Reviewed-by: Josh Durgin <josh.durgin@xxxxxxxxxxx>
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<elder@xxxxxxxxxxx>
---
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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