ID:               47152
 Comment by:       d_kelsey at uk dot ibm dot com
 Reported By:      d_kelsey at uk dot ibm dot com
 Status:           Open
 Bug Type:         Zlib Related
 Operating System: Windows XP
 PHP Version:      5.2.8
 New Comment:

There is also a problem using SEEK_END when opening a file for write
mode.

for example
<?php
$file = "test.txt.gz";
$h = gzopen($file, 'w');
gzwrite($h, "first sentence.");
gzseek($h, 0, SEEK_END);
var_dump(gztell($h));
gzwrite($h, "second sentence.");
var_dump(gztell($h));
gzclose($h);

$h = gzopen($file, 'r');
gzpassthru($h);
gzclose($h);
unlink($file)
?>

results in:
bool(false)
int(15)
first sentence.second sentence.

So the gztell results of bool(false)and then int(15) are both
incorrect. Yet the file did get written correctly.


Previous Comments:
------------------------------------------------------------------------

[2009-01-19 18:31:59] d_kelsey at uk dot ibm dot com

Description:
------------
I have opened a .gz file using gzopen for reading.
I can pass SEEK_END with offset of 0 (which would seek to the end of
the file) using either fseek or gzseek as a whence. This returns -1 (a
failure), but a subsequent gztell/ftell returns false, but I can still
read the stream from the position it was last in. 

The issue is
1. is a whence of SEEK_END supported for a zlib stream ? If it is then
SEEK_END is very broken as it doesn't move it to the end of the stream.

2. if not supported, I should get a warning saying invalid parameter.
Also a subsequent call to gztell/ftell returns false.a further read and
gztell/ftell returns an incorrect value 

I couldn't find any information to say it was not a valid value so
assumed that it was valid.

Reproduce code:
---------------
<?php
//004.txt.gz taken from zlib test directory
//first 20 bytes are: "When you're taught t"
$f = dirname(__FILE__)."/004.txt.gz";
$h = gzopen($f, 'r'); 
//read the first 10
var_dump(gzread($h, 10));
echo "move to the end\n";
echo "gzseek=";
var_dump(gzseek( $h, 0, SEEK_END ) );
echo "tell=";
var_dump(gztell($h));
echo "eof=";
var_dump(gzeof($h));
//read the next 10
var_dump(gzread($h, 10));
echo "tell=";
var_dump(gztell($h));
?>

Expected result:
----------------
If SEEK_END is not valid:
string(10) "When you'r"
move to the end
gzseek=
Warning: gzseek() SEEK_END not supported
tell=int(10)
eof=bool(false)
string(10) "e taught t"
tell=int(20)

if SEEK_END is valid:
string(10) "When you'r"
move to the end
gzseek=int(0)
tell=int(176)
eof=bool(true)
string(0) ""
tell=int(176)

Actual result:
--------------
string(10) "When you'r"
move to the end
gzseek=int(-1)
tell=bool(false)
eof=bool(false)
string(10) "e taught t"
tell=int(9)


------------------------------------------------------------------------


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