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>
---
v2: Made the function safe from overrunning the source memory, and
and added a gfp argument to pass to kmalloc()
include/linux/ceph/decode.h | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
Index: b/include/linux/ceph/decode.h
===================================================================
--- a/include/linux/ceph/decode.h
+++ b/include/linux/ceph/decode.h
@@ -130,6 +130,44 @@ bad:
}
/*
+ * 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
+ * it. 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 "end" will be updated
+ * if NULL is returned.
+ *
+ * There are two possible failures:
+ * - memory could not be allocated for the result
+ * - converting the string would require accessing memory at or
+ * beyond the "end" pointer provided
+ */
+static inline char *ceph_extract_encoded_string(void **p, void *end,
+ size_t *lenp, gfp_t gfp)
+{
+ ssize_t len;
+ char *buf;
+
+ len = ceph_decode_string(p, end, NULL, 0);
+ if (len < 0)
+ return NULL;
+
+ buf = kmalloc(len + 1, gfp);
+ if (!buf)
+ return NULL;
+
+ (void) ceph_decode_string(p, end, buf, len + 1);
+ if (lenp)
+ *lenp = (size_t) len;
+
+ return buf;
+}
+
+/*
* struct ceph_timespec <-> struct timespec
*/
static inline void ceph_decode_timespec(struct timespec *ts,
--
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