writing from kernel

writing from kernel

[anil vijarnia]

can any one tell me how to write into files from kernel space.i 
tried
sys_open(),sys_write() from my module but they don't work.

anil

writing from kernel

[anil vijarnia]

can any one tell me how to write into files from kernel space.
i tried sys_open(),sys_write() from my module but they don't 
work.

anil

writing from kernel

[anil vijarnia]

can anyone tell me how to write into i file from kernel space.
i tried sys_open,sys_write functions bbbbbut they don't work
 from
my module.


anil

Re: writing from kernel

[Christian Vogel]

Hi,

On Sat, Jan 04, 2003 at 04:02:55PM -0000, anil  vijarnia wrote:
> can anyone tell me how to write into i file from kernel space.
> i tried sys_open,sys_write functions bbbbbut they don't work
>  from my module.

As far as I understand the general oppinion on this list :-) the
preferred method is to have your module preset a character-device
to userspace. Then use a small program to do the I/O.

This normally keeps your kernel module simple and allows for
arbitrary compex I/O in userspace.

        Chris

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Re: writing from kernel

[Kasper Dupont]

anil vijarnia wrote:
> 
> can anyone tell me how to write into i file from kernel space.
> i tried sys_open,sys_write functions bbbbbut they don't work
> from my module.

That is rarely a good idea. But if you insist on doing it anyway,
you could use filp_open and the methods in the returned struct.
I have an old code example here:

http://www.daimi.au.dk/~kasperd/linux_kernel/kcp.c

-- 
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For sending spam use mailto:aaarep@daimi.au.dk
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Re: writing from kernel

[Olaf Dietsche]

"anil  vijarnia" <linux_ker@rediffmail.com> writes:

> can anyone tell me how to write into i file from kernel space.
> i tried sys_open,sys_write functions bbbbbut they don't work
>  from
> my module.

As others already pointed out, it's not always a good idea to do this
from kernel space. However, if you still want to do it, see snippet
below. If you want to write, you have to copy kernel_read() from
fs/exec.c and modify it for writing.

Regards, Olaf.

--cut here-->8--
#include <linux/fs.h>

struct file *filp;
unsigned long offset = 0;
char buf[1024];
int n;

filp = filp_open("/path/to/some/file", O_RDONLY, 0);
if (!filp || IS_ERR(filp)) {
   /* do some error handling */
}

n = kernel_read(filp, offset, buf, sizeof(buf));
if (n != sizeof(buf)) {
   /* do some checking */
}

filp_close(filp, 0);
--8<--cut here--