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SubjectRe: [PATCH 2/6] lib / string_helpers: introduce string_escape_mem()
On Wed,  2 Jul 2014 16:20:25 +0300 Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> This is almost the opposite function to string_unescape(). Nevertheless it
> handles \0 and could be used for any byte buffer.
>
> The documentation is supplied together with the function prototype.
>
> The test cases covers most of the scenarios and would be expanded later on.
>
> ...
>
> --- a/include/linux/string_helpers.h
> +++ b/include/linux/string_helpers.h
> @@ -71,4 +71,87 @@ static inline int string_unescape_any_inplace(char *buf)
> return string_unescape_any(buf, buf, 0);
> }
>
> +#define ESCAPE_SPACE 0x01
> +#define ESCAPE_SPECIAL 0x02
> +#define ESCAPE_NULL 0x04
> +#define ESCAPE_OCTAL 0x08
> +#define ESCAPE_ANY \
> + (ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_SPECIAL | ESCAPE_NULL)
> +#define ESCAPE_NP 0x10
> +#define ESCAPE_ANY_NP (ESCAPE_ANY | ESCAPE_NP)
> +#define ESCAPE_HEX 0x20
> +
> +/**
> + * string_escape_mem - quote characters in the given memory buffer

It drive me nuts when the kerneldoc is in the .h file. Who thinks of
looking there? I realise that string_unescape() already did that, but
I'd prefer that we fix string_unescape() rather than imitate it.

> --- a/lib/string_helpers.c
> +++ b/lib/string_helpers.c

This is a lot of code! Adds nearly a kbyte. I'm surprised that
escaping a string is so verbose.

I wonder if the implementation really needs to be so comprehensive?

Would a table-driven approach be more compact?

> static int __init test_string_helpers_init(void)
> {
> unsigned int i;
> @@ -112,6 +315,16 @@ static int __init test_string_helpers_init(void)
> test_string_unescape("unescape inplace",
> get_random_int() % (UNESCAPE_ANY + 1), true);
>
> + /* Without dictionary */
> + for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++)
> + test_string_escape("escape 0", escape0, i, TEST_STRING_2_DICT_0);
> +
> + /* With dictionary */
> + for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++)
> + test_string_escape("escape 1", escape1, i, TEST_STRING_2_DICT_1);
> +
> + test_string_escape_nomem();
> +
> return -EINVAL;
> }

I wonder why this returns -EINVAL.


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