gdbserver: introduce and use new gdb::argv_vec class

In gdbserver there are a couple of places where we perform manual
memory management using a 'std::vector<char *>' with the vector owning
the strings within it.  We need to take care to call
free_vector_argv() before leaving the scope to cleanup the strings
within the vector.

This commit introduces a new class gdb::argv_vec which wraps around a
'std::vector<char *>' and owns the strings within the vector, taking
care to xfree() them when the gdb::argv_vec is destroyed.

Right now I plan to use this class in gdbserver.

But this class will also be used to address review feedback on this
commit:

  https://inbox.sourceware.org/gdb-patches/72227f1c5a2e350ca70b2151d1b91306a0261bdc.1736860317.git.aburgess@redhat.com

where I tried to introduce another 'std::vector<char *>' which owns
the strings.  That patch will be updated to use gdb::argv_vec instead.

The obvious question is, instead of introducing this new class, could
we change the APIs to avoid having a std::vector<char *> that owns the
strings?  Could we use 'std::vector<std::string>' or
'std::vector<gdb::unique_xmalloc_ptr<char>>' instead?

The answer is yes we could.

I originally posted this larger patch set:

  https://inbox.sourceware.org/gdb-patches/cover.1730731085.git.aburgess@redhat.com

however, getting a 14 patch series reviewed is just not possible, so
instead, I'm posting the patches one at a time.  The earlier patch I
mentioned is pulled from the larger series.

The larger series already includes changes to gdbserver which removes
the need for the 'std::vector<char *>', however, getting those changes
in depends (I think) on the patch I mention above.  Hence we have a
bit of a circular dependency.

My proposal is to merge this patch (adding gdb::argv_vec) and make use
of it in gdbserver.

Then I'll update the patch above to also use gdb::argv_vec, which will
allow the above patch to get reviewed and merged.

Then I'll post, and hopefully merge additional patches from my larger
inferior argument series, which will remove the need for gdb::argv_vec
from gdbserver.

At this point, the only use of gdb::argv_vec will be in the above
patch, where I think it will remain, as I don't think that location
can avoid using 'std::vector<char *>'.

Approved-By: Tom Tromey <tom@tromey.com>

0 files changed, 0 insertions, 0 deletions