lwip: handle CONFIG_VFS_SUPPORT_IO=n and CONFIG_VFS_SUPPORT_SELECT=n

* If CONFIG_VFS_SUPPORT_IO=y, keep everything as it is now
* If CONFIG_VFS_SUPPORT_IO=n, defined syscalls which LwIP can
  implement, such as read/write/close
* Make LWIP-only select implementation dependent on
  CONFIG_VFS_SUPPORT_SELECT, deprecate CONFIG_LWIP_USE_ONLY_LWIP_SELECT

components/lwip/CMakeLists.txt

@@ -85,7 +85,6 @@ set(srcs
     "lwip/src/netif/ppp/upap.c"
     "lwip/src/netif/ppp/utils.c"
     "lwip/src/netif/ppp/vj.c"
-    "port/esp32/vfs_lwip.c"
     "port/esp32/debug/lwip_debug.c"
     "port/esp32/freertos/sys_arch.c"
     "port/esp32/netif/dhcp_state.c"
@@ -129,6 +128,12 @@ if(CONFIG_ETH_ENABLED)
     list(APPEND srcs "port/esp32/netif/ethernetif.c")
 endif()
 
+if(CONFIG_VFS_SUPPORT_IO)
+    list(APPEND srcs "port/esp32/vfs_lwip.c")
+else()
+    list(APPEND srcs "port/esp32/no_vfs_syscalls.c")
+endif()
+
 idf_component_register(SRCS "${srcs}"
                     INCLUDE_DIRS "${include_dirs}"
                     LDFRAGMENTS linker.lf

components/lwip/Kconfig

@@ -63,9 +63,12 @@ menu "LWIP"
             to 16.
 
     config LWIP_USE_ONLY_LWIP_SELECT
-        bool "Support LWIP socket select() only"
+        bool "Support LWIP socket select() only (DEPRECATED)"
         default n
         help
+            This option is deprecated. Use VFS_SUPPORT_SELECT instead, which is
+            the inverse of this option.
+
             The virtual filesystem layer of select() redirects sockets to
             lwip_select() and non-socket file descriptors to their respective driver
             implementations. If this option is enabled then all calls of select()

components/lwip/component.mk

@@ -29,6 +29,11 @@ COMPONENT_SRCDIRS := \
 ifndef CONFIG_IDF_TARGET_ESP32
     COMPONENT_OBJEXCLUDE := port/esp32/netif/ethernetif.o
 endif
+ifndef CONFIG_VFS_SUPPORT_IO
+    COMPONENT_OBJEXCLUDE += port/esp32/vfs_lwip.o
+else
+    COMPONENT_OBJEXCLUDE += port/esp32/no_vfs_syscalls.o
+endif
 
 ifdef CONFIG_LWIP_PPP_SUPPORT
     COMPONENT_SRCDIRS += lwip/src/netif/ppp lwip/src/netif/ppp/polarssl

components/lwip/port/esp32/no_vfs_syscalls.c

@@ -0,0 +1,83 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <string.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <sys/errno.h>
+#include <sys/lock.h>
+#include <sys/fcntl.h>
+#include <sys/ioctl.h>
+#include "sdkconfig.h"
+#include "lwip/sockets.h"
+#include "lwip/sys.h"
+
+#ifdef CONFIG_VFS_SUPPORT_IO
+#error This file should only be built when CONFIG_VFS_SUPPORT_IO=n
+#endif
+
+/* Default implementations of read/write provided in newlib component,
+ * used as a fallback for console I/O.
+ */
+extern ssize_t _write_r_console(struct _reent *r, int fd, const void * data, size_t size);
+extern ssize_t _read_r_console(struct _reent *r, int fd, const void * data, size_t size);
+
+ssize_t _write_r(struct _reent *r, int fd, const void * data, size_t size)
+{
+    if (fd < LWIP_SOCKET_OFFSET) {
+        return _write_r_console(r, fd, data, size);
+    }
+    return lwip_write(fd, data, size);
+}
+
+ssize_t _read_r(struct _reent *r, int fd, void * dst, size_t size)
+{
+    if (fd < LWIP_SOCKET_OFFSET) {
+        return _read_r_console(r, fd, dst, size);
+    }
+    return lwip_read(fd, dst, size);
+}
+
+int _close_r(struct _reent *r, int fd)
+{
+    if (fd < LWIP_SOCKET_OFFSET) {
+        errno = ENOSYS;
+        return -1;
+    }
+    return lwip_close(fd);
+}
+
+int _fcntl_r(struct _reent *r, int fd, int cmd, int arg)
+{
+    return lwip_fcntl(fd, cmd, arg);
+}
+
+int ioctl(int fd, int cmd, ...)
+{
+    va_list args;
+    va_start(args, cmd);
+    int res = lwip_ioctl(fd, cmd, va_arg(args, void*));
+    va_end(args);
+    return res;
+}
+
+int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
+{
+    return lwip_select(nfds, readfds, writefds, errorfds, timeout);
+}
+
+void esp_vfs_lwip_sockets_register(void)
+{
+    /* Doesn't register anything, just a hook to force linking this file */
+}

components/lwip/port/esp32/vfs_lwip.c

@@ -18,15 +18,20 @@
 #include <sys/errno.h>
 #include <sys/lock.h>
 #include <sys/fcntl.h>
-#include "esp_vfs.h"
-#include "esp_vfs_dev.h"
 #include "esp_attr.h"
-#include "lwip/sockets.h"
+#include "esp_vfs.h"
 #include "sdkconfig.h"
+#include "lwip/sockets.h"
 #include "lwip/sys.h"
 
+#ifndef CONFIG_VFS_SUPPORT_IO
+#error This file should only be built when CONFIG_VFS_SUPPORT_IO=y
+#endif
+
 _Static_assert(MAX_FDS >= CONFIG_LWIP_MAX_SOCKETS, "MAX_FDS < CONFIG_LWIP_MAX_SOCKETS");
 
+#ifdef CONFIG_VFS_SUPPORT_SELECT
+
 static void lwip_stop_socket_select(void *sem)
 {
     sys_sem_signal(sem); //socket_select will return
@@ -46,6 +51,14 @@ static void *lwip_get_socket_select_semaphore(void)
      */
     return (void *) sys_thread_sem_get();
 }
+#else // CONFIG_VFS_SUPPORT_SELECT
+
+int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
+{
+    return lwip_select(nfds, readfds, writefds, errorfds, timeout);
+}
+
+#endif // CONFIG_VFS_SUPPORT_SELECT
 
 static int lwip_fcntl_r_wrapper(int fd, int cmd, int arg)
 {
@@ -68,10 +81,12 @@ void esp_vfs_lwip_sockets_register(void)
         .read = &lwip_read,
         .fcntl = &lwip_fcntl_r_wrapper,
         .ioctl = &lwip_ioctl_r_wrapper,
+#ifdef CONFIG_VFS_SUPPORT_SELECT
         .socket_select = &lwip_select,
         .get_socket_select_semaphore = &lwip_get_socket_select_semaphore,
         .stop_socket_select = &lwip_stop_socket_select,
         .stop_socket_select_isr = &lwip_stop_socket_select_isr,
+#endif // CONFIG_VFS_SUPPORT_SELECT
     };
     /* Non-LWIP file descriptors are from 0 to (LWIP_SOCKET_OFFSET-1). LWIP
      * file descriptors are registered from LWIP_SOCKET_OFFSET to