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nbd/server: add nbd_read_opt_name helper 

Add helper to read name in format:

  uint32 len       (<= NBD_MAX_NAME_SIZE)
  len bytes string (not 0-terminated)

The helper will be reused in following patch.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180312152126.286890-3-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: grammar fixes, actually check error]
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2018-03-12 18:21:20 +03:00 committed by Eric Blake
parent 2e425fd568
commit 12296459f4
1 changed files with 43 additions and 10 deletions
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53
nbd/server.c
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@ -273,6 +273,48 @@ static int nbd_opt_read(NBDClient *client, void *buffer, size_t size,
return qio_channel_read_all(client->ioc, buffer, size, errp) < 0 ? -EIO : 1;
}
/* nbd_opt_read_name
*
* Read a string with the format:
* uint32_t len (<= NBD_MAX_NAME_SIZE)
* len bytes string (not 0-terminated)
*
* @name should be enough to store NBD_MAX_NAME_SIZE+1.
* If @length is non-null, it will be set to the actual string length.
*
* Return -errno on I/O error, 0 if option was completely handled by
* sending a reply about inconsistent lengths, or 1 on success.
*/
static int nbd_opt_read_name(NBDClient *client, char *name, uint32_t *length,
Error **errp)
{
int ret;
uint32_t len;
ret = nbd_opt_read(client, &len, sizeof(len), errp);
if (ret <= 0) {
return ret;
}
cpu_to_be32s(&len);
if (len > NBD_MAX_NAME_SIZE) {
return nbd_opt_invalid(client, errp,
"Invalid name length: %" PRIu32, len);
}
ret = nbd_opt_read(client, name, len, errp);
if (ret <= 0) {
return ret;
}
name[len] = '\0';
if (length) {
*length = len;
}
return 1;
}
/* Send a single NBD_REP_SERVER reply to NBD_OPT_LIST, including payload.
* Return -errno on error, 0 on success. */
static int nbd_negotiate_send_rep_list(NBDClient *client, NBDExport *exp,
@ -455,19 +497,10 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint16_t myflags,
2 bytes: N, number of requests (can be 0)
N * 2 bytes: N requests
*/
rc = nbd_opt_read(client, &namelen, sizeof(namelen), errp);
rc = nbd_opt_read_name(client, name, &namelen, errp);
if (rc <= 0) {
return rc;
}
be32_to_cpus(&namelen);
if (namelen >= sizeof(name)) {
return nbd_opt_invalid(client, errp, "name too long for qemu");
}
rc = nbd_opt_read(client, name, namelen, errp);
if (rc <= 0) {
return rc;
}
name[namelen] = '\0';
trace_nbd_negotiate_handle_export_name_request(name);
rc = nbd_opt_read(client, &requests, sizeof(requests), errp);