feat(storage/vfs): add /dev/null for unwanted output redirection

components/esp_system/system_init_fn.txt

@@ -50,6 +50,7 @@ CORE: 105: init_newlib_time in components/esp_system/startup_funcs.c on BIT(0)
 CORE: 110: init_vfs_uart in components/esp_driver_uart/src/uart_vfs.c on BIT(0)
 CORE: 111: init_vfs_usj in components/esp_driver_usb_serial_jtag/src/usb_serial_jtag_vfs.c on BIT(0)
 CORE: 112: init_vfs_usj_sec in components/esp_driver_usb_serial_jtag/src/usb_serial_jtag_vfs.c on BIT(0)
+CORE: 113: init_vfs_nullfs in components/vfs/nullfs.c on BIT(0)
 CORE: 114: init_vfs_console in components/esp_vfs_console/vfs_console.c on BIT(0)
 CORE: 115: init_newlib_stdio in components/newlib/newlib_init.c on BIT(0)
 

components/esp_system/test_apps/console/main/test_app_main.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 #include <stdio.h>
+#include <assert.h>
 #include "sdkconfig.h"
 
 #include "esp_rom_uart.h"
@@ -15,6 +16,9 @@
 #include "driver/uart.h"
 #include "soc/uart_channel.h"
 
+#include <fcntl.h>
+#include <unistd.h>
+
 #if CONFIG_ESP_CONSOLE_NONE
 /* Set up UART on UART_0 (console) to be able to
    notify pytest test case that app booted successfully
@@ -49,6 +53,15 @@ void app_main(void)
 {
     printf("Hello World\n");
 
+    int fd = open("/dev/null", O_RDWR);
+    assert(fd >= 0); // Standard check
+
+    // Check if correct file descriptor is returned
+    // In this case it should be neither of 0, 1, 2 (== stdin, stdout, stderr)
+    assert(fd > 2);
+
+    close(fd);
+
 #if CONFIG_ESP_CONSOLE_NONE
     console_none_print();
 #endif // CONFIG_ESP_CONSOLE_NONE