cifs: implement CIFSParseMFSymlink()

#include "cifsproto.h"

#include "cifs_debug.h"

#include "cifs_fs_sb.h"

#include "md5.h"

#define CIFS_MF_SYMLINK_LEN_OFFSET (4+1)

#define CIFS_MF_SYMLINK_MD5_OFFSET (CIFS_MF_SYMLINK_LEN_OFFSET+(4+1))

#define CIFS_MF_SYMLINK_LINK_OFFSET (CIFS_MF_SYMLINK_MD5_OFFSET+(32+1))

#define CIFS_MF_SYMLINK_LINK_MAXLEN (1024)

#define CIFS_MF_SYMLINK_FILE_SIZE \

	(CIFS_MF_SYMLINK_LINK_OFFSET + CIFS_MF_SYMLINK_LINK_MAXLEN)

#define CIFS_MF_SYMLINK_LEN_FORMAT "XSym\n%04u\n"

#define CIFS_MF_SYMLINK_MD5_FORMAT \

	"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n"

#define CIFS_MF_SYMLINK_MD5_ARGS(md5_hash) \

	md5_hash[0],  md5_hash[1],  md5_hash[2],  md5_hash[3], \

	md5_hash[4],  md5_hash[5],  md5_hash[6],  md5_hash[7], \

	md5_hash[8],  md5_hash[9],  md5_hash[10], md5_hash[11],\

	md5_hash[12], md5_hash[13], md5_hash[14], md5_hash[15]

static int

CIFSParseMFSymlink(const u8 *buf,

		   unsigned int buf_len,

		   unsigned int *_link_len,

		   char **_link_str)

{

	int rc;

	unsigned int link_len;

	const char *md5_str1;

	const char *link_str;

	struct MD5Context md5_ctx;

	u8 md5_hash[16];

	char md5_str2[34];

	if (buf_len != CIFS_MF_SYMLINK_FILE_SIZE)

		return -EINVAL;

	md5_str1 = (const char *)&buf[CIFS_MF_SYMLINK_MD5_OFFSET];

	link_str = (const char *)&buf[CIFS_MF_SYMLINK_LINK_OFFSET];

	rc = sscanf(buf, CIFS_MF_SYMLINK_LEN_FORMAT, &link_len);

	if (rc != 1)

		return -EINVAL;

	cifs_MD5_init(&md5_ctx);

	cifs_MD5_update(&md5_ctx, (const u8 *)link_str, link_len);

	cifs_MD5_final(md5_hash, &md5_ctx);

	snprintf(md5_str2, sizeof(md5_str2),

		 CIFS_MF_SYMLINK_MD5_FORMAT,

		 CIFS_MF_SYMLINK_MD5_ARGS(md5_hash));

	if (strncmp(md5_str1, md5_str2, 17) != 0)

		return -EINVAL;

	if (_link_str) {

		*_link_str = kstrndup(link_str, link_len, GFP_KERNEL);

		if (!*_link_str)

			return -ENOMEM;

	}

	*_link_len = link_len;

	return 0;

}

int

cifs_hardlink(struct dentry *old_file, struct inode *inode,