Marc Herbert wrote:
Chet Ramey a écrit :
Marc Herbert wrote:
The following script crashes bash versions 2.05, 3.2.25, 4.0.16,...
trap echo USR1caught USR1
read -t 1
foo=$( kill -USR1 $$ )
echo 'Yeah! no Segmentation fault!'
Thanks for the report.
Thanks for bash in the first place.
Fixed in the next version.
Chet, is there any workaround for existing versions?
Sure. There's the usual idiom. It's unusual to see a script that uses
command substitution for this. Most existing scripts use simple
subshells to do it, whether (command) or asynchronous commands using `'.
In general, if you want to do something like set an alarm to go off in
the future, say after 10 seconds, you do something like
{ sleep 10; kill -USR1 $$; }
and perform a potentially blocking operation.
I mean, there must be some memory corruption involved in here, so is it
possible to dodge it without upgrading? For instance, would simply avoiding
the -t option of read be enough to guarantee no memory corruption? Other?
Thanks a lot in advance!
It's a combination of the assignment statement and the trap handling.
Yes, there is memory corruption that occurs, because the trap handler
doesn't unwind-protect a global variable used by the expansion and
execution code.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
