I have an existing .so library (libgit2), and I would like to use this within a C program (the build system is Scons). I read through the entirety of the Scons documentation for "Chapter 4. Building and Linking with Libraries", but there is no mention of how to use an existing .so library. The only mention of .so in the entirety of chapter 4 is on the first page, and it is only about Scons using a .so file for output. How do I use an existing compiled .so library in Scons?
If you are using an sconscript then you should add a LIBS= arguments and a LIBS_PATH=.
if you want to directly add it to the build line, use -L for lib path and -l to link a lib.
You can find further information here: https://scons.org/doc/0.97/HTML/scons-user/x628.html
With help from the SCons Discord server and other places, I've gotten farther than when I first posted this question. I haven't solved my specific problem of using .so libraries with GDNative, but I think I've figured out the SCons side.
As of me posting this question, the SConstruct file was able to compile working code if I didn't use libgit2 and instead just printed out the text. With only the header included, my test call to git_libgit2_version compiled but didn't run, as Godot said undefined symbol: git_libgit2_version.
First of all, you need to add the named parameter for LIBS to your env.SharedLibrary or env.Program line. The lib prefix and .so suffix seem to be added automatically, I still haven't figured out how to make it point to libgit2.so.1.0.1 (so for now I have the library copied and named as libgit2.so, but I would like to have it point to libgit2.so.1.0.1 eventually instead). Also, the SCons team suggested adding LIBPATH, but this doesn't seem to actually do anything.
library = env.SharedLibrary(target=env["target_path"] + env["target_name"] , source=sources, LIBS=['git2'])
Then, the SConstruct file needs to have this magic line:
env['STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME'] = 1
With the above code, ldd will report not found, and Godot will say Error: libgit2.so.1.0: cannot open shared object file: No such file or directory (I have no idea why it's asking for .so.1.0 instead of the .so or .so.1.0.1 file, and yes I tried copying and naming as libgit2.so.1.0 and that doesn't change anything either).
I also added this, which was suggested by another GDNative user.
env.Append(LINKFLAGS=[
'-Wl,-rpath,addons/git_for_godot/gdnative/linuxbsd'
])
With all of the above code, this seems to allow ldd and Godot to find the library just fine with a relative path (when running ldd you have to be cd'd into the project folder). I can run the project fine without any errors, but the project crashes immediately after opening, with no error messages printed. If I comment out the call to git_libgit2_version but keep the header included, the file does compile and run. Any time I try to call anything from libgit2 it causes Godot to crash without printing any errors. At this point I'm stuck and I don't know what I'm doing wrong.
I did try adding libgit2 to the Dependencies section of the .gdnlib file, but this doesn't seem to affect anything. Another thing I tried which didn't work is this line (+ variants on the extension) which append to the sources list passed as the named source parameter. I'll post it here for completeness, but for the moment I have this line commented out because it doesn't work:
sources.append(File("project/addons/git_for_godot/gdnative/linuxbsd/libgit2.so"))
Related
Preface: I am very new to c and CLion, so apologies in advance if my phrasing is very wrong.
Essentially, I have an assignment that involves two c files (a "main", and one performing a conversion between imperial and metric units). The main c file simply #include-s the conversion file, performs a function within the conversion file, and prints the resulting value to the user. Simple enough, but I keep getting a message every time I try to run it:
"undefined reference to 'conversion'"
I have tried to suss out the problem, and my only idea relates to the banner at the top of conversion.c which says "This file does not belong to any project target, code insight features may not work properly.". I do not understand why I receive this message, because conversion.c and main.c are both within the main project directory, and this setup worked perfectly fine in my previous assignment.
I have searched for solutions online, and the only one that seemed to make sense was to update my CMakeLists.txt file to include add_executable(project conversion.c). This is what my CMakeLists.txt file looks like before I add this line:
cmake_minimum_required(VERSION 3.12)
project(project C)
set(CMAKE_C_STANDARD 11)
add_executable(project main.c)
However, when I add it, I get the error:
CMake Error at CMakeLists.txt:7 (add_executable):
add_executable cannot create target "directory" because another
target with the same name already exists. The existing target is an
executable created in source directory
"/home/john_s/CLionProjects/project". See documentation for
policy CMP0002 for more details.
Presumably this is because the previous line I have (add_executable(project main.c)) is linking to the same directory, but I have no idea how to resolve this. Any suggestions?
From cmake manual:
add_executable(< name> [WIN32] [MACOSX_BUNDLE]
[EXCLUDE_FROM_ALL]
[source1] [source2 ...])
Adds an executable target called to be built from the source files listed in the command invocation. (The source files can be omitted here if they are added later using target_sources().)
So to combile a single executable using two source files, you just use:
add_executable(target_name source1.c source2.c)
I would like to compile the following C file on an embedded platform:
https://github.com/openwsn-berkeley/openwsn-fw/blob/develop/firmware/openos/bsp/chips/at86rf231/radio.c
However, as you can see, on lines 20-26 of radio.c it references "radiotimer_capture_cbt":
typedef struct {
radiotimer_capture_cbt startFrame_cb;
radiotimer_capture_cbt endFrame_cb;
radio_state_t state;
} radio_vars_t;
radio_vars_t radio_vars;
So now I need to hunt down where it is defined and make sure I include the right header.
I have cloned the entire GIT repository here: https://github.com/openwsn-berkeley/openwsn-fw, and I'm looking for a way to compile this easily.
Is there a better way to get this compiled other than going through the brutal dependency nightmare?
My ultimate goal is only to get radio.c compiled and anything it needs. I do not see any makefiles in this project so I'm expecting they want us to use an IDE.
The project seems to use scons as a build system. So the simplest way is to dive into the scons files.
There's a small scons file in the directory containing the linked file and two main script in the top directory.
But if you want to play, first remove headers include, try to compile (using -c) to know which one are really needed. Once you get an object file (.o) you can use nm to identify missing symbols (marked with U.) Good luck …
When I compile with Compaq Visual Fortran, I get these errors (when it starts the linker process) that should be located in a .lib file I thought I added to the workspace:
X30XFULL.OBJ : error LNK2001: unresolved external symbol _BCON#4
X30XFULL.OBJ : error LNK2001: unresolved external symbol _RCON#16
According to where I've googled about, it looks like Compaq Visual Fortran (Version 6, FYI) can't find the library files...
My main question is, how do I use them? Could there possibly be other missing files? Here is what I've tried:
Right Click->Adding the files in the FileView window
Going under Project->Settings, Clicking the Link tab, and under the input category, adding the library files under object/library modules (bprop.lib rprop.lib) and having the Additional Library Path point to where the files are. I also did this under the Resources tab and where it says "Additional Resource Include Directories," I put the directory of where these files were located.
To cover my bases, I also put these files in where the project workspace file, where the compiled executable file would be generated, and pretty much any place I could think of that CVF might possibly look to in order to find these files.
A little background:
I have this Fortran executable that was last compiled in the 90s. From my research, it's a 16-bit compiled one which won't work on a 64-bit machine.
The original code has, at least from what we can gather, 16 bit compiled libraries. Without the original compiler, we can't figure out how to look at or use them. We also have a (semi)equivalent library file that's actually a .FOR file. For all we know, the BPROP.FOR and BPROP.LIB could be the same file (they were found in the same source code area). If we use the BPROP.FOR file, the program can compile, but we are having issues with results that we've traced down to information that is used/gathered/processed in that file.
However, we do have 32-bit versions of (what we think) are the same .lib files. So, we're trying to use that, which is what is being used to compile the Fortran executable which results in the errors above.
Found the answer, at least for me. I don't know how easy it'll be to extrapolate if anyone else finds these answers, but this is how I solved it.
With the old Fortran libraries, all I had to do was add them to the FileList view that has all of the different fortran files (.FOR, etc). I did not have to add these libraries in the settings like I mentioned, but that will work as well. Other then that, I didn't need to add any extra declarations or anything similar.
What we did find out is that the function in question (BCON and RCON) that calls those .LIB files required an additional argument. The only way I found this out was examining other source code that used those libaries, so if anyone is stuck like I was, that would be a good place to start. Alternatively, if you can read the .lib file in a hex editor, you can kind of make out functions and their arguments.
Of course, if you have the original source code for said arguments, that's even better. :)
I am working on a project which requires me to download and use this. Inside the downloaded folder, when extracted I am presented with three things:
A folder called "include"
A folder called "src"
A file called "Makefile"
After some research, I found out that I have to navigate to the directory which contains these files, and just type in the command make.
It seemed to install the library in my system. So I tried a sample bit of code which should use the library:
csp_conn_t * conn;
csp_packet_t * packet;
csp_socket_t * socket = csp_socket(0);
csp_bind(socket, PORT_4);
csp_listen(socket, MAX_CONNS_IN_Q);
while(1) {
conn = csp_accept(socket, TIMEOUT_MAX);
packet = csp_read(conn, TIMEOUT_NONE);
printf(“%S\r\n”, packet->data);
csp_buffer_free(packet);
csp_close(conn);
}
That's all that was given for the sample server end of the code. So I decided to add these to the top:
#include <csp.h>
#include <csp_buffer.h>
#include <csp_config.h>
#include <csp_endian.h>
#include <csp_interface.h>
#include <csp_platorm.h>
Thinking I was on the right track, I tried to compile the code with gcc, but I was given this error:
csptest_server.c:1: fatal error: csp.h: No such file or directory
compilation terminated.
I thought I may not have installed the library correctly after all, but to make sure, I found out I could check by running this command, and getting this result:
find /usr -iname csp.h
/usr/src/linux-headers-2.6.35-28-generic/include/config/snd/sb16/csp.h
/usr/src/linux-headers-2.6.35-22-generic/include/config/snd/sb16/csp.h
So it seems like the csp.h is installed, maybe I am referencing it incorrectly in the header include line? Any insight? Thanks a lot.
The make command is probably only building the library, but not installing it. You could try sudo make install. This is the "common" method, but I recommend you to check the library's documentation, if any.
The sudo command is only necessary if you have no permissions to write the system's include and library directories, which may be your case.
Another possibility (instead of installing the library) is telling GCC the location of the library's source code and generated binaries (by means of the -I and -L options of the gcc command.
That Makefile will not install anything, just translate the source into a binary format.
The csp.h in the Linux kernel has nothing to do with your project, it's just a naming collision, likely to happen with three letter names.
In your case, I would presume you need to add the include directory to the compilation flags for your server, like gcc -I/path/to/csp/include/csp csptest_server.c.
(Next, you'll run into linker errors because you'll also want to specify -L/path/to/csp -lcsp so that the linker can find the binary code to link to.)
I am still fairly new to programming with C and I am working on a program where I want to control the power to various ports on a hub I have. That is, however, not the issue I am having right now.
I found a program online that does what I want I am trying to compile it. However it uses #include<lsusb.h>. lsusb is located in a totally different folder than the file I am wanting to run (and not in a sub folder) and when I try to compile it, I, logically enough, get the error that the file lsusb.h is not found.
How can I link to this file so that it can be found?
This is more of a GCC toolchain question than a C question (although most C compilers do use the same Unixy flags).
The braces around the include file (<>) indicate you want the compiler to search its standard search path for the include file. So you can get access to that new include file either by putting it into a directory on your standard include file search path yourself, or by adding its directory to the file search path. With GCC you do the latter by giving gcc the flag -I"directoryname" where "directoryname" is the full file path to where you are keeping that new include file of yours.
Once your compiler finds it, your linker may have the exact same problem with the library file itself ("liblsusb.a"?). You fix that the same way. The flag GCC's linker will want is -L instead of -I.
See the "-I" parameter in the gcc man page. It allows you specify a directory in which to find a header file. See also -l and -L.
Or try #include "../../path_to_the_file/lsusb.h"