At 11:13 -0500 2003.11.19, Dan Sugalski wrote:
>On Wed, 19 Nov 2003, Rafael Garcia-Suarez wrote:
>
>> Dan Sugalski wrote:
>> > Basically you're using a variable that can be affected by external things
>> > in a way that pretty much guarantees that external things will be
>> > happening. That it changes isn't much of a surprise. ($!/$^E may get
>> > modified by some signal handlers too, depending on what you do, so there's
>> > not even any guarantee that "$^E = 42; $^E++;" will end up with $^E set to
>> > 43.
>>
>> Using the Mac OS X equivalent of truss/strace might help to find out
>> why errno changes there.
>
>My bet would be that the print triggers an errno update, which strikes me
>as perfectly reasonable.
Yes, I just realized you might think that, and I should have been more
descriptive: it happens regardless of print.
$ ktrace perl -le '$! = -1728; $x = $^E+0; $y = $^E+0; print $x; print $y'
-1728
22
It has nothing to do with addition, either: :-)
$ ktrace perl -le '$! = -1728; $x = $^E; $y = $^E; print $x; print $y'
Unknown error: -1728
Invalid argument
And since it doesn't change with $!, it is not merely because the error is
unknown:
$ ktrace perl -le '$! = -1728; $x = $!; $y = $!; print $x; print $y'
Unknown error: -1728
Unknown error: -1728
Also, the ktrace output of that is identical to the output of the original
(modulo addresses and PIDs):
$ ktrace perl -le '$! = -1728; print $^E+0 for 0,1'
-1728
22
No syscalls between the two assignments. No reason for errno to update.
And even if it did, why would it only update when $^E is printed, and not
$!?
ktrace/kdump output below if anyone cares. But there's got to be something
different about $^E from $! that is causing this bug.
1343 ktrace RET ktrace 0
1343 ktrace CALL execve(0xbffff3b0,0xbffff9e8,0xbffff9f8)
1343 ktrace NAMI "/Users/pudge/bin/perl"
1343 ktrace RET execve -1 errno 2 No such file or directory
1343 ktrace CALL execve(0xbffff3b0,0xbffff9e8,0xbffff9f8)
1343 ktrace NAMI "/usr/local/slash/bin/perl"
1343 ktrace RET execve -1 errno 2 No such file or directory
1343 ktrace CALL execve(0xbffff3b0,0xbffff9e8,0xbffff9f8)
1343 ktrace NAMI "/usr/local/apache/bin/perl"
1343 ktrace RET execve -1 errno 2 No such file or directory
1343 ktrace CALL execve(0xbffff3b0,0xbffff9e8,0xbffff9f8)
1343 ktrace NAMI "/usr/local/bin/perl"
1343 ktrace NAMI "/usr/lib/dyld"
1343 perl RET execve 0
1343 perl CALL getuid
1343 perl RET getuid 502/0x1f6
1343 perl CALL getuid
1343 perl RET getuid 502/0x1f6
1343 perl CALL getuid
1343 perl RET getuid 502/0x1f6
1343 perl CALL getgid
1343 perl RET getgid 20/0x14
1343 perl CALL getgid
1343 perl RET getgid 20/0x14
1343 perl CALL open(0x13d8,0,0)
1343 perl NAMI "/usr/local/lib/perl5/5.8.0/darwin/CORE/libperl.dylib"
1343 perl RET open 3
1343 perl CALL fstat(0x3,0xbffff770)
1343 perl RET fstat 0
1343 perl CALL close(0x3)
1343 perl RET close 0
1343 perl CALL open(0x1428,0,0)
1343 perl NAMI "/usr/lib/libSystem.B.dylib"
1343 perl RET open 3
1343 perl CALL fstat(0x3,0xbffff770)
1343 perl RET fstat 0
1343 perl CALL
load_shared_file(0x1428,0x22b000,0x1798fc,0xbffff580,0x4,0xbffff510,0xbffff584)
1343 perl NAMI "/usr/lib/libSystem.B.dylib"
1343 perl RET load_shared_file 0
1343 perl CALL close(0x3)
1343 perl RET close 0
1343 perl CALL open(0x900006e8,0,0)
1343 perl NAMI "/usr/lib/system/libmathCommon.A.dylib"
1343 perl RET open 3
1343 perl CALL fstat(0x3,0xbffff700)
1343 perl RET fstat 0
1343 perl CALL
load_shared_file(0x900006e8,0x7000,0x6ac4,0xbffff510,0x3,0xbffff4a0,0xbffff514)
1343 perl NAMI "/usr/lib/system/libmathCommon.A.dylib"
1343 perl RET load_shared_file 0
1343 perl CALL close(0x3)
1343 perl RET close 0
1343 perl CALL __sysctl(0xbffff918,0x2,0xbffff920,0xbffff924,0,0)
1343 perl RET __sysctl 0
1343 perl CALL sigaction(0x8,0xbffff850,0xbffff8c0)
1343 perl RET sigaction 0
1343 perl CALL getuid
1343 perl RET getuid 502/0x1f6
1343 perl CALL getuid
1343 perl RET getuid 502/0x1f6
1343 perl CALL getgid
1343 perl RET getgid 20/0x14
1343 perl CALL getgid
1343 perl RET getgid 20/0x14
1343 perl CALL open(0x3011c0,0,0x1b6)
1343 perl NAMI "/dev/null"
1343 perl RET open 3
1343 perl CALL fcntl(0x3,0x2,0x1)
1343 perl RET fcntl 0
1343 perl CALL sigaction(0x14,0,0xbffff3e0)
1343 perl RET sigaction 0
1343 perl CALL getpid
1343 perl RET getpid 1343/0x55a
1343 perl CALL close(0x3)
1343 perl RET close 0
1343 perl CALL fstat(0x1,0xbffff100)
1343 perl RET fstat 0
1343 perl CALL ioctl(0x1,FIODTYPE,0xbffff150)
1343 perl RET ioctl 0
1343 perl CALL write(0x1,0x7000,0x6)
1343 perl GIO fd 1 wrote 6 bytes
"-1728
"
1343 perl RET write 6
1343 perl CALL write(0x1,0x7000,0x3)
1343 perl GIO fd 1 wrote 3 bytes
"22
"
1343 perl RET write 3
1343 perl CALL exit(0)
--
Chris Nandor [EMAIL PROTECTED] http://pudge.net/
Open Source Development Network [EMAIL PROTECTED] http://osdn.com/
