Ubuntu Manpage: libbsd — utility functions from BSD systems

NAME

     libbsd — utility functions from BSD systems

DESCRIPTION

     The libbsd 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 pkgconf(1) library named libbsd-overlay.  Or by adding the system-specific include
     directory with the bsd/ suffix to the list of system include paths.  With gcc this could be
     -isystem ${includedir}/bsd.  In addition the LIBBSD_OVERLAY pre-processor variable needs to
     be defined.  The includes in this case should be the usual system ones, such as <unistd.h>.

     The other way to use the library is to use the namespaced headers, which is a discouraged
     way, being less portable as it makes using libbsd mandatory and it will not work on BSD-
     based systems, and requires modifying original BSD code.  This can be done with the
     pkgconf(1) library named libbsd.  The includes in this case should be namespaced with bsd/,
     such as <bsd/unistd.h>.

     The package also provides a libbsd-ctor static library that can be used to inject automatic
     constructors into a program so that the setproctitle_init(3bsd) function gets invoked
     automatically at startup time.  This can be done with the pkgconf(1) library named
     libbsd-ctor.

HEADERS

     The following are the headers provided by libbsd, that extend the standard system headers.
     They can work in normal or overlay modes, for the former they need to be prefixed with bsd/.

     <bitstring.h>
     <err.h>
     <getopt.h>
     <grp.h>
     <inttypes.h>
     <libutil.h>
     <md5.h>
     <netinet/ip_icmp.h>
     <nlist.h>
     <pwd.h>
     <readpassphrase.h>
     <stdio.h>
     <stdlib.h>
     <string.h>
     <stringlist.h>
     <sys/bitstring.h>
     <sys/cdefs.h>
     <sys/endian.h>
     <sys/param.h>
     <sys/poll.h>
     <sys/queue.h>
     <sys/time.h>
     <sys/tree.h>
     <timeconv.h>
     <unistd.h>
     <vis.h>
     <wchar.h>

     The following is a libbsd specific convenience header, that includes some of the extended
     headers.  It only works in non-overlay mode.

     <bsd/bsd.h>

VARIANTS

     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:

     strnvis(3bsd)
     strnunvis(3bsd)
           NetBSD added strnvis(3bsd) and strnunvis(3bsd) but unfortunately made it incompatible
           with the existing one in OpenBSD 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
           FreeBSD 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 NetBSD one in a later release, which is internally
           consistent with the other vis(3bsd) functions and is now more widespread.  Define
           LIBBSD_NETBSD_VIS to switch to the NetBSD one now.  Define LIBBSD_OPENBSD_VIS to keep
           using the OpenBSD one.

DEPRECATED

     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:

     fgetln(3bsd)
           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 getline(3) instead, which is
           available in many systems and required by IEEE Std 1003.1-2008 (“POSIX.1”).

     fgetwln(3bsd)
           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 fgetwc(3) instead, which is
           available in many systems and required by ISO/IEC 9899:1999 (“ISO C99”) and IEEE Std
           1003.1-2001 (“POSIX.1”).

     funopen(3bsd)
           Unportable, requires assistance from the stdio layer or some hook framework.  On
           glibc- and musl-based systems the fopencookie(3) function can be used.  Otherwise the
           code needs to be prepared for neither of these functions being available.

SUPERSEDED

     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 libc for example.

     MD5Init(3)
     MD5Update(3)
     MD5Pad(3)
     MD5Final(3)
     MD5Transform(3)
     MD5End(3)
     MD5File(3)
     MD5FileChunk(3)
     MD5Data(3)
           The set of MD5 digest functions are now proxies for the implementations provided by
           the libmd companion library, so it is advised to switch to use that directly instead.
     explicit_bzero(3bsd)
           This function is provided by glibc 2.25, and musl 1.1.20.
     reallocarray(3bsd)
           This function is provided by glibc 2.26, and musl 1.2.2.
     closefrom(3bsd)
           This function is provided by glibc 2.34.
     arc4random(3bsd)
     arc4random_buf(3bsd)
     arc4random_uniform(3bsd)
           These functions are provided by glibc 2.36.  Note that it does not provide the
           arc4random_stir(3bsd) and arc4random_addrandom(3bsd) functions.
     strlcpy(3bsd)
     strlcat(3bsd)
           These functions are provided by glibc 2.38, and musl 0.5.0.

HISTORY

     The libbsd 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.

NAME

DESCRIPTION

HEADERS

VARIANTS

DEPRECATED

SUPERSEDED

SEE ALSO

HISTORY