diff options
Diffstat (limited to 'tests/ubi-tests/common.c')
| -rw-r--r-- | tests/ubi-tests/common.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/tests/ubi-tests/common.c b/tests/ubi-tests/common.c index b605dd9..05cbecc 100644 --- a/tests/ubi-tests/common.c +++ b/tests/ubi-tests/common.c @@ -26,8 +26,10 @@ #include <errno.h> #include <string.h> #include <unistd.h> +#include <limits.h> #include <sys/types.h> #include <sys/stat.h> +#include <sys/time.h> #include <fcntl.h> #include "libubi.h" #include "common.h" @@ -332,3 +334,32 @@ close: close(fd); return -1; } + +/** + * seed_random_generator - randomly seed the standard pseudo-random generator. + * + * This helper function seeds the standard libc pseudo-random generator with a + * more or less random value to make sure the 'rand()' call does not return the + * same sequence every time UBI utilities run. Returns the random seed in case + * of success and a %-1 in case of error. + */ +int seed_random_generator(void) +{ + struct timeval tv; + struct timezone tz; + int seed; + + /* + * Just assume that a combination of the PID + current time is a + * reasonably random number. + */ + if (gettimeofday(&tv, &tz)) + return -1; + + seed = (unsigned int)tv.tv_sec; + seed += (unsigned int)tv.tv_usec; + seed *= getpid(); + seed %= INT_MAX; + srand(seed); + return seed; +} |