From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: [PATCH 03/16] libceph: define ceph_decode_string() Date: Wed, 11 Jul 2012 11:43:54 -0700 Message-ID: <4FFDC96A.2000605@inktank.com> References: <4FFD847C.7070205@inktank.com> <4FFD871B.6020704@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:59288 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755297Ab2GKSn5 (ORCPT ); Wed, 11 Jul 2012 14:43:57 -0400 Received: by pbbrp8 with SMTP id rp8so2386362pbb.19 for ; Wed, 11 Jul 2012 11:43:57 -0700 (PDT) In-Reply-To: <4FFD871B.6020704@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Alex Elder Cc: ceph-devel@vger.kernel.org Reviewed-by: Josh Durgin On 07/11/2012 07:00 AM, Alex Elder wrote: > There is no string decoding function defined in, so this > defines one. > > This function is a little different from the others in that the > length of the encoded string is not known a priori. So the > interface is defined a bit like snprintf(), where the value returned > indicates the space required--even if it's more than the space > allotted. > > Signed-off-by: Alex Elder > --- > include/linux/ceph/decode.h | 36 ++++++++++++++++++++++++++++++++++++ > 1 files changed, 36 insertions(+), 0 deletions(-) > > diff --git a/include/linux/ceph/decode.h b/include/linux/ceph/decode.h > index bcbd66c..7ead11fc 100644 > --- a/include/linux/ceph/decode.h > +++ b/include/linux/ceph/decode.h > @@ -44,6 +44,42 @@ static inline void ceph_decode_copy(void **p, void > *pv, size_t n) > } > > /* > + * Decode the wire-encoded string at *p into the buffer "s" > + * provided, whose size is indicated by "size". Note that "s" can > + * be a null pointer if size is 0. If it fits, the resulting string > + * will always be terminated with '\0'; otherwise the buffer will > + * be unchanged. > + * > + * Returns the length of the encoded string (which may be greater > + * than or equal to the buffer size). The return value does not > + * include the terminating '\0'. > + * > + * If the the return value is less than the size provided, *p will > + * be advanced past the decoded data; otherwise it is unchanged. > + * This allows for a two call sequence to be used to allocate > + * sufficient space for the string. > + * > + * NB It is assumed that *p refers to a block of valid memory > + * sufficient to hold the length field followed by the number > + * of bytes indicated by that field. > + */ > +static inline size_t ceph_decode_string(void **p, char *s, size_t size) > +{ > + size_t len; > + > + len = get_unaligned_le32(*p); > + if (size< len + 1) > + return len; > + > + if (len) > + memcpy(s, (char *) *p + sizeof (u32), len); > + *(s + len) = '\0'; > + *p += sizeof (u32) + len; > + > + return len; > +} > + > +/* > * bounds check input. > */ > static inline int ceph_has_room(void **p, void *end, size_t n)