Function eval_clause

scripts/config/preprocess.c:346–442

* Evaluate a clause with arguments. argc/argv are arguments from the upper * function call. * * Returned string must be freed when done */

 * Returned string must be freed when done
 */
static char *eval_clause(const char *str, size_t len, int argc, char *argv[])
{
	char *tmp, *name, *res, *endptr, *prev, *p;
	int new_argc = 0;
	char *new_argv[FUNCTION_MAX_ARGS];
	int nest = 0;
	int i;
	unsigned long n;

	tmp = xstrndup(str, len);

	/*
	 * If variable name is '1', '2', etc.  It is generally an argument
	 * from a user-function call (i.e. local-scope variable).  If not
	 * available, then look-up global-scope variables.
	 */
	n = strtoul(tmp, &endptr, 10);
	if (!*endptr && n > 0 && n <= argc) {
		res = xstrdup(argv[n - 1]);
		goto free_tmp;
	}

	prev = p = tmp;

	/*
	 * Split into tokens
	 * The function name and arguments are separated by a comma.
	 * For example, if the function call is like this:
	 *   $(foo,$(x),$(y))
	 *
	 * The input string for this helper should be:
	 *   foo,$(x),$(y)
	 *
	 * and split into:
	 *   new_argv[0] = 'foo'
	 *   new_argv[1] = '$(x)'
	 *   new_argv[2] = '$(y)'
	 */
	while (*p) {
		if (nest == 0 && *p == ',') {
			*p = 0;
			if (new_argc >= FUNCTION_MAX_ARGS)
				pperror("too many function arguments");
			new_argv[new_argc++] = prev;
			prev = p + 1;
		} else if (*p == '(') {
			nest++;
		} else if (*p == ')') {
			nest--;
		}

		p++;
	}

	if (new_argc >= FUNCTION_MAX_ARGS)
		pperror("too many function arguments");
	new_argv[new_argc++] = prev;