From 525092fa9fd6d1552c56303613a5b102b3831561 Mon Sep 17 00:00:00 2001
From: "Mr. E23" <e23@users.mediawiki.org>
Date: Sun, 14 Mar 2004 15:05:52 +0000
Subject: [PATCH] Experimental merging of edit conflicts

---
 includes/DefaultSettings.php |  4 ++++
 includes/EditPage.php        | 27 +++++++++++++++++++++-
 includes/GlobalFunctions.php | 45 ++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 11eae782a5..44ff573b45 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -210,6 +210,10 @@ $wgDisableAnonTalk = false;
 # Requires zlib support enabled in PHP.
 $wgUseGzip = function_exists( "gzencode" );
 
+# Path to the GNU diff3 utility. If the file doesn't exist,
+# edit conflicts will fall back to the old behaviour (no merging).
+$wgDiff3 = "/usr/bin/diff3";
+
 # We can also compress text in the old revisions table. If this is set on,
 # old revisions will be compressed on page save if zlib support is available.
 # Any compressed revisions will be decompressed on load regardless of this
diff --git a/includes/EditPage.php b/includes/EditPage.php
index f69192476b..d22df2d5aa 100644
--- a/includes/EditPage.php
+++ b/includes/EditPage.php
@@ -170,7 +170,12 @@ class EditPage {
 				# FIXME: This is confusing. In theory we should attempt to merge, finding
 				# the equivalent section if it's unchanged and avoid the conflict.
 				if($isConflict) {
-					$this->section = "";
+					if( $this->merge() ){
+						// Successful merge! Maybe we should tell the user the good news?
+						$isConflict = false;
+					} else {
+						$this->section = "";
+					}
 				}
 			}
 			if ( ! $isConflict ) {
@@ -446,6 +451,26 @@ htmlspecialchars( $wgLang->recodeForEdit( $this->textbox1 ) ) .
 			}
 		}
 	}
+
+	/* private */ function merge(){
+		$oldDate = $this->edittime;
+		$res = wfQuery("SELECT cur_text FROM cur WHERE cur_id=" . 
+			$this->mTitle->getArticleID() . " FOR UPDATE", DB_WRITE);
+		$obj = wfFetchObject($res);
+
+		$yourtext = $obj->cur_text;
+		$ns = $this->mTitle->getNamespace();
+		$title = wfStrencode( $this->mTitle->getDBkey() );
+		$res = wfQuery("SELECT old_text FROM old WHERE old_namespace = $ns AND ".
+		  "old_title = '{$title}' AND old_timestamp = '{$oldDate}'", DB_WRITE);
+		$obj = wfFetchObject($res);
+		if(wfMerge($obj->old_text, $this->textbox1, $yourtext, $result)){
+			$this->textbox1 = $result;
+			return true;
+		} else {
+			return false;
+		}
+	}
 }
 
 ?>
diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index e67e778083..8133b755fa 100644
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -849,4 +849,49 @@ function wfPurgeSquidServers ($urlArr) {
 	}
 	return;
 }
+
+
+# wfMerge attempts to merge differences between three texts. 
+# Returns true for a clean merge and false for failure or a conflict.
+
+function wfMerge( $old, $mine, $yours, &$result ){
+	global $wgDiff3;
+
+	# This check may also protect against code injection in 
+	# case of broken installations.
+	if(! file_exists( $wgDiff3 ) ){ 
+		return false;
+	}
+	$td = "/tmp/";
+	$oldtextFile = fopen( $oldtextName = tempnam( $td, "merge-old-" ), "w" );
+	$mytextFile = fopen( $mytextName = tempnam( $td, "merge-mine-" ), "w" );
+	$yourtextFile = fopen( $yourtextName = tempnam( $td, "merge-your-" ), "w" );
+			
+	fwrite( $oldtextFile, $old ); fclose( $oldtextFile ); 
+	fwrite( $mytextFile, $mine ); fclose( $mytextFile ); 
+	fwrite( $yourtextFile, $yours ); fclose( $yourtextFile );
+	$cmd = "{$wgDiff3} -a --overlap-only $mytextName $oldtextName $yourtextName";
+	$handle = popen( $cmd, "r" );
+
+	if( fgets( $handle ) ){
+		$conflict = true;
+	} else {
+		$conflict = false;
+	}
+	pclose( $handle );
+	$cmd = "{$wgDiff3} -a --merge $mytextName $oldtextName $yourtextName";
+	$handle = popen( $cmd, "r" );
+	$result = "";
+	do {
+		$data = fread( $handle, 8192 );
+		if ( strlen( $data ) == 0 ) {
+			break;
+		}
+		$result .= $data;
+	} while ( true );
+	pclose( $handle );
+	unlink( $mytextName ); unlink( $oldtextName ); unlink( $yourtextName );
+	return ! $conflict;
+}
+
 ?>
-- 
2.20.1