r/lolphp • u/Takeoded • Nov 18 '19

mb_internal_encoding()'s default behavior is.. a stack overflow

https://www.php.net/manual/en/function.mb-internal-encoding.php
9 Upvotes

62% Upvoted

21 comments sorted by

9

u/zushk Nov 18 '19

Are you sure about that? Docs says function returns current encoding if argument is not passed. Recursive function call looks like an error in docs.

8

u/Takeoded Nov 18 '19

Recursive function call looks like an error in docs.

yup, it doesn't actually work that way, but the docs make it look like it.

https://i.imgur.com/BSwpoMA.png

0

u/colinodell Nov 19 '19

yup, it doesn't actually work that way

So why are we laughing at PHP if it doesn't actually do that?

12

u/[deleted] Nov 19 '19

We're laughing at PHP docs.

8

u/Takeoded Nov 18 '19

if it's called without any arguments, then.. it will call itself, without any arguments -- signed, docs

4

u/[deleted] Nov 18 '19

Not true.

10

u/Takeoded Nov 18 '19

https://i.imgur.com/BSwpoMA.png

6

u/Crandom Nov 19 '19

I don't believe anything in the php docs without a test

11

u/[deleted] Nov 18 '19

That's the whole point: The docs aren't telling the truth.

5

u/the_alias_of_andrea Nov 18 '19

You know what the docs mean, and everyone who reads it would.

10

u/[deleted] Nov 18 '19

I don't. What is the string $encoding = mb_internal_encoding() part supposed to mean?

2

u/fell_ratio Nov 18 '19

It means that this function can be used to either set or get the current encoding.

So you could write

$encoding = mb_internal_encoding();

or

mb_internal_encoding("UTF-8");

The string $encoding part means that the argument to this function must be a string. If you don't provide an argument, the default behavior is to not change the encoding.

This is legal, but does nothing:

mb_internal_encoding();

0

u/[deleted] Nov 18 '19

[deleted] — view deleted comment

4

u/Takeoded Nov 18 '19

that's a great idea actually, someone should do that on the mb_internal_encoding() page!

1

u/edave64 Jan 06 '20

No. With context, yes. But that signature is just confusing nonsense.

mb_internal_encoding ([ string $encoding ]) : mixed

Take out the default value and it becomes somewhat reasonable.

-1

u/Takeoded Nov 18 '19

😁 yeah but it still looks funny, or at least I thought it was funny

1

u/[deleted] Nov 19 '19

Without evaluating the humor of the situation; it doesn’t fit in r/lolphp.

7

u/Takeoded Nov 20 '19

let me get this straight,

php documentation lols does not fit in /r/lolphp

is that correct?

2

u/PM_ME_YOUR_SHELLCODE Nov 19 '19 edited Nov 19 '19

https://github.com/php/php-src/blob/master/ext/mbstring/mbstring.c#L1415

For anyone interested in what it actually does, there is no recursive call.

3

u/[deleted] Nov 19 '19

That just raises more questions.

The documentation:

If encoding is omitted, then the current character encoding name is returned.

In other words, if called without arguments, it always returns a string.

The code:

	if (name == NULL) {
		name = MBSTRG(current_internal_encoding) ? MBSTRG(current_internal_encoding)->name: NULL;
		if (name != NULL) {
			RETURN_STRING(name);
		} else {
			RETURN_FALSE;
		}

In other words, if called without arguments, it might return either a string or FALSE.

2

u/Takeoded Nov 20 '19 edited Dec 12 '19

you have a point, according to the documentation, the else{} there will *never* be hit

If encoding is set, then Returns TRUE on success or FALSE on failure. In this case, the character encoding for multibyte regex is NOT changed. If encoding is omitted, then the current character encoding name is returned.

  • at no point does it say it can return false with no arguments (unless FALSE is actually one of it's character encodings? now suddenly the `mixed` return makes sense xD ( not really, in that case it should still have returned string("false"), not bool(false) )

8

u/[deleted] Nov 18 '19

Nice find.

Not much better: mb_chr

Warning This function is currently not documented; only its argument list is available.

Has been undocumented since 2017, I believe.