On Sun, Feb 25, 2024 at 11:16:16PM +0800, Zorro Lang wrote: > On Wed, Feb 21, 2024 at 03:09:51PM +0100, David Sterba wrote: > > Hi, > > > > reading [1] and how late it was found that effectively a "rm -rf /" can > > happen makes me worried about what I can expect from fstests after git > > pull. Many people contribute and the number for custom _cleanup() > > functions with unquoted 'rm' commands is just asking for more problems. > > > > [1] https://lore.kernel.org/all/20240205060016.7fgiyafbnrvf5chj@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > > > Unquoted arguments in shell scripts is IMO a big anti-pattern, > > unfortunately present everywhere in xfstests since the beginning. > > Rewriting all scripts would be quite a lot of work, could you at least > > provide safe versions of the cleanup helpers? > > Hi David, > > Thanks for taking care about it :) > > > > > For example: > > > > _rm_tmp() { > > rm -rf -- $tmp > > It's "$tmp.*" > > May I ask what problem does the "--" hope to avoid? If the "$tmp" is empty, > "rm -rf" and "rm -rf --"" looks like both doing nothing. So what kind > of situation does the "--" hope to fix? > > The root problem in above [1] is about "${FOO}*". If someone does "rm -rf ${FOO}*" > in its custom _cleanup_xxxxx function, then it's dangerous if "$FOO" is empty. > > I thought some ways to avoid that: > 1) Try to avoid doing rm -rf ${FOO}*, if not necessary. > 2) Must checks [ -n "$FOO" ] before doing any rm -rf ${FOO}* > 3) Someone's custom _cleanup_xxxxx better to be called before default _cleanup > does "cd /". > 4) Think about bringing in someone "Static program analysis" tool about bash > script, but I don't know if there're someone good, feel free to give me > suggestions. "--" prevents the following arguments from being interpreted as options if they begin with "-". That's a good practice, but it doesn't help with ${FOO} being empty. To cause the script to exit if ${FOO} is empty, it can be written as ${FOO:?}. Alternatively, 'set -u' can be used. - Eric
