https://bugzilla.kernel.org/show_bug.cgi?id=18372 Summary: A filled up named pipe always has a size of zero! Product: File System Version: 2.5 Kernel Version: 2.6.32-22-generic (also older and newer ones) Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: ext4 AssignedTo: fs_ext4@xxxxxxxxxxxxxxxxxxxx ReportedBy: tom.bzliknl83947@xxxxxxxxx CC: tom.bzliknl83947@xxxxxxxxx Regression: No Hi, there! The size of a filled named pipe is always zero. This is wrong! A read operation is going to hang for try to read from an empty pipe. To go around this trap it is necessary to do a conditional test on the filesize, [ -s pipe ]. Problem: The test doesn't work, because filesize is always zero. Try: mknod pipe & sleep 3600 <>pipe & echo 'date' >pipe [ -s pipe ] && echo "filled up" ls -l pipe; stat pipe # if size zero, it is wrong [ -s pipe ] && (read val <pipe; echo $val) This is a critical error. While parallel processing a script would be blocked. In worst case it causes a deadlock situation. Every changing of a condition of a file should be reported whithin the i-node. I found it in several disto: Ubuntu KarmicKoala 9.1, LucidLynx 10.04, Linux Mint Debian Edition 5, Slackware 13.1 x64 Best regards TOM -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
