I am trying to use a modified glibc library. The glibc library is statically linked to my code. I have declared a new variable (lets call it my_libc_var) in the glibc library. However, when I try to include that variable in my program (using the extern keyword ofcourse), I get undefined reference error. How can I solve this problem?
我正在尝试使用一个修改后的glibc库。glibc库静态地链接到我的代码。我已经在glibc库中声明了一个新变量(我们称之为_mylibc_var)。但是，当我试图在程序中包含该变量时(当然是使用extern关键字)，我将获得未定义的引用错误。我如何解决这个问题?
In glibc, the variable is declared as follows.
在glibc中，变量声明如下。
int my_libc_var;
whereas, in my program, it is declared as follows.
然而，在我的程序中，它被声明如下。
extern int my_libc_var;
1 个解决方案
#1
1
Check whether in the compilation process the variable you have added is included in a source file which is compiled using options like -fvisibility=hidden or -fvisibility=internal. This will make your symbol non-referenceable from other modules.
检查在编译过程中您添加的变量是否包含在使用-fvisibility=hidden或-fvisibility=internal等选项进行编译的源文件中。这将使您的符号不能从其他模块引用。
A similar behaviour, as long as you are using gcc, is obtained using either:
类似的行为，只要您使用gcc，也可以使用:
#pragma GCC visibility push("hidden")
which can be placed at the beginning of the source file, or:
可以放置在源文件的开头，或:
int var __attribute__ ((visibility ("hidden")));
in the definition of the symbol (which clearly you didn't place, but I placed it here for completing my answer).
在符号的定义中(很明显你没有把它放在这里，但我把它放在这里是为了完成我的答案)。
For further information, you can refer to gcc attribute overview page.
有关进一步的信息，可以参考gcc属性概览页面。
#1
1
Check whether in the compilation process the variable you have added is included in a source file which is compiled using options like -fvisibility=hidden or -fvisibility=internal. This will make your symbol non-referenceable from other modules.
检查在编译过程中您添加的变量是否包含在使用-fvisibility=hidden或-fvisibility=internal等选项进行编译的源文件中。这将使您的符号不能从其他模块引用。
A similar behaviour, as long as you are using gcc, is obtained using either:
类似的行为，只要您使用gcc，也可以使用:
#pragma GCC visibility push("hidden")
which can be placed at the beginning of the source file, or:
可以放置在源文件的开头，或:
int var __attribute__ ((visibility ("hidden")));
in the definition of the symbol (which clearly you didn't place, but I placed it here for completing my answer).
在符号的定义中(很明显你没有把它放在这里，但我把它放在这里是为了完成我的答案)。
For further information, you can refer to gcc attribute overview page.
有关进一步的信息，可以参考gcc属性概览页面。