URandom: replace /dev/urandom file with getrandom syscall

src/system/linux/system/urandom.hpp

@@ -9,55 +9,36 @@ SPDX-License-Identifier: GPL-2.0-or-later
 #include "core/error.hpp"
 #include "utils/log.hpp"
 #include "utils/random.hpp"
-#include "utils/sugar/unique_fd.hpp"
 
-#include <cerrno>
-#include <cstring>
-
-#include <unistd.h>
+#include <sys/random.h>
 
 
 class URandom final : public Random
 {
-    unique_fd ufd;
-
 public:
-    URandom()
-    : ufd(open("/dev/urandom", O_RDONLY))
-    {
-        if (ufd.is_open()) {
-            LOG(LOG_INFO, "using /dev/urandom as random source");
-        }
-        else {
-            LOG(LOG_INFO, "access to /dev/urandom failed: %s", strerror(errno));
-
-            ufd.reset(open("/dev/random", O_RDONLY));
-            if (ufd.is_open()) {
-                LOG(LOG_INFO, "using /dev/random as random source");
-            }
-            else {
-                LOG(LOG_ERR, "random source failed to provide random data : couldn't open device");
-                throw Error(ERR_RANDOM_SOURCE_FAILED);
-            }
-        }
-    }
-
     void random(writable_bytes_view buf) override
     {
-        // TODO This is basically a blocking read, we should provide timeout management and behaviour
         uint8_t* data = buf.data();
         size_t len = buf.size();
         while (len) {
-            ssize_t ret = ::read(ufd.fd(), data, len);
-            if (REDEMPTION_UNLIKELY(ret <= 0)) {
+#if defined(__sun) && defined(__SVR4)
+            /* On Solaris, getrandom() is limited to returning up to 1024 bytes. */
+            size_t len_max = 1024;
+#else
+            size_t len_max = LONG_MAX;
+#endif
+            // TODO This is basically a blocking read, we should provide timeout management and behaviour
+            ssize_t n = getrandom(data, len < len_max ? len : len_max, 0);
+            if (REDEMPTION_UNLIKELY(n < 0)) {
                 if (errno == EINTR) {
                     continue;
                 }
+                // ignore errno == EAGAIN because GRND_NONBLOCK flag is not used
                 LOG(LOG_ERR, "random source failed to provide random data [%s]", strerror(errno));
                 throw Error(ERR_RANDOM_SOURCE_FAILED);
             }
-            data += ret;
-            len -= ret;
+            data += n;
+            len -= n;
         }
     }
 };