Re: [PATCH] pakfire.cgi: Implement logic to lock the page until pakfire has been fully launched.

[Bernhard Bitsch <bbitsch@ipfire.org>]

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Reviewed-by: Bernhard Bitsch <bbitsch(a)ipfire.org>

The locking is functioning.
But the excerpt of /var/log/messages isn't displayed.

Am 18.10.2021 um 21:09 schrieb Stefan Schantl:
> When performing any action which requires pakfire, the page gets locked
> with an message informing the user that pakfire is working. The page
> will be reloaded when pakfire has been launched and is doing the
> requested operation - showing the well known log output. This also
> happens when pakfire has been launched via any kind of terminal or SSH
> session and the CGI gets accessed.
> 
> Internally before pakfire gets started a variable called page_lock will
> be set to lock the page. An while loop will keep the page locked until
> pakfire is launched fully and has written it's lock_file.
> 
> This approach will prevent us from any kind of required time intervall
> or race conditions.
> 
> Signed-off-by: Stefan Schantl <stefan.schantl(a)ipfire.org>
> ---
>   html/cgi-bin/pakfire.cgi | 49 ++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 47 insertions(+), 2 deletions(-)
> 
> diff --git a/html/cgi-bin/pakfire.cgi b/html/cgi-bin/pakfire.cgi
> index 0cf522ba1..f2381f031 100644
> --- a/html/cgi-bin/pakfire.cgi
> +++ b/html/cgi-bin/pakfire.cgi
> @@ -44,6 +44,8 @@ $cgiparams{'VALID'} = '';
>   $cgiparams{'INSPAKS'} = '';
>   $cgiparams{'DELPAKS'} = '';
>   
> +my $page_lock;
> +
>   sub refreshpage{&Header::openbox( 'Waiting', 1, "<meta http-equiv='refresh' content='1;'>" );print "<center><img src='/images/clock.gif' alt='' /><br/><font color='red'>$Lang::tr{'pagerefresh'}</font></center>";&Header::closebox();}
>   
>   &Header::getcgihash(\%cgiparams);
> @@ -57,8 +59,9 @@ sub refreshpage{&Header::openbox( 'Waiting', 1, "<meta http-equiv='refresh' cont
>   if (($cgiparams{'ACTION'} eq 'install') && (! -e $Pakfire::lockfile)) {
>   	my @pkgs = split(/\|/, $cgiparams{'INSPAKS'});
>   	if ("$cgiparams{'FORCE'}" eq "on") {
> +		# Lock the page.
> +		$page_lock = "1";
>   		&General::system_background("/usr/local/bin/pakfire", "install", "--non-interactive", "--no-colors", @pkgs);
> -		sleep(2);
>   	} else {
>   		&Header::openbox("100%", "center", $Lang::tr{'request'});
>   		my @output = &General::system_output("/usr/local/bin/pakfire", "resolvedeps", "--no-colors", @pkgs);
> @@ -95,8 +98,9 @@ END
>   } elsif (($cgiparams{'ACTION'} eq 'remove') && (! -e $Pakfire::lockfile)) {
>   	my @pkgs = split(/\|/, $cgiparams{'DELPAKS'});
>   	if ("$cgiparams{'FORCE'}" eq "on") {
> +		# Lock the page.
> +		$page_lock = "1";
>   		&General::system_background("/usr/local/bin/pakfire", "remove", "--non-interactive", "--no-colors", @pkgs);
> -		sleep(2);
>   	} else {
>   		&Header::openbox("100%", "center", $Lang::tr{'request'});
>   		my @output = &General::system_output("/usr/local/bin/pakfire", "resolvedeps", "--no-colors", @pkgs);
> @@ -132,8 +136,12 @@ END
>   	}
>   
>   } elsif (($cgiparams{'ACTION'} eq 'update') && (! -e $Pakfire::lockfile)) {
> +	# Set variable to lock the page.
> +	$page_lock = "1";
>   	&General::system_background("/usr/local/bin/pakfire", "update", "--force", "--no-colors");
>   } elsif (($cgiparams{'ACTION'} eq 'upgrade') && (!-e $Pakfire::lockfile)) {
> +	# Lock the page.
> +	$page_lock = "1";
>   	&General::system_background("/usr/local/bin/pakfire", "upgrade", "-y", "--no-colors");
>   } elsif ($cgiparams{'ACTION'} eq "$Lang::tr{'save'}") {
>   	$pakfiresettings{"TREE"} = $cgiparams{"TREE"};
> @@ -169,6 +177,43 @@ if ($errormessage) {
>   	&Header::closebox();
>   }
>   
> +# Check if a page lock is required.
> +if ($page_lock) {
> +	&Header::openbox('Waiting', 1, ,);
> +		print <<END;
> +		<table>
> +			<tr>
> +				<td>
> +					<img src='/images/indicator.gif' alt='$Lang::tr{'active'}' title='$Lang::tr{'active'}'>
> +				</td>
> +
> +				<td>
> +					$Lang::tr{'pakfire working'}
> +				</td>
> +			</tr>
> +		</table>
> +END
> +	&Header::closebox();
> +
> +	# Infinite loop to lock the page until pakfire lockfile is present.
> +	while($page_lock) {
> +		unless (-e $Pakfire::lockfile) {
> +			sleep(1);
> +		} else {
> +			# Release page lock.
> +			undef($page_lock);
> +
> +			# Break loop.
> +			last;
> +		}
> +	}
> +
> +	# Perform page reload.
> +	print "<meta http-equiv='refresh' content='1;'>\n";
> +	exit;
> +}
> +
> +# Check if pakfire is already running. In this case a lockfile is present.
>   if (-e $Pakfire::lockfile) {
>   	&Header::openbox( 'Waiting', 1, "<meta http-equiv='refresh' content='10;'>" );
>   	print <<END;
>