| Message ID | 4FFF05D4.9080006@inktank.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 12 Jul 2012, Alex Elder wrote: > This adds a new utility routine which will return a dynamically- > allocated buffer containing a string that has been decoded from ceph > over-the-wire format. It also returns the length of the string > if the address of a size variable is supplied to receive it. > > Signed-off-by: Alex Elder <elder@inktank.com> > --- > v3: Final version. Sage convinced me that there was no need for > ceph_decode_string() other than its use in this function, so > now this implements what that function had been doing directly. > > include/linux/ceph/decode.h | 44 > ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 44 insertions(+) > > Index: b/include/linux/ceph/decode.h > =================================================================== > --- a/include/linux/ceph/decode.h > +++ b/include/linux/ceph/decode.h > @@ -85,6 +85,50 @@ static inline int ceph_has_room(void **p > } while (0) > > /* > + * Allocate a buffer big enough to hold the wire-encoded string, and > + * decode the string into it. The resulting string will always be > + * terminated with '\0'. If successful, *p will be advanced > + * past the decoded data. Also, if lenp is not a null pointer, the > + * length (not including the terminating '\0') will be recorded in > + * *lenp. Note that a zero-length string is a valid return value. > + * > + * Returns a pointer to the newly-allocated string buffer, or a null > + * pointer if an error occurs. Neither *p nor *lenp will have been > + * updated if NULL is returned. > + * > + * There are two possible failures: > + * - converting the string would require accessing memory at or > + * beyond the "end" pointer provided > + * - memory could not be allocated for the result I think the caller should be able to distinguish between these two cases in the return value. What about: > + */ > +static inline char *ceph_extract_encoded_string(void **p, void *end, > + size_t *lenp, gfp_t gfp) int ceph_extract_encoded_string(void **p, void *end, char **str, gfp_t gfp) and return the length, or an error code? That avoids futzing with ERR_PTR and gives you the len a bit less awkwardly... sage > +{ > + u32 len; > + void *sp = *p; > + char *buf = NULL; > + > + ceph_decode_32_safe(&sp, end, len, out); > + if (!ceph_has_room(&sp, end, len)) > + return NULL; > + > + buf = kmalloc(len + 1, gfp); > + if (!buf) > + return NULL; > + > + if (len) > + memcpy(buf, sp, len); > + buf[len] = '\0'; > + > + *p = (char *) *p + sizeof (u32) + len; > + > + if (lenp) > + *lenp = (size_t) len; > +out: > + return buf; > +} > + > +/* > * struct ceph_timespec <-> struct timespec > */ > static inline void ceph_decode_timespec(struct timespec *ts, > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/12/2012 01:20 PM, Sage Weil wrote: > I think the caller should be able to distinguish between these two cases > in the return value. OK. I'll adjust and repost. -Alex -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/12/2012 01:20 PM, Sage Weil wrote: > I think the caller should be able to distinguish between these two cases > in the return value. What about: > >> > + */ >> > +static inline char *ceph_extract_encoded_string(void **p, void *end, >> > + size_t *lenp, gfp_t gfp) > > int ceph_extract_encoded_string(void **p, void *end, char **str, gfp_t gfp) > > and return the length, or an error code? That avoids futzing with ERR_PTR > and gives you the len a bit less awkwardly... > I opted to stick with my original prototype--returning the string--and using the ERR_PTR() etc. I return the string because I *always* want that. Only sometimes is the length needed. -Alex -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: b/include/linux/ceph/decode.h =================================================================== --- a/include/linux/ceph/decode.h +++ b/include/linux/ceph/decode.h @@ -85,6 +85,50 @@ static inline int ceph_has_room(void **p } while (0) /* + * Allocate a buffer big enough to hold the wire-encoded string, and + * decode the string into it. The resulting string will always be + * terminated with '\0'. If successful, *p will be advanced + * past the decoded data. Also, if lenp is not a null pointer, the + * length (not including the terminating '\0') will be recorded in + * *lenp. Note that a zero-length string is a valid return value. + * + * Returns a pointer to the newly-allocated string buffer, or a null + * pointer if an error occurs. Neither *p nor *lenp will have been + * updated if NULL is returned. + * + * There are two possible failures: + * - converting the string would require accessing memory at or + * beyond the "end" pointer provided + * - memory could not be allocated for the result + */ +static inline char *ceph_extract_encoded_string(void **p, void *end, + size_t *lenp, gfp_t gfp) +{ + u32 len; + void *sp = *p; + char *buf = NULL; + + ceph_decode_32_safe(&sp, end, len, out); + if (!ceph_has_room(&sp, end, len)) + return NULL; + + buf = kmalloc(len + 1, gfp); + if (!buf) + return NULL; + + if (len) + memcpy(buf, sp, len); + buf[len] = '\0'; + + *p = (char *) *p + sizeof (u32) + len; + + if (lenp) + *lenp = (size_t) len; +out: + return buf; +} + +/* * struct ceph_timespec <-> struct timespec */ static inline void ceph_decode_timespec(struct timespec *ts,
This adds a new utility routine which will return a dynamically- allocated buffer containing a string that has been decoded from ceph over-the-wire format. It also returns the length of the string if the address of a size variable is supplied to receive it. Signed-off-by: Alex Elder <elder@inktank.com> --- v3: Final version. Sage convinced me that there was no need for ceph_decode_string() other than its use in this function, so now this implements what that function had been doing directly. include/linux/ceph/decode.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html