MacOS -- 如何使用 gcc/ld 将动态库与相对路径链接
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MacOS -- how to link a dynamic library with a relative path using gcc/ld
提问by William Jockusch
If you are trying to understand dynamic linking, this questionis likely to be of interest.
如果您正在尝试了解动态链接，这个问题可能会引起您的兴趣。
One of the answers to that question provides a wonderful example of creating and using a dynamic library. Based on it, I some simple files:
该问题的一个答案提供了一个创建和使用动态库的绝妙示例。基于它，我有一些简单的文件：
main.c:
主文件：
extern void someFunction (int x);
int main (int argc, char** argv ) {
someFunction(666);
}
mylibrary.c:
mylibrary.c:
#include <stdio.h>
void someFunction (int x) {
printf ("\nsomeFunction called with x=%d\n", x);
}
makefile:
生成文件：
main: mylibrary.c main.c
gcc -c mylibrary.c
gcc -dynamiclib -current_version 1.0 mylibrary.o -o libmylibrary.dylib
gcc -c main.c
gcc -v main.o ./libmylibrary.dylib -o main
clean:
rm *.o
rm main
rm *.dylib
So far, everything works great. If I make and then enter ./main at the command prompt, I see the expected output:
到目前为止，一切都很好。如果我 make 然后在命令提示符下输入 ./main ，我会看到预期的输出：
someFunction called with x=666
Now, I want to mix things up a little. I've created a directory hidelib, which is a subdirectory of my main directory. And I'm adding one line to my makefile:
现在，我想把事情搞混一点。我创建了一个目录 hidelib，它是我的主目录的子目录。我在我的 makefile 中添加了一行：
main: mylibrary.c main.c
gcc -c mylibrary.c
gcc -dynamiclib -current_version 1.0 mylibrary.o -o libmylibrary.dylib
gcc -c main.c
mv libmylibrary.dylib hidelib # this is the new line
clean:
rm *.o
rm main
rm hidelib/*.*
Now, I want to add another line to the makefile so it will find libmylibrary.dylib in the hidelib subdirectory. I want to be able to run ./main in the same way. How can I do that?
现在，我想在 makefile 中添加另一行，以便在 hidelib 子目录中找到 libmylibrary.dylib。我希望能够以同样的方式运行 ./main。我怎样才能做到这一点？
EDIT: Thanks for the response. Having lots of options is wonderful, but a beginner just wants one concrete option that works. Here is what I am trying for the last line, but clearly I don't understand something. The makefile executes without errors, but at runtime it says "library not found."
编辑：感谢您的回应。有很多选择固然很棒，但初学者只需要一个可行的具体选择。这是我在最后一行尝试的内容，但显然我不明白一些事情。makefile 执行时没有错误，但在运行时显示“未找到库”。
gcc main.o -rpath,'$$ORIGIN/hidelib' -lmylibrary -o main
采纳答案by leedm777
One concrete option that works would be to set the install_nameflag when linking the .dylib.
一个可行的具体选项是install_name在链接.dylib.
gcc -dynamiclib -install_name '$(CURDIR)/hidelib/libmylibrary.dylib' -current_version 1.0 mylibrary.o -o libmylibrary.dylib
Then you can just link to the library normally:
然后你可以正常链接到库：
gcc main.o -L '$(CURDIR)/hidelib' -lmylibrary -o main
回答by wbyoung
You probably need the -Lcompiler/linker flag which adds to the search path for libraries.
您可能需要将-L编译器/链接器标志添加到库的搜索路径中。
Are trying to move things after linking, you'll need a dyldenvironment variable for where to search. man dyldand you should be able to get more information on DYLD_LIBRARY_PATHand other environment variables.
尝试在链接后移动事物，您需要一个dyld环境变量来搜索位置。man dyld并且您应该能够获得有关DYLD_LIBRARY_PATH和其他环境变量的更多信息。
Typically, though, you set the install name of the library before linking to something with the -install_namelinker flag to something like @rpath/mylibrary.dylibas the value, then set the run path search paths on the main executable while compiling with the -rpathflag to @executable_path/hidelib.
但是，通常情况下，您在使用-install_name链接器标志链接到某些东西之前设置库的安装名称@rpath/mylibrary.dylib，然后将主可执行文件上的运行路径搜索路径设置-rpath为@executable_path/hidelib.
For more information see install_name_tooland the -rpath& -install_namearguments of ld.
有关更多信息，请参阅install_name_tool和 的-rpath&-install_name参数ld。
Basically, there are a lot of options for what you're trying to do.
基本上，对于您要执行的操作有很多选择。
