Question

How To Set DT_RUNPATH or How To Augment dlopen() Search Path, At Link-time?

Asked by: videocoder

I'm linking an executable, on Linux (SuSE version 9.1, kernel version 2.6.6, ld version 2.15.90.0.1.1, gcc version 3.2.3 (old)), and I want to augment the shared library path used by dlopen().  In the manpage on that system, it says that, in addition to all the standard places to look, dlopen() will use DT_RUNPATH or fall back on DT_RPATH.

During the link (I use gcc as a front-end to ld), I specify '-Wl,-rpath,LOCATION' (equivalent to calling ld w/ '-rpath LOCATION'), among other options, yet dlopen() fails to find the library in LOCATION.  On an older system (SuSE version 9.0, kernel version 2.4.21, ld version 2.14.90.0.5, gcc version 3.2.3 (same)), dlopen() succeeds.  On either system, if I put LOCATION in LD_LIBRARY_PATH, dlopen() succeeds, yet that's an unreasonable requirement for this application.

I'm aware of the tool chrpath (http://freshmeat.net/projects/chrpath/?topic_id=46), but I want to know if there's a more straight-forward way to set DT_RUNPATH.  Such as via the command-line for ld.

BTW, isn't it a bit strange that someone had to write a dedicated tool for doing that?  Is it really true that binutils contains nothing for dumping or modifying DT_RPATH or DT_RUNPATH (or similar labels)?

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2004-08-29 at 21:30:48ID21111810
Tags

dt_runpath

,

dlopen

Topic

Linux Programming

Participating Experts
2
Points
500
Comments
6

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Bug: DrawText( ) with DT_PATH_ELLIPSIS?
    DrawText with DT_PATH_ELLIPSIS does not seem to perform the replacement with ellipses when the input string does not contain a backslash... instead, system attempts to draw the *whole* string and clips it. is is this a known bug?? I use the DevStudio 6.0. ( my format flags a...
  2. DTS job
    I have a DTS package that I want to schedule to run once a day. I right clicked on the package and chose my schedule. Now, there should be a job scheduled but I don't see one. Where did it go? Any ideas?

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: yuzhPosted on 2004-08-29 at 22:30:42ID: 11928748

In command line:

for sh/ksh/bash
you do:

DT_RUNPATH=/path-to/lib
export DT_RUNPATH

or simply use LD_LIBRARY_PATH
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/path-to-lib
export  LD_LIBRARY_PATH

For csh/tcsh
setenv LD_LIBRARY_PATH           $LD_LIBRARY_PATH:/path-to-lib

you can you them in your .profile (sh/ksh/bash) or .cshrc file (csh/tcsh)

 

by: videocoderPosted on 2004-08-29 at 23:05:18ID: 11928841

Huh?  Are you sure about that?

DT_RUNPATH is not documented as an environment variable related to ld, in it the ld manpage.  Furthermore, this seems to make no difference in the behavior I'm seeing, and running 'strings' on my program shows that the path I put in the DT_RUNPATH environment variable didn't even make it into the executable.


Finally, as I think the subject and question clearly state, I am looking for an ALTERNATIVE to using LD_LIBRARY_PATH (which must be specified at runtime, rather than link-time).


I appreciate your attempt to help, but it seems like you didn't try to read or understand the question very thoroughly.

 

by: yuzhPosted on 2004-08-29 at 23:55:36ID: 11928994

I have never used "DT_RUNPATH", I thought you want to define such a var for your app,
a lot of app defined their only ENV vars. I have use something like LD_RUN_PATH.

 

by: videocoderPosted on 2004-08-30 at 00:20:27ID: 11929056

Sorry, I assumed people wouldn't try to answer the question without actually knowing about DT_RPATH and DT_RUNPATH.  They're described in the dlopen() manpage as 'tags' in an ELF file.

I don't know much about ELF files, and I don't know what a 'tag' is, but I assume it's different from a 'section' or a 'symbol'.

 

by: mtmikePosted on 2004-08-30 at 09:29:04ID: 11932758

DT_RPATH and DT_RUNPATH are entries in the dynamic table. You can dump the dynamic table using "objdump -p /path/to/binary".

The manual page of dlopen() seems to suggest that RUNPATH is searched, but this is not the case. See http://sources.redhat.com/ml/libc-alpha/2004-06/msg00120.html

Using '-Wl,-rpath,LOCATION' should set RPATH and not RUNPATH. If the SUSE 9.1 linker does set RUNPATH, try passing '-Wl,-disable-new-dtags' to gcc.

 

by: videocoderPosted on 2004-08-30 at 22:37:47ID: 11939009

BTW, for the sake of anyone else reading this solution, I just wanted to note that '-rpath' appears to set both DT_RPATH and DT_RUNPATH (on the SuSE 9.1, kernel 2.6 system in question).

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...