class elf {
//date structure
Elf32_Ehdr ehdr;
Elf32_Shdr shdr;
Elf32_Phdr phdr;
//
void elf( void);
void ~elf( void);
void ehdr(void);
void shdr(void);
void phdr(void);
void StringTable(void);
void SymbolTable(void);
void Relocation(void);
};
void elf::elf( void)
{
/**
* Recently, I read some data about elf ,executable and link format. There are some experiences I hope
* to share, record it.And I know work behind closed doors is never a good way, So welcome to your
* advice at anytime,both in technique and in ENGLISH.
* the references is as following:
* ELF_format.pdf
* ......
* actually ,read those articles is a better choice than this text.
* In this article I will not introduce some concepts in detail, but introduce some examples
* that help me understand its operating principles.
*/
}
void elf::ehdr(void)
{
//what is elf header?
/**
* Any elf file have a elf header, that represent information about how to analyzing this file.
* it structure is
*/
typedef struct elf32_hdr {
unsigned char e_ident[EI_NIDENT]; /* magic + "ELF"*/
Elf32_Half e_type; /* */
Elf32_Half e_machine; /* */
Elf32_Word e_version; /* */
Elf32_Addr e_entry; /* Entry point of the program.For relocatable object file, it is zero*/
Elf32_Off e_phoff; /* program header tables' offset from the begin of the file to the first byte of this table*/
Elf32_Off e_shoff; /* section header tables' offset from the begin of the file to this table*/
Elf32_Word e_flags; /* */
Elf32_Half e_ehsize; /* size of the ELF head*/
Elf32_Half e_phentsize; /* size of a entry of program header*/
Elf32_Half e_phnum; /* number of program header*/
Elf32_Half e_shentsize; /* size of the section header entry*/
Elf32_Half e_shnum; /* number of section header*/
Elf32_Half e_shstrndx; /* help section header table to find it's section header strings table, */
} Elf32_Ehdr;
/*
* now , To help our analysis, we need to create a simply example.
*/
#include <stdio.h>
int main()
{
printf("aaaaa\n");
return 0;
}
/*
* compile it,and check it
*/
[root@localhost blog]# gcc main.c -o main
[root@localhost blog]# readelf -h main
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2 s complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Intel 80386
Version: 0x1
Entry point address: 0x80482b0
Start of program headers: 52 (bytes into file)
Start of section headers: 1912 (bytes into file)
Flags: 0x0
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 7
Size of section headers: 40 (bytes)
Number of section headers: 28
Section header string table index: 25
/*
* those informations are all from the structure above.see some interesting part:
*
* "Type: EXEC (Executable file)"
* --it tell us this file is a excutable file.Actually, elf file include three types :
* EXEC, DYN( shared object file), and REL(relocatable file).
*
* "Entry point address: 0x80482b0"
* --Entry point, gives the virtual address to which the system first transfers control, thus
* starting the process.
*
* "Size of this header: 52 (bytes)"
* --gives the size of this elf header.
*
* "Section header string table index: 25 "
* --this is a funy member.It tell us 25th section is a string table which contain of the section headers' name.
*
*/
}
void elf::shdr(void)
{
//what is section header table?
/*
* A elf file is consist of many container, called section. In another word, The section is meaning for a container.
* It maybe contain text, data and whatever it needed. when necessary, we will use those to
* building our process demo, just as build a house with some bricks.
* first at all, let me see it structure
*/
typedef struct {
Elf32_Word sh_name; /* the section's name, a index into the section header string table section. just "shstrtab"*/
Elf32_Word sh_type;
Elf32_Word sh_flags; /* attributes,*/
Elf32_Addr sh_addr; /* address of process's memory image*/
Elf32_Off sh_offset; /* section's offset in this program file. section postion by bytes*/
Elf32_Word sh_size; /* size of a section*/
Elf32_Word sh_link; /* a index into a section header table section,interpretation depends on the section type. Actually it index into the associated section*/
Elf32_Word sh_info; /* interpretation depends on the section type*/
Elf32_Word sh_addralign; /* some section have address alignment constraint */
Elf32_Word sh_entsize; /* some setction be divided to a smaller entry*/
} Elf32_Shdr;
/*
* just as we did above, see this
*/
[root@localhost blog]# readelf main -S
There are 28 section headers, starting at offset 0x778:
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] .interp PROGBITS 08048114 000114 000013 00 A 0 0 1
[ 2] .note.ABI-tag NOTE 08048128 000128 000020 00 A 0 0 4
[ 3] .gnu.hash GNU_HASH 08048148 000148 000020 04 A 4 0 4
[ 4] .dynsym DYNSYM 08048168 000168 000050 10 A 5 1 4
[ 5] .dynstr STRTAB 080481b8 0001b8 00004a 00 A 0 0 1
[ 6] .gnu.version VERSYM 08048202 000202 00000a 02 A 4 0 2
[ 7] .gnu.version_r VERNEED 0804820c 00020c 000020 00 A 5 1 4
[ 8] .rel.dyn REL 0804822c 00022c 000008 08 A 4 0 4
[ 9] .rel.plt REL 08048234 000234 000018 08 A 4 11 4
[10] .init PROGBITS 0804824c 00024c 000017 00 AX 0 0 4
[11] .plt PROGBITS 08048264 000264 000040 04 AX 0 0 4
[12] .text PROGBITS 080482b0 0002b0 0001a8 00 AX 0 0 16
[13] .fini PROGBITS 08048458 000458 00001c 00 AX 0 0 4
[14] .rodata PROGBITS 08048474 000474 000012 00 A 0 0 4
[15] .eh_frame PROGBITS 08048488 000488 000004 00 A 0 0 4
[16] .ctors PROGBITS 0804948c 00048c 000008 00 WA 0 0 4
[17] .dtors PROGBITS 08049494 000494 000008 00 WA 0 0 4
[18] .jcr PROGBITS 0804949c 00049c 000004 00 WA 0 0 4
[19] .dynamic DYNAMIC 080494a0 0004a0 0000c8 08 WA 5 0 4
[20] .got PROGBITS 08049568 000568 000004 04 WA 0 0 4
[21] .got.plt PROGBITS 0804956c 00056c 000018 04 WA 0 0 4
[22] .data PROGBITS 08049584 000584 000004 00 WA 0 0 4
[23] .bss NOBITS 08049588 000588 000008 00 WA 0 0 4
[24] .comment PROGBITS 00000000 000588 000114 00 0 0 1
[25] .shstrtab STRTAB 00000000 00069c 0000db 00 0 0 1
[26] .symtab SYMTAB 00000000 000bd8 000440 10 27 48 4
[27] .strtab STRTAB 00000000 001018 000258 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
/*
* there are 28 bricks.See some interesting parts:
* "[ 0] NULL 00000000 000000 000000 00 0 0 0"
* --this is to section table, just like NULL is to pointer. we use this as a
* NULL section to check invalid index of section table.
* "[ 1] .interp PROGBITS 08048114 000114 000013 00 A 0 0 1"
* --tell system where to find this file's loader, which help to link shared library
* into process demo. It is normally necessary to those files that use shared
* library.
*
* "
* [ 4] .dynsym DYNSYM 08048168 000168 000050 10 A 5 1 4
* [ 5] .dynstr STRTAB 080481b8 0001b8 00004a 00 A 0 0 1
* [ 8] .rel.dyn REL 0804822c 00022c 000008 08 A 4 0 4
* [ 9] .rel.plt REL 08048234 000234 000018 08 A 4 11 4
* [11] .plt PROGBITS 08048264 000264 000040 04 AX 0 0 4
* [20] .got PROGBITS 08049568 000568 000004 04 WA 0 0 4
* [21] .got.plt PROGBITS 0804956c 00056c 000018 04 WA 0 0 4
* "
* --about dynamic link, they will tell a very funny story. if possible, I will try to
* explain it in next part.
* "[12] .text PROGBITS 080482b0 0002b0 0001a8 00 AX 0 0 16"
* --your program, (instruction).
*
* "[23] .bss NOBITS 08049588 000588 000008 00 WA 0 0 4"
* --this section holds uninitialized data, and occupies no file space.
*
* "[24] .comment PROGBITS 00000000 000588 000114 00 0 0 1"
* --this section holds version control information.see this
*/
[root@localhost blog]# hexdump main -C -s 0x588 -n 276
00000588 00 47 43 43 3a 20 28 47 4e 55 29 20 34 2e 31 2e |.GCC: (GNU) 4.1.|
00000598 32 20 32 30 30 38 30 37 30 34 20 28 52 65 64 20 |2 20080704 (Red |
000005a8 48 61 74 20 34 2e 31 2e 32 2d 34 34 29 00 00 47 |Hat 4.1.2-44)..G|
000005b8 43 43 3a 20 28 47 4e 55 29 20 34 2e 31 2e 32 20 |CC: (GNU) 4.1.2 |
000005c8 32 30 30 38 30 37 30 34 20 28 52 65 64 20 48 61 |20080704 (Red Ha|
000005d8 74 20 34 2e 31 2e 32 2d 34 34 29 00 00 47 43 43 |t 4.1.2-44)..GCC|
000005e8 3a 20 28 47 4e 55 29 20 34 2e 31 2e 32 20 32 30 |: (GNU) 4.1.2 20|
000005f8 30 38 30 37 30 34 20 28 52 65 64 20 48 61 74 20 |080704 (Red Hat |
00000608 34 2e 31 2e 32 2d 34 34 29 00 00 47 43 43 3a 20 |4.1.2-44)..GCC: |
00000618 28 47 4e 55 29 20 34 2e 31 2e 32 20 32 30 30 38 |(GNU) 4.1.2 2008|
00000628 30 37 30 34 20 28 52 65 64 20 48 61 74 20 34 2e |0704 (Red Hat 4.|
00000638 31 2e 32 2d 34 34 29 00 00 47 43 43 3a 20 28 47 |1.2-44)..GCC: (G|
00000648 4e 55 29 20 34 2e 31 2e 32 20 32 30 30 38 30 37 |NU) 4.1.2 200807|
00000658 30 34 20 28 52 65 64 20 48 61 74 20 34 2e 31 2e |04 (Red Hat 4.1.|
00000668 32 2d 34 34 29 00 00 47 43 43 3a 20 28 47 4e 55 |2-44)..GCC: (GNU|
00000678 29 20 34 2e 31 2e 32 20 32 30 30 38 30 37 30 34 |) 4.1.2 20080704|
00000688 20 28 52 65 64 20 48 61 74 20 34 2e 31 2e 32 2d | (Red Hat 4.1.2-|
00000698 34 34 29 00 |44).|
/*
*
* " [25] .shstrtab STRTAB 00000000 00069c 0000db 00 0 0 1"
* --a string table for section header.
*/
[root@localhost blog]# hexdump main -C -s 0x69c -n 219
0000069c 00 2e 73 79 6d 74 61 62 00 2e 73 74 72 74 61 62 |..symtab..strtab|
000006ac 00 2e 73 68 73 74 72 74 61 62 00 2e 69 6e 74 65 |..shstrtab..inte|
000006bc 72 70 00 2e 6e 6f 74 65 2e 41 42 49 2d 74 61 67 |rp..note.ABI-tag|
000006cc 00 2e 67 6e 75 2e 68 61 73 68 00 2e 64 79 6e 73 |..gnu.hash..dyns|
000006dc 79 6d 00 2e 64 79 6e 73 74 72 00 2e 67 6e 75 2e |ym..dynstr..gnu.|
000006ec 76 65 72 73 69 6f 6e 00 2e 67 6e 75 2e 76 65 72 |version..gnu.ver|
000006fc 73 69 6f 6e 5f 72 00 2e 72 65 6c 2e 64 79 6e 00 |sion_r..rel.dyn.|
0000070c 2e 72 65 6c 2e 70 6c 74 00 2e 69 6e 69 74 00 2e |.rel.plt..init..|
0000071c 74 65 78 74 00 2e 66 69 6e 69 00 2e 72 6f 64 61 |text..fini..roda|
0000072c 74 61 00 2e 65 68 5f 66 72 61 6d 65 00 2e 63 74 |ta..eh_frame..ct|
0000073c 6f 72 73 00 2e 64 74 6f 72 73 00 2e 6a 63 72 00 |ors..dtors..jcr.|
0000074c 2e 64 79 6e 61 6d 69 63 00 2e 67 6f 74 00 2e 67 |.dynamic..got..g|
0000075c 6f 74 2e 70 6c 74 00 2e 64 61 74 61 00 2e 62 73 |ot.plt..data..bs|
0000076c 73 00 2e 63 6f 6d 6d 65 6e 74 00 |s..comment.|
00000777
/*
* "[27] .strtab STRTAB 00000000 001018 000258 00 0 0 1"
* --a string table for other string.
* --may be see this will useful. From our
*/
[root@localhost blog]# hexdump main -C -s 0x1018 -n 600
00001018 00 63 61 6c 6c 5f 67 6d 6f 6e 5f 73 74 61 72 74 |.call_gmon_start|
00001028 00 63 72 74 73 74 75 66 66 2e 63 00 5f 5f 43 54 |.crtstuff.c.__CT|
00001038 4f 52 5f 4c 49 53 54 5f 5f 00 5f 5f 44 54 4f 52 |OR_LIST__.__DTOR|
00001048 5f 4c 49 53 54 5f 5f 00 5f 5f 4a 43 52 5f 4c 49 |_LIST__.__JCR_LI|
00001058 53 54 5f 5f 00 64 74 6f 72 5f 69 64 78 2e 35 37 |ST__.dtor_idx.57|
00001068 39 30 00 63 6f 6d 70 6c 65 74 65 64 2e 35 37 38 |90.completed.578|
00001078 38 00 5f 5f 64 6f 5f 67 6c 6f 62 61 6c 5f 64 74 |8.__do_global_dt|
00001088 6f 72 73 5f 61 75 78 00 66 72 61 6d 65 5f 64 75 |ors_aux.frame_du|
00001098 6d 6d 79 00 5f 5f 43 54 4f 52 5f 45 4e 44 5f 5f |mmy.__CTOR_END__|
000010a8 00 5f 5f 46 52 41 4d 45 5f 45 4e 44 5f 5f 00 5f |.__FRAME_END__._|
000010b8 5f 4a 43 52 5f 45 4e 44 5f 5f 00 5f 5f 64 6f 5f |_JCR_END__.__do_|
000010c8 67 6c 6f 62 61 6c 5f 63 74 6f 72 73 5f 61 75 78 |global_ctors_aux|
000010d8 00 6d 61 69 6e 2e 63 00 5f 5f 70 72 65 69 6e 69 |.main.c.__preini|
000010e8 74 5f 61 72 72 61 79 5f 73 74 61 72 74 00 5f 5f |t_array_start.__|
000010f8 66 69 6e 69 5f 61 72 72 61 79 5f 65 6e 64 00 5f |fini_array_end._|
00001108 47 4c 4f 42 41 4c 5f 4f 46 46 53 45 54 5f 54 41 |GLOBAL_OFFSET_TA|
00001118 42 4c 45 5f 00 5f 5f 70 72 65 69 6e 69 74 5f 61 |BLE_.__preinit_a|
00001128 72 72 61 79 5f 65 6e 64 00 5f 5f 66 69 6e 69 5f |rray_end.__fini_|
00001138 61 72 72 61 79 5f 73 74 61 72 74 00 5f 5f 69 6e |array_start.__in|
00001148 69 74 5f 61 72 72 61 79 5f 65 6e 64 00 5f 5f 69 |it_array_end.__i|
00001158 6e 69 74 5f 61 72 72 61 79 5f 73 74 61 72 74 00 |nit_array_start.|
00001168 5f 44 59 4e 41 4d 49 43 00 64 61 74 61 5f 73 74 |_DYNAMIC.data_st|
00001178 61 72 74 00 5f 5f 6c 69 62 63 5f 63 73 75 5f 66 |art.__libc_csu_f|
00001188 69 6e 69 00 5f 73 74 61 72 74 00 5f 5f 67 6d 6f |ini._start.__gmo|
00001198 6e 5f 73 74 61 72 74 5f 5f 00 5f 4a 76 5f 52 65 |n_start__._Jv_Re|
000011a8 67 69 73 74 65 72 43 6c 61 73 73 65 73 00 5f 66 |gisterClasses._f|
000011b8 70 5f 68 77 00 5f 66 69 6e 69 00 5f 5f 6c 69 62 |p_hw._fini.__lib|
000011c8 63 5f 73 74 61 72 74 5f 6d 61 69 6e 40 40 47 4c |c_start_main@@GL|
000011d8 49 42 43 5f 32 2e 30 00 5f 49 4f 5f 73 74 64 69 |IBC_2.0._IO_stdi|
000011e8 6e 5f 75 73 65 64 00 5f 5f 64 61 74 61 5f 73 74 |n_used.__data_st|
000011f8 61 72 74 00 5f 5f 64 73 6f 5f 68 61 6e 64 6c 65 |art.__dso_handle|
00001208 00 5f 5f 44 54 4f 52 5f 45 4e 44 5f 5f 00 5f 5f |.__DTOR_END__.__|
00001218 6c 69 62 63 5f 63 73 75 5f 69 6e 69 74 00 5f 5f |libc_csu_init.__|
00001228 62 73 73 5f 73 74 61 72 74 00 5f 65 6e 64 00 70 |bss_start._end.p|
00001238 75 74 73 40 40 47 4c 49 42 43 5f 32 2e 30 00 5f |uts@@GLIBC_2.0._|
00001248 65 64 61 74 61 00 5f 5f 69 36 38 36 2e 67 65 74 |edata.__i686.get|
00001258 5f 70 63 5f 74 68 75 6e 6b 2e 62 78 00 6d 61 69 |_pc_thunk.bx.mai|
00001268 6e 00 5f 69 6e 69 74 00 |n._init.|
/*
*
* "[26] .symtab SYMTAB 00000000 000bd8 000440 10 27 48 4"
* --full name is symbol table, it is just like a identity card for elf file's object.
*/
}
void elf::phdr(void)
{
//next part
}
void elf::StringTable(void)
{
//what is a string table? How come we need it?
/*
* normally, if we want to create a identity card for a people, we maybe need to restore some attributes
* about it. For examples: name, sex, age, and the like. To sex and age, it is easy to assess it's size and
* allocate some space. But for name, we are in trouble, because we couldn't know it's size.
*/
/*
* Let me see a trick for deal this problem. if there are three object to store.
* 1: zhang Mr. , man, 24
* 2: Li Mrs. , woman, 30
* 3: Dr. loooooooooooooooooong, man, 35
* you may be create a struct like this
*/
struct IDCard{
char name[ the_longest_name];
int sex;
int age;
};
/*
* That's awful, we will waste many memory space.
* Ok, the second way, you create the following struct:
*/
struct IDCard {
char *name_index;
int sex;
int age;
};
struct String {
char[ len1+ len2 + len3]; //all strings are stored in this.
};
/*
* this is a funny way. That's the reason why we need a section called by StringTable.
*/
}
void elf::SymbolTable(void)
{
//What is symbol Table ?How come we need it?
/*
* Image this, there are many functions in a program and they call each other.
* some of them have been used by other function, some of them are waiting
* for use( for example: relocatable file, dynamic link file),How can we describe it?
*/
/*
* struct, struct is good for this.we could define object to record its's information.
* Actually , the symbol table is more useful. It not only working for describe some functions,
* but also other object. The follow is its struct:
*/
typedef struct elf32_sym{
Elf32_Word st_name; /* a index into string table*/
Elf32_Addr st_value; /* point the position of this symbol's define*/
Elf32_Word st_size;
unsigned char st_info; /* bind(global/local) and type( function, file, ....),*/
unsigned char st_other; /* reserved*/
Elf32_Half st_shndx; /* */
} Elf32_Sym;
/*
* see a examples:
*/
[root@localhost blog]# readelf -s main
Symbol table '.dynsym' contains 5 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 00000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
2: 00000000 415 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.0 (2)
3: 00000000 399 FUNC GLOBAL DEFAULT UND puts@GLIBC_2.0 (2)
4: 08048478 4 OBJECT GLOBAL DEFAULT 14 _IO_stdin_used
Symbol table '.symtab' contains 68 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 00000000 0 NOTYPE LOCAL DEFAULT UND
1: 08048114 0 SECTION LOCAL DEFAULT 1
2: 08048128 0 SECTION LOCAL DEFAULT 2
3: 08048148 0 SECTION LOCAL DEFAULT 3
4: 08048168 0 SECTION LOCAL DEFAULT 4
5: 080481b8 0 SECTION LOCAL DEFAULT 5
6: 08048202 0 SECTION LOCAL DEFAULT 6
7: 0804820c 0 SECTION LOCAL DEFAULT 7
8: 0804822c 0 SECTION LOCAL DEFAULT 8
9: 08048234 0 SECTION LOCAL DEFAULT 9
10: 0804824c 0 SECTION LOCAL DEFAULT 10
11: 08048264 0 SECTION LOCAL DEFAULT 11
12: 080482b0 0 SECTION LOCAL DEFAULT 12
13: 08048458 0 SECTION LOCAL DEFAULT 13
14: 08048474 0 SECTION LOCAL DEFAULT 14
15: 08048488 0 SECTION LOCAL DEFAULT 15
16: 0804948c 0 SECTION LOCAL DEFAULT 16
17: 08049494 0 SECTION LOCAL DEFAULT 17
18: 0804949c 0 SECTION LOCAL DEFAULT 18
19: 080494a0 0 SECTION LOCAL DEFAULT 19
20: 08049568 0 SECTION LOCAL DEFAULT 20
21: 0804956c 0 SECTION LOCAL DEFAULT 21
22: 08049584 0 SECTION LOCAL DEFAULT 22
23: 08049588 0 SECTION LOCAL DEFAULT 23
24: 00000000 0 SECTION LOCAL DEFAULT 24
25: 080482d4 0 FUNC LOCAL DEFAULT 12 call_gmon_start
26: 00000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
27: 0804948c 0 OBJECT LOCAL DEFAULT 16 __CTOR_LIST__
28: 08049494 0 OBJECT LOCAL DEFAULT 17 __DTOR_LIST__
29: 0804949c 0 OBJECT LOCAL DEFAULT 18 __JCR_LIST__
30: 08049588 4 OBJECT LOCAL DEFAULT 23 dtor_idx.5790
31: 0804958c 1 OBJECT LOCAL DEFAULT 23 completed.5788
32: 08048300 0 FUNC LOCAL DEFAULT 12 __do_global_dtors_aux
33: 08048360 0 FUNC LOCAL DEFAULT 12 frame_dummy
34: 00000000 0 FILE LOCAL DEFAULT ABS crtstuff.c
35: 08049490 0 OBJECT LOCAL DEFAULT 16 __CTOR_END__
36: 08048488 0 OBJECT LOCAL DEFAULT 15 __FRAME_END__
37: 0804949c 0 OBJECT LOCAL DEFAULT 18 __JCR_END__
38: 08048430 0 FUNC LOCAL DEFAULT 12 __do_global_ctors_aux
39: 00000000 0 FILE LOCAL DEFAULT ABS main.c
40: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __preinit_array_start
41: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __fini_array_end
42: 0804956c 0 OBJECT LOCAL HIDDEN 21 _GLOBAL_OFFSET_TABLE_
43: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __preinit_array_end
44: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __fini_array_start
45: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __init_array_end
46: 0804948c 0 NOTYPE LOCAL HIDDEN 16 __init_array_start
47: 080494a0 0 OBJECT LOCAL HIDDEN 19 _DYNAMIC
48: 08049584 0 NOTYPE WEAK DEFAULT 22 data_start
49: 080483b0 5 FUNC GLOBAL DEFAULT 12 __libc_csu_fini
50: 080482b0 0 FUNC GLOBAL DEFAULT 12 _start
51: 00000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
52: 00000000 0 NOTYPE WEAK DEFAULT UND _Jv_RegisterClasses
53: 08048474 4 OBJECT GLOBAL DEFAULT 14 _fp_hw
54: 08048458 0 FUNC GLOBAL DEFAULT 13 _fini
55: 00000000 415 FUNC GLOBAL DEFAULT UND __libc_start_main@@GLIBC_
56: 08048478 4 OBJECT GLOBAL DEFAULT 14 _IO_stdin_used
57: 08049584 0 NOTYPE GLOBAL DEFAULT 22 __data_start
58: 0804847c 0 OBJECT GLOBAL HIDDEN 14 __dso_handle
59: 08049498 0 OBJECT GLOBAL HIDDEN 17 __DTOR_END__
60: 080483c0 105 FUNC GLOBAL DEFAULT 12 __libc_csu_init
61: 08049588 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
62: 08049590 0 NOTYPE GLOBAL DEFAULT ABS _end
63: 00000000 399 FUNC GLOBAL DEFAULT UND puts@@GLIBC_2.0
64: 08049588 0 NOTYPE GLOBAL DEFAULT ABS _edata
65: 08048429 0 FUNC GLOBAL HIDDEN 12 __i686.get_pc_thunk.bx
66: 08048384 43 FUNC GLOBAL DEFAULT 12 main
67: 0804824c 0 FUNC GLOBAL DEFAULT 10 _init
}
void elf::Relocation(void)
{
//next part
}
ELF解析（part one）,布布扣,bubuko.com
原文：http://blog.csdn.net/u012301943/article/details/27379175