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GeezerVison is showing github.com — Race condition writing objects in LooseObjectDB · Issue #85 · gitpython-developers/gitdb

This repository was archived by the owner on Jul 26, 2026. It is now read-only.
This repository was archived by the owner on Jul 26, 2026. It is now read-only.

Race condition writing objects in LooseObjectDB #85

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#91
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Race condition writing objects in LooseObjectDB#85
#91
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Description

@lordmauve
lordmauve
opened on Feb 13, 2023
Issue body actions

There's a TOCTTOU in LooseObjectDB when storing a new object, that causes storing an object to fail with FileExistsError:

   File "patch_tree.py", line 132, in write_tree
     return self.db.store(istream).binsha
   File ".venv/lib/python3.9/gitdb/db/git.py", line 77, in store
     return self._loose_db.store(istream)
   File ".venv/lib/python3.9/gitdb/db/loose.py", line 226, in store
     mkdir(obj_dir)
FileExistsError: [Errno 17] File exists: '/tmp/tmp.flUcclypOQ/objects/a0'

The problem code is

            if not isdir(obj_dir):
                mkdir(obj_dir)

and what is happening is

  1. isdir() returns False because the directory does not exist at that moment
  2. The directory is created in another thread
  3. mkdir() fails with FileExistsError

This can be avoided by using an EAFP pattern, e.g.

with contextlib.suppress(FileExistsError):
    mkdir(obj_dir)

Activity

  1. lordmauve
    changed the title [-]Race condition in LooseDB[/-] [+]Race condition in LooseObjectDB[/+] on Feb 13, 2023
  2. lordmauve
    changed the title [-]Race condition in LooseObjectDB[/-] [+]Race condition writing objects in LooseObjectDB[/+] on Feb 13, 2023
  3. Byron
    added
    acknowledged
    help wanted
    on Feb 14, 2023

  4. Byron commented on Feb 14, 2023

    @Byron
    Byron
    on Feb 14, 2023
    Member
    More actions

    Thanks for reporting and for providing a suggestion for a fix. A PR is definitely welcome.

  5. Byron
    closed this as completedin #91on Sep 11, 2023
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