdinLaunch()) );
    closeStdin();
    emit launchFinished();
}


/*!
    \fn void QProcess::readyReadStdout()

    This signal is emitted when the process has written data to
    standard output. You can read the data with readStdout().

    Note that this signal is only emitted when there is new data and
    not when there is old, but unread data. In the slot connected to
    this signal, you should always read everything that is available
    at that moment to make sure that you don't lose any data.

    \sa readStdout() readLineStdout() readyReadStderr()
*/

/*!
    \fn void QProcess::readyReadStderr()

    This signal is emitted when the process has written data to
    standard error. You can read the data with readStderr().

    Note that this signal is only emitted when there is new data and
    not when there is old, but unread data. In the slot connected to
    this signal, you should always read everything that is available
    at that moment to make sure that you don't lose any data.

    \sa readStderr() readLineStderr() readyReadStdout()
*/

/*!
    \fn void QProcess::processExited()

    This signal is emitted when the process has exited.

    \sa isRunning() normalExit() exitStatus() start() launch()
*/

/*!
    \fn void QProcess::wroteToStdin()

    This signal is emitted if the data sent to standard input (via
    writeToStdin()) was actually written to the process. This does not
    imply that the process really read the data, since this class only
    detects when it was able to write the data to the operating
    system. But it is now safe to close standard input without losing
    pending data.

    \sa writeToStdin() closeStdin()
*/


/*!
    \overload

    The string \a buf is handled as text using the
    QString::local8Bit() representation.
*/
void QProcess::writeToStdin( const QString& buf )
{
    QByteArray tmp = buf.local8Bit();
    tmp.resize( qstrlen( tmp.data() ) );
    writeToStdin( tmp );
}


/*
 * Under Windows the implementation is not so nice: it is not that easy to
 * detect when one of the signals should be emitted; therefore there are some
 * timers that query the information.
 * To keep it a little efficient, use the timers only when they are needed.
 * They are needed, if you are interested in the signals. So use
 * connectNotify() and disconnectNotify() to keep track of your interest.
 */
/*!  \reimp
*/
void QProcess::connectNotify( const char * signal )
{
#if defined(QT_QPROCESS_DEBUG)
    qDebug( "QProcess::connectNotify(): signal %s has been connected", signal );
#endif
    if ( !ioRedirection )
	if ( qstrcmp( signal, SIGNAL(readyReadStdout()) )==0 ||
		qstrcmp( signal, SIGNAL(readyReadStderr()) )==0
	   ) {
#if defined(QT_QPROCESS_DEBUG)
	    qDebug( "QProcess::connectNotify(): set ioRedirection to TRUE" );
#endif
	    setIoRedirection( TRUE );
	    return;
	}
    if ( !notifyOnExit && qstrcmp( signal, SIGNAL(processExited()) )==0 ) {
#if defined(QT_QPROCESS_DEBUG)
	qDebug( "QProcess::connectNotify(): set notifyOnExit to TRUE" );
#endif
	setNotifyOnExit( TRUE );
	return;
    }
    if ( !wroteToStdinConnected && qstrcmp( signal, SIGNAL(wroteToStdin()) )==0 ) {
#if defined(QT_QPROCESS_DEBUG)
	qDebug( "QProcess::connectNotify(): set wroteToStdinConnected to TRUE" );
#endif
	setWroteStdinConnected( TRUE );
	return;
    }
}

/*!  \reimp
*/
void QProcess::disconnectNotify( const char * )
{
    if ( ioRedirection &&
	    receivers( SIGNAL(readyReadStdout()) ) ==0 &&
	    receivers( SIGNAL(readyReadStderr()) ) ==0
	    ) {
#if defined(QT_QPROCESS_DEBUG)
	qDebug( "QProcess::disconnectNotify(): set ioRedirection to FALSE" );
#endif
	setIoRedirection( FALSE );
    }
    if ( notifyOnExit && receivers( SIGNAL(processExited()) ) == 0 ) {
#if defined(QT_QPROCESS_DEBUG)
	qDebug( "QProcess::disconnectNotify(): set notifyOnExit to FALSE" );
#endif
	setNotifyOnExit( FALSE );
    }
    if ( wroteToStdinConnected && receivers( SIGNAL(wroteToStdin()) ) == 0 ) {
#if defined(QT_QPROCESS_DEBUG)
	qDebug( "QProcess::disconnectNotify(): set wroteToStdinConnected to FALSE" );
#endif
	setWroteStdinConnected( FALSE );
    }
}

#endif // QT_NO_PROCESS