Protect against --args being used twice

[mwleeds]

Found by coverity CID 1471678 in flatpak

[mwleeds]

Looks like the CI failed because there's a unit test that uses --args more than once:

+ printf '%s--dir\0/tmp/hello/world2\0' ''
+ printf '%s--dir\0/tmp/hello/world3\0' ''
+ /home/runner/work/bubblewrap/bubblewrap/_build/test-bwrap --bind / / --tmpfs /tmp --args 3 --args 4 --args 5 /bin/sh -c 'test -d /tmp/hello/world && test -d /tmp/hello/world2 && test -d /tmp/hello/world3'
bwrap: --args can only be used once

But I still think there's a bug here: opt_args_data only gets freed once in main() whereas it gets assigned to n times, n == number of times --args was specified.

[mwleeds]

On the other hand it's a memory leak on exit that's not likely to be huge so not sure how important it is.

[smcv]

I still think there's a bug here

Quite possibly: see #209, #224, #230, #237, #426, #444.

On the other hand it's a memory leak on exit

As long as it's only O(n) in the number of arguments, I don't think there is any real impact to leaking up to a few K of memory.

[mwleeds]

Oh if there are already various issues about this I'll close this one.