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LIBMAP.CONF(5)            FreeBSD File Formats Manual           LIBMAP.CONF(5)

NAME
     libmap.conf - configuration file for dynamic object dependency mapping

DESCRIPTION
     The libmap functionality of ld-elf.so.1(1) allows dynamic object
     dependencies to be mapped to arbitrary names.

     The configuration file consists of two whitespace separated columns; the
     left hand side containing the mapping candidate and the right hand side
     containing the mapping.  Dependencies are matched against candidates and
     replaced with the mappings.

     Constrained mappings may be specified by enclosing the name of the
     executable or library in brackets.  All mappings following a constraint
     will only be evaluated for that constraint.  Constraints can be one of
     three types:

     Exact   The constraint is matched literally so that only an executable
             with an identical fully qualified pathname will match the
             constraint.  This means that the executable /usr/bin/foo will not
             match a constraint for /usr/bin/./foo and vice-versa.  This is
             the default constraint type.

     Basename
             A constraint with no path is matched against the basename of the
             executable.  foo will match /bin/foo, /usr/local/sbin/foo, or any
             other executable named foo, no matter what its path is.

     Directory
             A constraint with a trailing slash is prefix-matched against the
             full pathname of the executable.  /usr/bin/ will match any
             executable with a path starting with /usr/bin.

     Note that the executable path matched against is the path parameter in an
     exec*() function call.  The Directory or Exact constraints can only match
     when the executable is called with a full pathname.  Most programs
     executed from a shell are run without a full path, via exec*p(), so the
     Basename constraint type is the most useful.

     WARNING!  Constrained mappings must never appear first in the
     configuration file.  While there is a way to specify the ``default''
     constraint, its use is not recommended.

     The most common use at the date of writing is for allowing multiple POSIX
     threading libraries to be used on a system without relinking or changing
     symlinks.

     On 64-bit architectures that provide 32-bit runtime support, the libmap
     mechanism is available for 32-bit binaries too.  The mappings has to be
     written into separate configuration file /etc/libmap32.conf.  Currently
     only supported on amd64.

     This mechanism has also been used to create shims to allow Linux shared
     libraries to be dynamically loaded into FreeBSD binaries.  In this case,
     an Exact constraint is used for the Linux shared library, mapping
     libraries it depends on to a wrapper.  The wrapper then defines any
     needed symbols for the Linux shared library and relies on its libraries
     not being mapped to provide actual implementations.  It appears that only
     libraries loaded via dlopen(3) will work correctly.  The symbol version
     information in shared libraries is checked at link time, but at run time
     the version information is currently ignored.

FILES
     /etc/libmap.conf        The libmap configuration file.
     /etc/libmap32.conf      The libmap configuration file for 32-bit binaries
                             on 64-bit system.

EXAMPLES
     # /etc/libmap.conf
     #
     # candidate             mapping
     #
     libc_r.so.6             libpthread.so.2 # Everything that uses 'libc_r'
     libc_r.so               libpthread.so   # now uses 'libpthread'

     [/tmp/mplayer]          # Test version of mplayer uses libc_r
     libpthread.so.2         libc_r.so.6
     libpthread.so           libc_r.so

     [/usr/local/jdk1.4.1/]  # All Java 1.4.1 programs use libthr
                             # This works because "javavms" executes
                             # programs with the full pathname
     libpthread.so.2         libthr.so.2
     libpthread.so           libthr.so

     # Glue for Linux-only EPSON printer .so to be loaded into cups, etc.
     [/usr/local/lib/pips/libsc80c.so]
     libc.so.6               pluginwrapper/pips.so
     libdl.so.2              pluginwrapper/pips.so

SEE ALSO
     ldd(1), rtld(1)

HISTORY
     The libmap.conf manual page and libmap functionality first appeared in
     FreeBSD 5.1.

AUTHORS
     This manual page was written by Matthew N. Dodd <winter@jurai.net>.

FreeBSD 11.0-PRERELEASE        January 31, 2004        FreeBSD 11.0-PRERELEASE

NAME | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

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