From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Subject: lib/cmdline: allow NULL to be an output for get_option() In the future we would like to use get_option() to only validate the string and parse it separately. To achieve this, allow NULL to be an output for get_option(). Link: https://lkml.kernel.org/r/20201112180732.75589-5-andriy.shevchenko@xxxxxxxxxxxxxxx Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Brendan Higgins <brendanhiggins@xxxxxxxxxx> Cc: David Gow <davidgow@xxxxxxxxxx> Cc: Mark Brown <broonie@xxxxxxxxxx> Cc: Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx> Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> Cc: Vitor Massaru Iha <vitor@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/cmdline.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/lib/cmdline.c~lib-cmdline-allow-null-to-be-an-output-for-get_option +++ a/lib/cmdline.c @@ -35,11 +35,14 @@ static int get_range(char **str, int *pi /** * get_option - Parse integer from an option string * @str: option string - * @pint: (output) integer value parsed from @str + * @pint: (optional output) integer value parsed from @str * * Read an int from an option string; if available accept a subsequent * comma as well. * + * When @pint is NULL the function can be used as a validator of + * the current option in the string. + * * Return values: * 0 - no int in string * 1 - int found, no subsequent comma @@ -53,13 +56,16 @@ static int get_range(char **str, int *pi int get_option(char **str, int *pint) { char *cur = *str; + int value; if (!cur || !(*cur)) return 0; if (*cur == '-') - *pint = -simple_strtoull(++cur, str, 0); + value = -simple_strtoull(++cur, str, 0); else - *pint = simple_strtoull(cur, str, 0); + value = simple_strtoull(cur, str, 0); + if (pint) + *pint = value; if (cur == *str) return 0; if (**str == ',') { _
