Re: mod_perl closes apache's stdin and/or stdout

[Stephane Chazelas]

On Thu, Mar 29, 2007 at 09:06:20PM +0100, Stephane Chazelas wrote:
[...]
> print STDOUT "...";
> actually did a write(16, "..."), so STDOUT was affected another
> fd that 1. Tomorrow, I'll try doing a system() within perl, but
> I suspect for instance system("echo foo") will no output
> anything to the socket.
[...]

I can confirm. This script:

print "Content-Type: text/plain\r\n\r\n";
print "test\n";
system 'lsof -p $$';
print "test\n";

outputs 

test
test

while

print "Content-Type: text/plain\r\n\r\n";
print "test\n";
system 'lsof -p $$ >&16';
print "test\n";

outputs

COMMAND   PID     USER   FD   TYPE   DEVICE    SIZE     NODE NAME
[...]
sh      19113 www-data    0r   CHR      1,3             1673 /dev/null
sh      19113 www-data    1w   CHR      1,3             1673 /dev/null
sh      19113 www-data    2w   REG      8,9 2041426   244362 
/var/log/apache2/error.log
[...]
sh      19113 www-data   16u  IPv4 14009527              TCP 
ant.artesyncp.com:www->ant.artesyncp.com:43127 (ESTABLISHED)

fds 0 and 1 are /dev/null as they should be if apache was not running modperl
because modperl does


dup(0);
close(0);
dup(1);
close(1);

so that the second dup assigns stdin as a copy of stdout!


Cheers,
Stephane