Dir
Dir class hierarchy
With a file system, the Dir class allows you to iterate over directories on the underlying storage. Directories, also called folders, are a way to group files. Each directory has a name that forms a part of the path to any files stored in that directory. Additionally, you can use rename operations at the file system level to change a directory's name and efficiently change the path to any files in that directory. To make a new directory, use the mkdir function in the FileSystem class.
The Dir class operates as an iterator or stream similarly to the File class, except operating on file names instead of bytes or other type. Each read call returns the next file name in the directory and increments the Dir position. Similarly to a file, you can seek a Dir object to a specific position; however, this is limited to a position previously returned by a call to the Dir's tell function.
Note: Iterating through a directory may return the file names '.' and '..', which are special file names for the current directory and the parent directory. When performing operations recursively, it is acceptable to treat any file starting with the character '.' as a special or "hidden" file.
Dir class API
| Public Member Functions | |
| Dir () | |
| Create an uninitialized directory. More... | |
| Dir (FileSystem *fs, const char *path) | |
| Open a directory on a filesystem. More... | |
| virtual | ~Dir () |
| Destroy a file. More... | |
| virtual int | open (FileSystem *fs, const char *path) |
| Open a directory on the filesystem. More... | |
| virtual int | close () |
| Close a directory. More... | |
| virtual ssize_t | read (struct dirent *ent) |
| Read the next directory entry. More... | |
| virtual void | seek (off_t offset) |
| Set the current position of the directory. More... | |
| virtual off_t | tell () |
| Get the current position of the directory. More... | |
| virtual void | rewind () |
| Rewind the current position to the beginning of the directory. More... | |
| virtual size_t | size () |
| Get the sizeof the directory. More... | |
File system example
/* mbed Microcontroller Library
* Copyright (c) 2006-2019 ARM Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mbed.h"
#include <stdio.h>
#include <errno.h>
#include <functional>
#include "BlockDevice.h"
// Maximum number of elements in buffer
#define BUFFER_MAX_LEN 10
#define FORCE_REFORMAT true
// This will take the system's default block device
BlockDevice *bd = BlockDevice::get_default_instance();
// Instead of the default block device, you can define your own block device.
// For example: HeapBlockDevice with size of 2048 bytes, read size 1, write size 1 and erase size 512.
// #include "HeapBlockDevice.h"
// BlockDevice *bd = new HeapBlockDevice(2048, 1, 1, 512);
// This example uses LittleFileSystem as the default file system
#include "LittleFileSystem.h"
LittleFileSystem fs("fs");
// Uncomment the following two lines and comment the previous two to use FAT file system.
// #include "FATFileSystem.h"
// FATFileSystem fs("fs");
// Set up the button to trigger an erase
InterruptIn irq(BUTTON1);
void erase() {
printf("Initializing the block device... ");
fflush(stdout);
int err = bd->init();
printf("%s\n", (err ? "Fail :(" : "OK"));
if (err) {
error("error: %s (%d)\n", strerror(-err), err);
}
printf("Erasing the block device... ");
fflush(stdout);
err = bd->erase(0, bd->size());
printf("%s\n", (err ? "Fail :(" : "OK"));
if (err) {
error("error: %s (%d)\n", strerror(-err), err);
}
printf("Deinitializing the block device... ");
fflush(stdout);
err = bd->deinit();
printf("%s\n", (err ? "Fail :(" : "OK"));
if (err) {
error("error: %s (%d)\n", strerror(-err), err);
}
}
static auto erase_event = mbed_event_queue()->make_user_allocated_event(erase);
// Entry point for the example
int main() {
printf("--- Mbed OS filesystem example ---\n");
// Setup the erase event on button press, use the event queue
// to avoid running in interrupt context
irq.fall(std::ref(erase_event));
// Try to mount the filesystem
printf("Mounting the filesystem... ");
fflush(stdout);
int err = fs.mount(bd);
printf("%s\n", (err ? "Fail :(" : "OK"));
if (err || FORCE_REFORMAT) {
// Reformat if we can't mount the filesystem
printf("formatting... ");
fflush(stdout);
err = fs.reformat(bd);
printf("%s\n", (err ? "Fail :(" : "OK"));
if (err) {
error("error: %s (%d)\n", strerror(-err), err);
}
}
// Open the numbers file
printf("Opening \"/fs/numbers.txt\"... ");
fflush(stdout);
FILE *f = fopen("/fs/numbers.txt", "r+");
printf("%s\n", (!f ? "Fail :(" : "OK"));
if (!f) {
// Create the numbers file if it doesn't exist
printf("No file found, creating a new file... ");
fflush(stdout);
f = fopen("/fs/numbers.txt", "w+");
printf("%s\n", (!f ? "Fail :(" : "OK"));
if (!f) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
for (int i = 0; i < 10; i++) {
printf("\rWriting numbers (%d/%d)... ", i, 10);
fflush(stdout);
err = fprintf(f, " %d\n", i);
if (err < 0) {
printf("Fail :(\n");
error("error: %s (%d)\n", strerror(errno), -errno);
}
}
printf("\rWriting numbers (%d/%d)... OK\n", 10, 10);
printf("Seeking file... ");
fflush(stdout);
err = fseek(f, 0, SEEK_SET);
printf("%s\n", (err < 0 ? "Fail :(" : "OK"));
if (err < 0) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
}
// Go through and increment the numbers
for (int i = 0; i < 10; i++) {
printf("\rIncrementing numbers (%d/%d)... ", i, 10);
fflush(stdout);
// Get current stream position
long pos = ftell(f);
// Parse out the number and increment
char buf[BUFFER_MAX_LEN];
if (!fgets(buf, BUFFER_MAX_LEN, f)) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
char *endptr;
int32_t number = strtol(buf, &endptr, 10);
if (
(errno == ERANGE) || // The number is too small/large
(endptr == buf) || // No character was read
(*endptr && *endptr != '\n') // The whole input was not converted
) {
continue;
}
number += 1;
// Seek to beginning of number
fseek(f, pos, SEEK_SET);
// Store number
fprintf(f, " %d\n", number);
// Flush between write and read on same file
fflush(f);
}
printf("\rIncrementing numbers (%d/%d)... OK\n", 10, 10);
// Close the file which also flushes any cached writes
printf("Closing \"/fs/numbers.txt\"... ");
fflush(stdout);
err = fclose(f);
printf("%s\n", (err < 0 ? "Fail :(" : "OK"));
if (err < 0) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
// Display the root directory
printf("Opening the root directory... ");
fflush(stdout);
DIR *d = opendir("/fs/");
printf("%s\n", (!d ? "Fail :(" : "OK"));
if (!d) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
printf("root directory:\n");
while (true) {
struct dirent *e = readdir(d);
if (!e) {
break;
}
printf(" %s\n", e->d_name);
}
printf("Closing the root directory... ");
fflush(stdout);
err = closedir(d);
printf("%s\n", (err < 0 ? "Fail :(" : "OK"));
if (err < 0) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
// Display the numbers file
printf("Opening \"/fs/numbers.txt\"... ");
fflush(stdout);
f = fopen("/fs/numbers.txt", "r");
printf("%s\n", (!f ? "Fail :(" : "OK"));
if (!f) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
printf("numbers:\n");
while (!feof(f)) {
int c = fgetc(f);
printf("%c", c);
}
printf("\rClosing \"/fs/numbers.txt\"... ");
fflush(stdout);
err = fclose(f);
printf("%s\n", (err < 0 ? "Fail :(" : "OK"));
if (err < 0) {
error("error: %s (%d)\n", strerror(errno), -errno);
}
// Tidy up
printf("Unmounting... ");
fflush(stdout);
err = fs.unmount();
printf("%s\n", (err < 0 ? "Fail :(" : "OK"));
if (err < 0) {
error("error: %s (%d)\n", strerror(-err), err);
}
printf("Mbed OS filesystem example done!\n");
}