打印自身的源代码的程序

demo.c

int printf(const char * format, ...);

extern char* _binary_demo_c_start;

int main()
{
    
    printf("%s\n", &_binary_demo_c_start);

    return 0;
}

makefile

all:
    gcc -c demo.c -o demo.o
    objcopy -I binary -O elf64-x86-64 demo.c code.o 
    gcc demo.o code.o

运行

$ make && ./a.out

查看链接情况

$ objdump -ht demo.o
...
0000000000000000 g     F .text  000000000000001a main
0000000000000000         *UND*  0000000000000000 _binary_demo_c_start
0000000000000000         *UND*  0000000000000000 _GLOBAL_OFFSET_TABLE_
...

$ objdump -ht code.o
节：
Idx Name          Size      VMA               LMA               File off  Algn
0 .data         00000098  0000000000000000  0000000000000000  00000040  2**0
                CONTENTS, ALLOC, LOAD, DATA
SYMBOL TABLE:
0000000000000000 g       .data  0000000000000000 _binary_demo_c_start
0000000000000098 g       .data  0000000000000000 _binary_demo_c_end
0000000000000098 g       *ABS*  0000000000000000 _binary_demo_c_size

$ objdump -ht a.out
...
00000000000040c8 g       .data  0000000000000000              _binary_demo_c_end
0000000000004030 g       .data  0000000000000000              _binary_demo_c_start
...

可以看到demo.o 中 _binary_demo_c_start 还没有被链接, code.o 放在 .data 区, 并且有一个全局的 SYMBOL _binary_demo_c_start, a.out 文件以及链接完成, 并给出 SYMBOL 地址