nikola/school
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
school/semester_4/namenska_programska_oprema/Naloga_5/vaje/ukazi.txt

530 lines
28 KiB
Plaintext
Raw Permalink Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

################################################################################################################
#
# STATICNA KNJIZNICA
################################################################################################################
$ gcc -c libprva.c -o libprva.o
$ ar rcs libprva.a libprva.o
r - Insert the files member into archive (with replacement)
c - Create the archive. The specified archive is always created if it did not exist, when you request an update
s - Write an object-file index into the archive, or update an existing one
$ gcc implicitna.c -o staticna libprva.a
$ readelf -h libprva.a # izpise zaglavje formata ELF od knjižnice
" ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: REL (Relocatable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 592 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 64 (bytes)
Number of section headers: 13
Section header string table index: 10
"
$ readelf -h ./staticna # izpise zaglavje formata ELF od izvedljivega modula
" ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x400460
Start of program headers: 64 (bytes into file)
Start of section headers: 6320 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 9
Size of section headers: 64 (bytes)
Number of section headers: 37
Section header string table index: 34
"
$ readelf -S -W libprva.a # izpise vse sekcije
" There are 13 section headers, starting at offset 0x250:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .text PROGBITS 0000000000000000 000040 00008c 00 AX 0 0 4
[ 2] .rela.text RELA 0000000000000000 000760 000120 18 11 1 8
[ 3] .data PROGBITS 0000000000000000 0000cc 000004 00 WA 0 0 4
[ 4] .bss NOBITS 0000000000000000 0000d0 000000 00 WA 0 0 4
[ 5] .rodata PROGBITS 0000000000000000 0000d0 000079 00 A 0 0 8
[ 6] .eh_frame PROGBITS 0000000000000000 000150 000078 00 A 0 0 8
[ 7] .rela.eh_frame RELA 0000000000000000 000880 000048 18 11 6 8
[ 8] .comment PROGBITS 0000000000000000 0001c8 000024 00 0 0 1
[ 9] .note.GNU-stack PROGBITS 0000000000000000 0001ec 000000 00 0 0 1
[10] .shstrtab STRTAB 0000000000000000 0001ec 000061 00 0 0 1
[11] .symtab SYMTAB 0000000000000000 000590 000180 18 12 9 8
[12] .strtab STRTAB 0000000000000000 000710 00004d 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)
"
$ readelf -s libprva.a # izpise simbolno tabelo knjiznice
" File: libprva.a(libprva.o)
Symbol table '.symtab' contains 16 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS libprva.c
2: 0000000000000000 0 SECTION LOCAL DEFAULT 1
3: 0000000000000000 0 SECTION LOCAL DEFAULT 3
4: 0000000000000000 0 SECTION LOCAL DEFAULT 4
5: 0000000000000000 0 SECTION LOCAL DEFAULT 5
6: 0000000000000000 0 SECTION LOCAL DEFAULT 6
7: 0000000000000000 0 SECTION LOCAL DEFAULT 9
8: 0000000000000000 0 SECTION LOCAL DEFAULT 8
9: 0000000000000000 4 OBJECT GLOBAL DEFAULT 3 vrednost
10: 0000000000000000 59 FUNC GLOBAL DEFAULT 1 izpisi_pozdrav
11: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND puts
12: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND printf
13: 0000000000000008 8 OBJECT GLOBAL DEFAULT COM kazalec
14: 000000000000003b 48 FUNC GLOBAL DEFAULT 1 vrni_vsoto
15: 000000000000006b 33 FUNC GLOBAL DEFAULT 1 izpisi_niz
"
$ readelf -r libprva.a # izpise relokacijske tabele knjiznice
"
Relocation section '.rela.text' at offset 0x760 contains 12 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000005 00050000000a R_X86_64_32 0000000000000000 .rodata + 0
00000000000a 000b00000002 R_X86_64_PC32 0000000000000000 puts + fffffffffffffffc
000000000010 000900000002 R_X86_64_PC32 0000000000000000 vrednost + fffffffffffffffc
000000000015 00050000000a R_X86_64_32 0000000000000000 .rodata + 20
00000000001f 000c00000002 R_X86_64_PC32 0000000000000000 printf + fffffffffffffffc
000000000026 000d00000002 R_X86_64_PC32 0000000000000008 kazalec + fffffffffffffffc
00000000002b 00050000000a R_X86_64_32 0000000000000000 .rodata + 40
000000000035 000c00000002 R_X86_64_PC32 0000000000000000 printf + fffffffffffffffc
000000000053 00050000000a R_X86_64_32 0000000000000000 .rodata + 5c
00000000005d 000c00000002 R_X86_64_PC32 0000000000000000 printf + fffffffffffffffc
00000000007c 00050000000a R_X86_64_32 0000000000000000 .rodata + 69
000000000086 000c00000002 R_X86_64_PC32 0000000000000000 printf + fffffffffffffffc
Relocation section '.rela.eh_frame' at offset 0x880 contains 3 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000020 00020000000a R_X86_64_32 0000000000000000 .text + 0
000000000040 00020000000a R_X86_64_32 0000000000000000 .text + 3b
000000000060 00020000000a R_X86_64_32 0000000000000000 .text + 6b
"
Offset . odmik od zacetka sekcije do mesta prenaslavljanja
Info - vstop v simbolno tabelo in tip prenaslavljanja
Sym.Value - vrednost simbola v simbolni tabeli
Sym.Name -ime simbola v simboni tabeli
$ readelf -s ./staticna # izpise simbolno tabelo izvedljivega modula
"
Symbol table '.dynsym' contains...
"
$ readelf -r ./staticna # izpise relokacijske tabele izvedljivega modula
"
Relocation section '.rela.dyn' at offset 0x3a8 contains 1 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000600fe0 000200000006 R_X86_64_GLOB_DAT 0000000000000000 __gmon_start__ + 0
Relocation section '.rela.plt' at offset 0x3c0 contains 3 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000601000 000100000007 R_X86_64_JUMP_SLO 0000000000000000 printf + 0
000000601008 000300000007 R_X86_64_JUMP_SLO 0000000000000000 puts + 0
000000601010 000400000007 R_X86_64_JUMP_SLO 0000000000000000 __libc_start_main + 0
"
Offset . odmik od zacetka sekcije do mesta prenaslavljanja
Info - vstop v simbolno tabelo in tip prenaslavljanja
Sym.Value - vrednost simbola v simbolni tabeli
Sym.Name -ime simbola v simboni tabeli
$ strip --strip-unneeded staticna # odstranimo vse nepotrebne simbole
$ readelf -s ./staticna # izpisemo simbolno tabelo
"
Symbol table '.dynsym' contains 5 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FUNC GLOBAL DEFAULT UND printf@GLIBC_2.2.5 (2)
2: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
3: 0000000000000000 0 FUNC GLOBAL DEFAULT UND puts@GLIBC_2.2.5 (2)
4: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.2.5 (2)
"
################################################################################################################
#
# DINAMICNA KNJIZNICA
################################################################################################################
#Generate position-independent code (PIC) suitable for use in a shared library, if supported for the target machine. Such code accesses all constant addresses through a global offset table (GOT). The dynamic loader resolves the GOT entries when the program starts (the dynamic loader is not part of GCC; it is part of the operating system).
$ gcc -c -fPIC libprva.c
$ readelf -r libprva.o # izpise relokacijske tabele izvedljivega modula
"
Relocation section '.rela.text' at offset 0x7a0 contains 12 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000007 000500000002 R_X86_64_PC32 0000000000000000 .rodata + fffffffffffffffc
00000000000c 000c00000004 R_X86_64_PLT32 0000000000000000 puts + fffffffffffffffc
000000000013 000900000009 R_X86_64_GOTPCREL 0000000000000000 vrednost + fffffffffffffffc
00000000001c 000500000002 R_X86_64_PC32 0000000000000000 .rodata + 1c
000000000026 000d00000004 R_X86_64_PLT32 0000000000000000 printf + fffffffffffffffc
00000000002d 000e00000009 R_X86_64_GOTPCREL 0000000000000008 kazalec + fffffffffffffffc
000000000037 000500000002 R_X86_64_PC32 0000000000000000 .rodata + 3c
000000000041 000d00000004 R_X86_64_PLT32 0000000000000000 printf + fffffffffffffffc
000000000061 000500000002 R_X86_64_PC32 0000000000000000 .rodata + 58
00000000006b 000d00000004 R_X86_64_PLT32 0000000000000000 printf + fffffffffffffffc
00000000008c 000500000002 R_X86_64_PC32 0000000000000000 .rodata + 65
000000000096 000d00000004 R_X86_64_PLT32 0000000000000000 printf + fffffffffffffffc
Relocation section '.rela.eh_frame' at offset 0x8c0 contains 3 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000020 000200000002 R_X86_64_PC32 0000000000000000 .text + 0
000000000040 000200000002 R_X86_64_PC32 0000000000000000 .text + 47
000000000060 000200000002 R_X86_64_PC32 0000000000000000 .text + 79
"
#Primerjaj z $ readelf -r libprva.a
$ ld -shared -soname libprva.so.1 -o libprva.so.1.0 libprva.o
# Z zastavico -shared povemo, da se mora modul pred izvajanjem povezal še z drugimi moduli (torej nima vstopne točke), z zastavico -soname ime_datoteke.so.verzija_vmesnika pa povemo, katera verzija vmesnika je implementirana. Vedno ko spremenimo vmesnik knjižnice, moramo spremeniti tudi to verzijo, saj se na ta način izognemo težavam z nekompatibilnimi knjižnicami. Vidimo, da ima tudi izhodni modul na koncu dve številki. Prva pove številko vmesnika, druga pa njegovo verzijo.
$ ldconfig -v -n .
" .:
libprva.so.1 -> libprva.so.1.0 (changed)
"
#Dobili smo knjižnico, ki jo moramo sedaj še namestiti. V kolikor jo želimo dani na voljo vsem, jo kopiramo v mapo /usr/lib ali /lib, v našem primeru pa jo bomo pustili kar v trenutni mapi. V vsakem primeru pa moramo pognati ukaz ldconfig, ki poišče zadnjo verzijo vsake knjižnice. V našem primeru smo napisali ukaz, ki bo iskal nove verzije samo v trenutni mapi.
# zastavice
# -v --verbose
# Verbose mode. Print current version number, the name of each directory as it is scanned and any links that are
# created.
# -n Only process directories specified on the command line. Don’t process the trusted directories (/usr/lib and
# /lib) nor those specified in /etc/ld.so.conf. Implies -N.
$ ls -all
# Sedaj je ustvarjena nova povezava z imenom libprva.so.1, ki kaže na libprva.so.1.0. Ukaz "ldconfig -v -n ." torej poskrbi, da nam ni potrebno skrbeti za podverzijo knjižnice.
$ ln -sf libprva.so.1 libprva.so
# Na koncu lahko naredimo še simbolično povezavo do te knjižnice (man ln)
$ ls -all
# bodite pozorni na simbolično povezavo libprva.so -> libprva.so.1
$ readelf -h libprva.so
" ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: DYN (Shared object file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x380
Start of program headers: 64 (bytes into file)
Start of section headers: 1840 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 4
Size of section headers: 64 (bytes)
Number of section headers: 19
Section header string table index: 16
"
$ readelf -s libprva.so
"Symbol table '.dynsym' contains 12 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000380 0 SECTION LOCAL DEFAULT 7
2: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND printf
3: 0000000000000380 71 FUNC GLOBAL DEFAULT 7 izpisi_pozdrav
4: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND puts
5: 0000000000200688 8 OBJECT GLOBAL DEFAULT 14 kazalec
6: 00000000000003f9 35 FUNC GLOBAL DEFAULT 7 izpisi_niz
7: 00000000000003c7 50 FUNC GLOBAL DEFAULT 7 vrni_vsoto
8: 0000000000200684 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
9: 0000000000200684 0 NOTYPE GLOBAL DEFAULT ABS _edata
10: 0000000000200690 0 NOTYPE GLOBAL DEFAULT ABS _end
11: 0000000000200680 4 OBJECT GLOBAL DEFAULT 13 vrednost
Symbol table '.symtab' contains 29 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
...
16: 0000000000000000 0 FILE LOCAL DEFAULT ABS libprva.c
17: 0000000000200518 0 OBJECT LOCAL HIDDEN ABS _DYNAMIC
18: 0000000000200658 0 OBJECT LOCAL HIDDEN ABS _GLOBAL_OFFSET_TABLE_
19: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND printf
20: 0000000000000380 71 FUNC GLOBAL DEFAULT 7 izpisi_pozdrav
21: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND puts
22: 0000000000200688 8 OBJECT GLOBAL DEFAULT 14 kazalec
23: 00000000000003f9 35 FUNC GLOBAL DEFAULT 7 izpisi_niz
24: 00000000000003c7 50 FUNC GLOBAL DEFAULT 7 vrni_vsoto
25: 0000000000200684 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
26: 0000000000200684 0 NOTYPE GLOBAL DEFAULT ABS _edata
27: 0000000000200690 0 NOTYPE GLOBAL DEFAULT ABS _end
28: 0000000000200680 4 OBJECT GLOBAL DEFAULT 13 vrednost
"
# Simbolna tabela .symtab podvaja vrednosti dinamične simbolne tabele .dynsym
#Primerjaj z $ readelf -s libprva.a
$ readelf -r libprva.so
"
Relocation section '.rela.dyn' at offset 0x2f0 contains 2 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000200648 000500000006 R_X86_64_GLOB_DAT 0000000000200688 kazalec + 0
000000200650 000b00000006 R_X86_64_GLOB_DAT 0000000000200680 vrednost + 0
Relocation section '.rela.plt' at offset 0x320 contains 2 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000200670 000200000007 R_X86_64_JUMP_SLO 0000000000000000 printf + 0
000000200678 000400000007 R_X86_64_JUMP_SLO 0000000000000000 puts + 0
"
$ readelf -SW libprva.so # izpisemo vse sekcije
" There are 19 section headers, starting at offset 0x730:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .hash HASH 0000000000000120 000120 000044 04 A 2 0 8
[ 2] .dynsym DYNSYM 0000000000000168 000168 000120 18 A 3 2 8
[ 3] .dynstr STRTAB 0000000000000288 000288 000068 00 A 0 0 1
[ 4] .rela.dyn RELA 00000000000002f0 0002f0 000030 18 A 2 0 8
[ 5] .rela.plt RELA 0000000000000320 000320 000030 18 A 2 6 8
[ 6] .plt PROGBITS 0000000000000350 000350 000030 10 AX 0 0 4
[ 7] .text PROGBITS 0000000000000380 000380 00009c 00 AX 0 0 4
[ 8] .rodata PROGBITS 0000000000000420 000420 000079 00 A 0 0 8
[ 9] .eh_frame PROGBITS 00000000000004a0 0004a0 000078 00 A 0 0 8
[10] .dynamic DYNAMIC 0000000000200518 000518 000130 10 WA 3 0 8
[11] .got PROGBITS 0000000000200648 000648 000010 08 WA 0 0 8
[12] .got.plt PROGBITS 0000000000200658 000658 000028 08 WA 0 0 8
[13] .data PROGBITS 0000000000200680 000680 000004 00 WA 0 0 4
[14] .bss NOBITS 0000000000200688 000684 000008 00 WA 0 0 8
[15] .comment PROGBITS 0000000000000000 000684 000024 00 0 0 1
[16] .shstrtab STRTAB 0000000000000000 0006a8 000088 00 0 0 1
[17] .symtab SYMTAB 0000000000000000 000bf0 0002b8 18 18 19 8
[18] .strtab STRTAB 0000000000000000 000ea8 000084 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)
"
$ objdump -d -j .plt libprva.so # izpišemo vsebino sekcije plt (Procedure Linkage Table)
"
libprva.so: file format elf64-x86-64
Disassembly of section .plt:
0000000000000350 <printf@plt-0x10>:
350: ff 35 0a 03 20 00 pushq 0x20030a(%rip) # 200660 <_GLOBAL_OFFSET_TABLE_+0x8>
356: ff 25 0c 03 20 00 jmpq *0x20030c(%rip) # 200668 <_GLOBAL_OFFSET_TABLE_+0x10>
35c: 0f 1f 40 00 nopl 0x0(%rax)
0000000000000360 <printf@plt>:
360: ff 25 0a 03 20 00 jmpq *0x20030a(%rip) # 200670 <_GLOBAL_OFFSET_TABLE_+0x18>
366: 68 00 00 00 00 pushq $0x0
36b: e9 e0 ff ff ff jmpq 350 <printf@plt-0x10>
0000000000000370 <puts@plt>:
370: ff 25 02 03 20 00 jmpq *0x200302(%rip) # 200678 <_GLOBAL_OFFSET_TABLE_+0x20>
376: 68 01 00 00 00 pushq $0x1
37b: e9 d0 ff ff ff jmpq 350 <printf@plt-0x10>
"
# za razlago delovanje tabele plt glej slikovni material na sistemu za vaje
$ objdump -s libprva.so | grep -A 2 got
"
Contents of section .got:
200648 00000000 00000000 00000000 00000000 ................
Contents of section .got.plt:
200658 18052000 00000000 00000000 00000000 .. .............
200668 00000000 00000000 66030000 00000000 ........f.......
"
$ readelf -I libprva.so
"
Histogram for bucket list length (total of 3 buckets):
Length Number % of total Coverage
0 0 ( 0.0%)
1 1 ( 33.3%) 10.0%
2 1 ( 33.3%) 30.0%
3 0 ( 0.0%) 30.0%
4 0 ( 0.0%) 30.0%
5 0 ( 0.0%) 30.0%
6 0 ( 0.0%) 30.0%
7 1 ( 33.3%) 100.0%
"
# 3 buckets - trije vstopi v hash tabelo
# length - dolžina verige (chain) v hash tabeli
# number - število vstopov v hash tabelo s specificirano dolžino verige
# še malo večji primer .so knjižnice
$ readelf -I /lib/libc.so.6
" Histogram for bucket list length (total of 1017 buckets):
Length Number % of total Coverage
0 116 ( 11.4%)
1 268 ( 26.4%) 12.7%
2 283 ( 27.8%) 39.4%
3 194 ( 19.1%) 66.9%
4 100 ( 9.8%) 85.8%
5 40 ( 3.9%) 95.3%
6 12 ( 1.2%) 98.7%
7 4 ( 0.4%) 100.0%
"
$ sudo apt-get install elfutils # eu-readelf pove še povprečno število iskanj v hash tabeli...
$ eu-readelf -I libprva.so
"
Histogram for bucket list length in section [ 1] '.hash' (total of 3 buckets):
Addr: 0x0000000000000120 Offset: 0x000120 Link to section: [ 2] '.dynsym'
Length Number % of total Coverage
0 0 0.0%
1 1 33.3% 10.0%
2 1 33.3% 30.0%
3 0 0.0% 30.0%
4 0 0.0% 30.0%
5 0 0.0% 30.0%
6 0 0.0% 30.0%
7 1 33.3% 100.0%
Average number of tests: successful lookup: 3.200000
unsuccessful lookup: 3.333333
"
$ eu-readelf -I /lib/libc.so.6
################################################################################################################
#
# DINAMICNA KNJIZNICA IMPLICITNO POVEZOVANJE
################################################################################################################
$ gcc implicitna.c -o implicitna -L. -lprva
#Ker uporabljamo dinamične knjižnice moramo program prevesti z dodatnimi zastavicami. Uporabiti moramo zastavico -L, s katero povemo, kje naj povezovalnik išče knjižnice in zastavico -l s katero vključimo knjižnico v program.
$ export LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH
#Preden lahko program zaženemo mu moramo na nek način sporočiti, kje lahko najde dinamično knjižnico. Ponavadi se vse knjižnice nahajajo v mapi /usr/lib, /usr/local/lib oz mapah, navedenih v datoteki /etc/ld.so.conf. Knjižnice se iščejo tudi v poteh navedenih v spremenljivki LD_LIBRARY_PATH. V našem primeru bomo knjižnico imeli kar v trenutni mapi, ki jo bomo dodali v spremenljivko z ukazom:
$ ./implicitna # Sedaj lahko zaženemo program.
$ readelf -h ./implicitna
" ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x400670
Start of program headers: 64 (bytes into file)
Start of section headers: 6304 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 9
Size of section headers: 64 (bytes)
Number of section headers: 37
Section header string table index: 34
"
$ readelf -s ./implicitna
"
Symbol table '.dynsym' contains 13 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FUNC GLOBAL DEFAULT UND printf@GLIBC_2.2.5 (2)
2: 0000000000000000 0 FUNC GLOBAL DEFAULT UND vrni_vsoto
3: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
4: 0000000000000000 0 FUNC GLOBAL DEFAULT UND puts@GLIBC_2.2.5 (2)
5: 0000000000000000 0 FUNC GLOBAL DEFAULT UND izpisi_niz
6: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.2.5 (2)
7: 0000000000000000 0 FUNC GLOBAL DEFAULT UND izpisi_pozdrav
8: 0000000000601060 0 NOTYPE GLOBAL DEFAULT ABS _end
9: 0000000000601040 0 NOTYPE GLOBAL DEFAULT ABS _edata
10: 0000000000601040 0 NOTYPE GLOBAL DEFAULT ABS __bss_start
11: 0000000000601040 4 OBJECT GLOBAL DEFAULT 25 vrednost
12: 0000000000601048 8 OBJECT GLOBAL DEFAULT 25 kazalec
"
# primirjaj z $ readelf -s ./staticna
$ readelf -r ./implicitna
"
Relocation section '.rela.dyn' at offset 0x510 contains 3 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000600fe0 000300000006 R_X86_64_GLOB_DAT 0000000000000000 __gmon_start__ + 0
000000601040 000b00000005 R_X86_64_COPY 0000000000601040 vrednost + 0
000000601048 000c00000005 R_X86_64_COPY 0000000000601048 kazalec + 0
Relocation section '.rela.plt' at offset 0x558 contains 6 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000601000 000100000007 R_X86_64_JUMP_SLO 0000000000000000 printf + 0
000000601008 000200000007 R_X86_64_JUMP_SLO 0000000000000000 vrni_vsoto + 0
000000601010 000400000007 R_X86_64_JUMP_SLO 0000000000000000 puts + 0
000000601018 000500000007 R_X86_64_JUMP_SLO 0000000000000000 izpisi_niz + 0
000000601020 000600000007 R_X86_64_JUMP_SLO 0000000000000000 __libc_start_main + 0
000000601028 000700000007 R_X86_64_JUMP_SLO 0000000000000000 izpisi_pozdrav + 0
"
# primerjaj z $ readelf -r ./staticna
$ strip --strip-unneeded implicitna
$ readelf -s ./implicitna
################################################################################################################
#
# DINAMICNA KNJIZNICA EXPLICITNO POVEZOVANJE
################################################################################################################
$ gcc eksplicitno.c -o eksplicitna -ldl
# Da lahko prevedemo program, moramo zraven vključiti še knjižnico libdl. Pri gcc uporabimo torej še zastavico -ldl.
$ readelf -h ./eksplicitna
"
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x400600
Start of program headers: 64 (bytes into file)
Start of section headers: 6320 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 9
Size of section headers: 64 (bytes)
Number of section headers: 37
Section header string table index: 34
"
$ readelf -s ./eksplicitna
"
...
"
$ readelf -r ./eksplicitna
" Relocation section '.rela.dyn' at offset 0x4a0 contains 1 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000600fe0 000200000006 R_X86_64_GLOB_DAT 0000000000000000 __gmon_start__ + 0
Relocation section '.rela.plt' at offset 0x4b8 contains 7 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000601000 000100000007 R_X86_64_JUMP_SLO 0000000000000000 printf + 0
000000601008 000400000007 R_X86_64_JUMP_SLO 0000000000000000 puts + 0
000000601010 000500000007 R_X86_64_JUMP_SLO 0000000000000000 __libc_start_main + 0
000000601018 000600000007 R_X86_64_JUMP_SLO 0000000000000000 dlclose + 0
000000601020 000700000007 R_X86_64_JUMP_SLO 0000000000000000 dlopen + 0
000000601028 000800000007 R_X86_64_JUMP_SLO 0000000000000000 dlsym + 0
000000601030 000900000007 R_X86_64_JUMP_SLO 0000000000000000 perror + 0
"
# primerjaj z $ readelf -r ./staticna
# primerjaj z $ readelf -r ./implicitna
$ strip --strip-unneeded eksplicitna
$ readelf -s ./eksplicitna
Reference in New Issue View Git Blame Copy Permalink