path: root/man/libbsd.7

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.Dd Feb 13, 2021
.Dt LIBBSD 7
.Os
.Sh NAME
.Nm libbsd
.Nd utility functions from BSD systems
.Sh DESCRIPTION
The
.Nm 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.
.Pp
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
.Xr pkg-config 1
library named
.Pa libbsd-overlay .
Or by adding the system-specific include directory with the
.Pa bsd/
suffix to the list of system include paths.
With
.Nm gcc
this could be
.Ar -isystem ${includedir}/bsd .
In addition the
.Dv LIBBSD_OVERLAY
pre-processor variable needs to be defined.
The includes in this case should be the usual system ones, such as
.In unistd.h .
.Pp
The other way to use the library is to use the namespaced headers,
this is less portable as it makes using
.Nm libbsd
mandatory and it will not work on BSD-based systems, and requires
modifying original BSD code.
This can be done with the
.Xr pkg-config 1
library named
.Pa libbsd .
The includes in this case should be namespaced with
.Pa bsd/ ,
such as
.In bsd/unistd.h .
.Pp
The package also provides a
.Nm libbsd-ctor
static library that can be used to inject automatic constructors into a
program so that the
.Fn setproctitle_init 3
function gets invoked automatically at startup time.
This can be done with the
.Xr pkg-config 1
library named
.Pa libbsd-ctor .
.Sh HEADERS
The following are the headers provided by
.Nm libbsd ,
that extend the standard system headers.
They can work in normal or overlay modes, for the former they need to
be prefixed with
.Pa bsd/ .
.Pp
.Bl -tag -width 4m -compact
.It In bitstring.h
.It In err.h
.It In getopt.h
.It In grp.h
.It In inttypes.h
.It In libutil.h
.It In md5.h
.It In netinet/ip_icmp.h
.It In nlist.h
.It In pwd.h
.It In readpassphrase.h
.It In stdio.h
.It In stdlib.h
.It In string.h
.It In stringlist.h
.It In sys/bitstring.h
.It In sys/cdefs.h
.It In sys/endian.h
.It In sys/param.h
.It In sys/poll.h
.It In sys/queue.h
.It In sys/time.h
.It In sys/tree.h
.It In timeconv.h
.It In unistd.h
.It In vis.h
.It In wchar.h
.El
.Pp
The following is a
.Pa libbsd
specific convenience header, that includes some of the extended headers.
It only works in non-overlay mode.
.Pp
.Bl -tag -width 4m -compact
.It In bsd/bsd.h
.El
.Sh ALTERNATIVES
Some functions have different prototypes depending on the BSD where they
originated from, and these various implementations provided are selectable
at build-time.
.Pp
This is the list of functions that provide multiple implementations:
.Bl -tag -width 4m
.It Fn strnvis 3
.It Fn strnunvis 3
.Nx
added
.Fn strnvis 3
and
.Fn strnunvis 3
but unfortunately made it incompatible with the existing one in
.Ox
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
.Fx
and later MacOS picked up this incompatible implementation.
.Pp
Provide both implementations and default for now to the historical one to
avoid breakage, but we will switch to the
.Nx
one in a later release, which is internally consistent with the other
.Xr vis 3
functions and is now more widespread.
Define
.Dv LIBBSD_NETBSD_VIS
to switch to the
.Nx one now.
Define
.Dv LIBBSD_OPENBSD_VIS
to keep using the
.Ox
one.
.El
.Sh 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.
.Pp
This is the list of currently deprecated macros and functions:
.Bl -tag -width 4m
.It Fn fgetln 3
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
.Fn getline 3
instead, which is available in many systems and required by
.St -p1003.1-2008 .
.It Fn fgetwln 3
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
.Fn fgetwc 3
instead, which is available in many systems and required by
.St -isoC-99
and
.St -p1003.1-2001 .
.It Fn funopen 3
Unportable, requires assistance from the stdio layer or some hook framework.
On GNU systems the
.Fn fopencookie 3
function can be used.
Otherwise the code needs to be prepared for neither of these functions being
available.
.El
.Sh 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
.Nm libc
for example.
.Pp
.Bl -tag -width 4m -compact
.It Fn MD5Init 3
.It Fn MD5Update 3
.It Fn MD5Pad 3
.It Fn MD5Final 3
.It Fn MD5Transform 3
.It Fn MD5End 3
.It Fn MD5File 3
.It Fn MD5FileChunk 3
.It Fn MD5Data 3
The set of MD5 digest functions are now proxies for the implementations
provided by the
.Nm libmd
companion library, so it is advised to switch to use that directly instead.
.It Fn explicit_bzero 3
This function is provided by
.Nm glibc
2.25.
.It Fn reallocarray 3
This function is provided by
.Nm glibc
2.26.
.El
.Sh SEE ALSO
.Xr arc4random 3bsd ,
.Xr bitstring 3bsd ,
.Xr byteorder 3bsd ,
.Xr closefrom 3bsd ,
.Xr errc 3bsd ,
.Xr expand_number 3bsd ,
.Xr explicit_bzero 3bsd ,
.Xr fgetln 3bsd ,
.Xr fgetwln 3bsd ,
.Xr flopen 3bsd ,
.Xr fmtcheck 3bsd ,
.Xr fparseln 3bsd ,
.Xr fpurge 3bsd ,
.Xr funopen 3bsd ,
.Xr getbsize 3bsd ,
.Xr getpeereid 3bsd ,
.Xr getprogname 3bsd ,
.Xr heapsort 3bsd ,
.Xr humanize_number 3bsd ,
.Xr md5 3bsd ,
.Xr nlist 3bsd ,
.Xr pidfile 3bsd ,
.Xr pwcache 3bsd ,
.Xr queue 3bsd ,
.Xr radixsort 3bsd ,
.Xr readpassphrase 3bsd ,
.Xr reallocarray 3bsd ,
.Xr reallocf 3bsd ,
.Xr setmode 3bsd ,
.Xr setproctitle 3bsd ,
.Xr stringlist 3bsd ,
.Xr strlcpy 3bsd ,
.Xr strmode 3bsd ,
.Xr strnstr 3bsd ,
.Xr strtoi 3bsd ,
.Xr strtonum 3bsd ,
.Xr strtou 3bsd ,
.Xr timeradd 3bsd ,
.Xr timeval 3bsd ,
.Xr tree 3bsd ,
.Xr unvis 3bsd ,
.Xr vis 3bsd ,
.Xr wcslcpy 3bsd .
.Sh HISTORY
The
.Nm 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.
.Pp
It is now distributed as part of most non-BSD distributions.