Testing patches for 2018-08-16

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Merge remote-tracking branch 'remotes/armbru/tags/pull-tests-2018-08-16' into staging

Testing patches for 2018-08-16

# gpg: Signature made Thu 16 Aug 2018 09:34:43 BST
# gpg:                using RSA key 3870B400EB918653
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>"
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>"
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-tests-2018-08-16: (25 commits)
  libqtest: Improve error reporting for bad read from QEMU
  tests/libqtest: Improve kill_qemu()
  libqtest: Rename qtest_FOOv() to qtest_vFOO() for consistency
  libqtest: Replace qtest_startf() by qtest_initf()
  libqtest: Enable compile-time format string checking
  migration-test: Clean up string interpolation into QMP, part 3
  migration-test: Clean up string interpolation into QMP, part 2
  migration-test: Clean up string interpolation into QMP, part 1
  migration-test: Make wait_command() cope with '%'
  tests: New helper qtest_qmp_receive_success()
  migration-test: Make wait_command() return the "return" member
  tests: Clean up string interpolation around qtest_qmp_device_add()
  cpu-plug-test: Don't pass integers as strings to device_add
  tests: Clean up string interpolation into QMP input (simple cases)
  tests: Pass literal format strings directly to qmp_FOO()
  qobject: qobject_from_jsonv() is dangerous, hide it away
  test-qobject-input-visitor: Avoid format string ambiguity
  libqtest: Simplify qmp_fd_vsend() a bit
  qobject: New qobject_from_vjsonf_nofail(), qdict_from_vjsonf_nofail()
  qobject: Replace qobject_from_jsonf() by qobject_from_jsonf_nofail()
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

qobject/qjson.c

@@ -39,7 +39,18 @@ static void parse_json(JSONMessageParser *parser, GQueue *tokens)
     s->result = json_parser_parse_err(tokens, s->ap, &s->err);
 }
 
-QObject *qobject_from_jsonv(const char *string, va_list *ap, Error **errp)
+/*
+ * Parse @string as JSON value.
+ * If @ap is non-null, interpolate %-escapes.
+ * Takes ownership of %p arguments.
+ * On success, return the JSON value.
+ * On failure, store an error through @errp and return NULL.
+ * Ownership of %p arguments becomes indeterminate then.  To avoid
+ * leaks, callers passing %p must terminate on error, e.g. by passing
+ * &error_abort.
+ */
+static QObject *qobject_from_jsonv(const char *string, va_list *ap,
+                                   Error **errp)
 {
     JSONParsingState state = {};
 
@@ -59,18 +70,56 @@ QObject *qobject_from_json(const char *string, Error **errp)
     return qobject_from_jsonv(string, NULL, errp);
 }
 
-QObject *qobject_from_jsonf(const char *string, ...)
+/*
+ * Parse @string as JSON value with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QObject.  It is never null.
+ */
+QObject *qobject_from_vjsonf_nofail(const char *string, va_list ap)
+{
+    va_list ap_copy;
+    QObject *obj;
+
+    /* va_copy() is needed when va_list is an array type */
+    va_copy(ap_copy, ap);
+    obj = qobject_from_jsonv(string, &ap_copy, &error_abort);
+    va_end(ap_copy);
+
+    assert(obj);
+    return obj;
+}
+
+/*
+ * Parse @string as JSON value with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QObject.  It is never null.
+ */
+QObject *qobject_from_jsonf_nofail(const char *string, ...)
 {
     QObject *obj;
     va_list ap;
 
     va_start(ap, string);
-    obj = qobject_from_jsonv(string, &ap, &error_abort);
+    obj = qobject_from_vjsonf_nofail(string, ap);
     va_end(ap);
 
     return obj;
 }
 
+/*
+ * Parse @string as JSON object with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QDict.  It is never null.
+ */
+QDict *qdict_from_vjsonf_nofail(const char *string, va_list ap)
+{
+    QDict *qdict;
+
+    qdict = qobject_to(QDict, qobject_from_vjsonf_nofail(string, ap));
+    assert(qdict);
+    return qdict;
+}
+
 /*
  * Parse @string as JSON object with %-escapes interpolated.
  * Abort on error.  Do not use with untrusted @string.
@@ -78,15 +127,13 @@ QObject *qobject_from_jsonf(const char *string, ...)
  */
 QDict *qdict_from_jsonf_nofail(const char *string, ...)
 {
-    QDict *obj;
+    QDict *qdict;
     va_list ap;
 
     va_start(ap, string);
-    obj = qobject_to(QDict, qobject_from_jsonv(string, &ap, &error_abort));
+    qdict = qdict_from_vjsonf_nofail(string, ap);
     va_end(ap);
-
-    assert(obj);
-    return obj;
+    return qdict;
 }
 
 typedef struct ToJsonIterState