NAME
library-specs —
shared library name
specifications
DESCRIPTION
Each WANTLIB item in the ports tree
conforms to
[path/]libname[=major[.minor]]
or
[path/]libname[>=major[.minor]]
All libraries that a package needs must be mentioned in that list.
Except for system and X11 libraries, they all must be reachable through
LIB_DEPENDS and RUN_DEPENDS,
directly, or indirectly through recursive dependencies.
Conversely, the ports tree uses WANTLIB to
check whether a given LIB_DEPENDS will be required
at runtime for shared libraries, and thus turn it into a
@depend line (see
pkg_create(1)).
The package system will embed correct dependency checks in the
built package in the form of @wantlib lines,
according to the normal shared library semantics: any library with the same
major number, and a greater or equal minor number will do.
Note that static libraries can only satisfy a library specification if no shared library has been found. Thus, if WANTLIB = foo>=5, and both libfoo.so.4.0 and libfoo.a are present, the check will fail.
Therefore, porters must strive to respect correct shared library semantics in their own ports: by bumping the minor number each time the interface is augmented, and by bumping the major number each time the interface changes. Note that adding functions to a library is an interface augmentation. Removing functions is an interface change.
The major.minor components of the library specification are used only as a build-time check, the run-time checks are computed by port-resolve-lib-helper(1). For ‘libname>=major[.minor]’, any library which is more recent than the given major.minor version will do. If a specific major number is needed, use the form ‘libname=major[.minor]’. If the minor component is left empty, any minor will do. If both components are left empty, any version will do.
Most specifications won't mention a path: port-resolve-lib-helper(1) will look in the default ldconfig(8) path automatically, namely /usr/local/lib, /usr/X11R6/lib, /usr/lib. It is generally a bad idea to put libraries elsewhere as they won't be reached directly.
However, distinct ports may install different major versions of the same library in /usr/local/lib, and disambiguate the build by creating a link in a separate directory, and specifying the right options to the linker.
These libraries will require a path
component in the corresponding WANTLIB to make sure
the right library is resolved. This path is rooted under
/usr/local. For instance, to refer to
/usr/local/lib/qt3/libqt-mt.so.33.0, one would use
‘lib/qt3/qt-mt>=33’.
SEE ALSO
check-lib-depends(1), ld(1), ld.so(1), pkg_add(1), port-resolve-lib-helper(1), bsd.port.mk(5), packages(7), packages-specs(7), ports(7), ldconfig(8)
HISTORY
Full support for library specifications first appeared in
OpenBSD 3.1. The format of specifications changed
slightly to include ‘>=’ before OpenBSD
4.0. The interactions between LIB_DEPENDS and
WANTLIB were modified and clarified for
OpenBSD 4.8. The format of specifications changed
again before OpenBSD 4.9 to remove extra noise.