On Sun, Apr 24, 2005 at 10:57:01PM +0200, Gergely Nagy wrote: > Anyways, a fix is in the works, and will be in the next upstream > release. (A workaround is ready already, but I want to fix this > properly). >
Hello, What is the status of fixing this bug? The following is my investigate of the bug. (1) Install thy. Set "THY_LISTEN=127.0.0.1/8001" in /etc/default/thy, restart thy. (2) Good CGI file. $ cat /usr/lib/cgi-bin/good.sh #!/bin/sh echo -en "Content-type: text/html\n\n" echo "hello, world." This works fine with both thy and apache. (3) Bad CGI file. $ cat /usr/lib/cgi-bin/bad.sh #!/bin/sh #echo -en "Content-type: text/html\n\n" #echo "hello, world." Apache shows 500 error (Internal Server Error), but thy makes firefox wait forever. wget also loops through multiple tries. The following command says "No data received". $ wget -t1 http://localhost:8001/cgi-bin/bad.sh --18:41:20-- http://localhost:8001/cgi-bin/bad.sh => `bad.sh' Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:8001... connected. HTTP request sent, awaiting response... No data received. Giving up. ngrep confirms nothing is sent back to wget. (4) Dive into the source code. [src/daemon.c:786]: premature end of file from CGI is detected and logged. control flows to: [src/daemon.c:814]: this code arranges the session to output HTTP_STATUS_500 to the client, and the CGI program to be killed by SIGKILL(?). This is very good, but: Before any data is sent to the client, the CGI program exited (in this case the program terminates, but otherwise it would be killed by SIGKILL). [src/main.c:145]: for each terminated child process (CGI), queue_del is called, which calls session_kill, which shutdown socket connections. Therefore no data can be sent to the client. Recommended fix: do not call queue_del in cleanup_children. BTW, it seems there is a race condition around the variable sigchild. Eg, if a SIGCHLD happens right after the while loop[src/main.c:169], sigchild will be reset to zero. This child is not waited until any other child dies. Recommended fix: do not use variable sigchild, instead, use a pipe to send the information[0]. [0] http://cr.yp.to/docs/selfpipe.html Hope this helps fix the bug. Regards, qingning
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