rewindDirectory doesn't?

Other Hardware Storage
1

I seem to have a situation where rewindDirectory(); doesn't.

On the first pass, my code gives a complete list of files in the root.
Second pass, none are shown, despite calling close after openNext(); and calling rewindDirectory(); before listing the files.

Is there some conflict with rewindDirectory() if there are other files still open?

I'll post a test routine shortly...

2

OK, this code works in a simple test sketch but only works once in my main sketch...

void list_files2()
{
File sd_dir;
File fn;
unsigned char eof;


  
sd_dir = SD.open("/");
eof=0;


sd_dir.rewindDirectory();

 while(!eof) 
    {
     fn = sd_dir.openNextFile();
     if (!fn) 
       {
       // no more files
       Serial.print("\n\rEND\n\r");
       eof=1;
       }
     else
       {
       Serial.print(fn.name());
       Serial.println(fn.size());
       
       fn.close(); 
       }
    }
}

So any ideas what circumstances that can stop rewindDirectory() working?

3

You need to post the code that doesn't work. We can't guess what you are doing.

rewindDirectory() is a simple wrapper for the SdFat rewind function.

Here is rewindDirectory:

void File::rewindDirectory(void) {  
  if (isDirectory())
    _file->rewind();
}

Here is the SdFat rewind function:

  void rewind(void) {
    curPosition_ = curCluster_ = 0;
  }

These are very simple functions so we need more info about your code.

4

That's the code I am using, In one sketch the function works in another sketch it doesn't (it only works once).

I'm not able to post the entire sketch, I have pasted the function as is though.

My question is what could cause rewindDrirectory() not to work?

Will having other files open stop it working correctly?

5

My question is what could cause rewindDrirectory() not to work?

If you call rewindDirectory with a file that is not an open directory, it will do nothing.

Put a test in your program to make sure the open works.

  if (!sd_dir) Serial.println("open failed for sd_dir");

You should close sd_dir before opening it again.

6

Thanks fat16lib.

I found the issue.

I had another file list routine that was filtering out specific filenames.

The file close(); you have to have with openNextFile(); was only called on the matching files so it was running out of file handles on the second pass...

I think the arduino SD reference example also omits the file close(); call too.

Nasty little bug but sorted now....

Thanks all.

7

I think the arduino SD reference example also omits the file close(); call too.

For years I have been pointing this out but the Arduino company is slow to fix things.