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authorEric Blake <eblake@redhat.com>2016-11-07 14:38:13 -0600
committerPaolo Bonzini <pbonzini@redhat.com>2016-11-10 16:01:30 +0100
commita5068244b4f0c994791303b6186b6f732adab6c2 (patch)
treeddd9d91c164f50d07796dfc1b66beb76aeceb6c1 /nbd/client.c
parent175cad36a599bb24ab2a5cd195c96b1f123e25a9 (diff)
nbd: Don't inf-loop on early EOF
Commit 7d3123e converted a single read_sync() into a while loop that assumed that read_sync() would either make progress or give an error. But when the server hangs up early, the client sees EOF (a read_sync() of 0) and never makes progress, which in turn caused qemu-iotest './check -nbd 83' to go into an infinite loop. Rework the loop to accomodate reads cut short by EOF. Reported-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1478551093-32757-1-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'nbd/client.c')
-rw-r--r--nbd/client.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/nbd/client.c b/nbd/client.c
index 7db4301d29..ffb0743bce 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -90,20 +90,21 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
* the amount of bytes consumed. */
static ssize_t drop_sync(QIOChannel *ioc, size_t size)
{
- ssize_t ret, dropped = size;
+ ssize_t ret = 0;
char small[1024];
char *buffer;
buffer = sizeof(small) < size ? small : g_malloc(MIN(65536, size));
while (size > 0) {
- ret = read_sync(ioc, buffer, MIN(65536, size));
- if (ret < 0) {
+ ssize_t count = read_sync(ioc, buffer, MIN(65536, size));
+
+ if (count <= 0) {
goto cleanup;
}
- assert(ret <= size);
- size -= ret;
+ assert(count <= size);
+ size -= count;
+ ret += count;
}
- ret = dropped;
cleanup:
if (buffer != small) {