Add and use rand_between.

btpd/btpd.c

@@ -145,7 +145,7 @@ btpd_init(void)
     m_peer_id[sizeof(BTPD_VERSION) - 1] = '|';
     srandom(time(NULL));
     for (int i = sizeof(BTPD_VERSION); i < 20; i++)
-        m_peer_id[i] = rint(random() * 255.0 / RAND_MAX);
+        m_peer_id[i] = rand_between(0, 255);
 
     net_init();
     ipc_init();

btpd/download_subr.c

@@ -305,7 +305,7 @@ dl_choose_rarest(struct peer *p, uint32_t *res)
         }
     }
     if (min_c > 1) {
-        min_c = 1 + rint((double)random() * (min_c - 1) / RAND_MAX);
+        min_c = rand_between(1, min_c);
         for (i = min_i; min_c > 0; i++) {
             if (dl_piece_startable(p, i)
                 && tp->piece_count[i] == tp->piece_count[min_i]) {

misc/subr.c

@@ -5,6 +5,7 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
+#include <math.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -139,3 +140,9 @@ round_to_page(size_t size)
         size += psize - rem;
     return size;
 }
+
+long
+rand_between(long min, long max)
+{
+    return min + (long)rint((double)random() * (max - min) / RAND_MAX);
+}

misc/subr.h

@@ -18,4 +18,6 @@ int canon_path(const char *path, char **res);
 
 size_t round_to_page(size_t size);
 
+long rand_between(long min, long max);
+
 #endif