File content as of revision 16:8051d8156c91:

#include "mbed.h"
#include "FATFileSystem.h"
#include "SDBlockDevice.h"
#include <stdio.h>
#include <errno.h>
/* mbed_retarget.h is included after errno.h so symbols are mapped to
 * consistent values for all toolchains */
#include "platform/mbed_retarget.h"


Serial pc(PA_9, PA_10);
SDBlockDevice sd(PB_15, PB_14, PB_13, PB_12);
FATFileSystem fs("sd", &sd);

void return_error(int ret_val){
  if (ret_val)
    pc.printf("Failure. %d\n", ret_val);
  else
    pc.printf("done.\n");
}

void errno_error(void* ret_val){
  if (ret_val == NULL)
    pc.printf(" Failure. %d \n", errno);
  else
    pc.printf(" done.\n");
}

int main()
{
    int error = 0;
    pc.printf("Welcome to the filesystem example.\n");

    pc.printf("Opening a new file, numbers.txt.");
    FILE* fd = fopen("/sd/numbers.txt", "w+");
    errno_error(fd);

    for (int i = 0; i < 20; i++){
        pc.printf("Writing decimal numbers to a file (%d/20)\r", i);
        fprintf(fd, "%d\n", i);
    }
    pc.printf("Writing decimal numbers to a file (20/20) done.\n");

    pc.printf("Closing file.");
    fclose(fd);
    pc.printf(" done.\n");

    pc.printf("Re-opening file read-only.");
    fd = fopen("/sd/numbers.txt", "r");
    errno_error(fd);

    pc.printf("Dumping file to screen.\n");
    char buff[16] = {0};
    while (!feof(fd)){
        int size = fread(&buff[0], 1, 15, fd);
        fwrite(&buff[0], 1, size, stdout);
    }
    pc.printf("EOF.\n");

    pc.printf("Closing file.");
    fclose(fd);
    pc.printf(" done.\n");

    pc.printf("Opening root directory.");
    DIR* dir = opendir("/sd/");
    errno_error(fd);

    struct dirent* de;
    pc.printf("Printing all filenames:\n");
    while((de = readdir(dir)) != NULL){
        pc.printf("  %s\n", &(de->d_name)[0]);
    }

    pc.printf("Closeing root directory. ");
    error = closedir(dir);
    return_error(error);
    pc.printf("Filesystem Demo complete.\n");

    while (true) {}
}