#35531 [NEW]: php wont get input from a serialport after writing to it
From: roman-lehnert at gmx dot de
Operating system: Linux 2.6.12
PHP version: 4.4.1
PHP Bug Type: Filesystem function related
Bug description: php wont get input from a serialport after writing to it
Description:
------------
Php doesn't get any input from a serialport, after opening the devicefile
and writing to it. Maybe this is thought to be so - and maybe it is a
feature. For those cases: sorry for stealing ur time.
Infact, there IS a response from the device. The difference between
"strace php -f example.php" and "strace cat /dev/ttyUSB0"
(nonblocking-mode in php):
php wont get the input. for php, the device is "temporarily unavailable":
"read(3, 0x17e4a4, 1024) = -1 EAGAIN (Resource temporarily
unavailable)"
cat gets the answer from the device:
"read(3, "\0\340", 4096) = 2"
There is no difference, if i use fopen, or dio_open: php wont get the
answer from my device.
There is also no difference, if i use fread, fgets or dio_read.
The lib i used can be seen here: http://nopaste.php-q.net/176167
Tested on a x86 and an embedded-arm machine, both running an actual linux
>2.6.12-r1 kernel. The chmods for the devices were set correctly.
Reproduce code:
---------------
<?php
$fp = fopen('/dev/ttyUSB0','r+');
#fp = fopen('/dev/ttyUSB0','w+');
fputs($fp,chr(0xff),1);
$buffer = fread($fp,1);
fclose($fp);
?>
<?php
$fp = dio_open('/dev/ttyUSB0', O_RDWR | O_NOCTTY | O_NONBLOCK |
O_APPEND);
dio_write($fp,chr(0xff));
$buffer = dio_read($fp,1);
dio_close($fp);
?>
Expected result:
----------------
I expected to get the answer in $buffer by fread, fgets or dio_read. But
the answer from the device (wich i can see in cat /dev/ttyUSB0) didnt came
up in php.
Actual result:
--------------
The strace of "cat /dev/ttyUSB0", you can see here:
<snip>
read(3, "\0\340", 4096) = 2
</snip>
Should appear also at "strace php -f example.php". but it doesnt. When the
devicefile is opened in nonblocking mode, the relevant strace-output is:
<snip>
read(3, 0x17e4a4, 1024) = -1 EAGAIN (Resource temporarily
unavailable)
</snip>
When the devicefile is opened in blockingmode, it just hangs at
<snip>
read(3,
</snip>
--
Edit bug report at http://bugs.php.net/?id=35531&edit=1
--
Try a CVS snapshot (PHP 4.4): http://bugs.php.net/fix.php?id=35531&r=trysnapshot44
Try a CVS snapshot (PHP 5.1): http://bugs.php.net/fix.php?id=35531&r=trysnapshot51
Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=35531&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=35531&r=fixedcvs
Fixed in release: http://bugs.php.net/fix.php?id=35531&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=35531&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=35531&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=35531&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=35531&r=support
Expected behavior: http://bugs.php.net/fix.php?id=35531&r=notwrong
Not enough info: http://bugs.php.net/fix.php?id=35531&r=notenoughinfo
Submitted twice: http://bugs.php.net/fix.php?id=35531&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=35531&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=35531&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=35531&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=35531&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=35531&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=35531&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=35531&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=35531&r=mysqlcfg
Thread (2 messages)
- roman-lehnert at gmx dot de