From db67a20595be279e7db9f5f8e27bd94534efb8d4 Mon Sep 17 00:00:00 2001 From: Vladimir Dronnikov Date: Thu, 15 Oct 2009 09:24:25 +0200 Subject: move generate_uuid from mkswap to libbb Signed-off-by: Vladimir Dronnikov Signed-off-by: Denys Vlasenko --- libbb/xfuncs.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) (limited to 'libbb') diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c index aa08129..e47b01d 100644 --- a/libbb/xfuncs.c +++ b/libbb/xfuncs.c @@ -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; +} -- cgit v1.1