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nbd/client: refactor nbd_read_eof

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Refactor nbd_read_eof to return 1 on success, 0 on eof, when no
data was read and <0 for other cases, because returned size of
read data is not actually used.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20170804151440.320927-3-vsementsov@virtuozzo.com>
[eblake: tweak function comments, rebase to test 083 enhancements]
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2017-08-04 18:14:25 +03:00 committed by Eric Blake
parent a0acf3a8f7
commit ab01df1fe2
3 changed files with 28 additions and 18 deletions
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5
nbd/client.c
View File

@ -925,11 +925,6 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp)
return ret;
}
if (ret != sizeof(buf)) {
error_setg(errp, "read failed");
return -EINVAL;
}
/* Reply
[ 0 .. 3] magic (NBD_REPLY_MAGIC)
[ 4 .. 7] error (0 == no error)

33
nbd/nbd-internal.h
View File

@ -77,21 +77,36 @@
#define NBD_ESHUTDOWN 108
/* nbd_read_eof
* Tries to read @size bytes from @ioc. Returns number of bytes actually read.
* May return a value >= 0 and < size only on EOF, i.e. when iteratively called
* qio_channel_readv() returns 0. So, there is no need to call nbd_read_eof
* iteratively.
* Tries to read @size bytes from @ioc.
* Returns 1 on success
* 0 on eof, when no data was read (errp is not set)
* negative errno on failure (errp is set)
*/
static inline ssize_t nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size,
Error **errp)
static inline int nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size,
Error **errp)
{
struct iovec iov = { .iov_base = buffer, .iov_len = size };
ssize_t ret;
/* Sockets are kept in blocking mode in the negotiation phase. After
* that, a non-readable socket simply means that another thread stole
* our request/reply. Synchronization is done with recv_coroutine, so
* that this is coroutine-safe.
*/
return nbd_rwv(ioc, &iov, 1, size, true, errp);
assert(size);
ret = nbd_rwv(ioc, &iov, 1, size, true, errp);
if (ret <= 0) {
return ret;
}
if (ret != size) {
error_setg(errp, "End of file");
return -EINVAL;
}
return 1;
}
/* nbd_read
@ -100,9 +115,9 @@ static inline ssize_t nbd_read_eof(QIOChannel *ioc, void *buffer, size_t size,
static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
Error **errp)
{
ssize_t ret = nbd_read_eof(ioc, buffer, size, errp);
int ret = nbd_read_eof(ioc, buffer, size, errp);
if (ret >= 0 && ret != size) {
if (ret == 0) {
ret = -EINVAL;
error_setg(errp, "End of file");
}

8
tests/qemu-iotests/083.out
View File

@ -69,12 +69,12 @@ read failed: Input/output error
=== Check disconnect 4 reply ===
read failed
End of file
read failed: Input/output error
=== Check disconnect 8 reply ===
read failed
End of file
read failed: Input/output error
=== Check disconnect before data ===
@ -180,12 +180,12 @@ read failed: Input/output error
=== Check disconnect 4 reply ===
read failed
End of file
read failed: Input/output error
=== Check disconnect 8 reply ===
read failed
End of file
read failed: Input/output error
=== Check disconnect before data ===