[U-Boot] [PATCH v1 1/4] Kconfig: Enable usage of escape char '\' in string values

Simon Glass
2015-05-11T22:41:42Z

Hi Stefan,

On 11 May 2015 at 07:27, Stefan Roese <mail@roese.nl> wrote:
> Hi Simon, Hi Masahiro,
>
>
> On 11.05.2015 09:58, Stefan Roese wrote:
>>
>> On 10.05.2015 16:48, Simon Glass wrote:
>>>
>>> On 7 May 2015 at 06:13, Stefan Roese <sr@denx.de> wrote:
>>>>
>>>> I might have missed something, but I failed to use the escape char '\'
>>>> in strings. To pass a printf format string like "foo %d bar\n" via
>>>> Kconfig to the code.
>>>>
>>>> Right now its not possible to use the escape character '\' in Kconfig
>>>> string values correctly to e.g. set this string value "test output\n".
>>>> The '\n' will be converted to 'n'.
>>>>
>>>> The current implementation removes some of the '\' chars from the input
>>>> string in conf_set_sym_val(). Examples:
>>>>
>>>> '\' -> ''
>>>> '\\' -> '\'
>>>> '\\\' -> '\'
>>>> '\\\\' -> '\\'
>>>> ...
>>>>
>>>> And then doubles the backslash chars in the output string in
>>>> sym_escape_string_value(). Example:
>>>>
>>>> '\' -> '' -> ''
>>>> '\\' -> '\' -> '\\'
>>>> '\\\' -> '\' -> '\\'
>>>> '\\\\' -> '\\' -> '\\\\'
>>>> ...
>>>>
>>>> As you see in these examples, its impossible to generate a single '\'
>>>> charater in the output string as its needed for something like '\n'.
>>>>
>>>> This patch now changes this behavior to not drop some backslashes in
>>>> conf_set_sym_val() and to not add new backslashes in the resulting
>>>> output string. Removing the function sym_escape_string_value()
>>>> completely as its not needed anymore.
>>>>
>>>> Signed-off-by: Stefan Roese <sr@denx.de>
>>>> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
>>>> Cc: Simon Glass <sjg@chromium.org>
>>>> ---
>>>>
>>>> scripts/kconfig/confdata.c | 20 +++++++++-----------
>>>> scripts/kconfig/symbol.c | 43
>>>> -------------------------------------------
>>>> 2 files changed, 9 insertions(+), 54 deletions(-)
>>>
>>>
>>> This looks right to me. But I do see one problem - the default string
>>> for CONFIG_AUTOBOOT_PROMPT appears as:
>>>
>>> "Autoboot in %d secondsn"
>>>
>>> so something is still removing the \ in the Kconfig default;
>>
>>
>> Right. Thanks for spotting. I'll fix this in v3.
>
>
> I could easily change the default string in the Kconfig file to "Autoboot in
> %d seconds\\n". This works. But its a different syntax regarding using the
> escape character backslash compared to editing the .config file or editing
> the string in "make menuconfig etc...". So I hesitate to "fix" it this way.
>
> Unfortunately fixing this issue in the code is not that easy. At least not
> for me. As the default values of the "string values" are set in the
> conf_parse() function (in scripts/kconfig/zconf.y). And I really have
> absolutely no experience with yacc / bison. Perhaps one of you guys has a
> quick fix to make this default value of strings compatible again so that
> this additional '\' is not needed in the Kconfig file?

Well I am familiar with those tools but I think Masahiro probably
knows a lot more here.

Regards,
Simon