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@xxxxxxxxxxx>
---
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
+ */
+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,
--
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