Creating a directory in linux assembly language - c

Question

I am trying to create a small assembly program to create a folder. I looked up the system call for creating a directory on this page. It says that it is identified by 27h. How would I go about implementing the mkdir somename in assembly?
I am aware that the program should move 27 into eax but I am unsure where to go next. I have googled quite a bit and no one seems to have posted anthing about this online.
This is my current code (I don't know in which register to put filename and so on):
section .data
section .text
global _start
mov eax, 27
mov ????????
....
int 80h
Thanks

Answer 1

One way of finding out, is using GCC to translate the following C code:
#include <stdio.h>
#include <sys/stat.h>
int main()
{
if (mkdir("testdir", 0777) != 0)
{
return -1;
}
return 0;
}
to assembly, with: gcc mkdir.c -S
.file "mkdir.c"
.section .rodata
.LC0:
.string "testdir"
.text
.globl main
.type main, #function
main:
.LFB0:
.cfi_startproc
pushl %ebp
.cfi_def_cfa_offset 8
.cfi_offset 5, -8
movl %esp, %ebp
.cfi_def_cfa_register 5
andl $-16, %esp
subl $16, %esp
movl $511, 4(%esp)
movl $.LC0, (%esp)
call mkdir ; interesting call
testl %eax, %eax
setne %al
testb %al, %al
je .L2
movl $-1, %eax
jmp .L3
.L2:
movl $0, %eax
.L3:
leave
.cfi_restore 5
.cfi_def_cfa 4, 4
ret
.cfi_endproc
.LFE0:
.size main, .-main
.ident "GCC: (GNU) 4.5.1 20100924 (Red Hat 4.5.1-4)"
.section .note.GNU-stack,"",#progbits
Anyway, ProgrammingGroundUp page 272 lists important syscalls, including mkdir:
%eax Name %ebx %ecx %edx Notes
------------------------------------------------------------------
39 mkdir NULL terminated Permission Creates the given
directory name directory. Assumes all
directories leading up
to it already exist.

Answer 2

You could also do like the Assembly Howto is suggesting. But indeed, calling mkdir from Libc is more portable. You need to look into asm/unistd.h to get the syscall number.