Date: Wed, 15 Sep 1999 15:59:55 -0400 From: "David E. Cross" <crossd@cs.rpi.edu> To: freebsd-hackers@freebsd.org Subject: perl stangeness on 3.3-RC Message-ID: <199909151959.PAA22581@cs.rpi.edu>
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We have a very hetergenous environment here (even among the FreeBSD boxes).
Each PC tends to be just a little bit different. This expecially causes
problems since we wish to have XDM on each machine on boot and have X
on a NFS partition. TO alleviate this we invented a simple Perl script
to replace /usr/X11R6/bin/X to run the correct program on each machine:
#!/usr/bin/perl -w
use Sys::Hostname;
read_servers();
$commandline="/usr/X11R6/bin/XF86_VGA16";
$host=hostname();
print STDERR "host is $host\n";
$screen=$ARGV[0];
$display= $host . $screen;
print STDERR "display is $display\n";
if ($server{$display}) {
$commandline = join (' ', $server{$display}, @ARGV);
}
elsif ($server{$host}) {
$commandline = join (' ',$server{$host}, @ARGV);
}
exec $commandline;
sub read_servers {
open (XSERVERLIST, "/usr/local/etc/xservers");
while ($hostline = <XSERVERLIST>) {
chomp ($hostline);
@fields = split ' ', $hostline, 2;
$server{$fields[0]} = $fields[1];
}
}
This worked fine up until about 3.3-RC, then it stopped with the following
error:
Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.pm line 100, <XSERVERLIST> chunk 13.
Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.pm line 109, <XSERVERLIST> chunk 13.
Can't exec "/com/host": No such file or directory at /usr/libdata/perl/5.00503/Sys/Hostname.pm line 115, <XSERVERLIST> chunk 13.
Cannot get host name of local machine at /usr/X11R6/bin/X line 6
Note that this is *only* a problem when this script is run by xdm by init.
If I run the script by hand, or I run xdm by hand it works OK. Also consider
the results of a ktrace on init (PID 1) when xdm was started (alot of stuff
has been deleted to ease readability:
445 perl RET execve 0
445 perl forks and execs 'hostname'
447 hostname RET execve 0
447 hostname CALL __sysctl(0xbfbfdcd0,0x2,0xbfbfdcf8,0xbfbfdcd8,0,0)
447 hostname RET __sysctl 0
447 hostname CALL fstat(0x1,0xbfbfd9e4)
447 hostname RET fstat 0
447 hostname CALL readlink(0x8050a1c,0xbfbfd9e4,0x3f)
447 hostname NAMI "/etc/malloc.conf"
447 hostname RET readlink -1 errno 2 No such file or directory
447 hostname CALL mmap(0,0x1000,0x3,0x1002,0xffffffff,0,0,0)
447 hostname RET mmap 671424512/0x28052000
447 hostname CALL break(0x8055000)
447 hostname RET break 0
447 hostname CALL break(0x8059000)
447 hostname RET break 0
447 hostname CALL write(0x1,0x8055000,0x10)
447 hostname GIO fd 1 wrote 16 bytes
"loot.cs.rpi.edu
"
445 perl GIO fd 1 read 16 bytes
"loot.cs.rpi.edu
"
445 perl RET read 16/0x10
445 perl CALL read(0x1,0x80e0000,0x4000)
447 hostname RET write 16/0x10
447 hostname CALL exit(0)
446 sh RET wait4 447/0x1bf
446 sh CALL exit(0)
445 perl GIO fd 1 read 0 bytes
""
445 perl RET read 0
445 perl CALL close(0x1)
445 perl RET close 0
445 perl GIO fd 2 wrote 106 bytes
"Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.p\
m line 100, <XSERVERLIST> chunk 13.
"
.
.
.
448 sh NAMI "/bin/uname"
448 sh RET stat -1 errno 2 No such file or directory
448 sh CALL stat(0x809ccb8,0xbfbfdc54)
448 sh NAMI "/usr/bin/uname"
448 sh RET stat 0
448 sh CALL break(0x80a3000)
.
.
.
449 uname RET execve 0
449 uname GIO fd 1 wrote 16 bytes
"loot.cs.rpi.edu
"
445 perl GIO fd 1 read 16 bytes
"loot.cs.rpi.edu
"
448 sh RET wait4 449/0x1c1
448 sh CALL exit(0)
445 perl GIO fd 1 read 0 bytes
""
445 perl RET read 0
445 perl CALL close(0x1)
445 perl RET close 0
445 perl GIO fd 2 wrote 106 bytes
"Use of uninitialized value at /usr/libdata/perl/5.00503/Sys/Hostname.p\
m line 109, <XSERVERLIST> chunk 13.
"
450 perl CALL execve(0x80dd140,0x808c2e0,0x8076e80)
450 perl NAMI "/com/host"
450 perl RET execve -1 errno 2 No such file or directory
450 perl CALL write(0x2,0x8070e00,0x81)
450 perl GIO fd 2 wrote 129 bytes
"Can't exec "/com/host": No such file or directory at /usr/libdata/perl\
/5.00503/Sys/Hostname.pm line 115, <XSERVERLIST> chunk 13.
"
450 perl RET write 129/0x81
450 perl CALL exit(0x1)
"Cannot get host name of local machine at /usr/X11R6/bin/X line 6
"
Any ideas what is going on here? It looks like it gets what it wants and then
just ignores it?!?
--
David Cross | email: crossd@cs.rpi.edu
Systems Administrator/Research Programmer | Web: http://www.cs.rpi.edu/~crossd
Rensselaer Polytechnic Institute, | Ph: 518.276.2860
Department of Computer Science | Fax: 518.276.4033
I speak only for myself. | WinNT:Linux::Linux:FreeBSD
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