On Mon, Feb 26, 2024 at 10:56:29AM +0800, Zorro Lang wrote: > On Sun, Feb 25, 2024 at 09:45:27AM -0800, Eric Biggers wrote: > > On Sun, Feb 25, 2024 at 09:03:04AM -0800, Darrick J. Wong wrote: > > > On Sun, Feb 25, 2024 at 08:51:28AM -0800, Eric Biggers wrote: > > > > 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 > > Thanks Eric, I know "--" can do that, just didn't understand how it helps the > empty variable problem. So looks like it doesn't. > > > > > empty. To cause the script to exit if ${FOO} is empty, it can be written as > > > > ${FOO:?}. Alternatively, 'set -u' can be used. > > > > > > I said that four days ago. Did nobody receive that reply? > > > > > > https://lore.kernel.org/fstests/20240225165128.GA1128@sol.localdomain/T/#m0efd851c5a1fb0dbe418f4aff818d20f4355638b > > > > > > > You didn't mention the :? option, and I thought that would be worth mentioning. I wasn't even aware that existed. It seems like a good way to enable erroring on unset variable on a case by case basis. Though TBH I suspect that setting -u and using ${FOO:-} for the cases where we're actually ok with unset variables is better practice. Too bad it's going to be a lot of work to do /that/. > Actually: > > [ -n "$FOO" ] && rm -rf ${FOO}* > > or > > rm -rf ${FOO:?}* > > Both of them are good to me, depends on what's expected. The 1st one ignore empty $FOO and > keep running, the 2nd one breaks case running if $FOO is empty. > > But they all need the programer to realize that his variable might be dangerous if > it's empty, and write as that. So it still depends on the programer or the reviewers > to notice that. <nod> --D > Thanks, > Zorro > > > > > Of course ideally -u would be used everywhere, as you said. > > > > - Eric > > > >
