implement shared file locks

[pve-common.git] / data / PVE / Tools.pm

diff --git a/data/PVE/Tools.pm b/data/PVE/Tools.pm
index a55e4270c58f21d414ecb8c557bd9e32f17160d4..235178a68cd68b4bebe08db263243905a46a48df 100644 (file)
--- a/data/PVE/Tools.pm
+++ b/data/PVE/Tools.pm
@@ -19,6 +19,7 @@ use String::ShellQuote;
 
 our @EXPORT_OK = qw(
 lock_file 
+lock_file_full
 run_command 
 file_set_contents 
 file_get_contents
@@ -79,22 +80,24 @@ sub run_with_timeout {
 
 my $lock_handles =  {};
 
-sub lock_file {
-    my ($filename, $timeout, $code, @param) = @_;
+sub lock_file_full {
+    my ($filename, $timeout, $shared, $code, @param) = @_;
 
     $timeout = 10 if !$timeout;
 
+    my $mode = $shared ? LOCK_SH : LOCK_EX;
+
     my $lock_func = sub {
         if (!$lock_handles->{$$}->{$filename}) {
             $lock_handles->{$$}->{$filename} = new IO::File (">>$filename") ||
                 die "can't open file - $!\n";
         }
 
-        if (!flock ($lock_handles->{$$}->{$filename}, LOCK_EX|LOCK_NB)) {
+        if (!flock ($lock_handles->{$$}->{$filename}, $mode|LOCK_NB)) {
             print STDERR "trying to aquire lock...";
            my $success;
            while(1) {
-               $success = flock($lock_handles->{$$}->{$filename}, LOCK_EX);
+               $success = flock($lock_handles->{$$}->{$filename}, $mode);
                # try again on EINTR (see bug #273)
                if ($success || ($! != EINTR)) {
                    last;
@@ -135,6 +138,13 @@ sub lock_file {
     return $res;
 }
 
+
+sub lock_file {
+    my ($filename, $timeout, $code, @param) = @_;
+
+    return lock_file_full($filename, $timeout, 0, $code, @param);
+}
+
 sub file_set_contents {
     my ($filename, $data, $perm)  = @_;