util: Add UUID API

A number of different places across the code base use CONFIG_UUID. Some
of them are soft dependency, some are not built if libuuid is not
available, some come with dummy fallback, some throws runtime error.

It is hard to maintain, and hard to reason for users.

Since UUID is a simple standard with only a small number of operations,
it is cleaner to have a central support in libqemuutil. This patch adds
qemu_uuid_* functions that all uuid users in the code base can
rely on. Except for qemu_uuid_generate which is new code, all other
functions are just copy from existing fallbacks from other files.

Note that qemu_uuid_parse is moved without updating the function
signature to use QemuUUID, to keep this patch simple.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-Id: <1474432046-325-2-git-send-email-famz@redhat.com>

2 files changed, 92 insertions, 0 deletions

diff --git a/util/Makefile.objs b/util/Makefile.objs
index ffca8f3002..36c7dcc1fa 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -21,6 +21,7 @@ util-obj-y += iov.o qemu-config.o qemu-sockets.o uri.o notify.o
 util-obj-y += qemu-option.o qemu-progress.o
 util-obj-y += hexdump.o
 util-obj-y += crc32c.o
+util-obj-y += uuid.o
 util-obj-y += throttle.o
 util-obj-y += getauxval.o
 util-obj-y += readline.o
diff --git a/util/uuid.c b/util/uuid.c
new file mode 100644
index 0000000000..6815904435
--- /dev/null
+++ b/util/uuid.c
@@ -0,0 +1,91 @@
+/*
+ *  QEMU UUID functions
+ *
+ *  Copyright 2016 Red Hat, Inc.
+ *
+ *  Authors:
+ *   Fam Zheng <famz@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu/uuid.h"
+#include "qemu/bswap.h"
+
+void qemu_uuid_generate(QemuUUID *uuid)
+{
+    int i;
+    uint32_t tmp[4];
+
+    QEMU_BUILD_BUG_ON(sizeof(QemuUUID) != 16);
+
+    for (i = 0; i < 4; ++i) {
+        tmp[i] = g_random_int();
+    }
+    memcpy(uuid, tmp, sizeof(tmp));
+    /* Set the two most significant bits (bits 6 and 7) of the
+      clock_seq_hi_and_reserved to zero and one, respectively. */
+    uuid->data[8] = (uuid->data[8] & 0x3f) | 0x80;
+    /* Set the four most significant bits (bits 12 through 15) of the
+      time_hi_and_version field to the 4-bit version number.
+      */
+    uuid->data[6] = (uuid->data[6] & 0xf) | 0x40;
+}
+
+int qemu_uuid_is_null(const QemuUUID *uu)
+{
+    QemuUUID null_uuid = { 0 };
+    return memcmp(uu, &null_uuid, sizeof(QemuUUID)) == 0;
+}
+
+void qemu_uuid_unparse(const QemuUUID *uuid, char *out)
+{
+    const unsigned char *uu = &uuid->data[0];
+    snprintf(out, UUID_FMT_LEN + 1, UUID_FMT,
+             uu[0], uu[1], uu[2], uu[3], uu[4], uu[5], uu[6], uu[7],
+             uu[8], uu[9], uu[10], uu[11], uu[12], uu[13], uu[14], uu[15]);
+}
+
+char *qemu_uuid_unparse_strdup(const QemuUUID *uuid)
+{
+    const unsigned char *uu = &uuid->data[0];
+    return g_strdup_printf(UUID_FMT,
+                           uu[0], uu[1], uu[2], uu[3], uu[4], uu[5], uu[6],
+                           uu[7], uu[8], uu[9], uu[10], uu[11], uu[12],
+                           uu[13], uu[14], uu[15]);
+}
+
+int qemu_uuid_parse(const char *str, uint8_t *uuid)
+{
+    int ret;
+
+    if (strlen(str) != 36) {
+        return -1;
+    }
+
+    ret = sscanf(str, UUID_FMT, &uuid[0], &uuid[1], &uuid[2], &uuid[3],
+                 &uuid[4], &uuid[5], &uuid[6], &uuid[7], &uuid[8], &uuid[9],
+                 &uuid[10], &uuid[11], &uuid[12], &uuid[13], &uuid[14],
+                 &uuid[15]);
+
+    if (ret != 16) {
+        return -1;
+    }
+    return 0;
+}
+
+/* Swap from UUID format endian (BE) to the opposite or vice versa.
+ */
+void qemu_uuid_bswap(QemuUUID *uuid)
+{
+    assert(QEMU_PTR_IS_ALIGNED(uuid, sizeof(uint32_t)));
+    bswap32s(&uuid->fields.time_low);
+    bswap16s(&uuid->fields.time_mid);
+    bswap16s(&uuid->fields.time_high_and_version);
+}