From be419a9e4cac9428c432d8d7907778d31c12d409 Mon Sep 17 00:00:00 2001
From: Dimitri Staessens <dimitri@ouroboros.rocks>
Date: Sun, 21 Jun 2026 12:44:13 +0200
Subject: lib: Loop getrandom on short reads and EINTR

The getrandom() function may return fewer bytes than requested or fail
with EINTR.  Loop until the buffer is filled, retrying on EINTR,
instead of trusting a single call to fill the buffer completely.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
---
 src/lib/random.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

(limited to 'src/lib')

diff --git a/src/lib/random.c b/src/lib/random.c
index 2c9a6c0d..a132f470 100644
--- a/src/lib/random.c
+++ b/src/lib/random.c
@@ -28,6 +28,8 @@
 #include <stdlib.h>
 #elif defined(HAVE_SYS_RANDOM)
 #include <sys/random.h>
+#include <errno.h>
+#include <stdint.h>
 #elif defined(HAVE_LIBGCRYPT)
 #include <gcrypt.h>
 #elif defined(HAVE_OPENSSL_RNG)
@@ -42,7 +44,21 @@ int random_buffer(void * buf,
         arc4random_buf(buf, len);
         return 0;
 #elif defined(HAVE_SYS_RANDOM)
-        return getrandom(buf, len, GRND_NONBLOCK);
+        size_t  off = 0;
+        ssize_t ret;
+
+        while (off < len) {
+                ret = getrandom((uint8_t *) buf + off, len - off,
+                                GRND_NONBLOCK);
+                if (ret < 0) {
+                        if (errno == EINTR)
+                                continue;
+                        return -1;
+                }
+                off += (size_t) ret;
+        }
+
+        return 0;
 #elif defined(HAVE_LIBGCRYPT)
         gcry_randomize(buf, len, GCRY_STRONG_RANDOM);
         return 0;
-- 
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