* Many changes to make ikiwiki very resistant to write failures

  including out of disk space situations. ikiwiki should never leave
  truncated files, and if the error occurs during a web-based file edit,
  the user will be given an opportunity to retry.
  Inspired by the many ways Moin Moin destroys itself when out of disk. :-)
* Fix syslogging of errors.

6 files changed, 82 insertions, 36 deletions

diff --git a/IkiWiki/CGI.pm b/IkiWiki/CGI.pm
index 6c489df8d..973053427 100644
--- a/IkiWiki/CGI.pm
+++ b/IkiWiki/CGI.pm
@@ -252,12 +252,15 @@ sub cgi_prefs ($$) { #{{{
 	elsif ($form->submitted eq 'Save Preferences' && $form->validate) {
 		foreach my $field (qw(email subscriptions)) {
 			if (defined $form->field($field) && length $form->field($field)) {
-				userinfo_set($user_name, $field, $form->field($field)) || error("failed to set $field");
+				userinfo_set($user_name, $field, $form->field($field)) ||
+					error("failed to set $field");
 			}
 		}
 		if (is_admin($user_name)) {
 			set_banned_users(grep { ! is_admin($_) }
-					split(' ', $form->field("banned_users")));
+					split(' ',
+						$form->field("banned_users"))) ||
+				error("failed saving changes");
 		}
 		$form->text(gettext("Preferences saved."));
 	}
@@ -487,7 +490,25 @@ sub cgi_editpage ($$) { #{{{
 
 		$content=~s/\r\n/\n/g;
 		$content=~s/\r/\n/g;
-		writefile($file, $config{srcdir}, $content);
+
+		$config{cgi}=0; # avoid cgi error message
+		eval { writefile($file, $config{srcdir}, $content) };
+		$config{cgi}=1;
+		if ($@) {
+			$form->field(name => "rcsinfo", value => rcs_prepedit($file),
+				force => 1);
+			$form->tmpl_param("failed_save", 1);
+			$form->tmpl_param("error_message", $@);
+			$form->field("editcontent", value => $content, force => 1);
+			$form->field(name => "comments", value => $form->field('comments'), force => 1);
+			$form->field("do", "edit)");
+			$form->tmpl_param("page_select", 0);
+			$form->field(name => "page", type => 'hidden');
+			$form->field(name => "type", type => 'hidden');
+			$form->title(sprintf(gettext("editing %s"), $page));
+			print $form->render(submit => \@buttons);
+			return;
+		}
 		
 		if ($config{rcs}) {
 			my $message="";
@@ -616,7 +637,7 @@ sub cgi (;$$) { #{{{
 					email => "",
 					password => "",
 					regdate => time,
-				});
+				}) || error("failed adding user");
 			}
 		}
 	}
diff --git a/IkiWiki/Plugin/aggregate.pm b/IkiWiki/Plugin/aggregate.pm
index 7fceb0df3..a6f850236 100644
--- a/IkiWiki/Plugin/aggregate.pm
+++ b/IkiWiki/Plugin/aggregate.pm
@@ -153,8 +153,11 @@ sub loadstate () { #{{{
 sub savestate () { #{{{
 	eval q{use HTML::Entities};
 	error($@) if $@;
-	open (OUT, ">$config{wikistatedir}/aggregate" ||
-		die "$config{wikistatedir}/aggregate: $!");
+	my $newfile="$config{wikistatedir}/aggregate.new";
+	# TODO: This cleanup function could use improvement. Any newly
+	# aggregated files are left behind unrecorded, and should be deleted.
+	my $cleanup = sub { unlink($newfile) };
+	open (OUT, ">$newfile") || error("open $newfile: $!", $cleanup);
 	foreach my $data (values %feeds, values %guids) {
 		if ($data->{remove}) {
 			if ($data->{name}) {
@@ -188,9 +191,11 @@ sub savestate () { #{{{
 				push @line, "$field=".$data->{$field};
 			}
 		}
-		print OUT join(" ", @line)."\n";
+		print OUT join(" ", @line)."\n" || error("write $newfile: $!", $cleanup);
 	}
-	close OUT;
+	close OUT || error("save $newfile: $!", $cleanup);
+	rename($newfile, "$config{wikistatedir}/aggregate") ||
+		error("rename $newfile: $!", $cleanup);
 } #}}}
 
 sub expire () { #{{{
diff --git a/IkiWiki/Plugin/passwordauth.pm b/IkiWiki/Plugin/passwordauth.pm
index 6d395324e..e0aa72a19 100644
--- a/IkiWiki/Plugin/passwordauth.pm
+++ b/IkiWiki/Plugin/passwordauth.pm
@@ -187,7 +187,8 @@ sub formbuilder (@) { #{{{
 			my $user_name=$form->field('name');
 	                foreach my $field (qw(password)) {
         	                if (defined $form->field($field) && length $form->field($field)) {
-					IkiWiki::userinfo_set($user_name, $field, $form->field($field)) || error("failed to set $field");
+					IkiWiki::userinfo_set($user_name, $field, $form->field($field)) ||
+						error("failed to set $field");
 	                        }
 	                }
 		}
diff --git a/IkiWiki/Plugin/search.pm b/IkiWiki/Plugin/search.pm
index 1b5c66716..d35c33e76 100644
--- a/IkiWiki/Plugin/search.pm
+++ b/IkiWiki/Plugin/search.pm
@@ -89,14 +89,20 @@ sub estcfg () { #{{{
 	my $estdir="$config{wikistatedir}/hyperestraier";
 	my $cgi=IkiWiki::basename($config{cgiurl});
 	$cgi=~s/\..*$//;
-	open(TEMPLATE, ">:utf8", "$estdir/$cgi.tmpl") ||
-		error("write $estdir/$cgi.tmpl: $!");
+
+	my $newfile="$estdir/$cgi.tmpl.new";
+	my $cleanup = sub { unlink($newfile) };
+	open(TEMPLATE, ">:utf8", $newfile) || error("open $newfile: $!", $cleanup);
 	print TEMPLATE IkiWiki::misctemplate("search", 
 		"<!--ESTFORM-->\n\n<!--ESTRESULT-->\n\n<!--ESTINFO-->\n\n",
-		baseurl => IkiWiki::dirname($config{cgiurl})."/");
-	close TEMPLATE;
-	open(TEMPLATE, ">$estdir/$cgi.conf") ||
-		error("write $estdir/$cgi.conf: $!");
+		baseurl => IkiWiki::dirname($config{cgiurl})."/") ||
+			error("write $newfile: $!", $cleanup);
+	close TEMPLATE || error("save $newfile: $!", $cleanup);
+	rename($newfile, "$estdir/$cgi.tmpl") ||
+		error("rename $newfile: $!", $cleanup);
+	
+	$newfile="$estdir/$cgi.conf";
+	open(TEMPLATE, ">$newfile") || error("open $newfile: $!", $cleanup);
 	my $template=template("estseek.conf");
 	eval q{use Cwd 'abs_path'};
 	$template->param(
@@ -105,13 +111,15 @@ sub estcfg () { #{{{
 		destdir => abs_path($config{destdir}),
 		url => $config{url},
 	);
-	print TEMPLATE $template->output;
-	close TEMPLATE;
+	print TEMPLATE $template->output || error("write $newfile: $!", $cleanup);
+	close TEMPLATE || error("save $newfile: $!", $cleanup);
+	rename($newfile, "$estdir/$cgi.conf") ||
+		error("rename $newfile: $!", $cleanup);
+
 	$cgi="$estdir/".IkiWiki::basename($config{cgiurl});
 	unlink($cgi);
 	my $estseek = defined $config{estseek} ? $config{estseek} : '/usr/lib/estraier/estseek.cgi';
-	symlink($estseek, $cgi) ||
-		error("symlink $estseek $cgi: $!");
+	symlink($estseek, $cgi) || error("symlink $estseek $cgi: $!");
 } # }}}
 
 sub estcmd ($;@) { #{{{
diff --git a/IkiWiki/Render.pm b/IkiWiki/Render.pm
index d8bc5a9d9..cbba28251 100644
--- a/IkiWiki/Render.pm
+++ b/IkiWiki/Render.pm
@@ -198,22 +198,26 @@ sub render ($) { #{{{
 		my $srcfd=readfile($srcfile, 1, 1);
 		delete $depends{$file};
 		will_render($file, $file, 1);
-		my $destfd=writefile($file, $config{destdir}, undef, 1, 1);
-		my $blksize = 16384;
-		my ($len, $buf, $written);
-		while ($len = sysread $srcfd, $buf, $blksize) {
-			if (! defined $len) {
-				next if $! =~ /^Interrupted/;
-				error("failed to read $srcfile: $!");
-			}
-			my $offset = 0;
-			while ($len) {
-				defined($written = syswrite OUT, $buf, $len, $offset)
-					or error("failed to write $file: $!");
-				$len -= $written;
-				$offset += $written;
+		writefile($file, $config{destdir}, undef, 1, sub {
+			my $destfd=shift;
+			my $cleanup=shift;
+
+			my $blksize = 16384;
+			my ($len, $buf, $written);
+			while ($len = sysread $srcfd, $buf, $blksize) {
+				if (! defined $len) {
+					next if $! =~ /^Interrupted/;
+					error("failed to read $srcfile: $!", $cleanup);
+				}
+				my $offset = 0;
+				while ($len) {
+					defined($written = syswrite $destfd, $buf, $len, $offset)
+						or error("failed to write $file: $!", $cleanup);
+					$len -= $written;
+					$offset += $written;
+				}
 			}
-		}
+		});
 		$oldpagemtime{$file}=time;
 	}
 } #}}}
diff --git a/IkiWiki/UserInfo.pm b/IkiWiki/UserInfo.pm
index 115a263ce..02c27991c 100644
--- a/IkiWiki/UserInfo.pm
+++ b/IkiWiki/UserInfo.pm
@@ -15,12 +15,19 @@ sub userinfo_retrieve () { #{{{
 sub userinfo_store ($) { #{{{
 	my $userinfo=shift;
 	
+	my $newfile="$config{wikistatedir}/userdb.new";
 	my $oldmask=umask(077);
-	my $ret=Storable::lock_store($userinfo, "$config{wikistatedir}/userdb");
+	my $ret=Storable::lock_store($userinfo, $newfile);
 	umask($oldmask);
+	if (defined $ret && $ret) {
+		if (! rename($newfile, "$config{wikistatedir}/userdb")) {
+			unlink($newfile);
+			$ret=undef;
+		}
+	}
 	return $ret;
 } #}}}
-	
+
 sub userinfo_get ($$) { #{{{
 	my $user=shift;
 	my $field=shift;