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Date: Sun, 28 Aug 2011 15:29:28 +0200
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Subject: Problems with the stream API
From: christian.kaps@mohiva.com (Christian Kaps)

Hi,

I have some problems with the stream API. The methods stream_tell and
stream_seek works not as expected in some cases.

Before reading the next lines, please look at the short
gist(https://gist.github.com/1176641).

First example:

$fp = fopen('mfx://test1', 'w');
fwrite($fp, '12345678');
fseek($fp, -1, SEEK_CUR);
fclose($fp);
// stream_seek: $offset = 7

If you call fseek with the arguments (-1, SEEK_CUR) then the $offset
parameter in the method stream_seek is 7. It seems that the internal API
takes the written bytes returned by fwrite and then it subtracts the
argument (-1) from it before passing it to stream_seek. For the
constants SEEK_SET and SEEK_END, the passed value is the same as defined
for the fseek call.

-----------------------------------

The second example:

$fp = fopen('mfx://test2', 'w');
fwrite($fp, '12345678');
fread($fp, 2);
fseek($fp, 1, SEEK_CUR);
fclose($fp);

For this example the stream_seek method gets never be called. The
difference here is that fread is called before fseek.

-----------------------------------

The third example:

$fp = fopen('mfx://test3', 'w');
fwrite($fp, '12345678');
fread($fp, 3);
ftell($fp);
fclose($fp);

For this example the stream_tell method gets never be called. It is
documented(http://www.php.net/manual/en/streamwrapper.stream-tell.php)
that the stream_tell method is called in response to ftell(). But it
seems that this method is only be called internally by the stream API.

There exists a Bug report at https://bugs.php.net/bug.php?id=30157

In one of the comments Pierre says: There is no bug but a feature
request which seems to be very discutable.

So with these words, I start the discussion.

Christian