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[Qemu-devel] [PATCH 02/21] libqtest: Work around a "QMP wants a newline"
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH 02/21] libqtest: Work around a "QMP wants a newline" bug |
Date: |
Thu, 23 Feb 2017 22:44:58 +0100 |
The next commit is going to add a test that calls qmp("null").
Curiously, this hangs. Here's why.
qmp_fd_sendv() doesn't send newlines. Not even when @fmt contains
some. At first glance, the QMP parser seems to be fine with that.
However, it turns out that it fails to react to input until it sees
either a newline, an object or an array. To reproduce, feed to a QMP
monitor like this:
$ echo -n 'null' | socat UNIX:/work/armbru/images/test-qmp STDIO
{"QMP": {"version": {"qemu": {"micro": 50, "minor": 8, "major": 2},
"package": " (v2.8.0-1195-gf84141e-dirty)"}, "capabilities": []}}
No output after the greeting.
Add a newline:
$ echo 'null' | socat UNIX:/work/armbru/images/test-qmp STDIO
{"QMP": {"version": {"qemu": {"micro": 50, "minor": 8, "major": 2},
"package": " (v2.8.0-1195-gf84141e-dirty)"}, "capabilities": []}}
{"error": {"class": "GenericError", "desc": "Expected 'object' in QMP
input"}}
Correct output for input 'null'.
Add an object instead:
$ echo -n 'null { "execute": "qmp_capabilities" }' | socat UNIX:qmp-socket
STDIO
{"QMP": {"version": {"qemu": {"micro": 50, "minor": 8, "major": 2},
"package": " (v2.8.0-1195-gf84141e-dirty)"}, "capabilities": []}}
{"error": {"class": "GenericError", "desc": "Expected 'object' in QMP
input"}}
{"return": {}}
Also correct output.
Work around this QMP bug by having qmp_fd_sendv() append a newline.
Signed-off-by: Markus Armbruster <address@hidden>
---
tests/libqtest.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/tests/libqtest.c b/tests/libqtest.c
index e54354d..ad23ce9 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -442,14 +442,20 @@ void qmp_fd_sendv(int fd, const char *fmt, va_list ap)
if (qobj) {
int log = getenv("QTEST_LOG") != NULL;
QString *qstr = qobject_to_json(qobj);
- const char *str = qstring_get_str(qstr);
- size_t size = qstring_get_length(qstr);
+ const char *str;
+
+ /*
+ * BUG: QMP doesn't react to input until it sees a newline, an
+ * object, or an array. Work-around: give it a newline.
+ */
+ qstring_append_chr(qstr, '\n');
+ str = qstring_get_str(qstr);
if (log) {
fprintf(stderr, "%s", str);
}
/* Send QMP request */
- socket_send(fd, str, size);
+ socket_send(fd, str, qstring_get_length(qstr));
QDECREF(qstr);
qobject_decref(qobj);
--
2.7.4
- Re: [Qemu-devel] [PATCH 03/21] qmp-test: New, covering basic QMP protocol, (continued)
- [Qemu-devel] [PATCH 14/21] qapi: Make string input and opts visitor require non-null input, Markus Armbruster, 2017/02/23
- [Qemu-devel] [PATCH 08/21] qmp: Improve QMP dispatch error messages, Markus Armbruster, 2017/02/23
- [Qemu-devel] [PATCH 02/21] libqtest: Work around a "QMP wants a newline" bug,
Markus Armbruster <=
- [Qemu-devel] [PATCH 05/21] qmp: Clean up how we enforce capability negotiation, Markus Armbruster, 2017/02/23
- [Qemu-devel] [PATCH 16/21] test-qobject-input-visitor: Use strict visitor, Markus Armbruster, 2017/02/23
- [Qemu-devel] [PATCH 07/21] qmp: Eliminate silly QERR_QMP_* macros, Markus Armbruster, 2017/02/23
- [Qemu-devel] [PATCH 06/21] qmp: Drop duplicated QMP command object checks, Markus Armbruster, 2017/02/23