feat(cli): Add support for USB CDC to cli component, for use on ESP32-S2 for example

components/cli/CMakeLists.txt

@@ -1,4 +1,4 @@
 idf_component_register(
   INCLUDE_DIRS "include" "detail/cli/include"
   SRC_DIRS "src"
-  REQUIRES driver esp_driver_uart esp_driver_usb_serial_jtag vfs logger)
+  REQUIRES driver esp_driver_uart esp_driver_usb_serial_jtag vfs esp_vfs_console logger)

components/cli/example/sdkconfig.defaults.esp32s2

@@ -0,0 +1,3 @@
+# on the ESP32S2, which has native USB, we need to set the console so that the
+# CLI can be configured correctly:
+CONFIG_ESP_CONSOLE_USB_CDC=y

components/cli/include/cli.hpp

@@ -11,16 +11,14 @@
 #include "driver/usb_serial_jtag_vfs.h"
 #include "esp_err.h"
 #include "esp_system.h"
+#include <fcntl.h>
 
+#include "esp_vfs_cdcacm.h"
 #include "esp_vfs_dev.h"
 #include "esp_vfs_usb_serial_jtag.h"
 
 #include "line_input.hpp"
 
-#ifdef CONFIG_ESP_CONSOLE_USB_CDC
-#error The cli component is currently incompatible with CONFIG ESP_CONSOLE_USB_CDC console.
-#endif // CONFIG_ESP_CONSOLE_USB_CDC
-
 #ifndef STRINGIFY
 #define STRINGIFY(s) STRINGIFY2(s)
 #define STRINGIFY2(s) #s
@@ -38,9 +36,9 @@ namespace espp {
  *
  * @note You should call configure_stdin_stdout() before creating a Cli object
  *       to ensure that std::cin works as needed. If you do not want to use the
- *       Cli over the ESP CONSOLE (e.g. the ESP's UART, USB Serial/JTAG) and
- *       instead want to run it over a different UART port, VFS, or some other
- *       configuration, then you should call one of
+ *       Cli over the ESP CONSOLE (e.g. the ESP's UART, USB Serial/JTAG, USB
+ *       CDC) and instead want to run it over a different UART port, VFS, or
+ *       some other configuration, then you should call one of
  *       - configure_stdin_stdout_uart()
  *       - configure_stdin_stdout_vfs()
  *       - configure_stdin_stdout_custom()
@@ -58,6 +56,7 @@ class Cli : private cli::CliSession {
    *       compiled to use. This will only work if the ESP_CONSOLE was
    *       configured to use one of the following:
    *       - CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+   *       - CONFIG_ESP_CONSOLE_USB_CDC
    *       - CONFIG_ESP_CONSOLE_UART
    *
    *       If you want to use a different console, you should use one of the
@@ -77,6 +76,8 @@ class Cli : private cli::CliSession {
 
 #if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
     configure_stdin_stdout_usb_serial_jtag();
+#elif CONFIG_ESP_CONSOLE_USB_CDC
+    configure_stdin_stdout_usb_cdc();
 #elif CONFIG_ESP_CONSOLE_UART
     configure_stdin_stdout_uart((uart_port_t)CONFIG_ESP_CONSOLE_UART_NUM,
                                 CONFIG_ESP_CONSOLE_UART_BAUDRATE);
@@ -182,6 +183,47 @@ class Cli : private cli::CliSession {
     configured_ = true;
   }
 
+  /**
+   * @brief Configure the USB CDC driver to support blocking input read, so
+   *        that std::cin (which assumes a blocking read) will function. This
+   *        should be primarily used when you want to use the std::cin/std::getline
+   *        and other std input functions or you want to use the cli library.
+   */
+  static void configure_stdin_stdout_usb_cdc(void) {
+    if (configured_) {
+      return;
+    }
+
+    // drain stdout before reconfiguring it
+    fflush(stdout);
+    fsync(fileno(stdout));
+
+    const std::string_view dev_name = "/dev/cdcacm";
+
+    // redirect stdin, stdout, stderr to the USB CDC interface
+    console_.in = freopen(dev_name.data(), "r", stdin);
+    console_.out = freopen(dev_name.data(), "w", stdout);
+    console_.err = freopen(dev_name.data(), "w", stderr);
+
+    esp_vfs_dev_cdcacm_register();
+
+    esp_vfs_dev_cdcacm_set_rx_line_endings(ESP_LINE_ENDINGS_CR);
+    esp_vfs_dev_cdcacm_set_tx_line_endings(ESP_LINE_ENDINGS_CRLF);
+
+    // Enable blocking mode on stdin and stdout
+    fcntl(fileno(stdout), F_SETFL, 0);
+    fcntl(fileno(stdin), F_SETFL, 0);
+
+    // Initialize VFS & UART so we can use std::cout/cin
+    // _IOFBF = full buffering
+    // _IOLBF = line buffering
+    // _IONBF = no buffering
+    // disable buffering on stdin
+    setvbuf(stdin, nullptr, _IONBF, 0);
+
+    configured_ = true;
+  }
+
   /**
    * @brief Configure stdin/stdout to use a custom VFS driver. This should be
    *        used when you have a custom VFS driver that you want to use for
@@ -218,8 +260,6 @@ class Cli : private cli::CliSession {
     // Register the USB CDC interface
     [[maybe_unused]] auto err = esp_vfs_register(dev_name.data(), &vfs, NULL);
 
-    // TODO: this function is mostly untested, so we should probably add some
-    //       error handling here and store the resultant pointers for later use
     // redirect stdin, stdout, stderr to the USB CDC interface
     console_.in = freopen(dev_name.data(), "r", stdin);
     console_.out = freopen(dev_name.data(), "w", stdout);

components/cli/src/cli.cpp

@@ -1,3 +1,4 @@
 #include "cli.hpp"
 
 bool espp::Cli::configured_ = false;
+espp::Cli::console_handle_t espp::Cli::console_ = {nullptr, nullptr, nullptr};