LittleFS.exists() is giving an error

[Adrianotiger]

Board

ESP32-S3

Device Description

ESP32-S3 16MB Dev-Kit

Hardware Configuration

Nothing

Version

v2.0.5

IDE Name

Arduino IDE 2.0.4

Operating System

Windows 10

Flash frequency

240MHz

PSRAM enabled

no

Upload speed

115200

Description

I am using the LittleFS library.
When I try to check if a file exists, this function is executed:

arduino-esp32/libraries/LittleFS/src/LittleFS.cpp

Line 46 in bb8c855

bool LittleFSImpl::exists(const char* path)

bool LittleFSImpl::exists(const char* path)
{
    File f = open(path, "r",false);
    return (f == true);
}

As it try to open a file, I get this error:
[E][vfs_api.cpp:104] open(): /littlefs/g00000/c001 does not exist, no permits for creation

From this line:

arduino-esp32/libraries/FS/src/vfs_api.cpp

Line 105 in bb8c855

log_e("%s does not exist, no permits for creation", temp);

I think this error should not be logged, if we just check if a file exists.

Sketch

char path[20];
createPath(path);  
if(!LittleFS.exists(path))
{
  LittleFS.mkdir(path);
}

Debug Message

[E][vfs_api.cpp:104] open(): /littlefs/g00000/c001 does not exist, no permits for creation

Other Steps to Reproduce

No response

I have checked existing issues, online documentation and the Troubleshooting Guide

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.

[mrengineer7777]

I agree. The message should be at info, debug, or verbose log level. However it's not that simple. exists() actually calls open() on the file (and then closes it) with read only permission, no create flag. In your case you are looking at a directory, so the solution is slightly different.

Workaround: use LittleFS.mkdir(path) instead of exists(). It will create the directory if it doesn't exist. Otherwise it just returns true. See bool VFSImpl::mkdir(const char *fpath) in vfs_api.cpp.

[Adrianotiger]

I believe you that's not that simple :)

But even as info or verbose, this is a wrong info: "XXX does not exist, no permits for creation". As I don't want create a file at this point of the code.

Rewrite the open function inside the exists functions is not a solution.

Maybe with a new argument with __builtin_FUNCTION() as parameter but it is probably also bad, for just a debug output.

Maybe opening the file with the exists mode?

[Anx2k]

I encountered this same issue, and instead of using their exists function I just use the normal sys/stat.h stat() function - it will return whether a file/directory exists or not, and won't print that error. This actually works for SD cards as well as a bonus.

[OttoKlaasen]

I have the same issue when i do a LittleFS.exist on an empty directory
It will show an error in the serial.
The code itself works fine.

Code snippet example:

  if (LittleFS.exists(FILE_PHOTO)) {
       //Returns true if a file with a given path exists; false otherwise.
       if(LittleFS.remove(FILE_PHOTO)) {
          //Deletes the file given its absolute path. Returns true if the file was deleted successfully.
           Serial.printf("FILE DELETED: %s\n", FILE_PHOTO);
       } else {
            Serial.println("ERROR WHILE DELETE FILE");
   }
  }
  delay(1000);   // Wait for it
  // Open dir folder
  dir = LittleFS.open("/");
  // Cycle all the content
  printDirectory(dir);
  Serial.println("Close dir connection.");
  dir.close();
  
  // next will call an error: [ 30214][E][vfs_api.cpp:105] open(): /littlefs/photo.jpg does not exist, no permits for creation
  // I will ignore the error as the code seems to work.
  bool FileExist = LittleFS.exists(FILE_PHOTO);

  if(!FileExist){
      Serial.println("FILE DOES NOT EXIST, so we can CREATE and WRITE to file..............");      
      file = LittleFS.open(FILE_PHOTO, FILE_WRITE);

[BlueAndi]

In my use case I avoid checking first with exists() and if yes, use open() to load it because of performance. I use always open() and check whether I got the file or not. My recommendation is to only show it in verbose mode.

[hsaturn]

I agree. The message should be at info, debug, or verbose log level. However it's not that simple. exists() actually calls open() on the file (and then closes it) with read only permission, no create flag. In your case you are looking at a directory, so the solution is slightly different.

Workaround: use LittleFS.mkdir(path) instead of exists(). It will create the directory if it doesn't exist. Otherwise it just returns true. See bool VFSImpl::mkdir(const char *fpath) in vfs_api.cpp.

This is not an answer. The library MUST not log in that case. I have the same problem, and I'm using the com port.
I tried many solutions to disable log with no success. And even with success, this would have been a workaround.
My roomba do not like at all receiving garbage through the serial port when I check for file existency !!!
LittleFS has to be fixed.

And technically:

• adding a parameter with default to open() is a solution
• using stat instead of open in exists is a solution
• reversing logic: open uses exists then opens instead of exists uses open then closes is a solution
• using a 'special mode' (nullptr, '*' etc) is one more solution
• other solutions for sure exists

Don't say that it's not that simple. It is ! Lazyness is not a solution !

And finally a workaround for this problem
build_flags = -DCORE_DEBUG_LEVEL=0

No log at all.