Merge pull request #156 from jouvin/fileeditor_source

FileEditor: add a 'source' option in constructor

src/main/perl/FileEditor.pm

@@ -47,24 +47,82 @@ the class constructor.
 =item new
 
 Returns a new object it accepts the same arguments as the constructor
-for C<CAF::FileWriter>
+for C<CAF::FileWriter> with one additional option: 
+
+=over
+
+=item source 
+
+This option, when present, must be a file name whose contents will be used
+as the initial contents for the edited file if the source modification time
+is more recent than the edited file modification time. This allows to rebuild
+the file contents based on a new version of the reference file. 
+
+The C<source> can be a pipe: in this case, it is always considered more recent
+than the edited file.
+
+=back
 
 =cut
 
 # FileEditor supports reading/editing a file
-sub _is_valid_source
+sub _is_valid_file
 {
     my ($self, $fn) = @_;
     return -f $fn;
 }
 
+# This method is only intended to be used in the context of the constructor
+# and entirely relies on the internal structure of the FileEditor object.
+# 'filename`  is the file name passed with instantiating the FileEditor and
+# 'options/sources' the 'source' parameter value (called a reference file
+# internally).
+sub _is_reference_newer
+{
+    my ($self) = @_;
+    my $is_newer = 0;   # Assume false
+    if (  exists(*$self->{options}->{source}) ) {
+        # It is valid for the source value to be a pipe: in this case consider it
+        # as newer than an existing file.
+        if ( -p *$self->{options}->{source} ) {
+            $is_newer = 1
+        } elsif ( $self->_is_valid_file(*$self->{options}->{source}) ) {
+            # stat()[9] is modification time
+            if ( !$self->_is_valid_file(*$self->{filename}) || 
+                 ((stat(*$self->{options}->{source}))[9] > (stat(*$self->{filename}))[9]) ) {
+                $is_newer = 1
+            }
+        }
+    }
+    #FIXME: replace by $self->debug() after PR #154 has been merged...
+    if ( *$self->{LOG} ) {
+        if ( $is_newer ) {
+            *$self->{LOG}->debug(1, "File ", *$self->{filename}, " older than reference file (", *$self->{options}->{source}, ",");
+        } else {
+            *$self->{LOG}->debug(1, "Reference file (", *$self->{options}->{source}, ") older than ", *$self->{filename});
+        };
+    };
+    return $is_newer;
+}
 
 sub new
 {
     my $class = shift;
     my $self = $class->SUPER::new (@_);
-    if ($self->_is_valid_source(*$self->{filename})) {
-        my $txt = LC::File::file_contents (*$self->{filename});
+    my $src_file;
+    my ($path, %opts) = @_;
+
+    *$self->{options}->{source} = $opts{source} if exists ($opts{source});
+    if ( $self->_is_reference_newer() ) {
+        # As this is a non reproducible event, be sure to log it when it happens
+        *$self->{LOG}->info("File ", *$self->{filename}, " contents reset to reference file (", *$self->{options}->{source}, ") contents.") if *$self->{LOG};
+        $src_file = *$self->{options}->{source};
+    } elsif ($self->_is_valid_file(*$self->{filename})) {
+        $src_file = *$self->{filename};
+    }
+    if ( $src_file ) {
+        *$self->{LOG}->debug(2, "Reading initial contents from $src_file") if *$self->{LOG};
+        my $txt = LC::File::file_contents ($src_file);
         $self->IO::String::open ($txt);
         $self->seek(IO_SEEK_END);
     }

src/main/perl/FileReader.pm

@@ -41,7 +41,7 @@ seek to the beginning and C<cancel> any (future) changes.
 =cut
 
 # FileReader supports reading a file or pipe
-sub _is_valid_source
+sub _is_valid_file
 {
     my ($self, $fn) = @_;
     return -f $fn || -p $fn;

src/test/perl/test-caffileeditor_source.t

@@ -0,0 +1,79 @@
+#!/usr/bin/perl
+use strict;
+use warnings;
+use FindBin qw($Bin);
+use lib "$Bin/modules";
+use CAF::FileEditor;
+use Test::More tests => 7;
+use Test::MockModule;
+use Test::Quattor::Object;
+use Carp qw(confess);
+use File::Path;
+use File::Temp qw(tempfile);
+use Readonly;
+
+$SIG{__DIE__} = \&confess;
+
+# FIXME:
+# LC::File::file_contents (used by CAF::FileEditor constructor) doesn't work 
+# in the unit test context. Mock it until we find a better solution...
+our $lcfile = Test::MockModule->new("LC::File");
+
+sub read_file_contents {
+    my $fname = shift;
+    my $fh;
+    open($fh, "<", $fname) || die ("failed to open $fname");
+    my $contents = join('', <$fh>);
+    return $contents;
+}
+$lcfile->mock("file_contents", \&read_file_contents);
+
+
+my $testdir = 'target/test/test_caffileeditor_source';
+mkpath($testdir);
+(undef, my $filename) = tempfile(DIR => $testdir);
+
+Readonly my $TEXT => <<EOF;
+En un lugar de La Mancha, de cuyo nombre no quiero acordarme
+no ha tiempo que vivía un hidalgo de los de lanza en astillero...
+EOF
+Readonly my $ANOTHER_TEXT => "adarga antigua, rocín flaco y galgo corredor.";
+
+my $fh;
+my $obj = Test::Quattor::Object->new();
+
+
+# Create a file and check that it is empty
+($fh, $filename) = tempfile(DIR => $testdir);
+$fh->close();
+$fh = CAF::FileEditor->new($filename, log => $obj);
+is("$fh","","Existing file ($filename) empty");
+$fh->close();
+
+# Check that reference file contents is used as the initial contents when it
+# is newer than the file edited.
+my $time=time();
+utime(undef, $time - 10, $filename); # make filename old enough
+my ($ref_fh, $ref_filename) = tempfile(DIR => $testdir);
+print $ref_fh $TEXT;
+$ref_fh->close();
+$fh = CAF::FileEditor->new($filename, log => $obj, source => $ref_filename);
+is(*$fh->{options}->{source},$ref_filename,"File source is correctly defined");
+ok($fh->_is_reference_newer(),"Source file ($ref_filename) is newer than actual file ($filename)");
+is("$fh",$TEXT,"Reference file ($filename) contents used");
+$fh->close();
+
+# Check that reference file contents is not used as the initial contents when it
+# is older than the file edited.
+$time=time();
+utime(undef, $time - 10, $ref_filename); # make ref_filename old enough
+my ($new_fh, $new_filename) = tempfile(DIR => $testdir);
+print $new_fh $ANOTHER_TEXT;
+$new_fh->close();
+$new_fh = CAF::FileEditor->new($new_filename, log => $obj, source => $ref_filename);
+is(*$new_fh->{options}->{source},$ref_filename,"File source is correctly defined");
+ok(!$new_fh->_is_reference_newer(),"Source file ($ref_filename) is older than actual file ($filename)");
+is("$new_fh",$ANOTHER_TEXT,"Existing file ($new_filename) contents used");
+$fh->close();
+
+done_testing();