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KProcess Class Reference

#include <kprocess.h>

Inheritance diagram for KProcess:

List of all members.

Public Types
enum	Communication
enum	RunMode { DontCare, NotifyOnExit, Block }
Signals
void	processExited (KProcess *proc)
void	receivedStdout (KProcess *proc, char *buffer, int buflen)
void	receivedStdout (int fd, int &len)
void	receivedStderr (KProcess *proc, char *buffer, int buflen)
void	wroteStdin (KProcess *proc)
Public Methods
	KProcess ()
virtual	~KProcess ()
bool	setExecutable (const QString &proc)
KProcess &	operator<< (const QString &arg)
KProcess &	operator<< (const char *arg)
KProcess &	operator<< (const QCString &arg)
KProcess &	operator<< (const QStringList &args)
void	clearArguments ()
virtual bool	start (RunMode runmode=NotifyOnExit, Communication comm=NoCommunication)
virtual bool	kill (int signo=SIGTERM)
bool	isRunning () const
pid_t	pid () const
pid_t	getPid () const
void	suspend ()
void	resume ()
bool	normalExit () const
int	exitStatus () const
bool	writeStdin (const char *buffer, int buflen)
bool	closeStdin ()
bool	closeStdout ()
bool	closeStderr ()
const QValueList< QCString > &	args ()
void	setRunPrivileged (bool keepPrivileges)
bool	runPrivileged () const
void	setEnvironment (const QString &name, const QString &value)
void	setWorkingDirectory (const QString &dir)
void	setUseShell (bool useShell, const char *shell=0)
void	detach ()
Static Public Methods
QString	quote (const QString &arg)
Protected Slots
void	slotChildOutput (int fdno)
void	slotChildError (int fdno)
void	slotSendData (int dummy)
Protected Methods
void	setupEnvironment ()
virtual int	setupCommunication (Communication comm)
virtual int	commSetupDoneP ()
virtual int	commSetupDoneC ()
virtual void	processHasExited (int state)
virtual void	commClose ()
int	childOutput (int fdno)
int	childError (int fdno)
Protected Attributes
QValueList< QCString >	arguments
RunMode	run_mode
bool	runs
pid_t	pid_
int	status
bool	keepPrivs
int	out [2]
QSocketNotifier *	innot
Communication	communication
Friends
class	KProcessController

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Detailed Description

Child process invocation, monitoring and control.

@sect General usage and features

This class allows a KDE application to start child processes without having to worry about UN*X signal handling issues and zombie process reaping.

See also:

KProcIO

Basically, this class distinguishes three different ways of running child processes:

• KProcess::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.

• KProcess::NotifyOnExit -- The child process is invoked and both the child and the parent process run concurrently.

When the child process exits, the KProcess instance corresponding to it emits the Qt signal processExited().

Since this signal is not emitted from within a UN*X signal handler, arbitrary function calls can be made.

Be aware: When the KProcess objects gets destructed, the child process will be killed if it is still running! This means in particular, that you cannot use a KProcess on the stack with KProcess::NotifyOnExit.

• KProcess::Block -- The child process starts and the parent process is suspended until the child process exits. (Really not recommended for programs with a GUI.)

KProcess 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:

 *KProcess *proc = new KProcess;

 **proc << "my_executable";
 **proc << "These" << "are" << "the" << "command" << "line" << "args";
 *QApplication::connect(proc, SIGNAL(processExited(KProcess *)),
                      pointer_to_my_object, SLOT(my_objects_slot(KProcess *)));
 *proc->start();
 *

This will start "my_executable" with the commandline arguments "These"...

When the child process exits, the respective Qt signal will be emitted.

@sect Communication with the child process

KProcess 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):

• bool writeStdin(char *buffer, int buflen);
• -- Transmit data to the child process's stdin.

• bool closeStdin();
• -- 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.

• bool closeStdout();
• -- 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.

• bool closeStderr();
• -- 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.

@sect QT signals:

• void receivedStdout(KProcess *proc, char *buffer, int buflen);
• void receivedStderr(KProcess *proc, char *buffer, int buflen);
• -- Indicates that new data has arrived from either the child process's stdout or stderr.

• void wroteStdin(KProcess *proc);
• -- Indicates that all data that has been sent to the child process by a prior call to writeStdin() has actually been transmitted to the client .

Author:

Christian Czezakte e9025461@student.tuwien.ac.at

Definition at line 146 of file kprocess.h.

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Member Enumeration Documentation

enum KProcess::Communication

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 Stdin | Stdout If NoRead is specified in conjunction with Stdout, no data is actually read from Stdout but only the signal childOutput(int fd) is emitted. Definition at line 164 of file kprocess.h.

enum KProcess::RunMode

Run-modes for a child process. Enumeration values: DontCare  The application does not receive notifications from the subprocess when it is finished or aborted. NotifyOnExit  The application is notified when the subprocess dies. Block  The application is suspended until the started process is finished. Definition at line 171 of file kprocess.h.

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Constructor & Destructor Documentation

KProcess::KProcess (    )

Constructor

virtual KProcess::~KProcess (    )  [virtual]

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 DontCare. Processes started as DontCare keep running anyway.

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Member Function Documentation

const QValueList<QCString>& KProcess::args (    )  [inline]

Lets you see what your arguments are for debugging. Returns: the list of arguments Definition at line 406 of file kprocess.h. References arguments.

int KProcess::childError (  int    fdno )  [protected]

Called by "slotChildOutput" this function copies data arriving from the child process's stdout to the respective buffer and emits the signal "receivedStderr"

int KProcess::childOutput (  int    fdno )  [protected]

Called by "slotChildOutput" this function copies data arriving from the child process's stdout to the respective buffer and emits the signal "receivedStderr".

void KProcess::clearArguments (    )

Clear a command line argument list that has been set by using the "operator<<".

bool KProcess::closeStderr (    )

This causes the stderr file descriptor of the child process to be closed. Returns: false if no communication to the process's stderr had been specified in the call to start().

bool KProcess::closeStdin (    )

This causes the stdin file descriptor of the child process to be closed indicating an "EOF" to the child. Returns: false if no communication to the process's stdin had been specified in the call to start().

bool KProcess::closeStdout (    )

This causes the stdout file descriptor of the child process to be closed. Returns: false if no communication to the process's stdout had been specified in the call to start().

virtual void KProcess::commClose (    )  [protected, virtual]

Should clean up the communication links to the child after it has exited. Should be called from "processHasExited".

virtual int KProcess::commSetupDoneC (    )  [protected, virtual]

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 KProcess::commSetupDoneP (    )  [protected, virtual]

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 KProcess member functions. For a more detailed explanation, it is best to have a look at the default implementation of "setupCommunication" in kprocess.cpp.

void KProcess::detach (    )

Detaches KProcess from child process. All communication is closed. No exit notification is emitted any more for the child process. Deleting the KProcess will no longer kill the child process. Note that the current process remains the parent process of the child process.

int KProcess::exitStatus (    )

Returns the exit status of the process. Please use KProcess::normalExit() to check whether the process has exited cleanly (i.e., KProcess::normalExit() returns true) before calling this function because if the process did not exit normally, it does not have a valid exit status. Returns: the exit status of the process

pid_t KProcess::getPid (    )  const [inline]

Use pid(). Deprecated: Definition at line 312 of file kprocess.h. References pid().

bool KProcess::isRunning (    )

Checks whether the process is running. Returns: true if the process is (still) considered to be running

virtual bool KProcess::kill (  int    signo = SIGTERM )  [virtual]

Stop the process (by sending it a signal). Parameters: signo  The signal to send. The default is SIGTERM. Returns: true if the signal was delivered successfully.

bool KProcess::normalExit (    )

Returns: 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 KProcess::exitStatus() to determine whether the process completed its task successful or not.

KProcess& KProcess::operator<< (  const QStringList &    args )

Sets the executable and the command line argument list for this process, in a single method call, or add a list of arguments. Parameters: arg  the arguments to add Returns: a reference to this KProcess

KProcess& KProcess::operator<< (  const QCString &    arg )

Similar to previous method, takes a QCString, supposed to be in locale 8 bit already. Parameters: arg  the argument to add Returns: a reference to this KProcess

KProcess& KProcess::operator<< (  const char *    arg )

Similar to previous method, takes a char *, supposed to be in locale 8 bit already.

KProcess& KProcess::operator<< (  const QString &    arg )

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: KProcess p; ... p << "ls" << "-l" << "/usr/local/bin" Parameters: arg  the argument to add Returns: a reference to this KProcess

pid_t KProcess::pid (    )

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 KProcess. Calling it before any child process has been started by this KProcess instance causes pid() to return 0. Returns: the pid of the process or 0 if no process has been started yet. Referenced by getPid().

void KProcess::processExited (  KProcess *    proc )  [signal]

Emitted after the process has terminated when the process was run in the NotifyOnExit (==default option to start()) or the Block mode. Parameters: proc  a pointer to the process that has exited

virtual void KProcess::processHasExited (  int    state )  [protected, virtual]

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).

QString KProcess::quote (  const QString &    arg )  [static]

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. Parameters: arg  the argument to quite Returns: the quoted argument Since: 3.1 Reimplemented in KShellProcess.

void KProcess::receivedStderr (  KProcess *    proc, char *    buffer, int    buflen )  [signal]

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 start(). You should copy the information contained in buffer to your private data structures before returning from this slot. Parameters: proc  a pointer to the process that has received the data buffer  The data received. buflen  The number of bytes that are available.

void KProcess::receivedStdout (  int    fd, int &    len )  [signal]

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 start() and the 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 fd. Parameters: fd  the file descriptor that provides the data len  the number of bytes that have been read from fd must be written here

void KProcess::receivedStdout (  KProcess *    proc, char *    buffer, int    buflen )  [signal]

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 start(). Parameters: proc  a pointer to the process that has received the output buffer  The data received. buflen  The number of bytes that are available. You should copy the information contained in buffer to your private data structures before returning from this slot. Example: QString myBuf = QString::fromLatin1(buffer, buflen);

void KProcess::resume (    )

Resume processing of data from stdout of the child process.

bool KProcess::runPrivileged (    )

Returns whether the started process will drop any setuid/segid privileges or whether it will keep them Returns: true if the process runs privileged

void KProcess::setEnvironment (  const QString &    name, const QString &    value )

Modifies the environment of the process to be started. This function must be called before starting the process. Parameters: name  the name of the environment variable value  the new value for the environment variable

bool KProcess::setExecutable (  const QString &    proc )

Deprecated: The use of this function is now deprecated. -- Please use the "operator<<" instead of "setExecutable". Sets the executable to be started with this KProcess object. Returns false if the process is currently running (in that case the executable remains unchanged.) See also: operator<<

void KProcess::setRunPrivileged (  bool    keepPrivileges )

Controls whether the started process should drop any setuid/segid privileges or whether it should keep them The default is false : drop privileges Parameters: true  to keep the privileges

virtual int KProcess::setupCommunication (  Communication    comm )  [protected, virtual]

This function is called from "KProcess::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 KProcess. 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.

void KProcess::setupEnvironment (    )  [protected]

Sets up the environment according to the data passed via setEnvironment(...)

void KProcess::setUseShell (  bool    useShell, const char *    shell = 0 )

Specify whether to start the command via a shell or directly. The default is to start the command directly. If useShell is true shell will be used as shell, or if shell is empty, the standard shell is used. 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 also: quote() Parameters: useShell  true if the command should be started via a shell shell  the path to the shell that will execute the process, or 0 to use the standard shell Since: 3.1

void KProcess::setWorkingDirectory (  const QString &    dir )

Changes the current working directory (CWD) of the process to be started. This function must be called before starting the process. Parameters: dir  the new directory

void KProcess::slotChildError (  int    fdno )  [protected, slot]

This slot gets activated when data from the child's stderr arrives. It usually calls "childError" Parameters: the  file descriptor for the output

void KProcess::slotChildOutput (  int    fdno )  [protected, slot]

This slot gets activated when data from the child's stdout arrives. It usually calls "childOutput" Parameters: the  file descriptor for the output

void KProcess::slotSendData (  int    dummy )  [protected, slot]

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". Parameters: dummy  ignore this argument

virtual bool KProcess::start (  RunMode    runmode = NotifyOnExit, Communication    comm = NoCommunication )  [virtual]

Starts the process. For a detailed description of the various run modes and communication semantics, have a look at the general description of the KProcess class. The following problems could cause this function to return false: The process is already running. The command line argument list is empty. The starting of the process failed (could not fork). The executable was not found. Parameters: runmode  The Run-mode for the process. 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. Returns: true on success, false on error (see above for error conditions) Reimplemented in KShellProcess.

void KProcess::suspend (    )

Suspend processing of data from stdout of the child process.

bool KProcess::writeStdin (  const char *    buffer, int    buflen )

Transmit data to the child process's stdin. KProcess::writeStdin may return false in the following cases: The process is not currently running. Communication to stdin has not been requested in the start() call. Transmission of data to the child process by a previous call to 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 wroteStdin() will be emitted. Please note that you must not free "buffer" or call writeStdin() again until either a wroteStdin() signal indicates that the data has been sent or a processHasExited() signal shows that the child process is no longer alive... Parameters: buffer  the buffer to write. Do not free or modify it until you got a wroteStdin() or processHasExited() signal Returns: false if an error has occurred

void KProcess::wroteStdin (  KProcess *    proc )  [signal]

Emitted after all the data that has been specified by a prior call to writeStdin() has actually been written to the child process. Parameters: proc  a pointer to the process

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Friends And Related Function Documentation

friend class KProcessController [friend]

KProcessController is a friend of KProcess because it has to have access to various data members. Definition at line 741 of file kprocess.h.

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Member Data Documentation

QValueList<QCString> KProcess::arguments [protected]

The list of the process' command line arguments. The first entry in this list is the executable itself. Definition at line 593 of file kprocess.h. Referenced by args().

Communication KProcess::communication [protected]

Lists the communication links that are activated for the child process. Should not be modified from derived classes. Definition at line 715 of file kprocess.h.

QSocketNotifier* KProcess::innot [protected]

The socket notifiers for the above socket descriptors. Definition at line 707 of file kprocess.h.

bool KProcess::keepPrivs [protected]

See setRunPrivileged() Definition at line 630 of file kprocess.h.

int KProcess::out[2] [protected]

the socket descriptors for stdin/stdout/stderr. Definition at line 700 of file kprocess.h.

pid_t KProcess::pid_ [protected]

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 KProcess. Definition at line 615 of file kprocess.h.

RunMode KProcess::run_mode [protected]

How to run the process (Block, NotifyOnExit, DontCare). You should not modify this data member directly from derived classes. Definition at line 598 of file kprocess.h.

bool KProcess::runs [protected]

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 KProcess. Definition at line 606 of file kprocess.h.

int KProcess::status [protected]

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 exitStatus than accessing this data member directly since it will probably be made private in further versions of KProcess. Definition at line 624 of file kprocess.h.

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The documentation for this class was generated from the following file:

• kprocess.h

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