Re: [Libvir] [patch 1/3] Add UUID generation to qemud

Monday, 26 February 2007

Mark McLoughlin wrote:

...
 +static int
 +qemudGenerateRandomBytes(unsigned char *buf,
 +                         int buflen)
 +{
 +    int fd;
 +
 +    if ((fd = open("/dev/urandom", O_RDONLY)) < 0)
 +        return errno;
 +
 +    while (buflen > 0) {
 +        int n;
 +
 +        if ((n = read(fd, buf, buflen)) <= 0) {
 +            if (errno == EINTR)
 +                continue;
 +            close(fd);
 +            return n < 0 ? errno : ENODATA;
 +        }
 +
 +        buf += n;
 +        buflen -= n;
 +    }
 +
 +    close(fd);
 +
 +    return 0;
 +} 
This function would actually be quite useful as a generally available 
function.  In the remote patch I have added the following to configure.in:

dnl /dev/urandom
AC_CHECK_FILES([/dev/urandom])

and then in C code I can write:

#if HAVE__DEV_URANDOM      /* NB double underscore */
  // random blah blah
#else
  // pseudorandom blah blah
#endif

Rich.

-- 
Emerging Technologies, Red Hat  http://et.redhat.com/~rjones/
64 Baker Street, London, W1U 7DF     Mobile: +44 7866 314 421
  "[Negative numbers] darken the very whole doctrines of the equations
  and make dark of the things which are in their nature excessively
  obvious and simple" (Francis Maseres FRS, mathematician, 1759)

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