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From: Bill Nottingham <notting@redhat.com>
To: linux-kernel@vger.kernel.org
Subject: random ioctls - are they supposed to be like this?
Date: Wed, 18 Aug 2004 16:42:13 -0400	[thread overview]
Message-ID: <20040818204213.GA19909@nostromo.devel.redhat.com> (raw)

include/linux/random.h has:

#define RNDADDENTROPY   _IOW( 'R', 0x03, int [2] )
#define RNDGETPOOL      _IOR( 'R', 0x02, int [2] )

However, these seem to be used differently in practice.
For example, the one user of RNDADDENTROPY I find does:

struct {
	int ent_count;
	int size;
	unsigned char data[size];
} entropy;

if (ioctl(fd, RNDADDENTROPY, &entropy) != 0) {
...

And, looking at the random driver, it does appear to expect
this format.

Now, RNDGETPOOL in the kernel does:

if (get_user(size, p) ||
    put_user(random_state->poolinfo.poolwords, p++))
	return -EFAULT;
...
if (!copy_to_user(p, tmp, size * sizeof(__u32))) {
...
if(put_user(ent_count, p++))
	return -EFAULT;

Which obviously isn't going to work right if you
just pass in a two-int structure.

Am I reading this wrong, or are callers just supposed
to know to use the other interface?

Bill

                 reply	other threads:[~2004-08-18 20:43 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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