Delete a directory safely (only when it's empty)

[Mistrel]

This is a special case for DeleteDirectory. It only applies to the directory itself (no use of Pattern$ or Mode parameters), and will only succeed if the directory is empty.

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;/ Only delete the directory is it is empty
Procedure DeleteDirectorySafely(Path.s)
  Protected PathID
  Protected Result
  Protected EntryName.s
  Protected PathNotEmpty
  Protected i
  
  If Not FileSize(Path.s)=-2
    ProcedureReturn #False
  EndIf
  
  PathID=ExamineDirectory(#PB_Any,Path.s,"")
  If PathID
    For i=1 To 3
      Result=NextDirectoryEntry(PathID)
      EntryName.s=DirectoryEntryName(PathID)
      If Result And EntryName.s<>"." And EntryName.s<>".."
        PathNotEmpty=#True
      EndIf
    Next i
    
    If Not PathNotEmpty
      FinishDirectory(PathID)
      Result=DeleteDirectory(Path.s,"")
      ProcedureReturn Result
    EndIf
    
    FinishDirectory(PathID)
  EndIf
  
  ProcedureReturn #False
EndProcedure

[PB]

Your solution is cross-platform, which is good. But I just want
to add that for Windows only, you can use this API call instead,
which won't delete the directory if it contains any files:

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RemoveDirectory_(dir$)

[Flower]

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Size.q = DirectoryEntrySize(#Directory)
If(Size > 2)
  ProcedureReturn
EndIf

I guess this will also work.

[Mistrel]

Yes but what if the file is larger than 9223372036854775808 bytes? I mean, surely there will be a day where we might encounter an 8 exabyte file.

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RemoveDirectory_(dir$)

Thanks for the tip, PB. I try to avoid using Win32 for the basic stuff I may need elsewhere.

[PB]

> I try to avoid using Win32 for the basic stuff I may need elsewhere

I know. Just pointing it out for folks who code for Windows only, like myself.
I'll always take a single API call over a dedicated procedure any time.

[Mistrel]

Fixed a minor bug. I forgot to close the directory before attempting to delete it!

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Size.q = DirectoryEntrySize(#Directory)
If(Size > 2)
  ProcedureReturn
EndIf

A directory may be full of zero-byte files. You really do need to examine it closely.

[Flower]

Well, my bad. DirectoryEntrySize does not return the number of files in the directory. Guess we have to use FindFirstFile / FindNextFile ...

[Trond]

What if you examine the directory and find it empty, then some program creates a file there just before your program reaches the line with DeleteDirectory()?

[Mistrel]

What if you examine the directory and find it empty, then some program creates a file there just before your program reaches the line with DeleteDirectory()?

The world will explode!

Actually, during the normal course of my program I might create a temporary folder, do some stuff in it, delete everything I wrote to it, and then finally delete the folder. The whole point of this function is just a sanity check to me to make sure I don't accidentally delete "C:\Program Files (x86)", "C:\Windows", or something else really dumb like that if I made a mistake somewhere when resolving the target path.

[PB]

> I might create a temporary folder, do some stuff in it,
> delete everything I wrote to it, and then finally delete
> the folder

Wow, I had the same such concept in one of my apps last week!
But, rather than delete the files first, I just delete the folder that
I created, so that it deletes all the files in that step.

Here's what I use to create my temp folder:

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t$=GetTemporaryDirectory() : If Right(t$,1)<>"\" : t$+"\" : EndIf
Repeat : tmpdir$=t$+"AppName"+Str(Random(99999999))+"\" : Until FileSize(tmpdir$)<>-2
If MakeSureDirectoryPathExists_(tmpdir$)=0 : End : Endif

So it creates a randomly-numbered folder inside the PC's official temp
folder, and checks to ensure the new folder doesn't already exist. If
it doesn't, then it becomes my app's folder as far as I'm concerned.

To delete it later, I do this before my app quits:

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DeleteDirectory(GetPathPart(tmpdir$),"",#PB_FileSystem_Recursive|#PB_FileSystem_Force)

This means I don't have to delete my temp files that I created, and
I will never accidentally delete C:\Windows by mistake either.

Now, Trond will say: what if another app creates files in that random
folder? My answer: if another app can even possibly come up with my
app's name PLUS the random 8-digit number appended to it, and then
decides to write to it, then too bad when my app kills all its data!

[Mistrel]

I'm not as brave as you are when it comes to DeleteDirectory, PB!

[PB]

Why? I know that tmpdir$ is my temp folder, so it's 100% safe to delete.
It's not like tmpdir$ is magically going to become "c:\windows" by itself.