#include <ccan/talloc/talloc.h>
#include "tools.h"
#include <assert.h>
#include <string.h>
#include <stdlib.h>

/* Walk up to find /ccan/ => ccan directory. */
static unsigned int ccan_dir_prefix(const char *fulldir)
{
	unsigned int i;

	assert(fulldir[0] == '/');
	for (i = strlen(fulldir) - 1; i > 0; i--) {
		if (strncmp(fulldir+i, "/ccan", 5) != 0)
			continue;
		if (fulldir[i+5] != '\0' && fulldir[i+5] != '/')
			continue;
		return i + 1;
	}
	return 0;
}

const char *find_ccan_dir(const char *base)
{
	unsigned int prefix = ccan_dir_prefix(base);

	if (!prefix)
		return NULL;

	return talloc_strndup(NULL, base, prefix);
}