Hello List,
I am new to perl.
I run following sample script, and see strace output.
I have 2 questions.
===========
#!/usr/bin/perl
use Fcntl qw/:DEFAULT :flock :seek F_GETFL/;
sysopen( LOCK_FILE, "./sample.txt", O_WRONLY | O_CREAT);
$PackedPattern = "ssllll";
$LockInfo = pack( $PackedPattern, F_WRLCK, SEEK_SET, 0, 0, $$ );
$ReturnValue = fcntl( LOCK_FILE, F_SETLK, $LockInfo ) || -1;
===========
Strace output.
open("./sample.txt", O_WRONLY|O_CREAT|O_LARGEFILE, 0666) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbfba5928) = -1 ENOTTY
(Inappropriate ioctl for device)
_llseek(3, 0, [0], SEEK_CUR) = 0
fstat64(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
fcntl64(3, F_SETFD, FD_CLOEXEC) = 0
fcntl64(3, F_SETLK64, {type=F_WRLCK, whence=SEEK_SET, start=0,
len=19946}, 0x9b30b50) = 0
close(3) = 0
exit_group(0) = ?
Process 19946 detached
===========
Questions
(1) I set F_SETLK in the script, but the perl returns F_SETLK64.
What makes it to do so?
My test environment is RHEL5 (ia32) perl-5.8.8
(2) I see len=19946 in strace output.
But I expect len should be "length of the file(sample.txt)".
So, it should be 0 byte. (st_size=0)
I know the 19946 is the PID of the script, and it is because I set "$$"
so that's why I see the PID in the strace output.
But my question is , why the PID value (19946) was put into the len field.
I am appreciate your advice.
Regards,
Masanari
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