プログラム実行の話と OSとメモリの挙動の話

#include <stdio.h>
int main()
{
printf("hello world!n");
return 0;
}
!13

$ ls
helloworld helloworld.c
$ file helloworld.c
# helloworld.c: C source, ASCII text
$ file helloworld
# helloworld: ELF 64-bit LSB pie executable,
x86-64, version 1 (SYSV), dynamically linked,
interpreter /lib64/ld-linux-x86-64.so.2, for
GNU/Linux 3.2.0,
BuildID[sha1]=02ed1e530f48620e34b1abc02079fc1
17ebb2279, not stripped
!14

$ ls -alh
# -rwxr-xr-x 1 root root 17K Nov 4 23:21
helloworld
# -rw-r--r-- 1 root root 62 Nov 4 23:20
helloworld.c
!15

$ cat helloworld
{¥rtf1¥ansi
¥deff1{¥fonttbl{¥f1¥fmodern¥fprq1¥fcharset0
Courier New;}}{¥colortbl;
¥red224¥green234¥blue238;¥red00¥green00¥blue0
0;¥red191¥green03¥blue03;¥red176¥green126¥blu
e00;¥red131¥green129¥blue131;¥red131¥green129
¥blue131;¥red255¥green00¥blue255;¥red00¥green
130¥blue00;¥red12
……
!16

$ gdb helloworld
(gdb) disass main
# Dump of assembler code for function main:
# 0x0000000000001135 <+0>: push rbp
# 0x0000000000001136 <+1>: mov rbp,rsp
# 0x0000000000001139 <+4>: lea rdi,
[rip+0xec4] # 0x2004
# 0x0000000000001140 <+11>: mov eax,0x0
# 0x0000000000001145 <+16>: call 0x1030
<printf@plt>
# 0x000000000000114a <+21>: mov eax,0x0
# 0x000000000000114f <+26>: pop rbp
# 0x0000000000001150 <+27>: ret
# End of assembler dump.
!17

$ gdb helloworld
(gdb) disass main
# 0x0000000000001135 <+0>: push rbp
# 0x0000000000001136 <+1>: mov rbp,rsp
# 0x0000000000001139 <+4>: lea rdi,
[rip+0xec4] # 0x2004
# 0x0000000000001140 <+11>: mov eax,0x0
# 0x0000000000001145 <+16>: call 0x1030
<printf@plt>
# 0x000000000000114a <+21>: mov eax,0x0
# 0x000000000000114f <+26>: pop rbp
# 0x0000000000001150 <+27>: ret
!18

$ file helloworldmac
helloworldmac: Mach-O 64-bit x86_64
executable, flags:<NOUNDEFS|DYLDLINK|
TWOLEVEL|PIE>
!19

$ ./helloworldmac
zsh: exec format error: ./helloworldmac
!20

(gdb) disass main
Dump of assembler code for function main:
0x0000000000001135 <+0>: push rbp
0x0000000000001136 <+1>: mov rbp,rsp
0x0000000000001139 <+4>: lea rdi,
[rip+0xec4] # 0x2004
0x0000000000001140 <+11>:mov eax,0x0
0x0000000000001145 <+16>:call 0x1030
<printf@plt>
0x000000000000114a <+21>:mov eax,0x0
0x000000000000114f <+26>:pop rbp
0x0000000000001150 <+27>:ret
End of assembler dump.
!25

void test_function(int a, int b, int c, int d)
{
int flag;
char buffer[10];
flag = 31337; //
buffer[0] = 'A';
}
int main()
{
test_function(1, 2, 3, 4); //
}
!33

gdb -q ./stack_example
Reading symbols from ./stack_example...done.
(gdb) list
1
2 void test_function(int a, int b, int c, int d)
3 {
4 int flag;
5 char buffer[10];
6
7 flag = 31337;
8 buffer[0] = 'A';
9 }
10
(gdb) list
11 int main()
12 {
13 test_function(1, 2, 3, 4);
14 test_function(5,6,7,8);
15 }
16
(gdb) break 13
Breakpoint 1 at 0x1147: file stack_example.c, line 13.
(gdb) break test_function
(gdb) break 14
!34

(gdb) run
Starting program: /root/rg/stack_example
Breakpoint 1, main () at stack_example.c:13
13 test_function(1, 2, 3, 4);
(gdb) i r rsp rbp
rsp 0x7fffffffe350 0x7fffffffe350
rbp 0x7fffffffe350 0x7fffffffe350
(gdb) cont
Continuing.
Breakpoint 2, test_function (a=1, b=2, c=3, d=4) at stack_example.c:7
7 flag = 31337;
(gdb) i r rsp rbp
(gdb) cont
Continuing.
Breakpoint 3, main () at stack_example.c:14
14 test_function(5,6,7,8);
(gdb) i r rsp rbp
!35

$ gcc -g -o memory_segments memory_seguments.c
!36

$ ./memory_segments
data segment:
global_init_var 0xaecf0040
static_init_var 0xaecf0044
bss segment
global_var 0xaecf0050
static_var 0xaecf004c
heap segment
heap_var_ptr 0xb098c260
stack segment
stack_var 0x9fefb384
function() stack_var 0x9fefb36c
!37

#include <stdio.h>
int main()
{
printf("hello world!n");
return 0;
}
!40

$ strace ./helloworld 
execve("./helloworld", ["./helloworld"], 0x7ffc2b36e160 /*
29 vars */) = 0
brk(NULL) = 0x55f838726000
.
.
.
mprotect(0x7f313a6c9000, 4096, PROT_READ) = 0
munmap(0x7f313a67e000, 145183) = 0
fstat(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136,
0), ...}) = 0
brk(NULL) = 0x55f838726000
brk(0x55f838747000) = 0x55f838747000
write(1, "hello world!", 12hello world!) = 12
exit_group(0) = ?
+++ exited with 0 +++
!43

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
int main()
{
int fd1, fd2;
fd1 = open("helloworld.c", O_RDONLY);
close(fd1);
close(fd2);
printf("fd1 = %d, fd2 = %dn", fd1, fd2);
close(fd1);
close(fd2);
printf("fd1 = %d, fd2 = %dn", fd1, fd2);
}
$ ./a.out
fd1 = 3, fd2 = 3
fd1 = 3, fd2 = 4
!46

cat tatsu-cat.c
#include <fcntl.h>
#include <unistd.h>
#define N 1024
int main(int argc, char *argv[])
{
int fd, buflen;
char buf[N];
if (argc < 2)
_exit(1);
for (int i = 1; i < argc; i++)
{
if ((fd = open(argv[i], O_RDONLY)) < 0)
{
close(fd);
continue;
}
while ((buflen = read(fd, buf, N)) > 0)
write(1, buf, buflen);
close(fd);
}
return 0;
}
!47

$ gdb helloworld
(gdb) disass main
# 0x0000000000001135 <+0>: push rbp
# 0x0000000000001136 <+1>: mov rbp,rsp
# 0x0000000000001139 <+4>: lea rdi,
[rip+0xec4] # 0x2004
# 0x0000000000001140 <+11>: mov eax,0x0
# 0x0000000000001145 <+16>: call 0x1030
<printf@plt>
# 0x000000000000114a <+21>: mov eax,0x0
# 0x000000000000114f <+26>: pop rbp
# 0x0000000000001150 <+27>: ret
!49

$ gdb helloworld
(gdb) disass main
# 0x0000000000001135 <+0>: push rbp
#
!50

$ gdb helloworld
(gdb) disass main
# 0x0000000000001135 <+0>: push rbp
#
!51

プログラム実行の話と OSとメモリの挙動の話

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to プログラム実行の話と OSとメモリの挙動の話

Similar to プログラム実行の話と OSとメモリの挙動の話 (20)

Recently uploaded

Recently uploaded (20)