DOKK / manpages / debian 12 / libbobcat-dev / eoibuf.3bobcat.en
FBB::EoiBuf(3bobcat) End-Of-Information Base class FBB::EoiBuf(3bobcat)

FBB::EoiBuf - std::streambuf class offering an eoi manipulator

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

The class EoiBuf inherits from Eoi and may therefore be used as a base class of classes specializing std::streambuf. It also provides a configurable character buffer for storing characters received from their devices. Often, when deriving classes from std::streambuf the derived classes must implement storage to and retrieval from a character buffer. By deriving from EoiBuf buffer-handling is automatically provided: it contains a (resizable) character buffer, and offers a setp member as well as a setg member that can be used to specify the index rage of the buffer from which extractions receive characters. Also, when overriding its base class’s eoi_ member it can be used to signal the end of input inserted into std::ostream classes using EoiBuf objects as std::streambuf objects.

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

FBB::Eoi (and thus from: std::streambuf)

Analogously to std::streambuf only protected constructors are available.

EoiBuf():
The default constructor initializes an empty buffer.
EoiBuf(size_t size):
This initializes an empty buffer of a predefined size of size characters .

Note that there’s no inherent limit to the size of the internal buffer: its size can always be enlarged or reduced.

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

All members of std:streambuf and Eoi are available, as FBB::EoiBuf inherits from these classes.

std::string &buffer():
A reference to the internal buffer is returned;
size_t bufSize() const:
The length (size) of the internal buffer is returned;
void resize(size_t size):
The size of the internal buffer is changed to size characters;
void setg(unsigned next, unsigned beyond):
The streambuf::eback member returns the address of the internal buffer’s first character, streambuf::gptr returns the address of the internal buffer’s next character, streambuf::egptr returns the the address of the internal buffer’s beyond character;
void setp():
The streambuf::pbase and pptr members return the address of the internal buffer’s first character, streambuf::epptr returns the address immediately beyond the internal buffer’s last character;
unsigned char *ucharPtr():
The address of the first character of the internal buffer is returned as a pointer to an unsigned character;
unsigned char const *ucharPtr() const:
Same as the previous member, but this time the address of the first character of the internal buffer is returned as a pointer to an immutable unsigned character.

The following two static members are provided as convenient functions for derived classes to convert the address of the first character of std::string objects to pointers to unsigned characters:

unsigned char *ucharPtr(std::string &str):
The address of the first character of str is returned as a pointer to an unsigned character;
unsigned char const *ucharPtr(std::string const &str) const:
Same as the previous member, but this time the address of the first character of str is returned as a pointer to an immutable unsigned character.

The following two functions are defined in the (internally used only) class FBB::OSymCryptBase, which is the base class of osymcryptstreambuf(3bobcat).

evpUpdate updates the ongoing encryption or decryption, e.g., using the openssl function EVP_EncryptUpdate, using ucharPtr to access characters currently in EoiBuf’s buffer:
#include "osymcryptbase.ih"
void OSymCryptBase::evpUpdate()
{

size_t inBufRead = pptr() - pbase(); // # read chars
checkOutBufSize(inBufRead);
int nOutputChars;
if (not ((*d_evpUpdate)( // en/decrypt the bytes in d_inBuf
ctx(),
uOutBuf(), &nOutputChars,
ucharPtr(), inBufRead
))
)
throw Exception{} << "EVP_{En,De}cryptUpdate failed";
d_outStream.write(outBuf(), nOutputChars); // write the processed
// chars to d_outSteam
setp(); }

eoi_ overrides FBB::Eoi::eoi_() function, preventing new information from being inserted into the FBB::OSymCryptBase object (and thus from being inserted into its FBB::OSymCryptStreambuf derived class):
#include "osymcryptbase.ih"
void OSymCryptBase::eoi_()
{

if (d_eoi)
return;
evpUpdate(); // process available chars in the input
d_eoi = true;
resize(0); // clear the input buffer
evpUpdate(); // update an empty buffer }

bobcat/eoibuf - defines the class interface

bobcat(7), eoi(3bobcat)

None Reported.

https://fbb-git.gitlab.io/bobcat/: gitlab project page;
bobcat_6.02.02-x.dsc: detached signature;
bobcat_6.02.02-x.tar.gz: source archive;
bobcat_6.02.02-x_i386.changes: change log;
libbobcat1_6.02.02-x_*.deb: debian package containing the libraries;
libbobcat1-dev_6.02.02-x_*.deb: debian package containing the libraries, headers and manual pages;

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

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

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

2005-2022 libbobcat-dev_6.02.02