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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Mon, 16 Apr 2018 00:12:06 +0900
Message-ID: <CAK7LNAT7pkTTuazD9AnQtj_Ut+qkfnmhNu0SJ+N8=uKNy4CUOg@mail.gmail.com>
Subject: Re: [PATCH 08/30] kconfig: add built-in function support
To:     Ulf Magnusson <ulfalizer@gmail.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Emese Revfy <re.emese@gmail.com>, X86 ML <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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2018-04-15 16:57 GMT+09:00 Ulf Magnusson <ulfalizer@gmail.com>:
> On Fri, Apr 13, 2018 at 7:06 AM, Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
>> This commit adds a new concept 'function' to do more text processing
>> in Kconfig.
>>
>> A function call looks like this:
>>
>>   $(function arg1, arg2, arg3, ...)
>>
>> This commit adds the basic infrastructure to expand functions.
>> Change the text expansion helpers to take arguments.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> ---
>>
>> Changes in v3:
>>   - Split base infrastructure and 'shell' function
>>     into separate patches.
>>
>> Changes in v2:
>>   - Use 'shell' for getting stdout from the comment.
>>     It was 'shell-stdout' in the previous version.
>>   - Symplify the implementation since the expansion has been moved to
>>     lexer.
>>
>>  scripts/kconfig/preprocess.c | 142 +++++++++++++++++++++++++++++++++++++++----
>>  1 file changed, 130 insertions(+), 12 deletions(-)
>>
>> diff --git a/scripts/kconfig/preprocess.c b/scripts/kconfig/preprocess.c
>> index fa4abc8..e77cf7c 100644
>> --- a/scripts/kconfig/preprocess.c
>> +++ b/scripts/kconfig/preprocess.c
>> @@ -8,6 +8,10 @@
>>
>>  #include "list.h"
>>
>> +#define ARRAY_SIZE(arr)                (sizeof(arr) / sizeof((arr)[0]))
>> +
>> +static char *expand_string_with_args(const char *in, int argc, char *argv[]);
>> +
>>  /*
>>   * Environment variables
>>   */
>> @@ -74,9 +78,47 @@ void env_write_dep(FILE *f, const char *autoconfig_name)
>>         }
>>  }
>>
>> -static char *eval_clause(const char *in)
>> +/*
>> + * Built-in Functions
>> + */
>> +struct function {
>> +       char *name;
>> +       char *(*func)(int argc, char *argv[]);
>> +};
>> +
>> +static const struct function function_table[] = {
>> +};
>> +
>> +static char *function_call(const char *name, int argc, char *argv[])
>>  {
>> -       char *res, *name;
>> +       const struct function *f;
>> +       int i;
>> +
>> +       for (i = 0; i < ARRAY_SIZE(function_table); i++) {
>> +               f = &function_table[i];
>> +               if (!strcmp(f->name, name))
>> +                       return f->func(argc, argv);
>> +       }
>> +
>> +       return NULL;
>> +}
>> +
>> +#define FUNCTION_MAX_ARGS              16
>> +
>> +/*
>> + * Evaluate a clause with arguments.  argc/argv are arguments from the upper
>> + * function call.
>> + *
>> + * Returned string must be freed when done
>> + */
>> +static char *eval_clause(const char *in, int argc, char *argv[])
>> +{
>> +       char *tmp, *prev, *p, *res, *name;
>> +       char delim = ' ';
>> +       int new_argc = 0;
>> +       char *new_argv[FUNCTION_MAX_ARGS];
>> +       int nest = 0;
>> +       int i;
>>
>>         /*
>>          * Returns an empty string because '$()' should be evaluated
>> @@ -85,10 +127,73 @@ static char *eval_clause(const char *in)
>>         if (!*in)
>>                 return xstrdup("");
>>
>> -       name = expand_string(in);
>> +       tmp = xstrdup(in);
>> +
>> +       prev = p = tmp;
>>
>> -       res = env_expand(name);
>> +       /*
>> +        * Split into tokens
>> +        * The function name and the first argument are separated by a space.
>> +        * Arguments are separated by a comma.
>> +        * For example, if the function call is like this:
>> +        *   $(foo abc,$(x),$(y))
>> +        *
>> +        * The input string for this helper should be:
>> +        *   foo abc,$(x),$(y)
>> +        *
>> +        * and split into:
>> +        *   new_argv[0]: foo
>> +        *   new_argv[1]: abc
>> +        *   new_argv[2]: $(x)
>> +        *   new_argv[3]: $(y)
>> +        */
>> +       while (*p) {
>> +               if (nest == 0 && *p == delim) {
>> +                       *p = 0;
>> +                       new_argv[new_argc++] = prev;
>
> Erroring out would be nicer than overflowing the array.


OK, will do.


-- 
Best Regards
Masahiro Yamada