Thomas Haller authored
With "main.rc-manager=file", if /etc/resolv.conf is a symlink, NetworkManager would follow the symlink and update the file instead. However, note that realpath() only returns a target, if the file actually exists. That means, if /etc/resolv.conf is a dangling symlink, NetworkManager would replace the symlink with a file. This was the only case in which NetworkManager would every change a symlink resolv.conf to a file. I think this is undesired behavior. This is a change in long established behavior. Although note that there were several changes regarding rc-manager settings in the past. See for example commit  and . Now, first still try using realpath() as before. Only if that fails, try to resolve /etc/resolv.conf as a symlink with readlink(). Following the dangling symlink is likely not a problem for the user, it probably is even desired. The part that most likely can cause problems is if the destination file is not writable. That happens for example, if the destination's parent directories are missing. In this case, NetworkManager will now fail to write resolv.conf and log a warning. This has the potential of breaking existing setups, but it really is a mis-configuration from the user's side. This fixes for example the problem, if the user configures /etc/resolv.conf as symlink to /tmp/my-resolv.conf. At boot, the file would not exist, and NetworkManager would previously always replace the link with a plain file. Instead, it should follow the symlink and create the file.  718fd224  15177a34 https://github.com/NetworkManager/NetworkManager/pull/127644aa42f
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