I'm trying to make the following project work on AIX systems. I have almost finished, the end is near but I srill have an issue at tha execution of the agent.
My AIX Systems do not have flock installed and that is problematic during the download process in this file
The result of the flock tests all return false
e.g I systematically have the following error message even when I delete the file
[Sat Jun 29 09:47:24 2024][error] [download] /opt/ocsinventory/var/lib/ocsinventory-agent/https:__hostname.com_ocsinventory/download/lock locked. Cannot begin work... :-(
which comes from the following failed flock test
# At the beginning of end handler
sub begin{
my ($pidfile,$logger) = @_;
open LOCK_R, "$pidfile" or die("Cannot open pid file: $!");
if (flock(LOCK_R,LOCK_EX|LOCK_NB)){
open LOCK_W, ">$pidfile" or die("Cannot open pid file: $!");
select(LOCK_W) and $|=1;
select(STDOUT) and $|=1;
print LOCK_W $$;
$logger->info("Beginning work. I am $$.");
return 0;
} else {
close(LOCK_R);
$logger->error("$pidfile locked. Cannot begin work... :-(");
return 1;
}
}
I tried to build util-linux 2.40 2.21 and 2.13 and they all fail
I also read here that flock wouldn't be so mandatory on Unix Systems
I think my analysis is good but I'm stuck abour how to implement a fix.
How would you do if you had to make it work. I really need to fix this coode so thhat it becomes compliant with AIX
Try use File::FcntlLock instead of flock. Here is an example:
use v5.38;
use Fcntl ':flock'; # Import LOCK_* constants
my $filename = 'example.txt';
open(my $fh, '<', $filename) or die "Could not open file '$filename': $!";
flock($fh, LOCK_SH) or die "Could not lock file '$filename': $!";
# Read from the file
while (my $line = <$fh>) {
print $line;
sleep 1; # Simulate a long operation
}
# Close the file (automatically releases the lock)
close($fh);
print "File has been read with a shared lock.\n";
use v5.38;
use Fcntl ':flock'; # Import LOCK_* constants
my $filename = 'example.txt';
# Open the file for both reading and writing
# NOTE: Do not open the for writing only, as this will truncate the file before acquiring the lock
open(my $fh, '+<', $filename) or die "Could not open file '$filename': $!";
# Try to acquire an exclusive lock
if (flock($fh, LOCK_EX | LOCK_NB)) {
print "Acquired exclusive lock on file '$filename'.\n";
truncate($fh, 0) or die "Could not truncate file '$filename': $!";
# Write to the file
print $fh "Adding a new line to the file.\n";
# Close the file handle (automatically releases the lock)
close($fh);
} else {
print "Could not acquire exclusive lock on file '$filename': $!\n";
}
print "Attempt to acquire exclusive lock has finished.\n";
Doing the same with File::FcntlLock:
use v5.38;
use File::FcntlLock;
my $filename = 'example.txt';
open(my $fh, '<', $filename) or die "Could not open file '$filename': $!";
my $lock = File::FcntlLock->new(
l_type => F_RDLCK,
l_whence => SEEK_SET, # Lock from the beginning of the file
l_start => 0,
l_len => 0, # Lock the entire file
l_pid => $$, # Lock is owned by the current process
);
# Acquire a shared lock
$lock->lock( $fh, F_SETLK ) or die "Could not lock file '$filename': $!";
while (my $line = <$fh>) {
print $line;
sleep 1; # Simulate a long operation
}
# Close the file (automatically releases the lock)
close($fh);
print "File has been read with a shared lock.\n";
use v5.38;
use File::FcntlLock;
use Fcntl qw(SEEK_SET);
my $filename = 'example.txt';
# Open the file for both reading and writing without truncating it
# NOTE: Do not open the for writing only, as this will truncate the file before acquiring the lock
open(my $fh, '+<', $filename) or die "Could not open file '$filename': $!";
# Create a File::FcntlLock object
my $lock = File::FcntlLock->new(
l_type => F_WRLCK,
l_whence => SEEK_SET, # Lock from the beginning of the file
l_start => 0,
l_len => 0, # Lock the entire file
l_pid => $$, # Lock is owned by the current process
);
# Try to acquire an exclusive lock in non-blocking mode
if ($lock->lock( $fh, F_SETLK )) {
print "Acquired exclusive lock on file '$filename'.\n";
# Truncate the file
truncate($fh, 0) or die "Could not truncate file '$filename': $!";
print $fh "Adding a new line to the file.\n";
# Close the file handle (automatically releases the lock)
close($fh);
} else {
print "Could not acquire exclusive lock on file '$filename': $!\n";
}
print "Attempt to acquire exclusive lock has finished.\n";