1 files changed, 72 insertions, 0 deletions
diff --git a/lib/random_dev_urandom.c b/lib/random_dev_urandom.c
new file mode 100644
index 000000000000..e508fe9f3e3c
--- /dev/null
+++ b/lib/random_dev_urandom.c
@@ -0,0 +1,72 @@
+/*
+                            __  __            _
+                         ___\ \/ /_ __   __ _| |_
+                        / _ \\  /| '_ \ / _` | __|
+                       |  __//  \| |_) | (_| | |_
+                        \___/_/\_\ .__/ \__,_|\__|
+                                 |_| XML parser
+
+   Copyright (c) 2017-2026 Sebastian Pipping <sebastian@pipping.org>
+   Copyright (c) 2026      Matthew Fernandez <matthew.fernandez@gmail.com>
+   Licensed under the MIT license:
+
+   Permission is  hereby granted,  free of charge,  to any  person obtaining
+   a  copy  of  this  software   and  associated  documentation  files  (the
+   "Software"),  to  deal in  the  Software  without restriction,  including
+   without  limitation the  rights  to use,  copy,  modify, merge,  publish,
+   distribute, sublicense, and/or sell copies of the Software, and to permit
+   persons  to whom  the Software  is  furnished to  do so,  subject to  the
+   following conditions:
+
+   The above copyright  notice and this permission notice  shall be included
+   in all copies or substantial portions of the Software.
+
+   THE  SOFTWARE  IS  PROVIDED  "AS  IS",  WITHOUT  WARRANTY  OF  ANY  KIND,
+   EXPRESS  OR IMPLIED,  INCLUDING  BUT  NOT LIMITED  TO  THE WARRANTIES  OF
+   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+   NO EVENT SHALL THE AUTHORS OR  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+   DAMAGES OR  OTHER LIABILITY, WHETHER  IN AN  ACTION OF CONTRACT,  TORT OR
+   OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+   USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include "random_dev_urandom.h"
+
+#if ! defined(_POSIX_C_SOURCE)                                                 \
+    || (defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE < 200809L))
+#  define _POSIX_C_SOURCE 200809L // for O_CLOEXEC
+#endif
+
+#include <errno.h>
+#include <fcntl.h>  // open
+#include <unistd.h> // close
+
+/* Extract entropy from /dev/urandom */
+bool
+writeRandomBytes_dev_urandom(void *target, size_t count) {
+  int success = false; /* full count bytes written? */
+  size_t bytesWrittenTotal = 0;
+
+  const int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
+  if (fd < 0) {
+    return 0;
+  }
+
+  do {
+    void *const currentTarget = (void *)((char *)target + bytesWrittenTotal);
+    const size_t bytesToWrite = count - bytesWrittenTotal;
+
+    errno = 0;
+
+    const ssize_t bytesWrittenMore = read(fd, currentTarget, bytesToWrite);
+
+    if (bytesWrittenMore > 0) {
+      bytesWrittenTotal += bytesWrittenMore;
+      if (bytesWrittenTotal >= count)
+        success = true;
+    }
+  } while (! success && (errno == EINTR));
+
+  close(fd);
+  return success;
+}