a6ceee591a
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>
133 lines
3.3 KiB
C
133 lines
3.3 KiB
C
/*
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* QEMU UUID functions
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*
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* Copyright 2016 Red Hat, Inc.
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*
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* Authors:
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* Fam Zheng <famz@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu/uuid.h"
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#include "qemu/bswap.h"
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void qemu_uuid_generate(QemuUUID *uuid)
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{
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int i;
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uint32_t tmp[4];
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QEMU_BUILD_BUG_ON(sizeof(QemuUUID) != 16);
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for (i = 0; i < 4; ++i) {
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tmp[i] = g_random_int();
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}
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memcpy(uuid, tmp, sizeof(tmp));
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/* Set the two most significant bits (bits 6 and 7) of the
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clock_seq_hi_and_reserved to zero and one, respectively. */
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uuid->data[8] = (uuid->data[8] & 0x3f) | 0x80;
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/* Set the four most significant bits (bits 12 through 15) of the
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time_hi_and_version field to the 4-bit version number.
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*/
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uuid->data[6] = (uuid->data[6] & 0xf) | 0x40;
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}
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int qemu_uuid_is_null(const QemuUUID *uu)
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{
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static QemuUUID null_uuid;
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return qemu_uuid_is_equal(uu, &null_uuid);
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}
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int qemu_uuid_is_equal(const QemuUUID *lhv, const QemuUUID *rhv)
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{
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return memcmp(lhv, rhv, sizeof(QemuUUID)) == 0;
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}
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void qemu_uuid_unparse(const QemuUUID *uuid, char *out)
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{
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const unsigned char *uu = &uuid->data[0];
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snprintf(out, UUID_FMT_LEN + 1, UUID_FMT,
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uu[0], uu[1], uu[2], uu[3], uu[4], uu[5], uu[6], uu[7],
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uu[8], uu[9], uu[10], uu[11], uu[12], uu[13], uu[14], uu[15]);
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}
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char *qemu_uuid_unparse_strdup(const QemuUUID *uuid)
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{
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const unsigned char *uu = &uuid->data[0];
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return g_strdup_printf(UUID_FMT,
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uu[0], uu[1], uu[2], uu[3], uu[4], uu[5], uu[6],
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uu[7], uu[8], uu[9], uu[10], uu[11], uu[12],
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uu[13], uu[14], uu[15]);
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}
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static bool qemu_uuid_is_valid(const char *str)
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{
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int i;
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for (i = 0; i < strlen(str); i++) {
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const char c = str[i];
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if (i == 8 || i == 13 || i == 18 || i == 23) {
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if (str[i] != '-') {
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return false;
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}
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} else {
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if ((c >= '0' && c <= '9') ||
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(c >= 'A' && c <= 'F') ||
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(c >= 'a' && c <= 'f')) {
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continue;
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}
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return false;
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}
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}
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return i == 36;
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}
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int qemu_uuid_parse(const char *str, QemuUUID *uuid)
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{
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unsigned char *uu = &uuid->data[0];
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int ret;
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if (!qemu_uuid_is_valid(str)) {
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return -1;
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}
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ret = sscanf(str, UUID_FMT, &uu[0], &uu[1], &uu[2], &uu[3],
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&uu[4], &uu[5], &uu[6], &uu[7], &uu[8], &uu[9],
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&uu[10], &uu[11], &uu[12], &uu[13], &uu[14],
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&uu[15]);
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if (ret != 16) {
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return -1;
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}
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return 0;
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}
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/* Swap from UUID format endian (BE) to the opposite or vice versa.
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*/
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QemuUUID qemu_uuid_bswap(QemuUUID uuid)
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{
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bswap32s(&uuid.fields.time_low);
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bswap16s(&uuid.fields.time_mid);
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bswap16s(&uuid.fields.time_high_and_version);
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return uuid;
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}
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/* djb2 hash algorithm */
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uint32_t qemu_uuid_hash(const void *uuid)
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{
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QemuUUID *qid = (QemuUUID *) uuid;
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uint32_t h = 5381;
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int i;
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for (i = 0; i < ARRAY_SIZE(qid->data); i++) {
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h = (h << 5) + h + qid->data[i];
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}
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return h;
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}
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