Re: [PATCH v2] dm: Add support for escaped characters in str_field_delimit()

Mikulas Patocka
2024-07-02T15:18:54Z

Hi

I'd like to ask why is this needed. AFAIK, none of the allowed targets use
',' on their table line.

Mikulas

On Thu, 13 Jun 2024, Abhinav Jain wrote:

> Remove all the escape characters that come before separator.
> Tested this code by writing a dummy program containing the two
> functions and testing it on below input, sharing results:
>
> Original string: "field1\,with\,commas,field2\,with\,more\,commas"
> Field: "field1"
> Field: "with"
> Field: "commas"
> Field: "field2"
> Field: "with"
> Field: "more"
> Field: "commas"
>
> Signed-off-by: Abhinav Jain <jain.abhinav177@gmail.com>
> ---
> PATCH v1:
> https://lore.kernel.org/all/20240609141721.52344-1-jain.abhinav177@gmail.com/
>
> Changes since v1:
> - Modified the str_field_delimit function as per shared feedback
> - Added remove_escaped_characters function
> ---
> ---
> drivers/md/dm-init.c | 53 +++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 47 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/md/dm-init.c b/drivers/md/dm-init.c
> index 2a71bcdba92d..0e31ecf1b48e 100644
> --- a/drivers/md/dm-init.c
> +++ b/drivers/md/dm-init.c
> @@ -76,6 +76,24 @@ static void __init dm_setup_cleanup(struct list_head *devices)
> }
> }
>
> +/* Remove escape characters from a given field string. */
> +static void __init remove_escape_characters(char *field)
> +{
> + char *src = field;
> + char *dest = field;
> +
> + while (*src) {
> + if (*src == '\\') {
> + src++;
> + if (*src)
> + *dest++ = *src++;
> + } else {
> + *dest++ = *src++;
> + }
> + }
> + *dest = '\0';
> +}
> +
> /**
> * str_field_delimit - delimit a string based on a separator char.
> * @str: the pointer to the string to delimit.
> @@ -87,16 +105,39 @@ static void __init dm_setup_cleanup(struct list_head *devices)
> */
> static char __init *str_field_delimit(char **str, char separator)
> {
> - char *s;
> + char *s, *escaped, *field;
>
> - /* TODO: add support for escaped characters */
> *str = skip_spaces(*str);
> s = strchr(*str, separator);
> - /* Delimit the field and remove trailing spaces */
> - if (s)
> +
> + /* Check for escaped character */
> + escaped = strchr(*str, '\\');
> + while (escaped && (s == NULL || escaped < s)) {
> + /*
> + * Move the separator search ahead if escaped
> + * character comes before.
> + */
> + s = strchr(escaped + 1, separator);
> + escaped = strchr(escaped + 1, '\\');
> + }
> +
> + /* If we found a separator, we need to handle escape characters */
> + if (s) {
> + *s = '\0';
> +
> + remove_escape_characters(*str);
> + field = *str;
> + *str = s + 1;
> + } else {
> + /* Handle the last field when no separator is present */
> + s = *str + strlen(*str);
> *s = '\0';
> - *str = strim(*str);
> - return s ? ++s : NULL;
> +
> + remove_escape_characters(*str);
> + field = *str;
> + *str = s;
> + }
> + return field;
> }
>
> /**
> --
> 2.34.1
>