New tool for detecting broken XML files (#211)

Author: alfsb

scripts/broken.php

@@ -0,0 +1,154 @@
+<?php /*
++----------------------------------------------------------------------+
+| Copyright (c) 1997-2025 The PHP Group                                |
++----------------------------------------------------------------------+
+| This source file is subject to version 3.01 of the PHP license,      |
+| that is bundled with this package in the file LICENSE, and is        |
+| available through the world-wide-web at the following url:           |
+| https://www.php.net/license/3_01.txt.                                |
+| If you did not receive a copy of the PHP license and are unable to   |
+| obtain it through the world-wide-web, please send a note to          |
+| [email protected], so we can mail you a copy immediately.              |
++----------------------------------------------------------------------+
+| Authors:     André L F S Bacci <ae php.net>                          |
++----------------------------------------------------------------------+
+
+# Description
+
+This command line utility test if an file is valid standalone XML file,
+accepting undefined entities references. If an directory is informed,
+the test is applied in all .xml files in directory and sub directories.
+
+This tool also cares for directories marked with .xmlfragmentdir, so
+theses files are tested in relaxed semantics for XML fragments.       */
+
+ini_set( 'display_errors' , 1 );
+ini_set( 'display_startup_errors' , 1 );
+error_reporting( E_ALL );
+
+if ( count( $argv ) < 2 )
+    print_usage_exit( $argv[0] );
+
+array_shift( $argv );
+foreach( $argv as $arg )
+{
+    if ( file_exists( $arg ) )
+    {
+        if ( is_file( $arg ) )
+            testFile( $arg );
+        if ( is_dir( $arg ) )
+            testDir( $arg );
+        continue;
+    }
+    echo "Path does not exist: $arg\n";
+}
+
+function print_usage_exit( $cmd )
+{
+    fwrite( STDERR , "  Wrong paramater count. Usage:\n" );
+    fwrite( STDERR , "    {$cmd} path:\n" );
+    exit;
+}
+
+function setup( string & $prefix , string & $suffix , string & $extra )
+{
+    // Undefined entities generate TWO different error messages on libxml
+    // - "Entity '?' not defined" (for entity inside elements)
+    // - "Extra content at the end of the document" (entity outside elements)
+
+    $inside = "<x>&ZZZ;</x>";
+    $outside = "<x/>&ZZZ;";
+
+    $doc = new DOMDocument();
+    $doc->recover            = true;
+    $doc->resolveExternals   = false;
+    $doc->substituteEntities = false;
+    libxml_use_internal_errors( true );
+
+    $doc->loadXML( $inside );
+    $message = trim( libxml_get_errors()[0]->message );
+    $message = str_replace( "ZZZ" , "\f" , $message );
+    [ $prefix , $suffix ] = explode( "\f" , $message );
+    libxml_clear_errors();
+
+    $doc->loadXML( $outside );
+    $extra = trim( libxml_get_errors()[0]->message );
+    libxml_clear_errors();
+}
+
+function testFile( string $filename , bool $fragment = false )
+{
+    static $prefix = "", $suffix = "", $extra = "";
+    if ( $extra == "" )
+        setup( $prefix , $suffix , $extra );
+
+    $doc = new DOMDocument();
+    $doc->recover            = true;
+    $doc->resolveExternals   = false;
+    $doc->substituteEntities = false;
+    libxml_use_internal_errors( true );
+
+    $contents = file_get_contents( $filename );
+    if ( $fragment )
+        $contents = "<f>{$contents}</f>";
+    $doc->loadXML( $contents );
+
+    $errors = libxml_get_errors();
+    libxml_clear_errors();
+
+    foreach( $errors as $error )
+    {
+        $message = trim( $error->message );
+        $hintFragDir = false;
+
+        if ( str_starts_with( $message , $prefix ) && str_ends_with( $message , $suffix ) )
+            continue;
+        //if ( $message == $extra ) // Disabled as unnecessary. Also, this indicates that some
+        //    continue;             // some entity reference is used at an unusual position.
+        if ( $message == $extra )
+            $hintFragDir = true;
+
+        $lin = $error->line;
+        $col = $error->column;
+        echo "Broken XML file:\n";
+        echo "  Path:  $filename [$lin,$col]\n";
+        echo "  Error: $message\n";
+        if ( $hintFragDir )
+            echo "  Hint:  Dir is marked with .xmlfragmentdir on doc-en? If not, check entity references.\n";
+        echo "\n";
+        return;
+    }
+}
+
+function testDir( string $dir )
+{
+    $dir = realpath( $dir );
+    $files = scandir( $dir );
+    $fragment = false;
+    $subdirs = [];
+
+    foreach( $files as $file )
+    {
+        if ( $file == ".xmlfragmentdir" )
+        {
+            $fragment = true;
+            continue;
+        }
+        if ( $file[0] == "." )
+            continue;
+
+        $fullpath = realpath( "$dir/$file" );
+
+        if ( is_dir ( $fullpath ) )
+        {
+            $subdirs[] = $fullpath;
+            continue;
+        }
+
+        if ( str_ends_with( $fullpath , ".xml" ) )
+            testFile( $fullpath , $fragment );
+    }
+
+    foreach( $subdirs as $dir )
+        testDir( $dir );
+}