From c306f4eab68ed5c084f993499a323cc98b480574 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 30 Oct 2014 21:34:49 -0400
Subject: util: unify how we see srand()

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
---
 src/cdrom_id/cdrom_id.c   |  2 +-
 src/scsi_id/scsi_serial.c |  2 +-
 src/shared/util.c         | 53 +++++++++++++++++++++++++++--------------------
 src/shared/util.h         |  1 +
 4 files changed, 33 insertions(+), 25 deletions(-)

diff --git a/src/cdrom_id/cdrom_id.c b/src/cdrom_id/cdrom_id.c
index 9b3ab7021e..e13657b495 100644
--- a/src/cdrom_id/cdrom_id.c
+++ b/src/cdrom_id/cdrom_id.c
@@ -925,7 +925,7 @@ int main(int argc, char *argv[])
                 goto exit;
         }
 
-        srand((unsigned int)getpid());
+        initialize_srand();
         for (cnt = 20; cnt > 0; cnt--) {
                 struct timespec duration;
 
diff --git a/src/scsi_id/scsi_serial.c b/src/scsi_id/scsi_serial.c
index 1806498503..3e30aed419 100644
--- a/src/scsi_id/scsi_serial.c
+++ b/src/scsi_id/scsi_serial.c
@@ -865,7 +865,7 @@ int scsi_get_serial(struct udev *udev,
         int retval;
 
         memzero(dev_scsi->serial, len);
-        srand((unsigned int)getpid());
+        initialize_srand();
         for (cnt = 20; cnt > 0; cnt--) {
                 struct timespec duration;
 
diff --git a/src/shared/util.c b/src/shared/util.c
index 3cad297873..e953363483 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -701,8 +701,36 @@ int dev_urandom(void *p, size_t n) {
         return 0;
 }
 
-void random_bytes(void *p, size_t n) {
+void initialize_srand(void) {
         static bool srand_called = false;
+        unsigned x;
+#ifdef HAVE_SYS_AUXV_H
+        void *auxv;
+#endif
+
+        if (srand_called)
+                return;
+
+        x = 0;
+
+#ifdef HAVE_SYS_AUXV_H
+        /* The kernel provides us with a bit of entropy in auxv, so
+         * let's try to make use of that to seed the pseudo-random
+         * generator. It's better than nothing... */
+
+        auxv = (void*) getauxval(AT_RANDOM);
+        if (auxv)
+                x ^= *(unsigned*) auxv;
+#endif
+
+        x ^= (unsigned) now(CLOCK_REALTIME);
+        x ^= (unsigned) gettid();
+
+        srand(x);
+        srand_called = true;
+}
+
+void random_bytes(void *p, size_t n) {
         uint8_t *q;
         int r;
 
@@ -713,28 +741,7 @@ void random_bytes(void *p, size_t n) {
         /* If some idiot made /dev/urandom unavailable to us, he'll
          * get a PRNG instead. */
 
-        if (!srand_called) {
-                unsigned x = 0;
-
-#ifdef HAVE_SYS_AUXV_H
-                /* The kernel provides us with a bit of entropy in
-                 * auxv, so let's try to make use of that to seed the
-                 * pseudo-random generator. It's better than
-                 * nothing... */
-
-                void *auxv;
-
-                auxv = (void*) getauxval(AT_RANDOM);
-                if (auxv)
-                        x ^= *(unsigned*) auxv;
-#endif
-
-                x ^= (unsigned) now(CLOCK_REALTIME);
-                x ^= (unsigned) gettid();
-
-                srand(x);
-                srand_called = true;
-        }
+        initialize_srand();
 
         for (q = p; q < (uint8_t*) p + n; q ++)
                 *q = rand();
diff --git a/src/shared/util.h b/src/shared/util.h
index 9550aa19f9..f57a73cec6 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -192,6 +192,7 @@ bool ignore_file(const char *filename) _pure_;
 
 int dev_urandom(void *p, size_t n);
 void random_bytes(void *p, size_t n);
+void initialize_srand(void);
 
 /* For basic lookup tables with strictly enumerated entries */
 #define __DEFINE_STRING_TABLE_LOOKUP(name,type,scope)                   \
-- 
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