我一直没有找到这个问题的答案。
使用GDB,我可以使用命令 "call "来获取函数的原型.示例。
(gdb) call fn
$1 = {void (int, int)} 0x8048414 <fn>
所以,GDB只能从elf文件中找出 fn()返回void并接受两个整数作为参数。
然而,我需要使用其他工具从elf文件中提取函数的原型。最好是使用objdump readelf。
有谁知道这是否可行?如果不可行,GDB是怎么做的?函数原型存储在elf文件的哪个部分?
GDB通过 DWARF debuginfo。readelf -w ELF
会转储。你可能想阅读 DWARF调试格式介绍 由Michael J. Eager. 使用 pyelftools 你可以从一个交互式的Python会话中探索和实验DWARF。
要提取函数原型,你需要用 subprogram
调试信息条目。DWARF格式教程中的一个例子是。
strndup.c
1: #include "ansidecl.h"
2: #include <stddef.h>
3:
4: extern size_t strlen (const char*);
5: extern PTR malloc (size_t);
6: extern PTR memcpy (PTR, const PTR, size_t);
7:
8: char *
9: strndup (const char *s, size_t n)
10: {
11: char *result;
12: size_t len = strlen (s);
13:
14: if (n < len)
15: len = n;
16:
17: result = (char *) malloc (len + 1);
18: if (!result)
19: return 0;
20:
21: result[len] = '\0';
22: return (char *) memcpy (result, s, len);
23: }
strndup.c的DWARF描述
<1>: DW_TAG_base_type
DW_AT_name = int
DW_AT_byte_size = 4
DW_AT_encoding = signed
<2>: DW_TAG_typedef
DW_AT_name = size_t
DW_AT_type = <3>
<3>: DW_TAG_base_type
DW_AT_name = unsigned int
DW_AT_byte_size = 4
DW_AT_encoding = unsigned
<4>: DW_TAG_base_type
DW_AT_name = long int
DW_AT_byte_size = 4
DW_AT_encoding = signed
<5>: DW_TAG_subprogram
DW_AT_sibling = <10>
DW_AT_external = 1
DW_AT_name = strndup
DW_AT_prototyped = 1
DW_AT_type = <10>
DW_AT_low_pc = 0
DW_AT_high_pc = 0x7b
<6>: DW_TAG_formal_parameter
DW_AT_name = s
DW_AT_type = <12>
DW_AT_location =
(DW_OP_fbreg: 0)
<7>: DW_TAG_formal_parameter
DW_AT_name = n
DW_AT_type = <2>
DW_AT_location =
(DW_OP_fbreg: 4)
<8>: DW_TAG_variable
DW_AT_name = result
DW_AT_type = <10>
DW_AT_location =
(DW_OP_fbreg: -28)
<9>: DW_TAG_variable
DW_AT_name = len
DW_AT_type = <2>
DW_AT_location =
(DW_OP_fbreg: -24)
<10>: DW_TAG_pointer_type
DW_AT_byte_size = 4
DW_AT_type = <11>
<11>: DW_TAG_base_type
DW_AT_name = char
DW_AT_byte_size = 1
DW_AT_encoding =
signed char
<12>: DW_TAG_pointer_type
DW_AT_byte_size = 4
DW_AT_type = <13>
<13>: DW_TAG_const_type
DW_AT_type = <11>
要想获得更完整的示例实现,请看一看 这个C语言反射库 由Petr Machata编写。它的代码可以满足你的需求,但有以下注意事项。
libdw
和 libdwfl
从 elfutils. 不知道你会怎么看待那些外部库的依赖性增长。