以编程方式获取共享库中的函数名称 [英] Get functions names in a shared library programmatically

问题描述

使用dl_open()时可以通过编程方式从共享库(仅Linux)中获取所有函数名称的列表吗?

Can I get list of all functions names from a shared library (Linux only) programmatically when I am using dl_open()?

我想要这样的东西:

std::vector<std::string> list_all_functions(void *dl) { 
   //... what can I do here?
}

int main() {
    void * dl = dl_open("./mylib.so", RTLD_NOW);
    auto functions = list_all_functions(dl);
    //...
    dl_close(dl);
    return 0;
}

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示例库(mylib.so)

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Example library (mylib.so)

标题(.h):

extern "C" {
    int sum (int a, int b);
}

来源(.c):

int sum (int a, int b) { return a + b; }

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我知道的肮脏黑客:使用nm或objdump实用程序

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Dirty hack that I know: use nm or objdump utility

推荐答案

没有libc函数可以执行此操作.但是，您可以自己编写(或从诸如readelf之类的工具中复制/粘贴代码).

There is no libc function to do that. However, you can write one yourself (or copy/paste the code from a tool like readelf).

在Linux上，dlopen()返回link_map结构的地址，该结构具有名为l_addr的成员，该成员指向已加载的共享库的基址(假设您的系统没有随机分配共享库的位置，并且您的媒体库尚未预链接).

On Linux, dlopen() returns the address of a link_map structure, which has a member named l_addr that points to the base address of the loaded shared object (assuming your system doesn't randomize shared library placement, and that your library has not been prelinked).

在Linux上，找到基地址(Elf*_Ehdr的地址)的一种方法是在dlopen()库之后使用dl_iterate_phdr().

On Linux, a way to find the base address (the address of Elf*_Ehdr) is to use dl_iterate_phdr() after dlopen()ing the library.

具有ELF标头，通过首先找到类型PT_DYNAMIC的Elf*_Phdr，然后找到DT_SYMTAB，DT_STRTAB，您应该能够遍历导出的符号列表(动态符号表).条目，并遍历动态符号表中的所有符号.使用/usr/include/elf.h指导您.

Having the ELF header, you should be able to iterate over a list of exported symbols (the dynamic symbol table), by first locating the Elf*_Phdr of type PT_DYNAMIC, and then locating DT_SYMTAB, DT_STRTAB entries, and iterating over all symbols in the dynamic symbol table. Use /usr/include/elf.h to guide you.

此外，您可以使用 libelf ，因为我个人不太了解

Additionally, you could use libelf, that I don't know very well personally.

但是，请注意，您将获得已定义函数的列表，但是您不知道如何调用它们.

However, note that you'll get a list of defined functions, but you'll have no idea how to call them.

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