//"sleep.c"
#include <stdlib.h>
int main(){
while(1){
sleep(1000);
}
return 0;
}
root@vultr:~/clang# gcc -static sleep.c
sleep.c: In function ‘main’:
sleep.c:4:7: warning: implicit declaration of function ‘sleep’ [-Wimplicit-function-declaration]
sleep(1000);
^
//"sleep.c"
#include<unistd.h>
#include <stdlib.h>
int main(){
while(1){
sleep(1000);
}
return 0;
}
root@vultr:~/clang# gcc -static sleep.c
root@vultr:~/clang# ls
a.out sleep.c
root@vultr:~/clang# ./a.out
^C
root@vultr:~/clang# readelf -S a.out
There are 33 section headers, starting at offset 0xde578:
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .note.ABI-tag NOTE 0000000000400190 00000190
0000000000000020 0000000000000000 A 0 0 4
[ 2] .note.gnu.build-i NOTE 00000000004001b0 000001b0
0000000000000024 0000000000000000 A 0 0 4
[ 3] .rela.plt RELA 00000000004001d8 000001d8
00000000000000f0 0000000000000018 AI 0 24 8
[ 4] .init PROGBITS 00000000004002c8 000002c8
000000000000001a 0000000000000000 AX 0 0 4
[ 5] .plt PROGBITS 00000000004002f0 000002f0
00000000000000a0 0000000000000000 AX 0 0 16
[ 6] .text PROGBITS 0000000000400390 00000390
000000000009e634 0000000000000000 AX 0 0 16
[ 7] __libc_freeres_fn PROGBITS 000000000049e9d0 0009e9d0
0000000000002529 0000000000000000 AX 0 0 16
[ 8] __libc_thread_fre PROGBITS 00000000004a0f00 000a0f00
00000000000000de 0000000000000000 AX 0 0 16
[ 9] .fini PROGBITS 00000000004a0fe0 000a0fe0
0000000000000009 0000000000000000 AX 0 0 4
[10] .rodata PROGBITS 00000000004a1000 000a1000
000000000001d244 0000000000000000 A 0 0 32
[11] __libc_subfreeres PROGBITS 00000000004be248 000be248
0000000000000050 0000000000000000 A 0 0 8
[12] __libc_atexit PROGBITS 00000000004be298 000be298
0000000000000008 0000000000000000 A 0 0 8
[13] .stapsdt.base PROGBITS 00000000004be2a0 000be2a0
0000000000000001 0000000000000000 A 0 0 1
[14] __libc_thread_sub PROGBITS 00000000004be2a8 000be2a8
0000000000000008 0000000000000000 A 0 0 8
[15] .eh_frame PROGBITS 00000000004be2b0 000be2b0
000000000000b00c 0000000000000000 A 0 0 8
[16] .gcc_except_table PROGBITS 00000000004c92bc 000c92bc
00000000000000a3 0000000000000000 A 0 0 1
[17] .tdata PROGBITS 00000000006c9eb8 000c9eb8
0000000000000020 0000000000000000 WAT 0 0 8
[18] .tbss NOBITS 00000000006c9ed8 000c9ed8
0000000000000030 0000000000000000 WAT 0 0 8
[19] .init_array INIT_ARRAY 00000000006c9ed8 000c9ed8
0000000000000010 0000000000000000 WA 0 0 8
[20] .fini_array FINI_ARRAY 00000000006c9ee8 000c9ee8
0000000000000010 0000000000000000 WA 0 0 8
[21] .jcr PROGBITS 00000000006c9ef8 000c9ef8
0000000000000008 0000000000000000 WA 0 0 8
[22] .data.rel.ro PROGBITS 00000000006c9f00 000c9f00
00000000000000e4 0000000000000000 WA 0 0 32
[23] .got PROGBITS 00000000006c9fe8 000c9fe8
0000000000000010 0000000000000008 WA 0 0 8
[24] .got.plt PROGBITS 00000000006ca000 000ca000
0000000000000068 0000000000000008 WA 0 0 8
[25] .data PROGBITS 00000000006ca080 000ca080
0000000000001ad0 0000000000000000 WA 0 0 32
[26] .bss NOBITS 00000000006cbb60 000cbb50
0000000000001878 0000000000000000 WA 0 0 32
[27] __libc_freeres_pt NOBITS 00000000006cd3d8 000cbb50
0000000000000030 0000000000000000 WA 0 0 8
[28] .comment PROGBITS 0000000000000000 000cbb50
0000000000000035 0000000000000001 MS 0 0 1
[29] .note.stapsdt NOTE 0000000000000000 000cbb88
0000000000000f18 0000000000000000 0 0 4
[30] .shstrtab STRTAB 0000000000000000 000de40f
0000000000000169 0000000000000000 0 0 1
[31] .symtab SYMTAB 0000000000000000 000ccaa0
000000000000b100 0000000000000018 32 712 8
[32] .strtab STRTAB 0000000000000000 000d7ba0
000000000000686f 0000000000000000 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
root@vultr:~/clang# readelf -l a.out
Elf file type is EXEC (Executable file)
Entry point 0x400890
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000400000 0x0000000000400000
0x00000000000c935f 0x00000000000c935f R E 200000
LOAD 0x00000000000c9eb8 0x00000000006c9eb8 0x00000000006c9eb8
0x0000000000001c98 0x0000000000003550 RW 200000
NOTE 0x0000000000000190 0x0000000000400190 0x0000000000400190
0x0000000000000044 0x0000000000000044 R 4
TLS 0x00000000000c9eb8 0x00000000006c9eb8 0x00000000006c9eb8
0x0000000000000020 0x0000000000000050 R 8
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RW 10
GNU_RELRO 0x00000000000c9eb8 0x00000000006c9eb8 0x00000000006c9eb8
0x0000000000000148 0x0000000000000148 R 1
Section to Segment mapping:
Segment Sections...
00 .note.ABI-tag .note.gnu.build-id .rela.plt .init .plt .text __libc_freeres_fn __libc_thread_freers_fn .fini .rodata __libc_subfreeres __libc_atexit .stapsdt.base __libc_thread_subfreeres .eh_frame .gcc_exept_table
01 .tdata .init_array .fini_array .jcr .data.rel.ro .got .got.plt .data .bss __libc_freeres_ptrs
02 .note.ABI-tag .note.gnu.build-id
03 .tdata .tbss
04
05 .tdata .init_array .fini_array .jcr .data.rel.ro .got
root@vultr:~/clang# ./a.out &
[2] 18711
root@vultr:~/clang# cat /proc/18711/maps
00400000-004ca000 r-xp 00000000 fd:01 258898 /root/clang/a.out
006c9000-006cc000 rw-p 000c9000 fd:01 258898 /root/clang/a.out
006cc000-006ce000 rw-p 00000000 00:00 0
021b1000-021d4000 rw-p 00000000 00:00 0 [heap]
7fff8a2fd000-7fff8a31e000 rw-p 00000000 00:00 0 [stack]
7fff8a381000-7fff8a384000 r--p 00000000 00:00 0 [vvar]
7fff8a384000-7fff8a386000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
root@vultr:~/clang# ps -a
PID TTY TIME CMD
18701 pts/1 00:00:00 a.out
18711 pts/1 00:00:00 a.out
18718 pts/0 00:00:00 ps
root@vultr:~/clang# kill 18701
root@vultr:~/clang# ps -a
PID TTY TIME CMD
18711 pts/1 00:00:00 a.out
18724 pts/0 00:00:00 ps
