sortix--sortix/libmount/uuid.c

/*
 * Copyright (c) 2015 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * uuid.c
 * Universally unique identifier.
 */

#include <assert.h>
#include <stdbool.h>
#include <string.h>

#include <mount/uuid.h>

static bool is_hex_digit(char c)
{
	return ('0' <= c && c <= '9') ||
	       ('a' <= c && c <= 'f') ||
	       ('A' <= c && c <= 'F');
}

static char base(unsigned char bit4)
{
	return "0123456789abcdef"[bit4];
}

static unsigned char debase(char c)
{
	if ( '0' <= c && c <= '9' )
		return (unsigned char) (c - '0');
	if ( 'a' <= c && c <= 'f' )
		return (unsigned char) (c - 'a' + 10);
	if ( 'A' <= c && c <= 'F' )
		return (unsigned char) (c - 'A' + 10);
	return 0;
}

bool uuid_validate(const char* uuid)
{
	// Format: 01234567-0123-0123-0123-0123456789AB
	if ( strlen(uuid) != 36 )
		return false;
	for ( size_t i = 0; i < 36; i++ )
	{
		if ( i == 8 || i == 13 || i == 18 || i == 23 )
		{
			if ( uuid[i] != '-' )
				return false;
		}
		else
		{
			if ( !is_hex_digit(uuid[i]) )
				return false;
		}
	}
	return true;
}

void uuid_from_string(unsigned char uuid[16], const char* string)
{
	size_t output_index = 0;
	size_t i = 0;
	while ( i < 36 )
	{
		assert(string[i + 0] != '\0');
		if ( i == 8 || i == 13 || i == 18 || i == 23 )
		{
			i++;
			continue;
		}
		uuid[output_index++] = debase(string[i + 0]) << 4 |
		                       debase(string[i + 1]) << 0;
		i += 2;
	}
}

void uuid_to_string(const unsigned char uuid[16], char* string)
{
	for ( size_t i = 0; i < 4; i++ )
	{
		*string++ = base((uuid[i] >> 4) & 0xF);
		*string++ = base((uuid[i] >> 0) & 0xF);
	}
	*string++ = '-';
	for ( size_t i = 4; i < 6; i++ )
	{
		*string++ = base((uuid[i] >> 4) & 0xF);
		*string++ = base((uuid[i] >> 0) & 0xF);
	}
	*string++ = '-';
	for ( size_t i = 6; i < 8; i++ )
	{
		*string++ = base((uuid[i] >> 4) & 0xF);
		*string++ = base((uuid[i] >> 0) & 0xF);
	}
	*string++ = '-';
	for ( size_t i = 8; i < 10; i++ )
	{
		*string++ = base((uuid[i] >> 4) & 0xF);
		*string++ = base((uuid[i] >> 0) & 0xF);
	}
	*string++ = '-';
	for ( size_t i = 10; i < 16; i++ )
	{
		*string++ = base((uuid[i] >> 4) & 0xF);
		*string++ = base((uuid[i] >> 0) & 0xF);
	}
	*string = '\0';
}