Wow, that was it. I'm happy to hear that because I thought it should end up with a system call anyway.

Then isn't there some codes making the system call? Or is it that the compiler understands that 'write' is a system call and inserts the assembly code for calling it by itself?

Thanks in adv.

Chan

From : "Mohan L" <l.mohanphy@gmail.com>
Sent : 2014-03-12 15:31:24 ( +09:00 )
To : Kim Chan <ckim@etri.re.kr>
Cc : Dave Hylands <dhylands@gmail.com>, kernelnewbies@kernelnewbies.org <kernelnewbies@kernelnewbies.org>
Subject : Re: where is the printf source for busybox?

ssize_t attribute_hidden _cs_write(void *cookie, const char *buf, size_t bufsize)
{
return write(*((int *) cookie), (char *) buf, bufsize);
}

what does cs stand for here? (Hm.. seems like custom streams..in the code) and I couldn't follow past write above. Where is the function write defined?

Hi Chan,

write is a system call.

$ man 2 write

syscall table for x86 architecture can be found in : <path>/arch/x86/syscalls/syscall_32.tbl

# cat <path>/arch/x86/syscalls/syscall_32.tbl | grep 'write'

4 i386 write sys_write

The format is:

search sys_write definition in kernel source.

Thanks

Mohan L