stream_set_blocking(true) toggles, not enables blocking
| Bug #35079 | stream_set_blocking(true) toggles, not enables blocking | ||||
|---|---|---|---|---|---|
| Submitted: | 2005-11-03 05:55 UTC | Modified: | 2005-11-17 15:20 UTC | ||
| From: | askalski at gmail dot com | Assigned: | wez (profile) | ||
| Status: | Closed | Package: | Filesystem function related | ||
| PHP Version: | 5CVS-2005-11-03 (snap) | OS: | linux | ||
| Private report: | No | CVE-ID: | None | ||
[2005-11-03 05:55 UTC] askalski at gmail dot com
Description:
------------
main/streams/plain_wrapper.c (5.0.5)
main/streams.c (4.4 and earlier)
In several places, the ^= operator is used to turn off a flag. This is incorrect. For example, stream_set_blocking() on a plain file hits this code in php_stdiop_set_option():
if (value)
flags ^= O_NONBLOCK;
else
flags |= O_NONBLOCK;
This should be:
if (value)
flags &= ~O_NONBLOCK;
else
flags |= O_NONBLOCK;
The same error is repeated elsewhere in the code.
Reproduce code:
---------------
$fp = fopen("test", "w");
stream_set_blocking($fp, true);
stream_set_blocking($fp, true);
stream_set_blocking($fp, true);
stream_set_blocking($fp, true);
fclose($fp);
Expected result:
----------------
The stream should remain in blocking mode throughout the script execution.
Actual result:
--------------
Here is abridged strace output showing the errant behavior. Notice how O_NONBLOCK is being turned on and off alternately.
open("/home/askalski/test", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
fcntl64(4, F_SETFL, O_WRONLY|O_NONBLOCK) = 0
fcntl64(4, F_SETFL, O_WRONLY) = 0
fcntl64(4, F_SETFL, O_WRONLY|O_NONBLOCK) = 0
fcntl64(4, F_SETFL, O_WRONLY) = 0
close(4) = 0
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[2005-11-03 18:56 UTC] askalski at gmail dot com
[2005-11-03 21:43 UTC] sniper@php.net
[2005-11-11 22:32 UTC] tony2001@php.net
[2005-11-17 15:20 UTC] tony2001@php.net