ASSA::Pipe Class Reference

#include <Pipe.h>

Public Member Functions
	Pipe ()
	A no-op constructor.
	~Pipe ()
	Destructor calls close () first in an attempt to close opened pipe.
FILE *	open (const string &cmd_, const string &type_)
	Starts a subshell and feed it the string cmd_ to be executed.
int	close ()
	Close the pipe.
int	kill ()
	Kill subprocess with SIGTERM.
pid_t	pid () const
	Get subprocess' PID.
FILE *	fp () const
	Get pipe's standard I/O file pointer.
int	fd () const
	Get pipe's file descriptor.

Private Member Functions
	Pipe (const Pipe &)
Pipe &	operator= (const Pipe &)

Private Attributes
FILE *	m_fp
	A standard I/O stream descriptor.
pid_t	m_child_pid
	Supbrocess' PID.

Detailed Description

Definition at line 28 of file Pipe.h.

Constructor & Destructor Documentation

Pipe() [1/2]

Pipe::Pipe

(

)

A no-op constructor.

Definition at line 33 of file Pipe.cpp.

    : m_fp (NULL), 
      m_child_pid (0)
 {
    trace_with_mask("Pipe::Pipe", PIPE);
    /* no-op */
}

References ASSA::PIPE, and trace_with_mask.

~Pipe()

Pipe::~Pipe

(

)

Destructor calls close () first in an attempt to close opened pipe.

Definition at line 42 of file Pipe.cpp.

{
    trace_with_mask("Pipe::~Pipe", PIPE);
    close ();
}

References close(), ASSA::PIPE, and trace_with_mask.

Pipe() [2/2]

ASSA::Pipe::Pipe ( const Pipe &  )

private

Member Function Documentation

close()

int Pipe::close

(

)

Close the pipe.

The subprocess' status is collected to ensure that the child process have finished.

Returns

0 on success; -1 on error.

Definition at line 135 of file Pipe.cpp.

{
    trace_with_mask("Pipe::close", PIPE);
 
    int ret = 0;
    if (m_child_pid == 0) {
        ret = EOF;
    }
 
    if (m_fp) {
        ret = fclose (m_fp);
    }
    m_fp = NULL;
    m_child_pid = 0;
    return ret == EOF ? -1 : 0;
}

References m_child_pid, m_fp, ASSA::PIPE, and trace_with_mask.

Referenced by kill(), open(), and ~Pipe().

fd()

int ASSA::Pipe::fd ( ) const

inline

Get pipe's file descriptor.

Definition at line 105 of file Pipe.h.

{ return fileno (m_fp); }

References m_fp.

Referenced by open().

fp()

FILE * ASSA::Pipe::fp ( ) const

inline

Get pipe's standard I/O file pointer.

Definition at line 108 of file Pipe.h.

{ return m_fp; }

References m_fp.

kill()

int Pipe::kill

(

)

Kill subprocess with SIGTERM.

You should most probably call close() afterwards to collect child process' status.

See also

close()

Returns

0 on success, -1 if kill(2) failed.

Definition at line 117 of file Pipe.cpp.

{
    trace_with_mask("Pipe::kill", PIPE);
 
#if !defined(WIN32)
    if (m_child_pid == 0) return -1;
 
    int ret = ::kill (m_child_pid, SIGTERM);
    close ();
    return ret;
#else
     DL((ASSAERR|PIPE,"Not implemented for win32!\n"));
     return -1;
#endif
}

References ASSA::ASSAERR, close(), DL, kill(), m_child_pid, ASSA::PIPE, and trace_with_mask.

Referenced by kill().

open()

FILE * Pipe::open	(	const string &	cmd_,
		const string &	type_
	)

Starts a subshell and feed it the string cmd_ to be executed.

The pipe is created and attached to the standard input or standard output of the subprocess, according to whether type_ is either "r" (read) or "w" (write). The other end of the pipe is returned to the calling code as a standard I/O stream, FILE, ready for buffered use with fprintf(), fscanf(), fgets, etc.

See also

Fork

Parameters

cmd_	command to execute
type_	"w" for write pipe and "r" for read pipe

Returns

pointer to a standard I/O stream. In case of error, NULL is returned with errno set to indicate the type of error encountered.

Definition at line 50 of file Pipe.cpp.

{
    trace_with_mask("Pipe::open", PIPE);
 
#if !defined(WIN32)       // not yet implemented
 
    if (type_ != "r" && type_ != "w") {
        EL((ASSAERR,"Wrong type \"%s\"\n", type_.c_str ()));
        errno = EINVAL;
        return NULL;
    }
    
    int fd [2]; 
    if (pipe (fd) < 0) {
        EL((ASSAERR,"failed: pipe(2)\n"));
        return NULL;
    }
    Fork f (Fork::KILL_ON_EXIT, Fork::IGNORE_STATUS);
 
    if (f.isChild ()) {
        if (type_ == "r") {
            ::close (fd [0]);
            if (fd [1] != STDOUT_FILENO) {
                dup2 (fd [1], STDOUT_FILENO);
                ::close (fd [1]);
            }
        }
        else {                  // 'w'
            ::close (fd [1]);
            if (fd [0] != STDIN_FILENO) {
                dup2 (fd [0], STDIN_FILENO);
                ::close (fd [0]);
            }
        }
 
        DL((PIPE,"Executing cmd: \"%s\"\n", cmd_.c_str ()));
        execl ("/bin/sh", "sh", "-c", cmd_.c_str (), (char* ) 0);
        EL((ASSAERR,"failed: execl(2)\n"));
        _exit (127);
    }
    /* parent */
    if (type_ == "r") {
        ::close (fd [1]);
        if ((m_fp = fdopen (fd [0], type_.c_str ())) == NULL) {
            EL((ASSAERR,"failed: fdopen ()\n"));
            return NULL;
        }
    }
    else {                  // 'w'
        ::close (fd [0]);
        if ((m_fp = fdopen (fd [1], type_.c_str ())) == NULL) {
            EL((ASSAERR,"failed: fdopen ()\n"));
            return NULL;
        }
    }
    m_child_pid = f.getChildPID ();
    DL((PIPE,"m_child_pid = %d\n",m_child_pid));
    return m_fp;
    
#else
     DL((ASSAERR|PIPE,"Not implemented for win32!\n"));
     return NULL;
#endif
}

References ASSA::ASSAERR, close(), DL, EL, fd(), ASSA::Fork::IGNORE_STATUS, ASSA::Fork::KILL_ON_EXIT, m_child_pid, m_fp, ASSA::PIPE, and trace_with_mask.

operator=()

Pipe & ASSA::Pipe::operator= ( const Pipe &  )

private

pid()

pid_t ASSA::Pipe::pid ( ) const

inline

Get subprocess' PID.

Definition at line 102 of file Pipe.h.

{ return m_child_pid; }

References m_child_pid.

Member Data Documentation

m_child_pid

pid_t ASSA::Pipe::m_child_pid

private

Supbrocess' PID.

Definition at line 98 of file Pipe.h.

Referenced by close(), kill(), open(), and pid().

m_fp

FILE* ASSA::Pipe::m_fp

private

A standard I/O stream descriptor.

Definition at line 93 of file Pipe.h.

Referenced by close(), fd(), fp(), and open().

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

• Pipe.h
• Pipe.cpp