No cleanup of temporary directory in case of an error for pdftocairo

[stefan6419846]

Describe the bug

If pdf2image is used with use_pdftocairo=True, a temporary output directory is being created if I am not passing one myself. This directory will not be cleaned up when an error occurs during runtime.

To Reproduce

Steps to reproduce the behavior:

1. Generate a faulty PDF (example: PDF with a PNG image that includes a color profile, as Pillow is not able to read such files).

2. pdf2image.convert_from_path(pdf_path, use_pdftocairo=True)

3. Error is produced:

   Traceback (most recent call last):
    File "/home/user/path/to/test/file.py", line 43, in __main__
      print(pdf2image.convert_from_path(path, use_pdftocairo=True))
    File "/home/user/lib/python3.6/site-packages/pdf2image/pdf2image.py", line 212, in convert_from_path
      output_folder, uid, final_extension, paths_only, in_memory=auto_temp_dir
    File "/home/user/lib/python3.6/site-packages/pdf2image/pdf2image.py", line 504, in _load_from_output_folder
      images.append(Image.open(os.path.join(output_folder, f)))
    File "/home/user/lib/python3.6/site-packages/PIL/Image.py", line 2818, in open
      raise IOError("cannot identify image file %r" % (filename if filename else fp))
   OSError: cannot identify image file '/tmp/tmpvn5xet47/c1b1aabe-b0d6-4127-bc15-e30987d6b948-6.png'

4. Directory /tmp/tmpvn5xet47/ is not being removed.

Expected behavior

pdf2image should be more transparent about the side-effects of the use_pdftocairo option. Ideally auto-created temporary directories would always be cleaned up in case of an error or at least accessible to the caller in some way to perform manual cleanup; if preferred, there might be a new option which optionally performs this cleanup.

Desktop

• OS: openSUSE Leap 15.3
• Python 3.6.13
• pdf2image 1.15.1

[Belval]

So to clarify, if you don't use pdftocairo the directory is cleaned up even if pdf2image raises an exception?

[stefan6419846]

No:

• With pdftoppm, no temporary directory seems to be required - if I pass one explicitly, it is used and not deleted automatically, giving me full control over the directory. I am free to delete the directory afterwards if I want - whether there has been an error or not (given that I have a suitable exception handling).
• With pdftocairo, https://github.com/Belval/pdf2image/blob/b7f683aff436498294d37af18150b463b29ac74d/pdf2image/pdf2image.py#L145-L148 will create a temporary directory implicitly, if I do not pass one. This seems to be undocumented and I do not have control over it anymore, leaving me with the mentioned directory in the file system in case of an error. This is because https://github.com/Belval/pdf2image/blob/b7f683aff436498294d37af18150b463b29ac74d/pdf2image/pdf2image.py#L227-L228 will never actually be reached then.

[Belval]

Ok now I remember (I wrote that part of the code a while ago so my memory can be spotty at times). This behaviour is caused by pdftocairo not having stdout. It will automatically generate files on disk instead of in memory which is the pdftoppm behaviour.

I agree that the temp directory should be discarded on exception, I will add a try/except to handle this edge case.

[Belval]

The PR should fix your issue and make the behaviour coherent, will be merging and releasing this soon.