hwdet::ForkAndPipe Class Reference

Fork process and automatically create pipes. More...

#include <ForkAndPipe.h>

Inheritance diagram for hwdet::ForkAndPipe:


Public Member Functions
	ForkAndPipe (const String &rep_name, MessageReporter *parent_reporter=NULL)
	Constructor.
virtual	~ForkAndPipe (void)
	Destructor.
bool	Run (void)
	Fork current process and create appropriate pipes.
virtual void	ParentProcess (pid_t child_pid, FILE *file)=0
	Method called in parent process.
virtual void	ChildProcess (void)=0
	Method called in the child process.
virtual void	OnError (int error_code, const String &message)
	Error handler.
Protected Member Functions
pid_t	GetChildPID (void) const
	Get PID of the child process created.
void	WaitForChildProcess (void)
	Wait for children process to end.
int	GetForkError (void) const
	Get error code after fork.
bool	AutoError (int result, const String &message="")
	Test if an error occured and output appropriate message.
Private Member Functions
	ForkAndPipe (const ForkAndPipe &)
	Empty copy ctor, this class should not be copied.
ForkAndPipe &	operator= (const ForkAndPipe &)
	Private assignment, never defined -> prevents copying.
Private Attributes
int	pipe_desc [2]
	Pipe descriptors.
pid_t	pid
	PID of the created child process.
int	error_num
	Error number (after fork).

Detailed Description

Fork process and automatically create pipes.

Constructor & Destructor Documentation

hwdet::ForkAndPipe::ForkAndPipe	(	const String &	rep_name,
		MessageReporter *	parent_reporter = `NULL`
	)

Constructor.

Parameters:

	rep_name	Name of the message reporter.
	parent_reporter	Parent message reporter. If NULL, messages are output directly to the stdout.

hwdet::ForkAndPipe::~ForkAndPipe ( void ) [virtual]

Destructor.

hwdet::ForkAndPipe::ForkAndPipe ( const ForkAndPipe & ) [inline, private]

Empty copy ctor, this class should not be copied.

Member Function Documentation

bool hwdet::ForkAndPipe::AutoError	(	int	result,
		const String &	message = `""`
	)			`[protected]`

Test if an error occured and output appropriate message.

If an error occured calls OnError handler with given message.

Parameters:

	result	Return value of the syscall or library fuction. Negative value means that the call failed.
	message	Message that will be forwarded to the OnError call. Empty string means no message (default value).

Returns:: true if no error occured, false if an error occured prior to the call.

virtual void hwdet::ForkAndPipe::ChildProcess ( void ) [pure virtual]

Method called in the child process.

This method is called in the child process. You can exec any process you want in it and output will be sent through the pipe to the parent process.

Implemented in hwdet::EqueryPackager::EqueryExec, hwdet::GentooFindPackager::FindExec, and hwdet::RPMPackager::RPMExec.

pid_t hwdet::ForkAndPipe::GetChildPID ( void ) const [inline, protected]

Get PID of the child process created.

Returns:: PID of the child process created.

int hwdet::ForkAndPipe::GetForkError ( void ) const [inline, protected]

Get error code after fork.

Call this to get error code after the fork has been called. Note that this does not represent current error code, so it will not change if other error occurs.

void hwdet::ForkAndPipe::OnError	(	int	error_code,
		const String &	message
	)			`[virtual]`

Error handler.

Basic error handler. Does nothing but print error name to the stdout.

Parameters:

	error_code	Error code (value of the errno).
	message	Message that will be printed alongside the error name. If message is empty, only error name will be output.

ForkAndPipe& hwdet::ForkAndPipe::operator= ( const ForkAndPipe & ) [private]

Private assignment, never defined -> prevents copying.

virtual void hwdet::ForkAndPipe::ParentProcess	(	pid_t	child_pid,
		FILE *	file
	)			`[pure virtual]`

Method called in parent process.

This method is called in parent process (parent is process from which run has been called). In this method you can read output produced by the child process(es) using pipe descriptors created in the run method. You do not need to wait for the child to terminate, it is done automatically.

Implemented in hwdet::EqueryPackager::EqueryExec, hwdet::GentooFindPackager::FindExec, and hwdet::RPMPackager::RPMExec.

bool hwdet::ForkAndPipe::Run ( void )

Fork current process and create appropriate pipes.

This will create new pipe and fork current process. In child it will call method ChildProcess. In parent process, it will call ParentProcess method. In case of error, error handler is called.

Returns:: true on success, false otherwise.

void hwdet::ForkAndPipe::WaitForChildProcess ( void ) [inline, protected]

Wait for children process to end.

This will wait until child process terminates. Do NOT call this in the child process. You should not call this in parent either since it is called automatically when parent method ends.