[ccan] Add new 'bytestring' module

[Rusty Russell]

On Mon, 21 May 2012 11:11:22 +1000, David Gibson <david at gibson.dropbear.id.au> wrote:
> This patch adds a new 'bytestring' module which manipulates bytestrings
> consisting of a const char pointer and length.  This makes for more
> convenient handling of subsections of a large fixed data buffer or buffers.
> 
> Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

Nice!

Nitpicks below:

> +/**
> + * bytestring_eq - test if bytestrings have identical content
> + * @a, @b: bytestrings
> + *
> + * Returns 1 if the given bytestrings have identical length and
> + * content, 0 otherwise.
> + */
> +static inline int bytestring_eq(struct bytestring a, struct bytestring b)
> +{
> +	return (a.len == b.len)
> +		&& (memcmp(a.ptr, b.ptr, a.len) == 0);
> +}

bool?

> diff --git a/ccan/bytestring/test/compile_fail-BYTESTRING.c b/ccan/bytestring/test/compile_fail-BYTESTRING.c
> new file mode 100644
> index 0000000..4ebab67
> --- /dev/null
> +++ b/ccan/bytestring/test/compile_fail-BYTESTRING.c
> @@ -0,0 +1,14 @@
> +#include <stdio.h>
> +
> +#include <ccan/bytestring/bytestring.h>
> +
> +int main(int argc, char *argv[])
> +{
> +	struct bytestring bs;
> +
> +#ifdef FAIL
> +	bs = BYTESTRING(argv[0]);
> +#endif
> +	printf("%zd\n", bs.len);
> +	return 0;
> +}

I think with optimization, this will fail due to a warning about bs.len
being uninitialized.  I prefer to put the FAIL around the minimal
amount, eg:

        bs = BYTESTRING(
#ifdef FAIL
                        argv[0]
#else
                        "literal"
#endif
        );

> +#define TEST_STRING	"test string"
> +#define TEST_STRING_2	"abc\0def"
> +
> +const char str1[] = TEST_STRING;
> +const char *str2 = TEST_STRING;
> +
> +int main(void)
> +{
> +	struct bytestring bs, bs1, bs2, bs3;
> +
> +	/* This is how many tests you plan to run */
> +	plan_tests(5);
> +
> +	bs = bytestring(str1, sizeof(str1) - 1);
> +	ok1(bs.ptr == str1);
> +	ok1(bs.len == (sizeof(str1) - 1));
> +
> +	bs1 = BYTESTRING(TEST_STRING);
> +	ok1(bytestring_eq(bs, bs1));
> +
> +	bs2 = BYTESTRING(TEST_STRING_2);
> +	ok1(bs2.len == 7);
> +
> +	bs3 = bytestring_from_string(str2);
> +	ok1(bytestring_eq(bs3, bs));

Want to test that bytestring_from_string on a nul-containing string
does as documented?

Cheers,
Rusty.