Index: lib/filestorage/file_exceptions.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/filestorage/file_exceptions.php,v
retrieving revision 1.2
diff -u -r1.2 file_exceptions.php
--- lib/filestorage/file_exceptions.php 21 Sep 2010 07:59:27 -0000  1.2
+++ lib/filestorage/file_exceptions.php 27 Nov 2010 12:00:31 -0000
@@ -83,8 +83,15 @@
  * @copyright  2008 Petr Skoda (http://skodak.org)
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class file_pool_content_exception extends file_exception {
-    function __construct($contenthash, $debuginfo = NULL) {
-        parent::__construct('hashpoolproblem', $contenthash, $debuginfo);
+class file_pool_put_exception extends file_exception {
+    function __construct($contenthash, $content, $sourcefilepath, $debuginfo = null) {
+        $a = new stdClass();
+        $a->hash = $contenthash;
+        if (!is_null($content)) {
+            $a->source = 'string: ' . shorten_text($content);
+        } else {
+            $a->source = 'file: ' . $sourcefilepath;
+        }
+        parent::__construct('hashpoolproblem', $a, $debuginfo);
     }
 }
Index: lib/filestorage/file_storage.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/filestorage/file_storage.php,v
retrieving revision 1.10
diff -u -r1.10 file_storage.php
--- lib/filestorage/file_storage.php    11 Nov 2010 18:58:06 -0000  1.10
+++ lib/filestorage/file_storage.php    27 Nov 2010 12:00:31 -0000
@@ -1022,37 +1022,7 @@
         }

         $filesize = filesize($pathname);
-
-        $hashpath = $this->path_from_hash($contenthash);
-        $hashfile = "$hashpath/$contenthash";
-
-        if (file_exists($hashfile)) {
-            if (filesize($hashfile) !== $filesize) {
-                throw new file_pool_content_exception($contenthash);
-            }
-            $newfile = false;
-
-        } else {
-            if (!is_dir($hashpath)) {
-                if (!mkdir($hashpath, $this->dirpermissions, true)) {
-                    throw new file_exception('storedfilecannotcreatefiledirs'); // permission trouble
-                }
-            }
-            $newfile = true;
-
-            if (!copy($pathname, $hashfile)) {
-                throw new file_exception('storedfilecannotread');
-            }
-
-            if (filesize($hashfile) !== $filesize) {
-                @unlink($hashfile);
-                throw new file_pool_content_exception($contenthash);
-            }
-            chmod($hashfile, $this->filepermissions); // fix permissions if needed
-        }
-
-
-        return array($contenthash, $filesize, $newfile);
+        return $this->put_file_in_pool($filesize, $contenthash, null, $pathname);
     }

     /**
@@ -1064,14 +1034,27 @@
     public function add_string_to_pool($content) {
         $contenthash = sha1($content);
         $filesize = strlen($content); // binary length
+        return $this->put_file_in_pool($filesize, $contenthash, $content, null);
+    }
+
+    /**
+     * Actually do the work of adding something to the sha1 pool. Used by
+     * {@link add_string_to_pool()} and {@link add_file_to_pool()}
+     *
+     * @param string $content file content - binary string
+     * @return array (contenthash, filesize, newfile)
+     */
+    protected function put_file_in_pool($filesize, $contenthash, $content, $sourcefilepath) {
+        if (is_null($content) != is_null($sourcefilepath)) {
+            throw new coding_exception('Exactly one of $content and $sourcefilepath must be non-null when calling put_file_in_pool.');
+        }

         $hashpath = $this->path_from_hash($contenthash);
         $hashfile = "$hashpath/$contenthash";

-
         if (file_exists($hashfile)) {
             if (filesize($hashfile) !== $filesize) {
-                throw new file_pool_content_exception($contenthash);
+                throw new file_pool_content_exception($contenthash, $content, $sourcefilepath);
             }
             $newfile = false;

@@ -1083,11 +1066,17 @@
             }
             $newfile = true;

-            file_put_contents($hashfile, $content);
+            if (!is_null($content)) {
+                file_put_contents($hashfile, $content);
+            } else {
+                if (!copy($pathname, $hashfile)) {
+                    throw new file_exception('storedfilecannotread');
+                }
+            }

             if (filesize($hashfile) !== $filesize) {
                 @unlink($hashfile);
-                throw new file_pool_content_exception($contenthash);
+                throw new file_pool_content_exception($contenthash, $content, $sourcefilepath);
             }
             chmod($hashfile, $this->filepermissions); // fix permissions if needed
         }
Index: lang/en/error.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lang/en/error.php,v
retrieving revision 1.58
diff -u -r1.58 error.php
--- lang/en/error.php   19 Nov 2010 03:40:45 -0000  1.58
+++ lang/en/error.php   27 Nov 2010 12:00:31 -0000
@@ -244,7 +244,7 @@
 $string['guestnorate'] = 'Guests are not allowed to rate entries';
 $string['guestsarenotallowed'] = 'The guest user is not allowed to do this';
 $string['hackdetected'] = 'Hack attack detected!';
-$string['hashpoolproblem'] = 'Incorrect pool file content {$a}.';
+$string['hashpoolproblem'] = 'Inconsistent data found in the file pool for hash {$a->hash} when trying to add a new file from {$a->source}.';
 $string['headersent'] = 'Headers already sent';
 $string['idnumbertaken'] = 'ID number is already used for another course';
 $string['importformatnotimplement'] = 'Sorry, importing this format is not yet implemented!';