From 83b80acad8431fcd56e9a331ba06c41edee48c91 Mon Sep 17 00:00:00 2001
From: David Rothstein <drothstein@gmail.com>
Date: Wed, 16 Jul 2014 16:03:02 -0400
Subject: Drupal 7.29

---
 includes/file.inc | 81 +++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 64 insertions(+), 17 deletions(-)

(limited to 'includes/file.inc')

diff --git a/includes/file.inc b/includes/file.inc
index 834699f18..d3008cc4f 100644
--- a/includes/file.inc
+++ b/includes/file.inc
@@ -1999,23 +1999,7 @@ function file_download() {
   $target = implode('/', $args);
   $uri = $scheme . '://' . $target;
   if (file_stream_wrapper_valid_scheme($scheme) && file_exists($uri)) {
-    // Let other modules provide headers and controls access to the file.
-    // module_invoke_all() uses array_merge_recursive() which merges header
-    // values into a new array. To avoid that and allow modules to override
-    // headers instead, use array_merge() to merge the returned arrays.
-    $headers = array();
-    foreach (module_implements('file_download') as $module) {
-      $function = $module . '_file_download';
-      $result = $function($uri);
-      if ($result == -1) {
-        // Throw away the headers received so far.
-        $headers = array();
-        break;
-      }
-      if (isset($result) && is_array($result)) {
-        $headers = array_merge($headers, $result);
-      }
-    }
+    $headers = file_download_headers($uri);
     if (count($headers)) {
       file_transfer($uri, $headers);
     }
@@ -2027,6 +2011,69 @@ function file_download() {
   drupal_exit();
 }
 
+/**
+ * Retrieves headers for a private file download.
+ *
+ * Calls all module implementations of hook_file_download() to retrieve headers
+ * for files by the module that originally provided the file. The presence of
+ * returned headers indicates the current user has access to the file.
+ *
+ * @param $uri
+ *   The URI for the file whose headers should be retrieved.
+ *
+ * @return
+ *   If access is allowed, headers for the file, suitable for passing to
+ *   file_transfer(). If access is not allowed, an empty array will be returned.
+ *
+ * @see file_transfer()
+ * @see file_download_access()
+ * @see hook_file_downlaod()
+ */
+function file_download_headers($uri) {
+  // Let other modules provide headers and control access to the file.
+  // module_invoke_all() uses array_merge_recursive() which merges header
+  // values into a new array. To avoid that and allow modules to override
+  // headers instead, use array_merge() to merge the returned arrays.
+  $headers = array();
+  foreach (module_implements('file_download') as $module) {
+    $function = $module . '_file_download';
+    $result = $function($uri);
+    if ($result == -1) {
+      // Throw away the headers received so far.
+      $headers = array();
+      break;
+    }
+    if (isset($result) && is_array($result)) {
+      $headers = array_merge($headers, $result);
+    }
+  }
+  return $headers;
+}
+
+/**
+ * Checks that the current user has access to a particular file.
+ *
+ * The return value of this function hinges on the return value from
+ * file_download_headers(), which is the function responsible for collecting
+ * access information through hook_file_download().
+ *
+ * If immediately transferring the file to the browser and the headers will
+ * need to be retrieved, the return value of file_download_headers() should be
+ * used to determine access directly, so that access checks will not be run
+ * twice.
+ *
+ * @param $uri
+ *   The URI for the file whose access should be retrieved.
+ *
+ * @return
+ *   Boolean TRUE if access is allowed. FALSE if access is not allowed.
+ *
+ * @see file_download_headers()
+ * @see hook_file_download()
+ */
+function file_download_access($uri) {
+  return count(file_download_headers($uri)) > 0;
+}
 
 /**
  * Finds all files that match a given mask in a given directory.
-- 
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