Back in commit 764c1ca (Nov 2009), we added qstring_append_int().
However, it did not see any use until commit 190c882 (Jan 2015).
Furthermore, it has a rather limited use case - to print anything
else, callers still have to format into a temporary buffer, unless
we want to introduce an explosion of new qstring_append_* methods
for each useful type to print.
A much better approach is to add a wrapper that merges printf
behavior onto qstring_append, via the new qstring_append_format()
(and its vararg counterpart). In fact, with that in place, we
no longer need qstring_append_int().
Other immediate uses for the new function include simplifying
an existing client of qstring_append() on a just-formatted
buffer, and the fact that we can take advantage of printf width
manipulations for more efficient indentation.
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
include/qapi/qmp/qstring.h | 7 ++++++-
qjson.c | 2 +-
qobject/qobject-json.c | 25 +++++--------------------
qobject/qstring.c | 23 +++++++++++++++++++----
4 files changed, 31 insertions(+), 26 deletions(-)
diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h
index cab1faf..1b1e130 100644
--- a/include/qapi/qmp/qstring.h
+++ b/include/qapi/qmp/qstring.h
@@ -14,6 +14,8 @@
#define QSTRING_H
#include <stdint.h>
+#include <stdarg.h>
+#include "qemu/compiler.h"
#include "qapi/qmp/qobject.h"
#include "qapi/error.h"
@@ -29,9 +31,12 @@ QString *qstring_from_str(const char *str);
QString *qstring_from_substr(const char *str, int start, int end);
size_t qstring_get_length(const QString *qstring);
const char *qstring_get_str(const QString *qstring);
-void qstring_append_int(QString *qstring, int64_t value);
void qstring_append(QString *qstring, const char *str);
void qstring_append_chr(QString *qstring, int c);
+void qstring_append_format(QString *qstring, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
+void qstring_append_vformat(QString *qstring, const char *fmt, va_list ap)
+ GCC_FMT_ATTR(2, 0);
void qstring_append_json_string(QString *qstring, const char *raw);
void qstring_append_json_number(QString *qstring, double number, Error **errp);
QString *qobject_to_qstring(const QObject *obj);
diff --git a/qjson.c b/qjson.c
index 25afaff..8c93c1b 100644
--- a/qjson.c
+++ b/qjson.c
@@ -70,7 +70,7 @@ void json_end_array(QJSON *json)
void json_prop_int(QJSON *json, const char *name, int64_t val)
{
json_emit_element(json, name);
- qstring_append_int(json->str, val);
+ qstring_append_format(json->str, "%" PRId64, val);
}
void json_prop_str(QJSON *json, const char *name, const char *str)
diff --git a/qobject/qobject-json.c b/qobject/qobject-json.c
index dbe0ab8..3a7b26b 100644
--- a/qobject/qobject-json.c
+++ b/qobject/qobject-json.c
@@ -79,16 +79,13 @@ static void to_json(const QObject *obj, QString *str, int
pretty, int indent);
static void to_json_dict_iter(const char *key, QObject *obj, void *opaque)
{
ToJsonIterState *s = opaque;
- int j;
if (s->count) {
qstring_append(s->str, s->pretty ? "," : ", ");
}
if (s->pretty) {
- qstring_append(s->str, "\n");
- for (j = 0 ; j < s->indent ; j++)
- qstring_append(s->str, " ");
+ qstring_append_format(s->str, "\n%*s", 4 * s->indent, "");
}
qstring_append_json_string(s->str, key);
@@ -101,16 +98,13 @@ static void to_json_dict_iter(const char *key, QObject
*obj, void *opaque)
static void to_json_list_iter(QObject *obj, void *opaque)
{
ToJsonIterState *s = opaque;
- int j;
if (s->count) {
qstring_append(s->str, s->pretty ? "," : ", ");
}
if (s->pretty) {
- qstring_append(s->str, "\n");
- for (j = 0 ; j < s->indent ; j++)
- qstring_append(s->str, " ");
+ qstring_append_format(s->str, "\n%*s", 4 * s->indent, "");
}
to_json(obj, s->str, s->pretty, s->indent);
@@ -125,10 +119,7 @@ static void to_json(const QObject *obj, QString *str, int
pretty, int indent)
break;
case QTYPE_QINT: {
QInt *val = qobject_to_qint(obj);
- char buffer[1024];
-
- snprintf(buffer, sizeof(buffer), "%" PRId64, qint_get_int(val));
- qstring_append(str, buffer);
+ qstring_append_format(str, "%" PRId64, qint_get_int(val));
break;
}
case QTYPE_QSTRING: {
@@ -147,10 +138,7 @@ static void to_json(const QObject *obj, QString *str, int
pretty, int indent)
qstring_append(str, "{");
qdict_iter(val, to_json_dict_iter, &s);
if (pretty) {
- int j;
- qstring_append(str, "\n");
- for (j = 0 ; j < indent ; j++)
- qstring_append(str, " ");
+ qstring_append_format(str, "\n%*s", 4 * indent, "");
}
qstring_append(str, "}");
break;
@@ -166,10 +154,7 @@ static void to_json(const QObject *obj, QString *str, int
pretty, int indent)
qstring_append(str, "[");
qlist_iter(val, (void *)to_json_list_iter, &s);
if (pretty) {
- int j;
- qstring_append(str, "\n");
- for (j = 0 ; j < indent ; j++)
- qstring_append(str, " ");
+ qstring_append_format(str, "\n%*s", 4 * indent, "");
}
qstring_append(str, "]");
break;
diff --git a/qobject/qstring.c b/qobject/qstring.c
index c83e63c..a348ae3 100644
--- a/qobject/qstring.c
+++ b/qobject/qstring.c
@@ -88,12 +88,27 @@ void qstring_append(QString *qstring, const char *str)
qstring->string[qstring->length] = 0;
}
-void qstring_append_int(QString *qstring, int64_t value)
+void qstring_append_format(QString *qstring, const char *fmt, ...)
{
- char num[32];
+ va_list ap;
- snprintf(num, sizeof(num), "%" PRId64, value);
- qstring_append(qstring, num);
+ va_start(ap, fmt);
+ qstring_append_vformat(qstring, fmt, ap);
+ va_end(ap);
+}
+
+void qstring_append_vformat(QString *qstring, const char *fmt, va_list ap)
+{
+ va_list ap2;
+ size_t len;
+
+ va_copy(ap2, ap);
+ len = vsnprintf(qstring->string + qstring->length, 0, fmt, ap2);
+ va_end(ap2);
+
+ capacity_increase(qstring, len);
+ vsnprintf(qstring->string + qstring->length, len + 1, fmt, ap);
+ qstring->length += len;
}
/**
--
2.4.3
