Fixes#689
Add symlink overwrite behavior to fix "file exists" error when restoring a symlink that already exists
Before creating the restored symlink, check `os.Lstat`:
- If it returns an error indicating the file does not exist, proceed to symlink creation
- If it returns any other error, propagate the error up to the caller
- If the fileInfo indicates the entry is a symlink AND `--no-overwrite-symlinks` was set in the restore command, propagate an error to the caller
- If `--no-overwrite-symlinks` was NOT set, remove the existing symlink before proceeding to symlink creation
- Else the file exists but it is not of type symlink. Halt the operation and propagate an error indicating we tried to restore a symlink over a file system entry that already existed but was not a symlink.
Added case to `TestSnapshotRestore` that fails before this fix and succeeds after. The case is simply to restore the same snapshot into the same directory twice in a row, where the second restore will be on top of the first one.
Added test case to ensure `--no-overwrite-symlinks` throws an error as expected if restoring into a directory where a symlink already exists at the path symlink creation is attempted.
Added test case to ensure that the restore operation fails if a symlink is needed to be restored to the same path as an existing non-symlink filesystem entry with the same name.
* Skip overwrite test on Windows
If test is run as non-admin it is likely to fail on Windows
with insufficient permissions to overwrite the previously
restored data.
* Add brief summary of overwrite behavior to help
Add a brief summary to the restore command help text
of expected behavior when restoring into a target location
that has existing data present.
122a31b905