From 7b8f69404fbd524bd1155633f7fc0db302aa62ba Mon Sep 17 00:00:00 2001
From: Ivan Grokhotkov <ivan@espressif.com>
Date: Fri, 15 Dec 2023 13:50:48 +0100
Subject: [PATCH] feat(linux): provide getrandom implementation for macOS

This makes getrandom(2) usable when compiling with IDF_TARGET=linux
on a macOS host.
---
 components/linux/CMakeLists.txt       |  7 ++++++-
 components/linux/getrandom.c          | 28 +++++++++++++++++++++++++++
 components/linux/include/sys/random.h | 15 ++++++++++++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 components/linux/getrandom.c
 create mode 100644 components/linux/include/sys/random.h

diff --git a/components/linux/CMakeLists.txt b/components/linux/CMakeLists.txt
index b7d2bd46a7..e29218d213 100644
--- a/components/linux/CMakeLists.txt
+++ b/components/linux/CMakeLists.txt
@@ -3,5 +3,10 @@ if(NOT "${target}" STREQUAL "linux")
     return()
 endif()
 
+if(CMAKE_HOST_SYSTEM_NAME STREQUAL "Darwin")
+    list(APPEND srcs getrandom.c)
+endif()
+
 idf_component_register(INCLUDE_DIRS include
-                       REQUIRED_IDF_TARGETS linux)
+                       REQUIRED_IDF_TARGETS linux
+                       SRCS ${srcs})
diff --git a/components/linux/getrandom.c b/components/linux/getrandom.c
new file mode 100644
index 0000000000..5f068ee3fd
--- /dev/null
+++ b/components/linux/getrandom.c
@@ -0,0 +1,28 @@
+/*
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "sys/random.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+
+
+// getrandom() is not available on macOS, so we read from /dev/urandom instead.
+
+int getrandom(void *buf, size_t buflen, unsigned int flags)
+{
+    int fd = open("/dev/urandom", O_RDONLY);
+    if (fd < 0) {
+        return -1;
+    }
+    ssize_t ret = read(fd, buf, buflen);
+    close(fd);
+    if (ret < 0) {
+        return -1;
+    }
+    return 0;
+}
diff --git a/components/linux/include/sys/random.h b/components/linux/include/sys/random.h
new file mode 100644
index 0000000000..b495f327bc
--- /dev/null
+++ b/components/linux/include/sys/random.h
@@ -0,0 +1,15 @@
+/*
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+
+#include_next "sys/random.h"
+
+#if __APPLE__
+#include <stddef.h>
+
+int getrandom(void *buf, size_t buflen, unsigned int flags);
+
+#endif  // __APPLE__