在 C 中，是否可以将导出的函数名称更改为不同的名称? [英] In C, is it possible to change exported function name to different one?

问题描述

全部.

我想链接一个调用 malloc() 函数的库.但是，我的目标环境是不同的malloc() 作为内联函数提供.

我怎样才能使库对 malloc() 的调用直接到我的目标环境的 malloc() 例程?

有什么办法可以改变导出的函数名吗?如果是这样我可以先编码 my_malloc() 并将其导出为 malloc() 并链接那个图书馆:

#include <my_environment.h>//malloc() 是在那里声明的内联函数无效my_malloc(无效){malloc(无效)；}

<小时>

更具体地说，该库是来自 linux 发行版的库，因此它依赖于 libc.但是我的环境是嵌入式的，没有 libc 库，并且 malloc(), free(), ... 是自定义实现的.有些是内联函数，有些是库函数.

解决方案

GNU 链接器 (ld) 支持 --wrap=functionname 参数.我将简单地引用手册页中的文档，因为它包含一个应该完全满足您需要的示例:

<块引用>

--wrap=symbol 对符号使用包装函数.任何未定义的符号引用都将解析为__wrap_symbol".任何对__real_symbol"的未定义引用都将被解析为符号.

这可以用来为系统函数提供一个包装器.包装函数应称为__wrap_symbol".如果它想调用系统函数，它应该调用__real_symbol".

这是一个简单的例子:

无效*__wrap_malloc (size_t c){printf ("使用 %zu
 调用 malloc", c);返回 __real_malloc (c);}

<块引用>

如果您使用 --wrap malloc 将其他代码与该文件链接，那么所有对malloc"的调用都会调用函数__wrap_malloc"代替.在__wrap_malloc"中对__real_malloc"的调用会调用真正的malloc"函数.

您可能还希望提供一个__real_malloc"函数，以便没有 --wrap 选项的链接会成功.如果这样做，则不应将__real_malloc"的定义与__wrap_malloc"放在同一个文件中；如果你这样做了，汇编器可能会在链接器有机会将它包装到malloc"之前解决调用.

all.

I want to link a library which calls malloc() function. However, my target environment is different one and malloc() is supplied as inline-function.

How can I make the library's call to malloc() direct to my target environment's malloc() routine?

Is it any way to change the exported function name? If so I can code my_malloc() first and export it as malloc() and link the library to that one:

#include <my_environment.h>  // malloc() is inline function declared there 
void my_malloc (void) {
   malloc (void);             
}

---

More specifically, the library is one from linux distro so it depends on libc. But my environment is embedded one and has no libc library and malloc(), free(), ... are custom-implemented. Some are inline functions and some are library functions.

解决方案

The GNU linker (ld) supports a --wrap=functionname parameter. I'll simply quote the documentation from the man page as it includes an example which should do exactly what you need:

--wrap=symbol Use a wrapper function for symbol. Any undefined reference to symbol will be resolved to "__wrap_symbol". Any undefined reference to "__real_symbol" will be resolved to symbol.

This can be used to provide a wrapper for a system function. The wrapper function should be called "__wrap_symbol". If it wishes to call the system function, it should call "__real_symbol".

Here is a trivial example:

void *
__wrap_malloc (size_t c)
{
    printf ("malloc called with %zu
", c);
    return __real_malloc (c);
}

If you link other code with this file using --wrap malloc, then all calls to "malloc" will call the function "__wrap_malloc" instead. The call to "__real_malloc" in "__wrap_malloc" will call the real "malloc" function.

You may wish to provide a "__real_malloc" function as well, so that links without the --wrap option will succeed. If you do this, you should not put the definition of "__real_malloc" in the same file as "__wrap_malloc"; if you do, the assembler may resolve the call before the linker has a chance to wrap it to "malloc".

这篇关于在 C 中，是否可以将导出的函数名称更改为不同的名称?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！