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move generate_uuid from mkswap to libbb

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Signed-off-by: Vladimir Dronnikov <dronnikov@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Vladimir Dronnikov
2009-10-15 09:24:25 +02:00
committed by Denys Vlasenko
parent 7eabffafa5
commit db67a20595
3 changed files with 79 additions and 79 deletions
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63
libbb/xfuncs.c
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@@ -209,3 +209,66 @@ int FAST_FUNC tcsetattr_stdin_TCSANOW(const struct termios *tp)
{
return tcsetattr(STDIN_FILENO, TCSANOW, tp);
}
void FAST_FUNC generate_uuid(uint8_t *buf)
{
/* http://www.ietf.org/rfc/rfc4122.txt
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | time_low |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | time_mid | time_hi_and_version |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |clk_seq_and_variant | node (0-1) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | node (2-5) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* IOW, uuid has this layout:
* uint32_t time_low (big endian)
* uint16_t time_mid (big endian)
* uint16_t time_hi_and_version (big endian)
* version is a 4-bit field:
* 1 Time-based
* 2 DCE Security, with embedded POSIX UIDs
* 3 Name-based (MD5)
* 4 Randomly generated
* 5 Name-based (SHA-1)
* uint16_t clk_seq_and_variant (big endian)
* variant is a 3-bit field:
* 0xx Reserved, NCS backward compatibility
* 10x The variant specified in rfc4122
* 110 Reserved, Microsoft backward compatibility
* 111 Reserved for future definition
* uint8_t node[6]
*
* For version 4, these bits are set/cleared:
* time_hi_and_version & 0x0fff | 0x4000
* clk_seq_and_variant & 0x3fff | 0x8000
*/
pid_t pid;
int i;
i = open("/dev/urandom", O_RDONLY);
if (i >= 0) {
read(i, buf, 16);
close(i);
}
/* Paranoia. /dev/urandom may be missing.
* rand() is guaranteed to generate at least [0, 2^15) range,
* but lowest bits in some libc are not so "random". */
srand(monotonic_us());
pid = getpid();
while (1) {
for (i = 0; i < 16; i++)
buf[i] ^= rand() >> 5;
if (pid == 0)
break;
srand(pid);
pid = 0;
}
/* version = 4 */
buf[4 + 2 ] = (buf[4 + 2 ] & 0x0f) | 0x40;
/* variant = 10x */
buf[4 + 2 + 2] = (buf[4 + 2 + 2] & 0x3f) | 0x80;
}