rand_unix.c: fix --with-rand-seed=none build

Fixes a compiler warning about an unused syscall_random()
and cleans up the OPENSSL_RAND_SEED preprocessor logic.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/779)

1 files changed, 22 insertions, 15 deletions

diff --git a/crypto/rand/rand_unix.c b/crypto/rand/rand_unix.c
index f7819611d5..e53b876dd3 100644
--- a/crypto/rand/rand_unix.c
+++ b/crypto/rand/rand_unix.c
@@ -77,6 +77,17 @@ static uint64_t get_timer_bits(void);
 # endif
 #endif /* defined(OPENSSL_SYS_UNIX) || defined(__DJGPP__) */
 
+#if defined(OPENSSL_RAND_SEED_NONE)
+/* none means none. this simplifies the following logic */
+# undef OPENSSL_RAND_SEED_OS
+# undef OPENSSL_RAND_SEED_GETRANDOM
+# undef OPENSSL_RAND_SEED_LIBRANDOM
+# undef OPENSSL_RAND_SEED_DEVRANDOM
+# undef OPENSSL_RAND_SEED_RDTSC
+# undef OPENSSL_RAND_SEED_RDCPU
+# undef OPENSSL_RAND_SEED_EGD
+#endif
+
 #if (defined(OPENSSL_SYS_VXWORKS) || defined(OPENSSL_SYS_UEFI)) && \
         !defined(OPENSSL_RAND_SEED_NONE)
 # error "UEFI and VXWorks only support seeding NONE"
@@ -86,8 +97,6 @@ static uint64_t get_timer_bits(void);
     || defined(OPENSSL_SYS_VMS) || defined(OPENSSL_SYS_VXWORKS) \
     || defined(OPENSSL_SYS_UEFI))
 
-static ssize_t syscall_random(void *buf, size_t buflen);
-
 # if defined(OPENSSL_SYS_VOS)
 
 #  ifndef OPENSSL_RAND_SEED_OS
@@ -244,6 +253,7 @@ static ssize_t sysctl_random(char *buf, size_t buflen)
 }
 #  endif
 
+#  if defined(OPENSSL_RAND_SEED_GETRANDOM)
 /*
  * syscall_random(): Try to get random data using a system call
  * returns the number of bytes returned in buf, or < 0 on error.
@@ -302,8 +312,9 @@ static ssize_t syscall_random(void *buf, size_t buflen)
     return -1;
 #  endif
 }
+#  endif    /* defined(OPENSSL_RAND_SEED_GETRANDOM) */
 
-#if  !defined(OPENSSL_RAND_SEED_NONE) && defined(OPENSSL_RAND_SEED_DEVRANDOM)
+#  if defined(OPENSSL_RAND_SEED_DEVRANDOM)
 static const char *random_device_paths[] = { DEVRANDOM };
 static struct random_device {
     int fd;
@@ -410,9 +421,7 @@ void rand_pool_keep_random_devices_open(int keep)
     keep_random_devices_open = keep;
 }
 
-#  else     /* defined(OPENSSL_RAND_SEED_NONE)
-             * || !defined(OPENSSL_RAND_SEED_DEVRANDOM)
-             */
+#  else     /* !defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 
 int rand_pool_init(void)
 {
@@ -427,9 +436,7 @@ void rand_pool_keep_random_devices_open(int keep)
 {
 }
 
-#  endif    /* !defined(OPENSSL_RAND_SEED_NONE)
-             * && defined(OPENSSL_RAND_SEED_DEVRANDOM)
-             */
+#  endif    /* defined(OPENSSL_RAND_SEED_DEVRANDOM) */
 
 /*
  * Try the various seeding methods in turn, exit when successful.
@@ -450,14 +457,14 @@ void rand_pool_keep_random_devices_open(int keep)
  */
 size_t rand_pool_acquire_entropy(RAND_POOL *pool)
 {
-#  ifdef OPENSSL_RAND_SEED_NONE
+#  if defined(OPENSSL_RAND_SEED_NONE)
     return rand_pool_entropy_available(pool);
 #  else
     size_t bytes_needed;
     size_t entropy_available = 0;
     unsigned char *buffer;
 
-#   ifdef OPENSSL_RAND_SEED_GETRANDOM
+#   if defined(OPENSSL_RAND_SEED_GETRANDOM)
     {
         ssize_t bytes;
         /* Maximum allowed number of consecutive unsuccessful attempts */
@@ -487,7 +494,7 @@ size_t rand_pool_acquire_entropy(RAND_POOL *pool)
     }
 #   endif
 
-#   ifdef OPENSSL_RAND_SEED_DEVRANDOM
+#   if defined(OPENSSL_RAND_SEED_DEVRANDOM)
     bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
     {
         size_t i;
@@ -524,19 +531,19 @@ size_t rand_pool_acquire_entropy(RAND_POOL *pool)
     }
 #   endif
 
-#   ifdef OPENSSL_RAND_SEED_RDTSC
+#   if defined(OPENSSL_RAND_SEED_RDTSC)
     entropy_available = rand_acquire_entropy_from_tsc(pool);
     if (entropy_available > 0)
         return entropy_available;
 #   endif
 
-#   ifdef OPENSSL_RAND_SEED_RDCPU
+#   if defined(OPENSSL_RAND_SEED_RDCPU)
     entropy_available = rand_acquire_entropy_from_cpu(pool);
     if (entropy_available > 0)
         return entropy_available;
 #   endif
 
-#   ifdef OPENSSL_RAND_SEED_EGD
+#   if defined(OPENSSL_RAND_SEED_EGD)
     bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
     if (bytes_needed > 0) {
         static const char *paths[] = { DEVRANDOM_EGD, NULL };