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Commit f8c36c58 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

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: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent ad4f232f

include/linux/ceph/decode.h

+47 −0
Original line number Diff line number Diff line 
#ifndef __CEPH_DECODE_H

#define __CEPH_DECODE_H



#include <linux/err.h>

#include <linux/bug.h>

#include <linux/time.h>

#include <asm/unaligned.h>
@@ -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

 */