setting a variable from $echo_it results to crashing

[ovh]

set $var $echo_it;

results to nginx crashing:
2012/05/02 12:30:13 [notice] 22517#0: signal 17 (SIGCHLD) received
2012/05/02 12:30:13 [alert] 22517#0: worker process 22518 exited on signal 11
2012/05/02 12:30:13 [notice] 22517#0: start worker process 22535
2012/05/02 12:30:13 [notice] 22517#0: signal 29 (SIGIO) received

conf:
location = /getFile {
echo_foreach_split ',' $filelist
set $file $echo_it;
echo_subrequest GET '/getFile' -q 'sha256=$file' ;
echo_end;
}

[agentzh]

On Wed, May 2, 2012 at 6:31 PM, baqs
[email protected]
wrote:

set $var $echo_it;

results to nginx crashing:
2012/05/02 12:30:13 [notice] 22517#0: signal 17 (SIGCHLD) received
2012/05/02 12:30:13 [alert] 22517#0: worker process 22518 exited on signal 11
2012/05/02 12:30:13 [notice] 22517#0: start worker process 22535
2012/05/02 12:30:13 [notice] 22517#0: signal 29 (SIGIO) received

You're using the $echo_it variable at rewrite phase (because
ngx_rewrite's set directive runs at the rewrite phase) and it indeed
leads to a segfault. I've committed a patch to ngx_echo's git
repository to make it evaluate to empty (or "not found", to be more
accurate):

openresty/echo-nginx-module@08d36f31

conf:
location = /getFile {
echo_foreach_split ',' $filelist
set $file $echo_it;
echo_subrequest GET '/getFile' -q 'sha256=$file' ;
echo_end;
}

Your directives in location = /getFile will not run in the order as
they are written, because the "set" directive always runs in the
rewrite processing phase of nginx while those ngx_echo directives
always run in a later phase, i.e., the content phase. So your
directives will actually run in the order like below:

set $file $echo_it;
echo_foreach_split ',' $filelist;
echo_subrequest GET '/getFile' -q 'sha256=$file';
echo_end;

This is surely not what you want (but still it should not crash in any
event). For more details regarding nginx processing phases, please
read our nginx tutorials here:

http://agentzh.org/misc/nginx/agentzh-nginx-tutorials-enuk.html

Thanks!
-agentzh

[ovh]

On 02/mai - 06:09, agentzh (章亦春) wrote:

On Wed, May 2, 2012 at 6:31 PM, baqs
[email protected]
wrote:

set $var $echo_it;

results to nginx crashing:
2012/05/02 12:30:13 [notice] 22517#0: signal 17 (SIGCHLD) received
2012/05/02 12:30:13 [alert] 22517#0: worker process 22518 exited on signal 11
2012/05/02 12:30:13 [notice] 22517#0: start worker process 22535
2012/05/02 12:30:13 [notice] 22517#0: signal 29 (SIGIO) received

You're using the $echo_it variable at rewrite phase (because
ngx_rewrite's set directive runs at the rewrite phase) and it indeed
leads to a segfault. I've committed a patch to ngx_echo's git
repository to make it evaluate to empty (or "not found", to be more
accurate):

openresty/echo-nginx-module@08d36f31
ok thx

conf:
location = /getFile {
echo_foreach_split ',' $filelist
set $file $echo_it;
echo_subrequest GET '/getFile' -q 'sha256=$file' ;
echo_end;
}

Your directives in location = /getFile will not run in the order as
they are written, because the "set" directive always runs in the
rewrite processing phase of nginx while those ngx_echo directives
always run in a later phase, i.e., the content phase. So your
directives will actually run in the order like below:

set $file $echo_it;
echo_foreach_split ',' $filelist;
echo_subrequest GET '/getFile' -q 'sha256=$file';
echo_end;

This is surely not what you want (but still it should not crash in any
event). For more details regarding nginx processing phases, please
read our nginx tutorials here:

thanks a lot for your explanations, I'll try to work-around that.

http://agentzh.org/misc/nginx/agentzh-nginx-tutorials-enuk.html

Thanks!
-agentzh

---

Reply to this email directly or view it on GitHub:
#2 (comment)