NAME¶

FBB::Pipe - Defines a system level pipe

SYNOPSIS¶

#include <bobcat/pipe> Linking option: -lbobcat

DESCRIPTION¶

FBB::Pipe objects may be used to construct a pipe. FBB::Pipe objects offer a simple interface to the reading and writing ends of pipes. FBB::Pipe objects are object-wrappers around the pipe(2) system call.

NAMESPACE¶

FBB All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.

INHERITS FROM¶

-

CONSTRUCTORS¶

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Pipe():

 

The default Pipe() constructor constructs a basic pipe, calling pipe(2).

This constructor throws an Errno exception if the default Pipe constructor did not properly complete. The thrown Errno object’s which() member shows the system’s errno value set by the failing pipe(2) function.

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Pipe(int const *fd):

 

This constructor expects two file descriptors, which already define a pipe, stored at fd. Following the construction of the Pipe object the array at by fd is no longer used by the Pipe object. The copy constructor is available.

Note that when the pipe goes out of scope, no close(2) operation is performed on the pipe’s ends. If the pipe should be closed by the desctructor, derive a class from Pipe(3bobcat), whose destructor performs the required closing-operation.

MEMBER FUNCTIONS¶

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int readFd() const:

 

Returns the pipe’s file descriptor that is used for reading

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void readFrom(int filedescriptor):

 

Sets up redirection from the internal read filedescriptor to the given filedescriptor: information is read from the FBB::Pipe object when reading from the provided filedescriptor.

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void readFrom(int const *filedescriptors, size_t n):

 

Sets up redirection from the internal read filedescriptor to the given filedescriptors: information is read from the FBB::Pipe object when reading from any of the n provided filedescriptors (experimental).

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int readOnly():

 

Closes the writing end of the pipe, returns the reading end’s file descriptor.

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void verify() const:

 

Obsoleted, will be removed in a future Bobcat release.

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int writeFd() const:

 

Returns the pipe’s file descriptor that is used for writing

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void writtenBy(int filedescriptor):

 

Sets up redirection from the internal write filedescriptor to the given filedescriptor: information is written to the FBB::Pipe object when writing to the provided filedescriptor.

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void writtenBy(int const *filedescriptors, size_t n):

 

Sets up redirection from the internal write filedescriptor to the given filedescriptors: information is written to the FBB::Pipe object when writing to each of the n provided filedescriptors.

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int writeOnly():

 

Closes the reading end of the pipe, returns the writing end’s file descriptor.

 

PROTECTED ENUMERATION¶

The RW protected enumeration has the following elements:

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READ:

 

The index in d_fd[] (see below) of the element holding the pipe’s reading file descriptor;

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WRITE:

 

The index in d_fd[] (see below) of the element holding the pipe’s writing file descriptor

 

PROTECTED DATA¶

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int d_fd[2]:

 

The array holding the pipe’s file descriptors. The READ element contains the pipe’s reading file descriptor, the WRITE element contains the pipe’s writing file descriptor,

 

EXAMPLE¶

    #include <bobcat/pipe>
    #include <sys/types.h>
    #include <sys/wait.h>
    #include <unistd.h>
    #include <iostream>
    #include <string>
    
    using namespace std;
    using namespace FBB;
    
    int main()
    {
        Pipe p;                         // construct a pipe
    
        cout << "Read file descriptor: " << p.getReadFd() << endl;
        cout << "Write file descriptor: " << p.getWriteFd() << endl;
    
        int pid = fork();
    
        if (pid == -1)
            return 1;
    
        if (!pid)                       //child
        {
            p.readFrom(STDIN_FILENO);   // read what goes into the pipe
    
            string s;

            getline(cin, s);
            cout << "CHILD: Got `" << s << "’" << endl;    
    
            getline(cin, s);
            cout << "CHILD: Got `" << s << "’" << endl;    
    
            return 0;
        }
    
        p.writtenBy(STDOUT_FILENO);      // write to the pipe via cout
    
        cout << "first line" << endl;
        cout << "second line" << endl;
    
        waitpid(pid, 0, 0);
    
        return 0;
    }
        

FILES¶

bobcat/pipe - defines the class interface

SEE ALSO¶

bobcat(7), pipe(2), mkfifo(3)

BUGS¶

Note that when the pipe goes out of scope, no close(2) operation is performed on the pipe’s ends. If the pipe should be closed by the desctructor, derive a class from Pipe(3bobcat), whose destructor performs the required closing-operation.

DISTRIBUTION FILES¶

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bobcat_3.01.00-x.dsc: detached signature;

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bobcat_3.01.00-x.tar.gz: source archive;

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bobcat_3.01.00-x_i386.changes: change log;

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libbobcat1_3.01.00-x_*.deb: debian package holding the libraries;

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libbobcat1-dev_3.01.00-x_*.deb: debian package holding the libraries, headers and manual pages;

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http://sourceforge.net/projects/bobcat: public archive location;

 

BOBCAT¶

Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.

COPYRIGHT¶

This is free software, distributed under the terms of the GNU General Public License (GPL).

AUTHOR¶

Frank B. Brokken ( f.b.brokken@rug.nl).