LibC: Add sys/random.h with getrandom

userspace/libraries/LibC/CMakeLists.txt

@@ -49,6 +49,7 @@ set(LIBC_SOURCES
 	sys/futex.cpp
 	sys/ioctl.cpp
 	sys/mman.cpp
+	sys/random.cpp
 	sys/resource.cpp
 	sys/select.cpp
 	sys/shm.cpp

userspace/libraries/LibC/include/sys/random.h

@@ -0,0 +1,19 @@
+#ifndef _SYS_RANDOM_H
+#define _SYS_RANDOM_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_size_t
+#define __need_ssize_t
+#include <sys/types.h>
+
+#define GRND_RANDOM   0x01
+#define GRND_NONBLOCK 0x02
+
+ssize_t getrandom(void* buf, size_t size, unsigned int flags);
+
+__END_DECLS
+
+#endif

userspace/libraries/LibC/sys/random.cpp

@@ -0,0 +1,37 @@
+#include <fcntl.h>
+#include <sys/random.h>
+
+ssize_t getrandom(void* buf, size_t size, unsigned int flags)
+{
+	const unsigned int valid_flags = GRND_RANDOM | GRND_NONBLOCK;
+	if ((flags & valid_flags) != flags)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	const char* path = (flags & GRND_RANDOM) ? "/dev/random" : "/dev/urandom";
+
+	int oflag = O_RDONLY;
+	if (flags & GRND_NONBLOCK)
+		oflag |= O_NONBLOCK;
+
+	int fd = open(path, oflag);
+	if (fd == -1)
+		return -1;
+
+	uint8_t* ubuf = static_cast<uint8_t*>(buf);
+
+	size_t total_read = 0;
+	while (total_read < size)
+	{
+		const ssize_t nread = read(fd, ubuf + total_read, size - total_read);
+		if (nread <= 0)
+			break;
+		total_read += nread;
+	}
+
+	close(fd);
+
+	return total_read;
+}