The library provides a set of compatibility macros and functions
commonly found on BSD-based systems. Its purpose is to make
those available on non-BSD based systems to ease portability.
The library can be used in an overlay mode, which is the
preferred way, so that the code is portable and requires no
modification to the original BSD code. This can be done easily
with the library named Or by adding the system-specific include
directory with the suffix to the list of system include paths.
With this could be In addition the pre-processor variable needs
to be defined. The includes in this case should be the usual
system ones, such as The other way to use the library is to use
the namespaced headers, this is less portable as it makes using
mandatory and it will not work on BSD-based systems, and requires
modifying original BSD code. This can be done with the library
named The includes in this case should be namespaced with such as
The package also provides a static library that can be used to
inject automatic constructors into a program so that the function
gets invoked automatically at startup time. This can be done
with the library named The following are the headers provided by
that extend the standard system headers. They can work in normal
or overlay modes, for the former they need to be prefixed with
The following is a specific convenience header, that includes
some of the extended headers. It only works in non-overlay mode.
Some functions have different prototypes depending on the BSD
where they originated from, and these various implementations
provided are selectable at build-time. This is the list of
functions that provide multiple implementations: added and but
unfortunately made it incompatible with the existing one in and
Freedesktop's libbsd (the former having existed for over ten
years). Despite this incompatibility being reported during
development (see http://gnats.netbsd.org/44977) they still
shipped it. Even more unfortunately and later MacOS picked up
this incompatible implementation. Provide both implementations
and default for now to the historical one to avoid breakage, but
we will switch to the one in a later release, which is internally
consistent with the other functions and is now more widespread.
Define to switch to the Define to keep using the one. Some
functions have been deprecated, they will emit warnings at
compile time and possibly while being linked at run-time. This
might be due to the functions not being portable at all to other
systems, making the package not buildable there; not portable in
a correct or non-buggy way; or because there are better more
portable replacements now. This is the list of currently
deprecated macros and functions: Unportable, requires assistance
from the stdio layer. An implementation has to choose between
leaking buffers or being reentrant for a limited amount of
streams (this implementation chose the latter with a limit of
32). Use instead, which is available in many systems and
required by Unportable, requires assistance from the stdio layer.
An implementation has to choose between leaking buffers or being
reentrant for a limited amount of streams (this implementation
chose the latter with a limit of 32). Use instead, which is
available in many systems and required by and Unportable,
requires assistance from the stdio layer or some hook framework.
On GNU systems the function can be used. Otherwise the code
needs to be prepared for neither of these functions being
available. Some functions have been superseded by
implementations in other system libraries, and might disappear on
the next SONAME bump, assuming those other implementation have
widespread deployment, or the implementations are present in all
major for example. The set of MD5 digest functions are now
proxies for the implementations provided by the companion
library, so it is advised to switch to use that directly instead.
This function is provided by 2.25. This function is provided by
2.26. The project started in the Debian GNU/kFreeBSD port as a
way to ease porting code from FreeBSD to the GNU-based system.
Pretty early on it was generalized and a project created on
FreeDesktop.org for other distributions and projects to use. It
is now distributed as part of most non-BSD distributions.