Reviewed-by: Josh Durgin <[email protected]>
On 07/11/2012 07:00 AM, Alex Elder wrote:
There is no string decoding function defined in<decode.h>, 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<[email protected]> --- 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)
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