"Gabriel L. Somlo" <gso...@gmail.com> writes:
> Hi,
>
> Assuming I'm trying to add a new command line option to qemu in vl.c:
>
> ...
>
> static QemuOptsList qemu_foo_opts = {
> .name = "foo",
> .implied_opt_name = "name",
> .head = QTAILQ_HEAD_INITIALIZER(qemu_foo_opts.head),
> .desc = {
> {
> .name = "name",
> .type = QEMU_OPT_STRING,
> }, {
> .name = "file",
> .type = QEMU_OPT_STRING,
> },
> { /* end of list */ }
> },
> };
>
> ...
>
> main() {
>
> ...
> qemu_add_opts(&qemu_foo_opts);
>
> ...
>
> /* second pass of option parsing */
> ...
> for(;;) {
> ...
> switch(popt->index) {
> ...
>
> case QEMU_OPTION_foo:
> opts = qemu_opts_parse(qemu_find_opts("foo"), optarg, 0);
> if (!foo_option_add(qemu_opt_get(opts, "name"),
> qemu_opt_get(opts, "file"))) {
> fprintf(stderr, "invalid foo entry config %s\n", optarg);
> exit(1);
> }
> break;
>
> ...
> }
>
>
> Somewhere else in the source I have
>
> bool foo_option_add(const char *name, const char *file) {
>
> if (/* everything OK */) {
> return true;
> }
>
> return false;
> }
Looks sane so far.
> Assuming the above is correct (and that the appropriate glue is added
> to qemu-options.hx to tie "-foo name=abc,file=xyz" to QEMU_OPTION_foo),
> I'm wondering about preventing "name" and "file" from being turned
> into Booleans should their arguments be omitted on the command line.
>
> To clarify:
>
> -foo abcxyz results in a parse error generated by qemu_opts_parse()
> which is as it should be
>
> -foo file=abc,name=xyz results in a call to foo_option_add("xyz", "abc")
> which is the desired behavior
>
> -foo file=,name= results in a call to foo_option_add("", "")
> which is also OK, as I can sanity-check my
> arguments from within foo_option_add()
>
> However,
>
> -foo file,name results in a call to foo_option_add("on", "on")
> i.e., in the absence of string values, both
> "file" and "name" are converted into Booleans
> and given the string value "on" by qemu_opts_parse()
> which is NOT what I want, and I'm wondering if
> that behavior can somehow be turned off for
> any given QemuOptsList ?
>
> I guess I could be looking for a file named "on" in the current
> directory, and attempt to use the value "on" to insert the object
> from the given file (and fail if no file named "on" could be found,
> but this is not as clean as I would like it to be, and I'm wondering
> if there's a better way).
Reproduced:
$ upstream-qemu -nodefaults -S -display vnc=:0 -monitor stdio -name
process=foo,guest
QEMU 2.2.50 monitor - type 'help' for more information
(qemu) info name
on
QemuOpts is baroque.
No, you can't switch it off. I'm afraid adding such a switch is not a
good idea, because it would make QemuOpts even more baroque.
Perhaps we can limit the convenience syntax "omitted value means =on" to
boolean options. Could be hairy, because .desc can be empty, which
defers part of the checking until later.
