Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 69 insertions, 0 deletions

diff --git a/util/id.c b/util/id.c
new file mode 100644
index 000000000..ded41c502
--- /dev/null
+++ b/util/id.c
@@ -0,0 +1,69 @@
+/*
+ * Dealing with identifiers
+ *
+ * Copyright (C) 2014 Red Hat, Inc.
+ *
+ * Authors:
+ *  Markus Armbruster <armbru@redhat.com>,
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1
+ * or later.  See the COPYING.LIB file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/ctype.h"
+#include "qemu/id.h"
+
+bool id_wellformed(const char *id)
+{
+    int i;
+
+    if (!qemu_isalpha(id[0])) {
+        return false;
+    }
+    for (i = 1; id[i]; i++) {
+        if (!qemu_isalnum(id[i]) && !strchr("-._", id[i])) {
+            return false;
+        }
+    }
+    return true;
+}
+
+#define ID_SPECIAL_CHAR '#'
+
+static const char *const id_subsys_str[ID_MAX] = {
+    [ID_QDEV]  = "qdev",
+    [ID_BLOCK] = "block",
+    [ID_CHR] = "chr",
+    [ID_NET] = "net",
+};
+
+/*
+ *  Generates an ID of the form PREFIX SUBSYSTEM NUMBER
+ *  where:
+ *
+ *  - PREFIX is the reserved character '#'
+ *  - SUBSYSTEM identifies the subsystem creating the ID
+ *  - NUMBER is a decimal number unique within SUBSYSTEM.
+ *
+ *    Example: "#block146"
+ *
+ * Note that these IDs do not satisfy id_wellformed().
+ *
+ * The caller is responsible for freeing the returned string with g_free()
+ */
+char *id_generate(IdSubSystems id)
+{
+    static uint64_t id_counters[ID_MAX];
+    uint32_t rnd;
+
+    assert(id < ARRAY_SIZE(id_subsys_str));
+    assert(id_subsys_str[id]);
+
+    rnd = g_random_int_range(0, 100);
+
+    return g_strdup_printf("%c%s%" PRIu64 "%02" PRId32, ID_SPECIAL_CHAR,
+                                                        id_subsys_str[id],
+                                                        id_counters[id]++,
+                                                        rnd);
+}