- Check if unlocking of the list of files in use was successful

[devedit.git] / modules / File / Access.pm

diff --git a/modules/File/Access.pm b/modules/File/Access.pm
index bc1e37d57437f7c248c0ac7ce556d624cdd020b8..4c4d0daafd56f3b32fb73c93e501383c560c7c6f 100644 (file)
--- a/modules/File/Access.pm
+++ b/modules/File/Access.pm
@@ -3,48 +3,41 @@ package File::Access;
 #
 # Dev-Editor - Module File::Access
 #
-# Some simple routines for doing things with files
-# with only one command
+# Some simple routines for doing things with files by
+# using only one command
 #
-# Author:        Patrick Canterino <patshaping@gmx.net>
-# Last modified: 2004-08-01
+# Author:        Patrick Canterino <patrick@patshaping.de>
+# Last modified: 2005-02-10
 #
 
 use strict;
 
-use vars qw(@EXPORT);
+use vars qw(@EXPORT
+            $has_flock);
 
-use Carp qw(croak);
+use Fcntl qw(:DEFAULT
+             :flock);
 
 ### Export ###
 
 use base qw(Exporter);
 
-@EXPORT = qw(chgrp
-             dir_read
+@EXPORT = qw(dir_read
              file_create
+             file_lock
              file_read
              file_save
-             file_unlock);
+             file_unlock
 
-# chgrp()
-#
-# Change the group of files or directories
-#
-# Params: 1. Group name
-#         2. List of files
-#
-# Return: Number of files group successfully changed
-#         (or false)
+             LOCK_SH
+             LOCK_EX
+             LOCK_UN
+             LOCK_NB);
 
-sub chgrp($@)
-{
- my ($group,@files) = @_;
- my $gid = ($group !~ /^\d+$/) ? getgrnam($group): $group;
+# Check if flock() is available
+# I found this piece of code somewhere in the internet
 
- return unless($gid);
- return chown(-1,$gid,@files);
-}
+$has_flock = eval { local $SIG{'__DIE__'}; flock(STDOUT,0); 1 };
 
 # dir_read()
 #
@@ -77,9 +70,9 @@ sub dir_read($)
 
  foreach my $entry(@entries)
  {
-  next if($entry eq "." || $entry eq "..");
+  next if($entry eq '.' || $entry eq '..');
 
-  if(-d $dir."/".$entry)
+  if(-d $dir.'/'.$entry)
   {
    push(@dirs,$entry);
   }
@@ -94,7 +87,11 @@ sub dir_read($)
 
 # file_create()
 #
-# Create a file
+# Create a file, but only if it doesn't already exist
+#
+# (I wanted to use O_EXCL for this, but `perldoc -f sysopen`
+# doesn't say that it is available on every system - so I
+# created this workaround using O_RDONLY and O_CREAT)
 #
 # Params: File to create
 #
@@ -108,28 +105,54 @@ sub file_create($)
 
  return if(-e $file);
 
- open(FILE,">$file") or return;
- close(FILE)         or return;
+ sysopen(FILE,$file,O_RDONLY | O_CREAT) or return;
+ close(FILE)                            or return;
 
  return 1;
 }
 
+# file_lock()
+#
+# System independent wrapper function for flock()
+# On systems where flock() is not available, this function
+# always returns true.
+#
+# Params: 1. Filehandle
+#         2. Locking mode
+#
+# Return: Status code (Boolean)
+
+sub file_lock(*$)
+{
+ my ($handle,$mode) = @_;
+
+ return 1 unless($has_flock);
+ return flock($handle,$mode);
+}
+
 # file_read()
 #
 # Read out a file completely
 #
-# Params: File
+# Params: 1. File
+#         2. true  => open in binary mode
+#            false => open in normal mode (default)
 #
 # Return: Contents of the file (Scalar Reference)
 
-sub file_read($)
+sub file_read($;$)
 {
- my $file = shift;
+ my ($file,$binary) = @_;
  local *FILE;
 
- open(FILE,"<$file") or return;
+ sysopen(FILE,$file,O_RDONLY) or return;
+ file_lock(FILE,LOCK_SH)      or do { close(FILE); return };
+ binmode(FILE) if($binary);
+
  read(FILE, my $content, -s $file);
- close(FILE)         or return;
+
+ file_lock(FILE,LOCK_UN)      or do { close(FILE); return };
+ close(FILE)                  or return;
 
  return \$content;
 }
@@ -140,17 +163,24 @@ sub file_read($)
 #
 # Params: 1. File
 #         2. File content as Scalar Reference
+#         3. true  => open in binary mode
+#            false => open in normal mode (default)
 #
 # Return: Status code (Boolean)
 
-sub file_save($$)
+sub file_save($$;$)
 {
- my ($file,$content) = @_;
+ my ($file,$content,$binary) = @_;
  local *FILE;
 
- open(FILE,">$file")  or return;
- print FILE $$content or do { close(FILE); return };
- close(FILE)          or return;
+ sysopen(FILE,$file,O_WRONLY | O_CREAT | O_TRUNC) or return;
+ file_lock(FILE,LOCK_EX)                          or do { close(FILE); return };
+ binmode(FILE) if($binary);
+
+ print FILE $$content                             or do { close(FILE); return };
+
+ file_lock(FILE,LOCK_UN)                          or do { close(FILE); return };
+ close(FILE)                                      or return;
 
  return 1;
 }
@@ -162,16 +192,16 @@ sub file_save($$)
 # Params: 1. File::UseList object
 #         2. File to remove
 #
-# Return: -nothing-
+# Return: Status code (Boolean)
 
 sub file_unlock($$)
 {
  my ($uselist,$file) = @_;
 
- $uselist->remove_file($file);
- $uselist->save;
+ $uselist->remove_file($file) or return;
+ $uselist->save               or return;
 
- return;
+ return 1;
 }
 
 # it's true, baby ;-)