From: Markus Armbruster <armbru@pond.sub.org>
Date: Sun, 28 Apr 2013 13:22:11 +0000 (+0200)
Subject: Make mksubj.pl touch subject files only when it needs to change
X-Git-Tag: v4.3.31~33
X-Git-Url: http://git.pond.sub.org/?p=empserver;a=commitdiff_plain;h=156930c51505e6a5d53f709229f3998e6ce87bbf

Make mksubj.pl touch subject files only when it needs to change

Avoids unnecessary reformatting of subject pages again.
---

diff --git a/info/mksubj.pl b/info/mksubj.pl
index 4e966b123..e178c97a5 100644
--- a/info/mksubj.pl
+++ b/info/mksubj.pl
@@ -25,7 +25,7 @@
 #
 #   ---
 #
-#   mksubj.pl: Create the subject index pages
+#   mksubj.pl: Update the subject index pages
 #
 #   Known contributors to this file:
 #      Ken Stevens (when it was still info.pl)
@@ -33,14 +33,12 @@
 #
 # Usage: mksubj.pl SUBJECT... INFO-FILE...
 #
-# Read the INFO-FILE..., create info/SUBJECT.t for each SUBJECT.
+# Read the INFO-FILE..., update info/SUBJECT.t for each SUBJECT.
 
 use strict;
 use warnings;
 use File::stat;
 
-use Fcntl qw(O_WRONLY O_EXCL O_CREAT);
-
 # The chapters, in order
 my @Chapters = qw/Introduction Concept Command Server/;
 
@@ -84,7 +82,9 @@ for my $t (sort keys %desc) {
     parse_see_also($t);
 }
 
-create_subjects();
+for (keys %Subjects) {
+    update_subj($_);
+}
 
 # Parse an info file
 # Set $filename, $filename{TOPIC}, $long{TOPIC}, $chapter{TOPIC},
@@ -194,22 +194,20 @@ sub set_subject {
     $largest{$sub} = $topic if length $topic > length $largest{$sub};
 }
 
-# Create a Subject.t file
-sub create_subj {
+# Update a Subject.t file
+sub update_subj {
     my ($subj) = @_;
     my $fname = "info/$subj.t";
+    my $out = "";
     my ($any_topic, $any_basic, $any_obsolete, $any_long);
 
-    sysopen(SUBJ, $fname, O_WRONLY | O_EXCL | O_CREAT)
-	or die "Unable to create $fname: $!\n";
-
-    print SUBJ '.\" DO NOT EDIT THIS FILE.  It was automatically generated by mksubj.pl'."\n";
-    print SUBJ ".TH Subject \U$subj\n";
+    $out .= '.\" DO NOT EDIT THIS FILE.  It was automatically generated by mksubj.pl'."\n";
+    $out .= ".TH Subject \U$subj\n";
     $largest{$subj} =~ s/-/M/g;
-    print SUBJ ".in \\w'$largest{$subj}XX\\0\\0\\0\\0'u\n";
+    $out .= ".in \\w'$largest{$subj}XX\\0\\0\\0\\0'u\n";
     for my $chap (@Chapters) {
 	next unless exists $subject{$subj}{$chap};
-	print SUBJ ".s1\n";
+	$out .= ".s1\n";
 	for my $topic (split(/\n/, $subject{$subj}{$chap})) {
 	    $any_topic = 1;
 	    my $flags = "";
@@ -226,40 +224,43 @@ sub create_subj {
 		$any_long = 1;
 	    }
 	    $flags = sprintf("%-2s", $flags);
-	    print SUBJ ".L \"$topic $flags\"\n";
-	    print SUBJ "$desc{$topic}\n";
+	    $out .= ".L \"$topic $flags\"\n";
+	    $out .= "$desc{$topic}\n";
 	}
     }
     unless ($any_topic) {
 	print STDERR "$0: Subject $subj has no topics\n";
 	exit 1;
     }
-    print SUBJ ".s1\n"
+    $out .= ".s1\n"
 	. ".in 0\n"
 	. "For info on a particular subject, type \"info <subject>\" where <subject> is\n"
 	. "one of the subjects listed above.\n";
-    print SUBJ "Subjects marked by * are the most important and should be read by new players.\n"
+    $out .= "Subjects marked by * are the most important and should be read by new players.\n"
 	if $any_basic;
-    print SUBJ "Subjects marked by + are obsolete.\n"
+    $out .= "Subjects marked by + are obsolete.\n"
 	if $any_obsolete;
-    print SUBJ "Unusually long subjects are marked with a !.\n"
+    $out .= "Unusually long subjects are marked with a !.\n"
 	if $any_long;
+
+    return if (same_contents($fname, $out));
+    open(SUBJ, ">$fname")
+	or die "Can't open $fname for writing: $!";
+    print SUBJ $out;
     close SUBJ;
 }
 
-# Remove the old Subject.t files and create new ones
-sub create_subjects {
-    my (@subj);
+sub same_contents {
+    my ($fname, $contents) = @_;
+    local $/;
 
-    for (keys %Subjects) {
-	unlink "info/$_.t";
-    }
-
-    @subj = sort keys %subject;
-
-    for my $subj (@subj) {
-	create_subj($subj);
+    if (!open(SUBJ, "<$fname")) {
+	return 0 if ($!{ENOENT});
+	die "Can't open $fname for reading: $!";
     }
+    my $old = <SUBJ>;
+    close SUBJ;
+    return $contents eq $old;
 }
 
 # Print an integrity error message and exit with code 1