Merged revisions 214194 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r214194 | dvossel | 2009-08-26 11:36:42 -0500 (Wed, 26 Aug 2009) | 19 lines
  
  ast_write() ignores ast_audiohook_write() results
  
  In ast_write(), if a channel has a list of audiohooks, those
  lists are written to and the resulting frame is what ast_write()
  should continue with.  The problem was the returned audiohook frame
  was not being handled at all, and the original frame passed
  into it did not contain the mixed audio, so essentially audio
  was being lost.  One result of this was chan_spy's whisper
  mode no longer worked.  To complicate the issue, frames
  passed into ast_write may either be a single frame, or a list
  of frames.  So, as the list of frames is processed in the
  audiohook_write, the returned frames had to be added to a new
  list.
  
  (closes issue #15660)
  Reported by: corruptor
  Tested by: dvossel
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@214195 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/channel.c

@@ -3958,13 +3958,36 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
 		}
 
 		if (chan->audiohooks) {
-			struct ast_frame *new_frame, *cur;
+			struct ast_frame *prev = NULL, *new_frame, *cur, *dup;
 
+			/* Since ast_audiohook_write may return a new frame, and the cur frame is
+			 * an item in a list of frames, create a new list adding each cur frame back to it
+			 * regardless if the cur frame changes or not. */
 			for (cur = f; cur; cur = AST_LIST_NEXT(cur, frame_list)) {
 				new_frame = ast_audiohook_write_list(chan, chan->audiohooks, AST_AUDIOHOOK_DIRECTION_WRITE, cur);
+
+				/* if this frame is different than cur, preserve the end of the list,
+				 * free the old frames, and set cur to be the new frame */
 				if (new_frame != cur) {
+					/* doing an ast_frisolate here seems silly, but we are not guaranteed the new_frame
+					 * isn't part of local storage, meaning if ast_audiohook_write is called multiple
+					 * times it may override the previous frame we got from it unless we dup it */
+					if ((dup = ast_frisolate(new_frame))) {
+						AST_LIST_NEXT(dup, frame_list) = AST_LIST_NEXT(cur, frame_list);
 						ast_frfree(new_frame);
+						ast_frfree(cur);
+						cur = dup;
+					}
+				}
+
+				/* now, regardless if cur is new or not, add it to the new list,
+				 * if the new list has not started, cur will become the first item. */
+				if (prev) {
+					AST_LIST_NEXT(prev, frame_list) = cur;
+				} else {
+					f = cur; /* set f to be the beginning of our new list */
 				}
+				prev = cur;
 			}
 		}