random-util: change high_quality_required bool parameter into a flags parameter

No change in behaviour, just some refactoring.

src/basic/random-util.c

@@ -65,19 +65,17 @@ int rdrand64(uint64_t *ret) {
 #endif
 }
 
-int genuine_random_bytes(void *p, size_t n, bool high_quality_required) {
+int genuine_random_bytes(void *p, size_t n, RandomFlags flags) {
         static int have_syscall = -1;
 
         _cleanup_close_ int fd = -1;
         size_t already_done = 0;
         int r;
 
-        /* Gathers some randomness from the kernel. This call will never block. If
-         * high_quality_required, it will always return some data from the kernel,
-         * regardless of whether the random pool is fully initialized or not.
-         * Otherwise, it will return success if at least some random bytes were
-         * successfully acquired, and an error if the kernel has no entropy whatsover
-         * for us. */
+        /* Gathers some randomness from the kernel. This call will never block. If RANDOM_EXTEND_WITH_PSEUDO is unset,
+         * it will always return some data from the kernel, regardless of whether the random pool is fully initialized
+         * or not.  Otherwise, it will return success if at least some random bytes were successfully acquired, and an
+         * error if the kernel has no entropy whatsover for us. */
 
         /* Use the getrandom() syscall unless we know we don't have it. */
         if (have_syscall != 0 && !HAS_FEATURE_MEMORY_SANITIZER) {
@@ -86,7 +84,7 @@ int genuine_random_bytes(void *p, size_t n, bool high_quality_required) {
                         have_syscall = true;
                         if ((size_t) r == n)
                                 return 0;
-                        if (!high_quality_required) {
+                        if (FLAGS_SET(flags, RANDOM_EXTEND_WITH_PSEUDO)) {
                                 /* Fill in the remaining bytes using pseudorandom values */
                                 pseudo_random_bytes((uint8_t*) p + r, n - r);
                                 return 0;
@@ -110,7 +108,7 @@ int genuine_random_bytes(void *p, size_t n, bool high_quality_required) {
                          * a best-effort basis. */
                         have_syscall = true;
 
-                        if (!high_quality_required) {
+                        if (FLAGS_SET(flags, RANDOM_EXTEND_WITH_PSEUDO)) {
                                 uint64_t u;
                                 size_t k;
 
@@ -207,7 +205,7 @@ void pseudo_random_bytes(void *p, size_t n) {
 
 void random_bytes(void *p, size_t n) {
 
-        if (genuine_random_bytes(p, n, false) >= 0)
+        if (genuine_random_bytes(p, n, RANDOM_EXTEND_WITH_PSEUDO) >= 0)
                 return;
 
         /* If for some reason some user made /dev/urandom unavailable to us, or the kernel has no entropy, use a PRNG instead. */

src/basic/random-util.h

@@ -5,9 +5,13 @@
 #include <stddef.h>
 #include <stdint.h>
 
-int genuine_random_bytes(void *p, size_t n, bool high_quality_required); /* returns "genuine" randomness, optionally filled upwith pseudo random, if not enough is available */
-void pseudo_random_bytes(void *p, size_t n);                             /* returns only pseudo-randommess (but possibly seeded from something better) */
-void random_bytes(void *p, size_t n);                                    /* returns genuine randomness if cheaply available, and pseudo randomness if not. */
+typedef enum RandomFlags {
+        RANDOM_EXTEND_WITH_PSEUDO = 1 << 0, /* If we can't get enough genuine randomness, but some, fill up the rest with pseudo-randomness */
+} RandomFlags;
+
+int genuine_random_bytes(void *p, size_t n, RandomFlags flags); /* returns "genuine" randomness, optionally filled upwith pseudo random, if not enough is available */
+void pseudo_random_bytes(void *p, size_t n);                    /* returns only pseudo-randommess (but possibly seeded from something better) */
+void random_bytes(void *p, size_t n);                           /* returns genuine randomness if cheaply available, and pseudo randomness if not. */
 
 void initialize_srand(void);
 

src/firstboot/firstboot.c

@@ -647,7 +647,7 @@ static int process_root_password(void) {
         if (!arg_root_password)
                 return 0;
 
-        r = genuine_random_bytes(raw, 16, true);
+        r = genuine_random_bytes(raw, 16, 0);
         if (r < 0)
                 return log_error_errno(r, "Failed to get salt: %m");
 

src/libsystemd/sd-id128/sd-id128.c

@@ -272,7 +272,7 @@ _public_ int sd_id128_randomize(sd_id128_t *ret) {
 
         assert_return(ret, -EINVAL);
 
-        r = genuine_random_bytes(&t, sizeof t, true);
+        r = genuine_random_bytes(&t, sizeof t, 0);
         if (r < 0)
                 return r;
 

src/test/test-random-util.c

@@ -5,14 +5,14 @@
 #include "log.h"
 #include "tests.h"
 
-static void test_genuine_random_bytes(bool high_quality_required) {
+static void test_genuine_random_bytes(RandomFlags flags) {
         uint8_t buf[16] = {};
         unsigned i;
 
         log_info("/* %s */", __func__);
 
         for (i = 1; i < sizeof buf; i++) {
-                assert_se(genuine_random_bytes(buf, i, high_quality_required) == 0);
+                assert_se(genuine_random_bytes(buf, i, flags) == 0);
                 if (i + 1 < sizeof buf)
                         assert_se(buf[i] == 0);
 
@@ -54,8 +54,8 @@ static void test_rdrand64(void) {
 int main(int argc, char **argv) {
         test_setup_logging(LOG_DEBUG);
 
-        test_genuine_random_bytes(false);
-        test_genuine_random_bytes(true);
+        test_genuine_random_bytes(RANDOM_EXTEND_WITH_PSEUDO);
+        test_genuine_random_bytes(0);
 
         test_pseudo_random_bytes();