GFile: Clean up file_copy_fallback to fix SEGV with btrfs

Ok, this function was just an awful mess before.  Now the problem
domain is not trivial, and I won't claim this new code is *beautiful*,
but it should fix the bug at hand, and be somewhat less prone to
failure for the next person who tries to modify it.  There's only one
unref call for each object now.

https://bugzilla.gnome.org/show_bug.cgi?id=692408

diff --git a/gio/gfile.c b/gio/gfile.c
index 21c9f59..3d78d72 100644 (file)
--- a/gio/gfile.c
+++ b/gio/gfile.c
@@ -2982,11 +2982,11 @@ file_copy_fallback (GFile                  *source,
                     gpointer                progress_callback_data,
                     GError                **error)
 {
-  GInputStream *in;
-  GOutputStream *out;
-  GFileInfo *info;
+  gboolean ret = FALSE;
+  GInputStream *in = NULL;
+  GOutputStream *out = NULL;
+  GFileInfo *info = NULL;
   const char *target;
-  gboolean result;
 
   /* need to know the file type */
   info = g_file_query_info (source,
@@ -2994,9 +2994,8 @@ file_copy_fallback (GFile                  *source,
                             G_FILE_QUERY_INFO_NOFOLLOW_SYMLINKS,
                             cancellable,
                             error);
-
-  if (info == NULL)
-          return FALSE;
+  if (!info)
+    goto out;
 
   /* Maybe copy the symlink? */
   if ((flags & G_FILE_COPY_NOFOLLOW_SYMLINKS) &&
@@ -3006,16 +3005,12 @@ file_copy_fallback (GFile                  *source,
       if (target)
         {
           if (!copy_symlink (destination, flags, cancellable, target, error))
-            {
-              g_object_unref (info);
-              return FALSE;
-            }
+            goto out;
 
-          g_object_unref (info);
-          goto copied_file;
+          ret = TRUE;
+          goto out;
         }
         /* ... else fall back on a regular file copy */
-        g_object_unref (info);
     }
   /* Handle "special" files (pipes, device nodes, ...)? */
   else if (g_file_info_get_file_type (info) == G_FILE_TYPE_SPECIAL)
@@ -3023,16 +3018,14 @@ file_copy_fallback (GFile                  *source,
       /* FIXME: could try to recreate device nodes and others? */
       g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
                            _("Can't copy special file"));
-      g_object_unref (info);
-      return FALSE;
+      goto out;
     }
+
   /* Everything else should just fall back on a regular copy. */
-  else
-    g_object_unref (info);
 
   in = open_source_for_copy (source, destination, flags, cancellable, error);
-  if (in == NULL)
-    return FALSE;
+  if (!in)
+    goto out;
 
   if (flags & G_FILE_COPY_OVERWRITE)
     {
@@ -3047,29 +3040,33 @@ file_copy_fallback (GFile                  *source,
       out = (GOutputStream *)g_file_create (destination, 0, cancellable, error);
     }
 
-  if (out == NULL)
-    {
-      g_object_unref (in);
-      return FALSE;
-    }
+  if (!out)
+    goto out;
 
 #ifdef HAVE_SYS_IOCTL_H
   if (G_IS_FILE_DESCRIPTOR_BASED (in) && G_IS_FILE_DESCRIPTOR_BASED (out))
     {
       GError *reflink_err = NULL;
 
-      result = btrfs_reflink_with_progress (in, out, info, cancellable,
-                                            progress_callback, progress_callback_data,
-                                            &reflink_err);
-
-      if (result || !g_error_matches (reflink_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+      if (!btrfs_reflink_with_progress (in, out, info, cancellable,
+                                        progress_callback, progress_callback_data,
+                                        &reflink_err))
         {
-          if (!result)
-            g_propagate_error (error, reflink_err);
-          goto cleanup;
+          if (g_error_matches (reflink_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+            {
+              g_clear_error (&reflink_err);
+            }
+          else
+            {
+              g_propagate_error (error, reflink_err);
+              goto out;
+            }
         }
       else
-        g_clear_error (&reflink_err);
+        {
+          ret = TRUE;
+          goto out;
+        }
     }
 #endif
 
@@ -3078,45 +3075,60 @@ file_copy_fallback (GFile                  *source,
     {
       GError *splice_err = NULL;
 
-      result = splice_stream_with_progress (in, out, cancellable,
-                                            progress_callback, progress_callback_data,
-                                            &splice_err);
-
-      if (result || !g_error_matches (splice_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+      if (!splice_stream_with_progress (in, out, cancellable,
+                                        progress_callback, progress_callback_data,
+                                        &splice_err))
         {
-          if (!result)
-            g_propagate_error (error, splice_err);
-          goto cleanup;
+          if (g_error_matches (splice_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED))
+            {
+              g_clear_error (&splice_err);
+            }
+          else
+            {
+              g_propagate_error (error, splice_err);
+              goto out;
+            }
         }
       else
-        g_clear_error (&splice_err);
+        {
+          ret = TRUE;
+          goto out;
+        }
     }
 
 #endif
-  result = copy_stream_with_progress (in, out, source, cancellable,
-                                      progress_callback, progress_callback_data,
-                                      error);
-
-cleanup:
-  /* Don't care about errors in source here */
-  g_input_stream_close (in, cancellable, NULL);
-
-  /* But write errors on close are bad! */
-  if (!g_output_stream_close (out, cancellable, result ? error : NULL))
-    result = FALSE;
-
-  g_object_unref (in);
-  g_object_unref (out);
+  
+  /* A plain read/write loop */
+  if (!copy_stream_with_progress (in, out, source, cancellable,
+                                  progress_callback, progress_callback_data,
+                                  error))
+    goto out;
+
+  ret = TRUE;
+ out:
+  /* Ignore errors here. Failure to copy metadata is not a hard error */
+  if (ret)
+    (void) g_file_copy_attributes (source, destination,
+                                   flags, cancellable, NULL);
 
-  if (result == FALSE)
-    return FALSE;
+  if (in)
+    {
+      /* Don't care about errors in source here */
+      (void) g_input_stream_close (in, cancellable, NULL);
+      g_object_unref (in);
+    }
 
-copied_file:
-  /* Ignore errors here. Failure to copy metadata is not a hard error */
-  g_file_copy_attributes (source, destination,
-                          flags, cancellable, NULL);
+  if (out)
+    {
+      /* But write errors on close are bad! */
+      if (!g_output_stream_close (out, cancellable, ret ? error : NULL))
+        ret = FALSE;
+      g_object_unref (out);
+    }
+  
+  g_clear_object (&info);
 
-  return TRUE;
+  return ret;
 }
 
 /**