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authorEric Blake <eblake@redhat.com>2017-09-05 14:11:13 -0500
committerEric Blake <eblake@redhat.com>2017-09-06 10:11:54 -0500
commite8ffaa311080a570a7c86d03c139c160cd11a831 (patch)
treedd1a6cd2859b757a20dd9248dc98ada5c3b23755 /io/channel.c
parent9ffb8270205a274a18ee4f8a735e2fccaf957246 (diff)
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io: Add new qio_channel_read{, v}_all_eof functions
Some callers want to distinguish between clean EOF (no bytes read) vs. a short read (at least one byte read, but EOF encountered before reaching the desired length), as it allows clients the ability to do a graceful shutdown when a server shuts down at defined safe points in the protocol, rather than treating all shutdown scenarios as an error due to EOF. However, we don't want to require all callers to have to check for early EOF. So add another wrapper function that can be used by the callers that care about the distinction. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20170905191114.5959-3-eblake@redhat.com> Acked-by: Daniel P. Berrange <berrange@redhat.com>
Diffstat (limited to 'io/channel.c')
-rw-r--r--io/channel.c48
1 files changed, 40 insertions, 8 deletions
diff --git a/io/channel.c b/io/channel.c
index 9e62794..ec4b86d 100644
--- a/io/channel.c
+++ b/io/channel.c
@@ -86,16 +86,16 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
}
-
-int qio_channel_readv_all(QIOChannel *ioc,
- const struct iovec *iov,
- size_t niov,
- Error **errp)
+int qio_channel_readv_all_eof(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ Error **errp)
{
int ret = -1;
struct iovec *local_iov = g_new(struct iovec, niov);
struct iovec *local_iov_head = local_iov;
unsigned int nlocal_iov = niov;
+ bool partial = false;
nlocal_iov = iov_copy(local_iov, nlocal_iov,
iov, niov,
@@ -114,21 +114,43 @@ int qio_channel_readv_all(QIOChannel *ioc,
} else if (len < 0) {
goto cleanup;
} else if (len == 0) {
- error_setg(errp,
- "Unexpected end-of-file before all bytes were read");
+ if (partial) {
+ error_setg(errp,
+ "Unexpected end-of-file before all bytes were read");
+ } else {
+ ret = 0;
+ }
goto cleanup;
}
+ partial = true;
iov_discard_front(&local_iov, &nlocal_iov, len);
}
- ret = 0;
+ ret = 1;
cleanup:
g_free(local_iov_head);
return ret;
}
+int qio_channel_readv_all(QIOChannel *ioc,
+ const struct iovec *iov,
+ size_t niov,
+ Error **errp)
+{
+ int ret = qio_channel_readv_all_eof(ioc, iov, niov, errp);
+
+ if (ret == 0) {
+ ret = -1;
+ error_setg(errp,
+ "Unexpected end-of-file before all bytes were read");
+ } else if (ret == 1) {
+ ret = 0;
+ }
+ return ret;
+}
+
int qio_channel_writev_all(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
@@ -205,6 +227,16 @@ ssize_t qio_channel_write(QIOChannel *ioc,
}
+int qio_channel_read_all_eof(QIOChannel *ioc,
+ char *buf,
+ size_t buflen,
+ Error **errp)
+{
+ struct iovec iov = { .iov_base = buf, .iov_len = buflen };
+ return qio_channel_readv_all_eof(ioc, &iov, 1, errp);
+}
+
+
int qio_channel_read_all(QIOChannel *ioc,
char *buf,
size_t buflen,