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[Qemu-devel] [PATCH 29/36] qapi: Add qstring_append_printf()
From: |
Eric Blake |
Subject: |
[Qemu-devel] [PATCH 29/36] qapi: Add qstring_append_printf() |
Date: |
Wed, 30 Nov 2016 13:44:47 -0600 |
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_printf()
(and its vararg counterpart), with a name based on glib's
g_string_append_printf(). In fact, with our wrapper in place, we
no longer need qstring_append_int().
Other immediate uses for the new function include simplifying
two existing clients 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 <address@hidden>
---
previously posted in 'Add qapi-to-JSON visitor' series:
v6: no change
[no v5 due to series split]
v4: retitle, s/_format/_printf/, drop R-b, move up in series
v3: rebase to master
v2: also simplify qstring_append_json_string(), add assertion that
format is well-formed
---
include/qapi/qmp/qstring.h | 7 +++++--
migration/qjson.c | 2 +-
qobject/qjson.c | 38 ++++++++++----------------------------
qobject/qstring.c | 26 +++++++++++++++++++++-----
4 files changed, 37 insertions(+), 36 deletions(-)
diff --git a/include/qapi/qmp/qstring.h b/include/qapi/qmp/qstring.h
index 10076b7..a987f3b 100644
--- a/include/qapi/qmp/qstring.h
+++ b/include/qapi/qmp/qstring.h
@@ -1,7 +1,7 @@
/*
* QString Module
*
- * Copyright (C) 2009 Red Hat Inc.
+ * Copyright (C) 2009-2016 Red Hat Inc.
*
* Authors:
* Luiz Capitulino <address@hidden>
@@ -27,9 +27,12 @@ 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_printf(QString *qstring, const char *fmt, ...)
+ GCC_FMT_ATTR(2, 3);
+void qstring_append_vprintf(QString *qstring, const char *fmt, va_list ap)
+ GCC_FMT_ATTR(2, 0);
QString *qobject_to_qstring(const QObject *obj);
void qstring_destroy_obj(QObject *obj);
diff --git a/migration/qjson.c b/migration/qjson.c
index 741f9e6..f11effd 100644
--- a/migration/qjson.c
+++ b/migration/qjson.c
@@ -77,7 +77,7 @@ 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_printf(json->str, "%" PRId64, val);
}
void json_prop_str(QJSON *json, const char *name, const char *str)
diff --git a/qobject/qjson.c b/qobject/qjson.c
index daeeb82..4929008 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -81,16 +81,13 @@ 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_printf(s->str, "\n%*s", 4 * s->indent, "");
}
qstring_append_json_string(s->str, key);
@@ -103,16 +100,13 @@ 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_printf(s->str, "\n%*s", 4 * s->indent, "");
}
to_json(obj, s->str, s->pretty, s->indent);
@@ -127,10 +121,7 @@ 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_printf(str, "%" PRId64, qint_get_int(val));
break;
}
case QTYPE_QSTRING: {
@@ -151,10 +142,7 @@ 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_printf(str, "\n%*s", 4 * indent, "");
}
qstring_append(str, "}");
break;
@@ -170,10 +158,7 @@ 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_printf(str, "\n%*s", 4 * indent, "");
}
qstring_append(str, "]");
break;
@@ -251,7 +236,6 @@ int qstring_append_json_string(QString *qstring, const char
*str)
{
const char *ptr;
int cp;
- char buf[16];
char *end;
int result = 0;
@@ -288,16 +272,14 @@ int qstring_append_json_string(QString *qstring, const
char *str)
}
if (cp > 0xFFFF) {
/* beyond BMP; need a surrogate pair */
- snprintf(buf, sizeof(buf), "\\u%04X\\u%04X",
- 0xD800 + ((cp - 0x10000) >> 10),
- 0xDC00 + ((cp - 0x10000) & 0x3FF));
+ qstring_append_printf(qstring, "\\u%04X\\u%04X",
+ 0xD800 + ((cp - 0x10000) >> 10),
+ 0xDc00 + ((cp - 0x10000) & 0x3FF));
} else if (cp < 0x20 || cp >= 0x7F) {
- snprintf(buf, sizeof(buf), "\\u%04X", cp);
+ qstring_append_printf(qstring, "\\u%04X", cp);
} else {
- buf[0] = cp;
- buf[1] = 0;
+ qstring_append_chr(qstring, cp);
}
- qstring_append(qstring, buf);
}
};
diff --git a/qobject/qstring.c b/qobject/qstring.c
index 5da7b5f..fbfae27 100644
--- a/qobject/qstring.c
+++ b/qobject/qstring.c
@@ -1,7 +1,7 @@
/*
* QString Module
*
- * Copyright (C) 2009 Red Hat Inc.
+ * Copyright (C) 2009-2016 Red Hat Inc.
*
* Authors:
* Luiz Capitulino <address@hidden>
@@ -88,12 +88,28 @@ 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_printf(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_vprintf(qstring, fmt, ap);
+ va_end(ap);
+}
+
+void qstring_append_vprintf(QString *qstring, const char *fmt, va_list ap)
+{
+ va_list ap2;
+ int len;
+
+ va_copy(ap2, ap);
+ len = vsnprintf(NULL, 0, fmt, ap2);
+ assert(len >= 0);
+ va_end(ap2);
+
+ capacity_increase(qstring, len);
+ vsnprintf(qstring->string + qstring->length, len + 1, fmt, ap);
+ qstring->length += len;
}
/**
--
2.7.4
- [Qemu-devel] [PATCH 15/36] blockdev: Use simpler QAPI_TO_QOBJECT(), (continued)
- [Qemu-devel] [PATCH 15/36] blockdev: Use simpler QAPI_TO_QOBJECT(), Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 34/36] qapi: Rip out dynamic JSON parser frontend, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 32/36] qtest: Avoid dynamic JSON in qom-test, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 17/36] qtest: Avoid dynamic JSON in ahci-test, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 36/36] qapi: Rip out dynamic JSON parser backend, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 02/36] qdict: Add convenience helpers for wrapped puts, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 23/36] qtest: Avoid dynamic JSON in virtio-blk-test, Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 30/36] qtest: Avoid dynamic JSON in qmp_fd_sendv(), Eric Blake, 2016/11/30
- [Qemu-devel] [PATCH 29/36] qapi: Add qstring_append_printf(),
Eric Blake <=
- Re: [Qemu-devel] [PATCH 00/36] Rip out dynamic JSON parsing, Eric Blake, 2016/11/30