qemu-e2k/nbd/nbd-internal.h

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/*
* NBD Internal Declarations
*
* Copyright (C) 2016 Red Hat, Inc.
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef NBD_INTERNAL_H
#define NBD_INTERNAL_H
#include "block/nbd.h"
#include "sysemu/block-backend.h"
#include "io/channel-tls.h"
#include "qemu/iov.h"
#ifndef _WIN32
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_IOCCOM_H
#include <sys/ioccom.h>
#endif
#ifdef __linux__
#include <linux/fs.h>
#endif
#include "qemu/bswap.h"
/* This is all part of the "official" NBD API.
*
* The most up-to-date documentation is available at:
* https://github.com/yoe/nbd/blob/master/doc/proto.md
*/
/* Size of all NBD_OPT_*, without payload */
#define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4)
/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */
#define NBD_REPLY_SIZE (4 + 4 + 8)
/* Size of reply to NBD_OPT_EXPORT_NAME */
#define NBD_REPLY_EXPORT_NAME_SIZE (8 + 2 + 124)
/* Size of oldstyle negotiation */
#define NBD_OLDSTYLE_NEGOTIATE_SIZE (8 + 8 + 8 + 4 + 124)
#define NBD_INIT_MAGIC 0x4e42444d41474943LL /* ASCII "NBDMAGIC" */
#define NBD_REQUEST_MAGIC 0x25609513
#define NBD_OPTS_MAGIC 0x49484156454F5054LL /* ASCII "IHAVEOPT" */
#define NBD_CLIENT_MAGIC 0x0000420281861253LL
#define NBD_REP_MAGIC 0x0003e889045565a9LL
#define NBD_SET_SOCK _IO(0xab, 0)
#define NBD_SET_BLKSIZE _IO(0xab, 1)
#define NBD_SET_SIZE _IO(0xab, 2)
#define NBD_DO_IT _IO(0xab, 3)
#define NBD_CLEAR_SOCK _IO(0xab, 4)
#define NBD_CLEAR_QUE _IO(0xab, 5)
#define NBD_PRINT_DEBUG _IO(0xab, 6)
#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
#define NBD_DISCONNECT _IO(0xab, 8)
#define NBD_SET_TIMEOUT _IO(0xab, 9)
#define NBD_SET_FLAGS _IO(0xab, 10)
/* nbd_write
nbd: read_sync and friends: return 0 on success functions read_sync, drop_sync, write_sync, and also nbd_negotiate_write, nbd_negotiate_read, nbd_negotiate_drop_sync returns number of processed bytes. But what this number can be, except requested number of bytes? Actually, underlying nbd_wr_syncv function returns a value >= 0 and != requested_bytes only on eof on read operation. So, firstly, it is impossible on write (let's add an assert) and on read it actually means, that communication is broken (except nbd_receive_reply, see below). Most of callers operate like this: if (func(..., size) != size) { /* error path */ } , i.e.: 1. They are not interested in partial success 2. Extra duplications in code (especially bad are duplications of magic numbers) 3. User doesn't see actual error message, as return code is lost. (this patch doesn't fix this point, but it makes fixing easier) Several callers handles ret >= 0 and != requested-size separately, by just returning EINVAL in this case. This patch makes read_sync and friends return EINVAL in this case, so final behavior is the same. And only one caller - nbd_receive_reply() does something not so obvious. It returns EINVAL for ret > 0 and != requested-size, like previous group, but for ret == 0 it returns 0. The only caller of nbd_receive_reply() - nbd_read_reply_entry() handles ret == 0 in the same way as ret < 0, so for now it doesn't matter. However, in following commits error path handling will be improved and we'll need to distinguish success from fail in this case too. So, this patch adds separate helper for this case - read_sync_eof. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20170516094533.6160-3-vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-16 11:45:30 +02:00
* Writes @size bytes to @ioc. Returns 0 on success.
*/
static inline int nbd_write(QIOChannel *ioc, const void *buffer, size_t size,
Error **errp)
{
return qio_channel_write_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
}
struct NBDTLSHandshakeData {
GMainLoop *loop;
bool complete;
Error *error;
};
void nbd_tls_handshake(QIOTask *task,
void *opaque);
int nbd_drop(QIOChannel *ioc, size_t size, Error **errp);
#endif