Messages in this thread | | | From | Kyle Moffett <> | Subject | Re: [PATCH] Smackv10: Smack rules grammar + their stateful parser | Date | Sat, 3 Nov 2007 14:30:30 -0400 |
| |
On Nov 03, 2007, at 12:43:06, Ahmed S. Darwish wrote: > Bashv3 builtin "echo" behaves very strangely to -EINVAL. It sends > all the buffers that causes -EINVAL again in subsequent echo > invocations. > > i.e. > echo "Invalid Rule" > /smack/load # -EINVAL returned > echo "Valid Rule" > /smack/load > > In seconod iteration, echo sends the first invalid buffer again > then sends the new one. This causes a "Invalid Rule\nValid Rule" > buffer sent to write(). > > IMHO, this is a bug in builtin echo. The external /bin/echo doesn't > cause such strange behaviour.
Actually, what causes problems here is something between a bug and a feature in libc's buffering. Basically the -EINVAL error causes libc to leave its data in the file-output buffer despite the file being closed and reopened. Since a standalone echo just exits that buffer is discarded, but for the bash builtin it hangs around in the buffer for a while and ends up getting prepended to the following echo statement. There's actually multiple ways to make this fail; this is just the simplest.
Cheers, Kyle Moffett
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |