qemu/util/uuid.c
Albert Esteve a6ceee591a util/uuid: add a hash function
Add hash function to uuid module using the
djb2 hash algorithm.

Add a couple simple unit tests for the hash
function, checking collisions for similar UUIDs.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
Message-Id: <20231002065706.94707-2-aesteve@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2023-10-04 18:15:06 -04:00

133 lines
3.3 KiB
C

/*
* 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/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)
{
static QemuUUID null_uuid;
return qemu_uuid_is_equal(uu, &null_uuid);
}
int qemu_uuid_is_equal(const QemuUUID *lhv, const QemuUUID *rhv)
{
return memcmp(lhv, rhv, 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]);
}
static bool qemu_uuid_is_valid(const char *str)
{
int i;
for (i = 0; i < strlen(str); i++) {
const char c = str[i];
if (i == 8 || i == 13 || i == 18 || i == 23) {
if (str[i] != '-') {
return false;
}
} else {
if ((c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'F') ||
(c >= 'a' && c <= 'f')) {
continue;
}
return false;
}
}
return i == 36;
}
int qemu_uuid_parse(const char *str, QemuUUID *uuid)
{
unsigned char *uu = &uuid->data[0];
int ret;
if (!qemu_uuid_is_valid(str)) {
return -1;
}
ret = sscanf(str, 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]);
if (ret != 16) {
return -1;
}
return 0;
}
/* Swap from UUID format endian (BE) to the opposite or vice versa.
*/
QemuUUID qemu_uuid_bswap(QemuUUID uuid)
{
bswap32s(&uuid.fields.time_low);
bswap16s(&uuid.fields.time_mid);
bswap16s(&uuid.fields.time_high_and_version);
return uuid;
}
/* djb2 hash algorithm */
uint32_t qemu_uuid_hash(const void *uuid)
{
QemuUUID *qid = (QemuUUID *) uuid;
uint32_t h = 5381;
int i;
for (i = 0; i < ARRAY_SIZE(qid->data); i++) {
h = (h << 5) + h + qid->data[i];
}
return h;
}