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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 depen-
     dencies 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	exe-
     cutable 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 con-
	     straint.  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	exe-
	     cutable 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	exe-
     cuted 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 configura-
     tion 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	10.1		       January 31, 2004			  FreeBSD 10.1

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

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