Re: [gentoo-user] [OT] How to add library to dynamically linked executable?
On Jun 22, 2015, at 19:13, Grant Edwards grant.b.edwa...@gmail.com wrote: Is there any way to add a library to the list of libraries required by an ELF dynamically linked executable? I have an executable (let's call it foo) which was written and built by somebody else [I don't have sources]. It requires the librt to run on one particular platform, but librt isn't in the exeuctable's list of libraries. [I'll skip the story of how it ended up this way. It will be fixed with the next version of that application.] # foo foo: can't resolve symbol 'shm_open' If I run it like this, it's fine: # LD_PRELOAD=/lib/librt.so.0 foo Is there any way to fix the ELF executable file to add librt.so.0 to its list of libraries? I'm aware I can create a shell script that does this: #!/bin/sh export LD_PRELOAD=/lib/librt.so.0 exec foo What I'm wondering about is whether there is a way to fix the ELF executable file itself so as to add librt.so.0 to its list of shared libraries. I've found chrpath(1), but it only changes the search path used to look for libraires, not the list of libraries themselves. The question you have has multiple solutions to it... Doing it as it should be done is only possible if you have all the needed object files at hand. A ready made tool that just adds a shared library to an executable does not exist. But i believe you have a hexeditor, that is able to do it ;) I have tryed many of these options and it is quite tricky if you don't have the ELF object-files. There are various tools for you available objcopy etc... One option is to make a library that load two libraries e.g. librt and another library needed by the executable. Then hexedit your executable to load the new library you created and it will load the two libraries needed. Also you can write a c program that modifies the elf executable, but i don't think you need to for this problem. -- -Matti
[gentoo-user] [OT] How to add library to dynamically linked executable?
Is there any way to add a library to the list of libraries required by an ELF dynamically linked executable? I have an executable (let's call it foo) which was written and built by somebody else [I don't have sources]. It requires the librt to run on one particular platform, but librt isn't in the exeuctable's list of libraries. [I'll skip the story of how it ended up this way. It will be fixed with the next version of that application.] # foo foo: can't resolve symbol 'shm_open' If I run it like this, it's fine: # LD_PRELOAD=/lib/librt.so.0 foo Is there any way to fix the ELF executable file to add librt.so.0 to its list of libraries? I'm aware I can create a shell script that does this: #!/bin/sh export LD_PRELOAD=/lib/librt.so.0 exec foo What I'm wondering about is whether there is a way to fix the ELF executable file itself so as to add librt.so.0 to its list of shared libraries. I've found chrpath(1), but it only changes the search path used to look for libraires, not the list of libraries themselves. -- Grant Edwards grant.b.edwardsYow! Okay ... I'm going at home to write the I HATE gmail.comRUBIK's CUBE HANDBOOK FOR DEAD CAT LOVERS ...
Re: [gentoo-user] [OT] How to add library to dynamically linked executable?
On Mon, 22 Jun 2015 16:13:57 + (UTC) Grant Edwards grant.b.edwa...@gmail.com wrote: Is there any way to add a library to the list of libraries required by an ELF dynamically linked executable? I have an executable (let's call it foo) which was written and built by somebody else [I don't have sources]. It requires the librt to run on one particular platform, but librt isn't in the exeuctable's list of libraries. [I'll skip the story of how it ended up this way. It will be fixed with the next version of that application.] # foo foo: can't resolve symbol 'shm_open' If I run it like this, it's fine: # LD_PRELOAD=/lib/librt.so.0 foo Is there any way to fix the ELF executable file to add librt.so.0 to its list of libraries? I'm aware I can create a shell script that does this: #!/bin/sh export LD_PRELOAD=/lib/librt.so.0 exec foo What I'm wondering about is whether there is a way to fix the ELF executable file itself so as to add librt.so.0 to its list of shared libraries. I've found chrpath(1), but it only changes the search path used to look for libraires, not the list of libraries themselves. Perhaps elfsh[1] would do the trick. There's an example[2] that demonstrates editing the dynamic section, so you might be able to add an entry that way, though it's not as simple as an addneeded command. Although it sounds[3] like elfsh might not be very stable. Actually, scratch all that, NixOS's patchelf command[4] supports editing NEEDED entries now, that'll be the easiest way. Cheers, Bryan [1] http://www.eresi-project.org/wiki/TheELFsh [2] http://www.eresi-project.org/browser/trunk/testsuite/elf/elf-tests.esh [3] https://stackoverflow.com/a/2287737 [4] https://github.com/NixOS/patchelf pgpPTP2uvQQRv.pgp Description: OpenPGP digital signature
