site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.in; h=Message-ID:Received:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=6WXEod/stdsxlIDrrSkQler0cQFXUDHgsB/qGMGD4dBxbDN66iN4a1mWU4dvDOzQVDBCmNyeS5AMnKICw7snyRiSDBruqKJuRb9wtVKyopuV8zR2MEvdw17CzCqdZYU7hG8Bt1iBt1t19ybuXkyu/1DnYlYCn+NPPqBvm9+4OMI= ; I am implementing write func for a character device. I am using the accessor methods uio_curriovlen(uio) and uio_curriovbase(uio) provided in the <sys/uio.h> file to get the length value of the current iovec associated with the given uio and the base address of the current iovec associated with the given uio respectively.However, both the calls are returning zero as the return value.Hence unable to copy the data from userspace to kernel space.Even tried using uiomove() inplace of copyin() but doesnt work. I have attached the code for reference.. Please let me know if something wrong in the code. INT32 device_write ( dev_t device, struct uio *uio, int ioflag ) { INT ret = SUCCESS; PUCHAR tmp_buff = NULL; UINT32 minor_num; user_size_t buff_len = 0, buff_base = 0; /* Get the minor number */ minor_num = minor(device); buff_len = uio_curriovlen(uio); buff_base = uio_curriovbase(uio); IOLog ("uio_curriovlen is %d & uio_curriovbase is %d\n ",buff_len,buff_base); tmp_buff = (PUCHAR) mem_alloc(buff_len); if (NULL == tmp_buff) { IOLog("%s: Buffer is NULL\n", __FUNCTION__); return FAILURE; } if(ret = copyin(buff_base, tmp_buff,buff_len)!= 0) { mem_free(tmp_buff,buff_len); IOlog("%s: Copy from user failed\n", __FUNCTION__); return FAILURE; } *(tmp_buff+ buff_len ) = 0; } --- Terry Lambert <tlambert@apple.com> wrote:

On Sep 12, 2006, at 2:13 AM, sanjay yaragatti wrote:

...

Hi all, I am writing a kernel driver.I have

regestered it

...

as character device. I am unable to implement the device write method (dev_write( dev_t device, struct uio *uio, int ioflag)) since I don't know how to retrieve the buffer from struct uio.

However on trying to dereference uio as uio->uio_iov->iov_base gave a compilation error.

Is there a KPI to retrieve the buffer sent from user space?

You may want to read /usr/include/sys/uio.h...

/* * uio_curriovbase - return the base address of the current iovec associated * with the given uio_t. May return 0. */ user_addr_t uio_curriovbase( uio_t a_uio );

You can also look at the kernel sources; in this case, the function is implemented in:

<http://www.opensource.apple.com/darwinsource/10.4.7.ppc/xnu-792.6.76/bsd/ker...

...

-- Terry

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