ddf: use better random number generation.

use /dev/urandom rather than calls to 'random()' if possible.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/super-ddf.c b/super-ddf.c
index 8725eabddf5c5def8c9509c8d3101f7cfbf748d5..009fbfb6e8e20fcc215eb1d98d228c532481cc03 100644 (file)
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -1493,10 +1493,20 @@ static int update_super_ddf(struct supertype *st, struct mdinfo *info,
        return rv;
 }
 
+__u32 random32(void)
+{
+       __u32 rv;
+       int rfd = open("/dev/urandom", O_RDONLY);
+       if (rfd < 0 || read(rfd, &rv, 4) != 4)
+               rv = random();
+       if (rfd >= 0)
+               close(rfd);
+       return rv;
+}
+
 static void make_header_guid(char *guid)
 {
        __u32 stamp;
-       int rfd;
        /* Create a DDF Header of Virtual Disk GUID */
 
        /* 24 bytes of fiction required.
@@ -1511,11 +1521,8 @@ static void make_header_guid(char *guid)
        memcpy(guid+12, &stamp, 4);
        stamp = __cpu_to_be32(time(0) - DECADE);
        memcpy(guid+16, &stamp, 4);
-       rfd = open("/dev/urandom", O_RDONLY);
-       if (rfd < 0 || read(rfd, &stamp, 4) != 4)
-               stamp = random();
+       stamp = random32();
        memcpy(guid+20, &stamp, 4);
-       if (rfd >= 0) close(rfd);
 }
 
 static int init_super_ddf_bvd(struct supertype *st,
@@ -2148,12 +2155,12 @@ static int add_to_super_ddf(struct supertype *st,
        tm = localtime(&now);
        sprintf(dd->disk.guid, "%8s%04d%02d%02d",
                T10, tm->tm_year+1900, tm->tm_mon+1, tm->tm_mday);
-       *(__u32*)(dd->disk.guid + 16) = random();
-       *(__u32*)(dd->disk.guid + 20) = random();
+       *(__u32*)(dd->disk.guid + 16) = random32();
+       *(__u32*)(dd->disk.guid + 20) = random32();
 
        do {
                /* Cannot be bothered finding a CRC of some irrelevant details*/
-               dd->disk.refnum = random();
+               dd->disk.refnum = random32();
                for (i = __be16_to_cpu(ddf->active->max_pd_entries) - 1;
                     i >= 0; i--)
                        if (ddf->phys->entries[i].refnum == dd->disk.refnum)