关于ELF文件分析

[jody_go]

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libelf.h>
#include <gelf.h>

char* src_01 = "123456";
int src_02 = 800;

void test(int i)
{
	printf("[int test]i is %d\n", i);
}

int main(int argc, char* argv[])
{
	Elf *elf = NULL;
	Elf_Scn *scn = NULL;
	GElf_Shdr shdr;
	Elf_Data *data = NULL;
	int fd, i, count;
	void (*func)(int);

	elf_version(EV_CURRENT);
	fd = open(argv[1], O_RDONLY);
	elf = elf_begin(fd, ELF_C_READ, NULL);
    while((scn=elf_nextscn(elf,scn)) != NULL)
	{
		gelf_getshdr(scn, &shdr);
		if (shdr.sh_type == SHT_SYMTAB)
		{
			break;
		}
	}

	data = elf_getdata(scn, NULL);
	count = shdr.sh_size/shdr.sh_entsize;
	for (i=0; i<count; i++)
	{
		GElf_Sym sym;
		gelf_getsym(data, i, &sym);
		if (!(strcmp("test", elf_strptr(elf, shdr.sh_link, sym.st_name))))
		{
			func = (void(*)(int))(unsigned long)(sym.st_value&0xffffffff);
			func(7);
		}
		
		if (!(strcmp("src_01", elf_strptr(elf, shdr.sh_link, sym.st_name))))
		{
			char* ps = (char *)((unsigned long)(sym.st_value&0xffffffff));
			printf("sym.st_size = %d, ps = %s\n", sym.st_size, ps);
		}

		if (!(strcmp("src_02", elf_strptr(elf, shdr.sh_link, sym.st_name))))
		{
			int pi = (int)((unsigned long)(sym.st_value&0xffffffff));
			printf("sym.st_size = %d, pi = %d\n", sym.st_size, pi);
		}
	}

	elf_end(elf);
	close(fd);

	return 0;
}

我想根据elf中的st_value值来获得变量src_01和src_02的值，为什么不行呢？test函数则是可以获取的！

[赵4老师]

参考objdump源代码？

[liucsdn7]

夜深了。。。。。