Consider replacing shutil.copyfile() with os.rename()

[rukkal]

If subuid_tfile and subuid_file/subgid_file are on the same filesystem, you could use os.rename() instead of shutil.copyfile().

os.rename() will perform the rename(2) syscall under the hood, hence the operation will be atomic and subuid_file/subgid_file will always be in a valid state.

Alternatively you could use shutil.move(), but I think that os.rename() is safer because os.rename() fails if src and dst are not on the same device. IMO the failure is good because it means that either we get atomicity or a failure.

I would use os.rename() here

fakerootuidsync/fakerootuidsync

Line 126 in 425ee20

shutil.copyfile(subuid_tfile.name, cfg['subuid_file'])

and here

fakerootuidsync/fakerootuidsync

Line 127 in 425ee20

shutil.copyfile(subuid_tfile.name, cfg['subgid_file'])

what do you think?

[santisis]

Have you notice that the source file on both 126 and 127 lines is the same? Renaming one file as two files just doesn't work.