[PATCH v2] emacs: show: lazy part bugfix

[Mark Walters <markwalters1009@gmail.com>]

The lazy part handling had a subtle bug. Notmuch stores the part
information as a text property with the displayed part so attachment
handling (saving viewing etc work).

Now, some mime parts have subparts and to avoid overwriting the
sub-part data notmuch checks and if part data is already recorded it
does not overwrite it.

Now with lazy part handling this could fail: there is already part
data stored. In the common case it works as the part type information
was stored when the lazy-part button was inserted. However, this fails
if the lazy part has sub-parts: notmuch had no idea these existed
until the lazy part insertion.

We fix this by removing any existing part-information from the
relevant region before doing the lazy insertion.
---
This is the same as the previous patch
id:1377246875-7784-1-git-send-email-markwalters1009@gmail.com except I
have added a substantial comment. I now believe the +1 in the remove
part information is genuinely correct for the reason detailed in the comment.
 
This does seem to fix an actual bug (see parent message and links there).

Best wishes

Mark


 emacs/notmuch-show.el |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index 20844f0..58ef4df 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -852,7 +852,20 @@ message at DEPTH in the current thread."
   ;; from a message header etc) so instead we start from the last
   ;; character of the button by adding a newline and finish by
   ;; removing the extra newline from the end of the part.
+  ;;
+  ;; Essentially, this function wants text properties to be
+  ;; front-nonsticky (where most of the other functions need
+  ;; front-sticky so that is what they actually are) and this is a way
+  ;; of faking the front-nonsticky for this one function.
+  ;;
+  ;; For exactly this reason we also remove existing part-information
+  ;; from one extra character: this extra character is the newline
+  ;; that we delete at the end.
+
   (save-excursion
+    ;; Remove part-information from lazy part-region
+    (put-text-property (button-start button) (1+ (button-end button)) :notmuch-part nil)
+
     (goto-char (button-end button))
     (insert "\n")
     (let* ((inhibit-read-only t)
-- 
1.7.9.1