Import from old repository commit 61ef2b42a9c4ba8e1600f15bb0236765edc2ad45.

lib/random.c

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+/*
+ * Copyright (c) 2008, 2009 Nicira Networks.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+#include "random.h"
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+#include "util.h"
+
+void
+random_init(void)
+{
+    static bool inited = false;
+    if (!inited) {
+        struct timeval tv;
+        inited = true;
+        if (gettimeofday(&tv, NULL) < 0) {
+            ovs_fatal(errno, "gettimeofday");
+        }
+        srand(tv.tv_sec ^ tv.tv_usec);
+    }
+}
+
+void
+random_bytes(void *p_, size_t n)
+{
+    uint8_t *p = p_;
+    random_init();
+    while (n--) {
+        *p++ = rand();
+    }
+}
+
+uint8_t
+random_uint8(void)
+{
+    random_init();
+    return rand();
+}
+
+uint16_t
+random_uint16(void)
+{
+    if (RAND_MAX >= UINT16_MAX) {
+        random_init();
+        return rand();
+    } else {
+        uint16_t x;
+        random_bytes(&x, sizeof x);
+        return x;
+    }
+}
+
+uint32_t
+random_uint32(void)
+{
+    if (RAND_MAX >= UINT32_MAX) {
+        random_init();
+        return rand();
+    } else if (RAND_MAX == INT32_MAX) {
+        random_init();
+        return rand() | ((rand() & 1u) << 31);
+    } else {
+        uint32_t x;
+        random_bytes(&x, sizeof x);
+        return x;
+    }
+}
+
+int
+random_range(int max) 
+{
+    return random_uint32() % max;
+}