From f8c36c58accd5c53a472b5c289910565b3df9f9d Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Wed, 11 Jul 2012 08:24:45 -0500 Subject: [PATCH] libceph: define ceph_extract_encoded_string() 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 Reviewed-by: Sage Weil --- include/linux/ceph/decode.h | 47 +++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/include/linux/ceph/decode.h b/include/linux/ceph/decode.h index bcbd66c84890..4bbf2db45f46 100644 --- a/include/linux/ceph/decode.h +++ b/include/linux/ceph/decode.h @@ -1,6 +1,7 @@ #ifndef __CEPH_DECODE_H #define __CEPH_DECODE_H +#include #include #include #include @@ -84,6 +85,52 @@ static inline int ceph_has_room(void **p, void *end, size_t n) ceph_decode_copy(p, pv, n); \ } 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 + * pointer-coded errno if an error occurs. Neither *p nor *lenp + * will have been updated if an error is returned. + * + * There are two possible failures: + * - converting the string would require accessing memory at or + * beyond the "end" pointer provided (-E + * - 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; + + ceph_decode_32_safe(&sp, end, len, bad); + if (!ceph_has_room(&sp, end, len)) + goto bad; + + buf = kmalloc(len + 1, gfp); + if (!buf) + return ERR_PTR(-ENOMEM); + + if (len) + memcpy(buf, sp, len); + buf[len] = '\0'; + + *p = (char *) *p + sizeof (u32) + len; + if (lenp) + *lenp = (size_t) len; + + return buf; + +bad: + return ERR_PTR(-ERANGE); +} + /* * struct ceph_timespec <-> struct timespec */