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oamg / leapp-repository

Leapp repositories containing actors for the Leapp framework (https://github.com/oamg/leapp). Currently provides leapp repositories for in-place upgrades of RHEL systems.
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Fix symlink to same exterior location #1167

Open abadger opened 7 months ago

abadger commented 7 months ago

Note: https://github.com/oamg/leapp-repository/pull/1166 must be merged first and then this PR should be rebased.

In the present code, when we have two separate links to the same file outside of /etc/pki, the real file is copied to the location of both links. The problem with this is when the user makes changes to the file in the future, they will have to edit both files whereas before they would only have had to edit one of the files (since they linked to the same underlying file). Example:

  Host:
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileA -> /etc/sourceFile
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileB -> /etc/sourceFile

  Becomes:

  -rw-r--r--.  1 badger badger  12 Jan 22 03:43 fileA
  -rw-r--r--.  1 badger badger  12 Jan 22 03:43 fileB

fileA and fileB are separate copies of /etc/sourceFile.

This change makes it so anytime two links eventually point to the same exterior file, the first link will be copied and the second link will becone a symlinks to that copy like this:

  -rw-r--r--.  1 badger badger  12 Jan 22 03:43 fileA
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileB -> /etc/pki/fileA

This is the behaviour even if the second link went through several other exterior links to reach the same sourceFile (but not if there is another interior link in between). Example:

  Host:
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileA -> /etc/sourceFile
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileB -> /etc/sourceFile
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileC -> /etc/external-to-same-file
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileD -> /etc/external-to-interior-link

  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 /etc/external-to-same-file -> /etc/sourceFile
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 /etc/external-to-interior-link -> pki/fileB

  Becomes:
  -rw-r--r--.  1 badger badger  12 Jan 22 03:43 fileA
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileB -> /etc/pki/fileA
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileC -> /etc/pki/fileA
  lrwxrwxrwx.  1 badger badger  13 Jan 22 03:42 fileD -> /etc/pki/fileB

The drawback to the end user is that, unless you trace all the way through the chain of symlinks, it is confusing that fileA ends up being a real file and fileC ends up pointing to it. It's not immediately obvious how the two are related.

The advantage is if the end user makes any changes to either fileA or fileC, then the changes will be visible in both files which is the behaviour that existed on the host system.

github-actions[bot] commented 7 months ago

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