Fix #76954 Use while loop in func add_response_header

[stodorovic]

Related issues:

https://bugs.php.net/bug.php?id=76954
https://github.com/Automattic/wp-super-cache/issues/539

PHP 5.6 uses while loop, but PHP 7.x uses do ... while which decreases len before condition. Parameter len in function memcpy has decreased length and last character isn't copied.

[staabm]

Could you add a unit test?

[cmb69]

Indeed, the refactoring in 4cba2f9 looks fishy. If len == 1 we would access h->header[-1]. It seems to me that we could stick with the do-loop, if we change the indexes from len-1 to len in the while-clause. @weltling Am I missing something?

Regarding the unit test: I'm not sure if we can use the --HEADERS-- section since the docs say it would only be supported by server-tests.php, but sapi/tests/test006.phpt and sapi/tests/test007.phpt use it.

[stodorovic]

Regarding to do ... while, possible solution is:

if (NULL != p) {
	len = p - h->header + 1;
}
if (len > 0) {
	do {
		len--;
	} while (len != 0 && (h->header[len-1] == ' ' || h->header[len-1] == '\t'));

It works fine even if : is first or last character (which doesn't make sense).

@cmb69 If we use h->header[len] in condition, then correct solution is:

if (NULL != p) {
	len = p - h->header;
}
if (len > 0) {
	do {
		len--;
	} while (len != 0 && (h->header[len] == ' ' || h->header[len] == '\t'));
	if (len) {
		len++; // Include last character.

If len == 0 then condition is false without evaluation of h->header[len-1] (regardless to type of loop). So, I think that's better to use while loop because we should keep original value of len (if whitespace doesn't exist) and it's little faster (and more clear solution for me).

I've added test and we don't need --HEADERS-- because we should use header function to send header.

[cmb69]

@stodorovic Thanks, that sounds plausible. (And yes, I've confused apache_response_headers with apache_request_headers).

[KalleZ]

This should be in a --CLEAN-- section for consistency

[KalleZ]

Since this is a full path (from the $filename variable), the $filename should be quoted for escapes in case the full path contains a space

[php-pulls]

Comment on behalf of cmb at php.net:

Thanks! Applied via 47b89bc.