Revert "Move random-related defines from e_os.h to rand_unix.c"

This reverts commit 7b18d1a53f932391bbc599a4717d6f98a597849c, which moved the
DEVRANDOM and DEVRANDOM_EGD defines into rand_unix.c. That change introduced
the regression that the compiler complains about missing declarations in
apps/version.c when OpenSSL is configured using `--with-rand-seed=devrandom`
(resp. `--with-rand-seed=egd`):

apps/version.c:173:42: error: 'DEVRANDOM' undeclared
             static const char *dev[] = { DEVRANDOM, NULL };
                                          ^~~~~~~~~

Fixes #10759

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10764)

1 files changed, 45 insertions, 0 deletions

diff --git a/e_os.h b/e_os.h
index 336c821c3b..f607045e14 100644
--- a/e_os.h
+++ b/e_os.h
@@ -22,6 +22,51 @@
  * outside; this file e_os.h is not part of the exported interface.
  */
 
+# ifndef DEVRANDOM
+/*
+ * set this to a comma-separated list of 'random' device files to try out. By
+ * default, we will try to read at least one of these files
+ */
+#  define DEVRANDOM "/dev/urandom", "/dev/random", "/dev/hwrng", "/dev/srandom"
+#  if defined(__linux) && !defined(__ANDROID__)
+#   ifndef DEVRANDOM_WAIT
+#    define DEVRANDOM_WAIT   "/dev/random"
+#   endif
+/*
+ * Linux kernels 4.8 and later changes how their random device works and there
+ * is no reliable way to tell that /dev/urandom has been seeded -- getentropy(2)
+ * should be used instead.
+ */
+#   ifndef DEVRANDOM_SAFE_KERNEL
+#    define DEVRANDOM_SAFE_KERNEL        4, 8
+#   endif
+/*
+ * Some operating systems do not permit select(2) on their random devices,
+ * defining this to zero will force the use of read(2) to extract one byte
+ * from /dev/random.
+ */
+#   ifndef DEVRANDM_WAIT_USE_SELECT
+#    define DEVRANDM_WAIT_USE_SELECT     1
+#   endif
+/*
+ * Define the shared memory identifier used to indicate if the operating
+ * system has properly seeded the DEVRANDOM source.
+ */
+#   ifndef OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID
+#    define OPENSSL_RAND_SEED_DEVRANDOM_SHM_ID 114
+#   endif
+
+#  endif
+# endif
+# if !defined(OPENSSL_NO_EGD) && !defined(DEVRANDOM_EGD)
+/*
+ * set this to a comma-separated list of 'egd' sockets to try out. These
+ * sockets will be tried in the order listed in case accessing the device
+ * files listed in DEVRANDOM did not return enough randomness.
+ */
+#  define DEVRANDOM_EGD "/var/run/egd-pool", "/dev/egd-pool", "/etc/egd-pool", "/etc/entropy"
+# endif
+
 # if defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)
 #  define NO_CHMOD
 #  define NO_SYSLOG