git: rtld: Implement DT_RUNPATH and -z nodefaultlib

[John Marino <marino@xxxxxxxxxxxxxxxxxxxxxxx>]

commit 4f0bc915b65fcf5a23214f6d221d65c80be68ad4
Author: John Marino <draco@marino.st>
Date:   Sat Mar 24 06:40:50 2012 +0100

    rtld: Implement DT_RUNPATH and -z nodefaultlib
    
    DT_RUNPATH is incorrectly being considered as an alias of DT_RPATH.  The
    purpose of DT_RUNPATH is to have two different types of rpath: one that
    can be overridden by the environment variable LD_LIBRARY_PATH and one that
    can't.  With the currently implementation, LD_LIBRARY_PATH will always
    trump any embedded rpath or runpath tags.
    
    Current path search order by rtld:
    ==================================
    LD_LIBRARY_PATH
    DT_RPATH / DT_RUNPATH (always the same)
    ldconfig hints file (default: /var/run/ld-elf.so.hints)
    /usr/lib
    
    New path search order by rtld:
    ==============================
    DT_RPATH of the calling object if no DT_RUNPATH
    DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
    LD_LIBRARY_PATH
    DT_RUNPATH
    ldconfig hints file
    /usr/lib
    
    The new path search matches how the linux runtime loader works.  The other
    major added feature is support for linker flag "-z nodefaultlib".  When
    this flag is passed to the linker, rtld will skip all references to the
    standard library search path ("/usr/lib" in this case but it could handle
    more color delimited paths) except in DT_RPATH and DT_RUNPATH.
    
    New path search order by rtld with -z nodefaultlib flag set:
    ============================================================
    DT_RPATH of the calling object if no DT_RUNPATH
    DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
    LD_LIBRARY_PATH
    DT_RUNPATH
    ldconfig hints file (skips all references to /usr/lib)
    
    Currently gcc41 and gcc44 are embedding /usr/lib directly in every
    DT_RPATH tag of every binary and shared library it creates.  This is
    both unnecessary due to rtld default search path order and it also
    defaults the purpose of -z nodefaultlib, so this behavior must be
    changed before the flag works.  This will be done in a separate commit.

Summary of changes:
 libexec/rtld-elf/rtld.c |  171 ++++++++++++++++++++++++++++++++++++-----------
 libexec/rtld-elf/rtld.h |   10 +++
 2 files changed, 143 insertions(+), 38 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/4f0bc915b65fcf5a23214f6d221d65c80be68ad4


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