Add the system call eventfd (#7835)

components/libc/posix/Kconfig

@@ -25,6 +25,11 @@ if RT_USING_POSIX_FS
         bool "Enable I/O Multiplexing select() <sys/select.h>"
         select RT_USING_POSIX_POLL
         default n
+    
+    config RT_USING_POSIX_EVENTFD
+        bool "Enable I/O event eventfd <sys/eventfd.h>"
+        select RT_USING_POSIX_POLL
+        default n
 
     config RT_USING_POSIX_SOCKET
         bool "Enable BSD Socket I/O <sys/socket.h> <netdb.h>"

components/libc/posix/io/eventfd/SConscript

@@ -0,0 +1,14 @@
+# RT-Thread building script for component
+
+from building import *
+
+cwd     = GetCurrentDir()
+src     = []
+CPPPATH = [cwd]
+
+if GetDepend('RT_USING_POSIX_EVENTFD'):
+    src += ['eventfd.c']
+
+group = DefineGroup('POSIX', src, depend = [''], CPPPATH = CPPPATH)
+
+Return('group')

components/libc/posix/io/eventfd/eventfd.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2006-2023, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-07-20    zmq810150896  First version
+ */
+
+#ifndef __EVENTFD_H__
+#define __EVENTFD_H__
+
+int eventfd(unsigned int count, int flags);
+
+#endif /* __EVENTFD_H__ */

components/lwp/lwp_syscall.c

@@ -41,6 +41,7 @@
 #include <sys/utsname.h>
 
 #ifdef RT_USING_DFS
+#include <eventfd.h>
 #include <poll.h>
 #include <sys/select.h>
 #include <dfs_file.h>
@@ -5317,6 +5318,14 @@ sysret_t sys_symlink(const char *existing, const char *new)
     return (ret < 0 ? GET_ERRNO() : ret);
 }
 
+sysret_t sys_eventfd2(unsigned int count, int flags)
+{
+    int ret;
+
+    ret = eventfd(count, flags);
+    return (ret < 0 ? GET_ERRNO() : ret);
+}
+
 static const struct rt_syscall_def func_table[] =
 {
     SYSCALL_SIGN(sys_exit),            /* 01 */
@@ -5548,6 +5557,7 @@ static const struct rt_syscall_def func_table[] =
     SYSCALL_SIGN(sys_sigtimedwait),
     SYSCALL_SIGN(sys_notimpl),
     SYSCALL_SIGN(sys_notimpl),                          /* 190 */
+    SYSCALL_SIGN(sys_eventfd2),
 };
 
 const void *lwp_get_sys_api(rt_uint32_t number)