child_reader Class Reference

#include <child_reader.h>

Public Member Functions
	child_reader (std::string const &cmd, std::vector< std::string > const &args)
	~child_reader ()
bool	getline (std::string &result)
bool	get_data (std::ostream &out, std::ostream &err)
int	terminate_process ()
int	error () const
std::string	error_str () const
Private Member Functions
void	exec_command (std::string const &cmd, std::vector< std::string > const &args)
bool	block_read ()
Private Attributes
int	fd1
int	fd2
ssize_t	pos1
ssize_t	end1
ssize_t	pos2
ssize_t	end2
pid_t	pid
int	first_error
char *	buf2
ssize_t	sz_buf2
char *	buf1
std::string	process_name
bool	is_terminated
bool	terminate_on_exception
bool	forked

Detailed Description

a class to read stdout / stderr from a child process.

two interfaces are provided. read line by line: getline() or read all data in one : get_data(). In all case get_data() must be called once to flush the stderr child output

Definition at line 39 of file child_reader.h.

Constructor & Destructor Documentation

child_reader::child_reader	(	std::string const &	cmd,
		std::vector< std::string > const &	args
	)

fork a process. use error() to get error code. Do not try to use other public member interface if error() return non-zero

child_reader::~child_reader ( )

wait for the termination of the child process if this have not already occur. In this case return code of the child process is not available.

Definition at line 45 of file child_reader.cpp.

References buf1, buf2, and terminate_process().

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Member Function Documentation

bool child_reader::block_read ( ) [private]

Definition at line 122 of file child_reader.cpp.

References buf1, buf2, end1, end2, fd1, fd2, and sz_buf2.

int child_reader::error ( ) const [inline]

return the status of the first error encoutered != 0 : something feel wrong, use error_str() to get an error message

Definition at line 71 of file child_reader.h.

References first_error.

Referenced by _get_vmlinux_address_info(), and do_exec_command().

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string child_reader::error_str ( ) const

return an error message if appropriate, if the process has been successfully exec'ed and is not terminate the error message is always empty. Error message is also empty if the child process terminate successfully. Else three type of error message exist:

"unable to fork" followed by sterror(errno)
"process_name return xxx" xxx is return code
"process_name terminated by signal xxx" xxx is signal number

Definition at line 256 of file child_reader.cpp.

References first_error, forked, is_terminated, process_name, and terminate_on_exception.

Referenced by _get_vmlinux_address_info(), and do_exec_command().

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void child_reader::exec_command	(	std::string const &	cmd,
		std::vector< std::string > const &	args
	)			`[private]`

bool child_reader::get_data	(	std::ostream &	out,
		std::ostream &	err
	)

fill out / err with the stdout / stderr of the child process. You can call this after calling one or more time getline(...). This call is blocking until the child die and so on all subsequent call will fail

Referenced by _get_vmlinux_address_info(), and do_exec_command().

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