clib | C package

I am trying to build a simple "hello_there" Ada app to run on a Raspberry Pi 2/Raspbian machine but have come across a linkage issue.

So far, I've done the following and had the following issues:

1. Downloaded the "Raspberry Pi 2 Linux" GNAT GPL Ada toolchain for cross compiling (linux-on-linux) on the host machine (Ubuntu 16.04)

2. Ran "doinstall" on the host machine successfully.

3. Created a simple "hello_there.adb" file which just prints a message to the console.

4. Ran {INSTALL_ROOT}/gnat-gpl-2016-raspberrypi-linux-linux-bin/bin/arm-linux-gnueabihf-gnatmake -v hello_there.adb to build this small app.

5. That complained that the crt1.o | crti.o | crtn.o files cannot be found and since I couldn't use the ones under /usr/lib/x86_64-linux-gnu/ on the host machine (as I assume, these can only be used for a x86 target) the only solution I could find was to copy these files from the target machine which are located under /usr/lib/arm-linux-gnueabihf to the gnatmake command dir. That stopped the linker complaining about these.

6. Ran again {INSTALL_ROOT}/gnat-gpl-2016-raspberrypi-linux-linux-bin/bin/arm-linux-gnueabihf-gnatmake -v hello_there.adb but now the linker is complaining with the following error:

   {INSTALL_ROOT}/gnat-gpl-2016-raspberrypi-linux-linux-bin/bin/../libexec/gcc/arm-linux-gnueabihf/4.9.4/ld: cannot find -lc

   It looks like compilation and binding complete fine but but linking fails. The full output is the following:

   ...

I have a small project in django rest framework and I want to dockerize it. In my requirements.txt file there is a package called ruamel.yaml.clib==0.2.6. While downloading all other requirements is successfull, there is a problem when it tries to download this package.

I am trying to call C functions inside python and discovered the ctypes library (I'm fairly new to both C and python's ctypes), motive (however stupid) is to make python code's speed on par with c++ or close enough on a competitive website. I have written the C code and made a shared library with the following command cc -fPIC -shared -o lib.so test.c and imported it into python with ctypes using the following code:

After some initial problems I was finally able to set up a self-hosted GitLab Runner on my personal laptop.

I'm now looking into how this runner works and how I can tweak it's environment to my needs. I modified the YML file to run a simple command echoing the PATH environment variable:

I want to redirect the stdout and stderr C streams to Java, but I am struggling to do so. I used the result of this thread: https://users.jna.dev.java.narkive.com/VdgNgCIb/jna-solutions-to-catch-stdout-stderr-of-dll but it still does not work as intended.

Here is my C code (I compiled it as a TestPrintf.dll library):

realloc may simply update bookkeeping info here and there to increase your allocation size, or it may actually malloc a new one and memcpy the previous allocation (or may fail).

I want to be able to query the memory manager if an allocation is trivially resizable (either because it reserved more than I mallocd or because it was able coalesce adjacent blocks , etc...) and if yes, then I'll ask it to go ahead and do so, else I'd want to malloc and memcpy an arbitrary subset of the original allocation in an arbitrary order myself.

Other StackOverflow answers seem to do one of these four :

• Suggest realloc anyways. This can be quite inefficient for large quantities of data, where the double-copy can have serious effect. Usually, it is the fastest portable route.
• Suggest manual malloc + memcpy + free. This is worse, because now instead of some double copying when allocation may not be resized, everything is double copied every time the allocation fills up. Performs terribly.
• Suggest a platform specific extension. This is not practical, as my code, like a lot of C code, requires portability.
• Suggest it's impossible. C already assumes the presence of a memory manager with ability to either resize allocations in place or create a new one. So, why can't I have one more level of control on it? We can have aligned malloc; why not this ?

NOTE : This question is posted under both C and C++ tags because solutions from either language are acceptable and relevant.

EDIT 1:

In the words of FB vector :

But wait, there's more. Many memory allocators do not support in- place reallocation, although most of them could. This comes from the now notorious design of realloc() to opaquely perform either in-place reallocation or an allocate-memcpy-deallocate cycle. Such lack of control subsequently forced all clib-based allocator designs to avoid in-place reallocation, and that includes C++'s new and std::allocator. This is a major loss of efficiency because an in-place reallocation, being very cheap, may mean a much less aggressive growth strategy. In turn that means less slack memory and faster reallocations.

See this.

I have two collections, viz: clib and mp. The schema for clib is : {name: String, type: Number} and that for mp is: {clibId: String}.

Sample Document for clib:

I have several python executables available from within a default powershell prompt as shown by where.exe python:

I have written some c++ code that I want to integrate with matlab in the following method https://www.mathworks.com/help/matlab/matlab_external/publish-interface-to-shared-c-library-on-linux.html

1. The first step: Generate Interface on Linux goes well.
2. The second step: Define Missing Constructs is not really necessary, my example is so simple it can do this automatically
3. Build Interface is where I get the problem.

Here is my matlab code: