Static linking of Libc - linux

I'd need to statically link all the dependencies of a binary in the binary itself (that is also the libc). I've tried the option -static-libgcc but it did not worked, the size of compiled binary is the same as the dynamic compiled one (that is without the static option).
Is it possible to do that? If so, how?

The answer was pretty simple and has been given in a comment by the user Faust, merely just add -static as gcc option.

Related

How to compile ARM32 only binary (no thumb)

Is there a GCC configuration which will produce an executable only containing ARM32 code?
I know the -marm switch tells the compiler not to produce Thumb code, but it applies only to the user code of the program, while initialization routines (e.g. _start, frame_dummy, ...) still contain Thumb instructions.
I am using the Linaro cross compiler tool-chain (arm-linux-gnueabihf-) on a Linux x86-64 system.
EDIT :
While recompiling the tool-chain I found the (probable) solution myself. The initialization routines encoded as Thumb are part of glibc and can be found in the object files crt1.o, crti.o and crtbegin.o. I haven't tried recompiling it, but there may be a configuration value which forces the whole libc to be encoded as ARM32.
Is there a GCC configuration which will produce an executable only containing ARM32 code? I know the -marm switch ...
Your main problem is that that code (e.g. _start) is not produced by the compiler but it is already present pre-compiled (as thumb code).
If you want to have these functions to be non-thumb code you'll have to "replace" the existing files (thumb) by your own ones (non-thumb).
(You don't have to overwrite the existing files but you can instruct the linker to search for these files in a different directory.)
If you don't find pre-built non-thumb files you'll have to create them yourself (what may be a lot of work).

In Ubuntu (14.04), is there an equivalent to /etc/ld.so.conf.d for the linker?

This is a question about centrally-located path specs, like PATH, LD_LIBRARY_PATH, and LIBRARY_PATH.
I know that there are two ways of specifying shared library paths for the loader: add them to LD_LIBRARY_PATH, or add files to /etc/ld.so.conf.d/. I also know that the latter is considered the more modern and preferred way to do it.
I also know that you can specify standard library paths for the linker by editing LIBRARY_PATH. Is this still the "modern" way to do it, or is there now a "ld.so.conf.d-style" alternative that I should be using?
EDIT: People are asking "why", so:
I'm using a Python package (Theano) that dynamically generates and compiles CUDA and C++ code when run. One of the libraries it links to is NVidia's cuDNN. I don't know why Theano's developer's have it link to the static lib and not the dynamic lib.
There isn't any equivalent to ld.so.conf.d/ for static libraries. You still just specify the standard linker search paths via the LIBRARY_PATH environment variable, and additional paths through command-line flags to the linker.
To be clear:
LIBRARY_PATH: Used by the linker at compile time. Is used by the linker to find both static and dynamic libraries.
LD_LIBRARY_PATH: Used by the loader at run time to find dynamic libraries.
static libraries are resolved at (static) link time and by definition don't have any runtime aspects.
My opinion is that you should avoid using static libraries and always prefer shared libraries.

Can I install both shared .so and static .a versions of a library?

My questions is related to this: Creating both static and shared C++ libraries
I'm compiling a library in order to install it in ~/local on two different systems. It seems that every time I do this I end up with linker problems that take me hours to figure out. The specific library I'm looking at is primesieve. In that library, it's the default to build static libraries only. Unfortunately the example code count_primes.cpp wouldn't link with the static version of the library on one of my systems, for whatever reason. Eventually I figured out how to build the shared version and the code now compiles nicely, with no ugly hacks necessary.
Given the above, it seems to be that compiling both static and shared versions is a good idea if you're working with multiple systems and want the best chance of having your code compile. Is this true? Are there reasons not to build both versions? I realize that this is a bit of a subjective question but it's a serious programming issue that I think many people here have probably encountered.
PS.
This is what I ended up using to compile and install both shared and static versions of primesieve to ~/local:
make
make lib
make install PREFIX=~/local
make clean
make lib SHARED=yes
make install PREFIX=~/local
The make clean is because of this. I then added this to my .bash_profile:
export LIBRARY_PATH=$LIBRARY_PATH:~/local/lib
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:~/local/lib
export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:~/local/include
Alternatively, without changing the environment variables I was able to compile the example program count_primes.cpp like this:
g++ -I ~/local/include/ -L ~/local/lib/ -lprimesieve count_primes.cpp
To use a static library you can just include it in the compilation as if it were a regular object file, e.g.
g++ -o foo foo.cpp /path/to/mylib.a
Of course, this means static linking too.
You can still statically link with a dynamic library, so there's not much use for static libraries really.
There is no reason not to build both. Neither library will "do" anything. The shared library will only be loaded if it is in a path viable to the dynamic linker (like you did by adding it to your LD library path). The static one won't be used unless you explicitly link against it - but that is only done at compile (link) time.

Is it possible to statically link against a shared object?

My question is not the same as this question.
I'm working on a project with a standalone binary that has no dynamic/external linkage, and runs in a *nix environment.
I'm attempting to move to a newer toolset to build with, but some of the static libraries that are available with the older toolset aren't available now -- for example, the crt libraries that provided _start aren't provided in this toolset.
I've been digging through the files provided with the vendor's toolset and found some shared objects with the symbols I needed from the crt libraries (eg, _start, _fini, etc) but I'm unsure whether there's a straightforward way to statically link a shared object into a binary, and further have that binary be executable.
Short version: Can a non-shared-object binary be statically linked with a shared object without the result becoming another shared object?
There's a fundamental difference between a shared library and a static library. First off, do search this site for previous discussions, and check out this question too (and the answers therein).
Basically, a static library is just a collection of objects, and the linker resolves the symbol names into fixed addresses -- this is required for static linking. On the other hand, a shared library is much more like an independent executable, which is loaded into memory by the loader and has entry point addresses to which the program jumps. However, relocation tables that static libraries have are generally not preserved when a shared library is being linked, so it's in general not possible to extract linkable object code from inside a linked shared library.
Yeah, I know this is an 6 year-old question. I was told that it was possible to statically link against a shared-object library, but I've also discovered that it is not.
To actually demonstrate that statically linking a shared-object library is not possible with ld (gcc's linker), use the following gcc command:
gcc -o executablename objectname.o -Wl,-Bstatic -l:libnamespec.so
(Of course you'll have to compile objectname.o from sourcename.c, and you should probably make up your own shared-object library as well. If you do, use -Wl,--library-path,. so that ld can find your library in the local directory.)
The actual error you receive is:
/usr/bin/ld: attempted static link of dynamic object `libnamespec.so'
collect2: error: ld returned 1 exit status
Clearly, attempting to pull the object out of the shared-object library is something about which ld will balk.
There were some suggestions made here, but my interest in this question was merely academic.
Hope that helps.

How to statically-link a complex program

In Linux, downloaded a program source and want it to be statically linked.
Have a huge Makefile there,
I
./configure
make
to compile.
prehpes it's a bit too general to ask, but how can I make the binary statically linked?
EDIT: the reason for this is wanting to make sure the binary will
have no dependencies (or at least as few as possible), making it possible to run on any Linux based computer, even one without Internet connection, and non-updated Linux.
Most autoconf generated configure script will allow you to make a static build:
./configure --enable-static
make
If that doesn't work, you may be able to pass linker flags in via LDFLAGS, like this:
./configure LDFLAGS=-static
Yeah, you need to edit the make file and add the -static parameter to gcc during the link.
I assume it's using gcc to compile a series of c programs, although you will have to look in the Makefile to find out.
If so, you can adjust the gcc lines in the makefile to do static linking, although depending upon the structure of the program, this may be a complex change. Take a look at man gcc to see how this is done.
I'd be interested to know why you are statically linking. Have you considered using prelinking instead?
You should be aware that there may be licence problems to doing this if all components are not GPL.
If you cannot compile a static binary, I've had good results using Statifier.

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