Re: [PATCH for-5.1 5/8] qemu-option: Fix has_help_option()'s sloppy parsing

[Markus Armbruster]

Eric Blake <address@hidden> writes:

> On 4/9/20 10:30 AM, Markus Armbruster wrote:
>> has_help_option() uses its own parser.  It's inconsistent with
>> qemu_opts_parse(), as demonstrated by test-qemu-opts case
>> /qemu-opts/has_help_option.  Fix by reusing the common parser.
>>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>   tests/test-qemu-opts.c |  2 +-
>>   util/qemu-option.c     | 39 +++++++++++++++++++--------------------
>>   2 files changed, 20 insertions(+), 21 deletions(-)
>>
>> diff --git a/tests/test-qemu-opts.c b/tests/test-qemu-opts.c
>> index 27c24bb1a2..58a4ea2408 100644
>> --- a/tests/test-qemu-opts.c
>> +++ b/tests/test-qemu-opts.c
>> @@ -744,7 +744,7 @@ static void test_has_help_option(void)
>>           { "a,help", true, true, true },
>>           { "a=0,help,b", true, true, true },
>>           { "help,b=1", true, true, false },
>> -        { "a,b,,help", false /* BUG */, true, true },
>> +        { "a,b,,help", true, true, true },
>
> Okay, this revisits my question from 1/8.
>
> I guess the argument is that since 'b,help' is NOT a valid option name
> (only as an option value), that we are instead parsing three separate
> options 'b', '', and 'help', and whether or not the empty option is
> valid, the face that 'help' is valid is what makes this return true?

Parsing is oblivious of which option names are valid.  It's actually
oblivious of the entire QemuOpts definition.

Desugaring may depend on the QemuOpts definition, however.

"a,b,,help" gets parsed as four option parameters:

    "a",    which gets desugared to either "a=on" or "firstname=a"
    "b",    which gets desugared to "b=on"
    "" ,    which gets desugared to "=on"
    "help", which gets desugared to "help=on"

A user of the parse that supports help should clue on the last one,
throw away the parse, and provide help.

The first desugaring is one that depends on the QemuOpts definition.

>> +++ b/util/qemu-option.c
>> @@ -165,26 +165,6 @@ void parse_option_size(const char *name, const char 
>> *value,
>>       *ret = size;
>>   }
>>   -bool has_help_option(const char *param)
>> -{
>> -    const char *p = param;
>> -    bool result = false;
>> -
>> -    while (*p && !result) {
>> -        char *value;
>> -
>> -        p = get_opt_value(p, &value);
>> -        if (*p) {
>> -            p++;
>> -        }
>> -
>> -        result = is_help_option(value);
>
> Old code: both 'help' and '?' are accepted.
>
>> +bool has_help_option(const char *params)
>> +{
>> +    const char *p;
>> +    char *name, *value;
>> +    bool ret;
>> +
>> +    for (p = params; *p;) {
>> +        p = get_opt_name_value(p, NULL, &name, &value);
>> +        ret = !strcmp(name, "help");
>
> New code: only 'help' is accepted.  Is the loss of '?' intentional?

No.  Will fix, thanks!