Read and write to mbed filesystem on Arduino Portenta Machine Control

FlashManagement.ino

#include "PluggableUSBMSD.h"
#include "QSPIFBlockDevice.h"
#include "MBRBlockDevice.h"
#include "FATFileSystem.h"

REDIRECT_STDOUT_TO(Serial)
static QSPIFBlockDevice root;
mbed::MBRBlockDevice fs_data(&root, 1);
static mbed::FATFileSystem fs("fs");
void USBMSD::begin() {
  fs.mount(&fs_data);
}
USBMSD MassStorage(&root);

void setup() {
  Serial.begin(115200);
  MassStorage.begin();
  
  while(!Serial){}
  
  // Write to file
  FILE* fd = fopen("/fs/numbers.txt", "w");
  for (int i = 0; i < 20; i++) {
    fprintf(fd, "%d\r\n", i);
  }
  fclose(fd);

  // List dir
  DIR* dir = opendir("/fs/");
  struct dirent* de;
  while ((de = readdir(dir)) != NULL) {
    Serial.println(&(de->d_name)[0]);
  }
  closedir(dir);

  // Read file
  fd = fopen("/fs/numbers.txt", "r");
  char buff[16] = { 0 };
  if (feof(fd)) {
    Serial.println("Missing or empty file");
  }
  while (!feof(fd)) {
    int size = fread(&buff[0], 1, 15, fd);
    fwrite(&buff[0], 1, size, stdout);
  }
  fclose(fd);
}

void loop {
}