Introduce QString

QString is a high-level data type that can be used to represent
C strings.

The following functions are available:

- qstring_from_str() Create a new QString
- qstring_get_str()  Get a pointer to the stored string

Note that qstring_get_str() is too low-level for a data type like
this, but it's interesting for quick read-only accesses.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Makefile

@@ -91,7 +91,7 @@ obj-y += buffered_file.o migration.o migration-tcp.o net.o qemu-sockets.o
 obj-y += qemu-char.o aio.o net-checksum.o savevm.o
 obj-y += msmouse.o ps2.o
 obj-y += qdev.o qdev-properties.o ssi.o
-obj-y += qint.o
+obj-y += qint.o qstring.o
 
 obj-$(CONFIG_BRLAPI) += baum.o
 obj-$(CONFIG_WIN32) += tap-win32.o

qobject.h

@@ -38,6 +38,7 @@
 typedef enum {
     QTYPE_NONE,
     QTYPE_QINT,
+    QTYPE_QSTRING,
 } qtype_code;
 
 struct QObject;

qstring.c

+/*
+ * QString data type.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+#include "qobject.h"
+#include "qstring.h"
+#include "qemu-common.h"
+
+static const QType qstring_type;
+
+/**
+ * qstring_from_str(): Create a new QString from a regular C string
+ *
+ * Return strong reference.
+ */
+QString *qstring_from_str(const char *str)
+{
+    QString *qstring;
+
+    qstring = qemu_malloc(sizeof(*qstring));
+    qstring->string = qemu_strdup(str);
+    QOBJECT_INIT(qstring, &qstring_type);
+
+    return qstring;
+}
+
+/**
+ * qobject_to_qstring(): Convert a QObject to a QString
+ */
+QString *qobject_to_qstring(const QObject *obj)
+{
+    if (qobject_type(obj) != QTYPE_QSTRING)
+        return NULL;
+
+    return container_of(obj, QString, base);
+}
+
+/**
+ * qstring_get_str(): Return a pointer to the stored string
+ *
+ * NOTE: Should be used with caution, if the object is deallocated
+ * this pointer becomes invalid.
+ */
+const char *qstring_get_str(const QString *qstring)
+{
+    return qstring->string;
+}
+
+/**
+ * qstring_destroy_obj(): Free all memory allocated by a QString
+ * object
+ */
+static void qstring_destroy_obj(QObject *obj)
+{
+    QString *qs;
+
+    assert(obj != NULL);
+    qs = qobject_to_qstring(obj);
+    qemu_free(qs->string);
+    qemu_free(qs);
+}
+
+static const QType qstring_type = {
+    .code = QTYPE_QSTRING,
+    .destroy = qstring_destroy_obj,
+};

qstring.h

+#ifndef QSTRING_H
+#define QSTRING_H
+
+#include "qobject.h"
+
+typedef struct QString {
+    QObject_HEAD;
+    char *string;
+} QString;
+
+QString *qstring_from_str(const char *str);
+const char *qstring_get_str(const QString *qstring);
+QString *qobject_to_qstring(const QObject *obj);
+
+#endif /* QSTRING_H */