Merge pull request adafruit#8860 from jepler/create-sd-placeholder

supervisor: Create a file /sd/placeholder.txt with a note

Author: tannewt

ports/espressif/boards/lolin_s3_mini/mpconfigboard.mk

@@ -16,6 +16,7 @@ CIRCUITPY_ESP_PSRAM_FREQ = 40m
 OPTIMIZATION_FLAGS = -Os
 CIRCUITPY_ESPCAMERA = 0
 CIRCUITPY_BITMAPFILTER = 0
+CIRCUITPY_CODEOP=0
 
 # Include these Python libraries in firmware.
 FROZEN_MPY_DIRS += $(TOP)/frozen/Adafruit_CircuitPython_NeoPixel

supervisor/shared/filesystem.c

@@ -64,26 +64,30 @@ inline void filesystem_tick(void) {
 }
 
 
+__attribute__((unused)) // this function MAY be unused
 static void make_empty_file(FATFS *fatfs, const char *path) {
     FIL fp;
     f_open(fatfs, &fp, path, FA_WRITE | FA_CREATE_ALWAYS);
     f_close(&fp);
 }
 
+#if CIRCUITPY_FULL_BUILD
+#define MAKE_FILE_WITH_OPTIONAL_CONTENTS(fatfs, filename, string_literal) do { \
+        const byte buffer[] = string_literal; \
+        make_file_with_contents(fatfs, filename, buffer, sizeof(buffer) - 1); \
+} while (0)
 
-static void make_sample_code_file(FATFS *fatfs) {
-    #if CIRCUITPY_FULL_BUILD
+static void make_file_with_contents(FATFS *fatfs, const char *filename, const byte *content, UINT size) {
     FIL fs;
-    UINT char_written = 0;
-    const byte buffer[] = "print(\"Hello World!\")\n";
     // Create or modify existing code.py file
-    f_open(fatfs, &fs, "/code.py", FA_WRITE | FA_CREATE_ALWAYS);
-    f_write(&fs, buffer, sizeof(buffer) - 1, &char_written);
+    f_open(fatfs, &fs, filename, FA_WRITE | FA_CREATE_ALWAYS);
+    f_write(&fs, content, size, &size);
     f_close(&fs);
-    #else
-    make_empty_file(fatfs, "/code.py");
-    #endif
 }
+#else
+#define MAKE_FILE_WITH_OPTIONAL_CONTENTS(fatfs, filename, string_literal) \
+    make_empty_file(fatfs, filename)
+#endif
 
 // we don't make this function static because it needs a lot of stack and we
 // want it to be executed without using stack within main() function
@@ -137,11 +141,20 @@ bool filesystem_init(bool create_allowed, bool force_create) {
         // https://specifications.freedesktop.org/trash-spec/trashspec-latest.html
         #endif
 
+        #if CIRCUITPY_SDCARDIO || CIRCUITPY_SDIOIO
+        res = f_mkdir(&vfs_fat->fatfs, "/sd");
+        #if CIRCUITPY_FULL_BUILD
+        MAKE_FILE_WITH_OPTIONAL_CONTENTS(&vfs_fat->fatfs, "/sd/placeholder.txt",
+            "SD cards mounted at /sd will hide this file from Python."
+            " SD cards are not visible via USB CIRCUITPY.\n");
+        #endif
+        #endif
+
         #if CIRCUITPY_OS_GETENV
         make_empty_file(&vfs_fat->fatfs, "/settings.toml");
         #endif
         // make a sample code.py file
-        make_sample_code_file(&vfs_fat->fatfs);
+        MAKE_FILE_WITH_OPTIONAL_CONTENTS(&vfs_fat->fatfs, "/code.py", "print(\"Hello World!\")\n");
 
         // create empty lib directory
         res = f_mkdir(&vfs_fat->fatfs, "/lib");