# FBB::OFdBuf(3bobcat)

## File Descriptor Output Stream Buffer
(libbobcat-dev_6.06.02)

## 2005-2024

## NAME

FBB::OFdBuf - Output stream buffer initialized by a file descriptor

## SYNOPSIS

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

## DESCRIPTION

FBB::OFdBuf objects may be used as a std::streambuf of std::ostream objects to allow insertions into a file descriptor.

File descriptors are not defined within the context of C++, but they can be used on operating systems that support the concept. Realize that using file descriptors introduces operating system dependencies.

## NAMESPACE

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

## INHERITS FROM

std::streambuf

## ENUMERATION

The public enumeration Mode defined in the class FBB::OFdStreamBuf has the following values:

- CLOSE_FD, indicating that the file descriptor used by the object must be closed;
- KEEP_FD (the default) indicating that the file descriptor used by the object must not be closed.

## CONSTRUCTORS

- OFdBuf():
  This constructor initializes the streambuf, without associating it to a file descriptor, and without using buffering. The member reset can be used to associate the object later on with a file descriptor and optionally a buffer size. When the object is destroyed or if the mode-less overloaded version of the reset member is called, the file descriptor is closed.

- OFdBuf(Mode mode):
  This constructor initializes the streambuf, without associating it to a file descriptor, and without using buffering. The member reset can be used to associate the object later on with a file descriptor and optionally a buffer size. When the object is destroyed or if the mode-less overloaded version of the member reset is called, the Mode argument determines whether the file descriptor will be closed or will remain open.

- OFdBuf(int fd, size_t n = 1):
  This constructor initializes the streambuf, associating it to file descriptor fd, and an optional unget buffer size (by default having size 1). When reset is called subsequently, or if the object is destroyed the provided file descriptor will be closed.

- OFdBuf(int fd, size_t n = 1):
  This constructor initializes the streambuf, associating it to file descriptor fd, and an optional unget buffer size (by default having size 1). When the object is destroyed or if the mode-less overloaded version of the member reset is called, the file descriptor will be closed.

- OFdBuf(int fd, Mode mode, size_t n = 1):
  This constructor initializes the streambuf, associating it to file descriptor fd, and an optional unget buffer size (by default having size 1). When the object is destroyed or if the mode-less overloaded version of the member reset is called, the Mode argument determines whether the file descriptor will be closed or will remain open.

Copy and move constructors (and assignment operators) are not available.

## MEMBER FUNCTIONS

All members of std::streambuf are available, as FBB::OFdBuf inherits from this class.

- void eoi():
  The file descriptor used by the OFdBuf is closed, irrespective of the Mode that was specified when the OFdBuf object was constructed. Following eoi the OFdBuf object can no longer be used until one of its reset members has been called. Instead of using this member the eoi manipulator can also be used.

- int fd() const:
  The file descriptor used by the OFdBuf object is returned. If the OFdBuf is not associated with a file descriptor -1 is returned.

- void reset(int xfd, size_t n = 1):
  The streambuf is (re)initialized, using file descriptor fd, and an optional unget buffer size (by default having size 1). When called repeatedly, the Mode specification used whem the object was constructed determines whether the file descriptor will be closed or will remain open.

- void reset(int xfd, Mode mode, size_t n = 1):
  The streambuf is (re)initialized, using file descriptor fd, a file descriptor closing parameter and an optional unget buffer size (by default having size 1). Depending on the Mode argument the object's currently used file descriptor will be closed or will remain open when the IFdBuf object is destroyed.

- void warn(bool on):
  When on == true a warning is written to the standard error stream when its sync member returns -1. If warn is not explicitly called on == true is used.

## MANIPULATOR

- FBB::eoi:
  The eoi manipulator can be inserted into the ostream instead of calling the OFdBuf::end member. It performs the same actions as the eoi member. If inserted into a plain std::ostream nothing happens.

## EXAMPLE

    #include <unistd.h>

    #include <ostream>
    #include <string>

    #include "../ofdbuf"

    using namespace std;
    using namespace FBB;

    int main(int argc, char **argv)
    {
                               // define a streambuf of 20 or argv[1] characters
        OFdBuf buf{ STDOUT_FILENO, argc == 1 ? 20 : stoul(argv[1]) };

        ostream out{ &buf };

        out << "First line, just to start the insertions\n" <<
                argv[0] << endl <<          // using an explicit flush
                argc << "\n"
                "a long line to end this multiple-insertions statement\n";
    }

## FILES

bobcat/ofdbuf - defines the class interface

## SEE ALSO

bobcat(7), ifdbuf(3bobcat), ofdstream(3bobcat), std::streambuf

## BUGS

None reported

## BOBCAT PROJECT FILES

- https://fbb-git.gitlab.io/bobcat/: gitlab project page;
- bobcat_6.06.02-x.dsc: detached signature;
- bobcat_6.06.02-x.tar.gz: source archive;
- bobcat_6.06.02-x_i386.changes: change log;
- libbobcat1_6.06.02-x_*.deb: debian package containing the libraries;
- libbobcat1-dev_6.06.02-x_*.deb: debian package containing the libraries, headers and manual pages;

## 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).