emacs: document/defcustom notmuch-multipart/alternative-discouraged

This variable is important for people who want to change the default
behaviour when displaying multipart/alternative messages.  Previously
it was undocumented.  Add a defcustom to help users and copy some
documentation from the wiki. The usual machinery of re-using
docstrings is a bit tricky to use here because it mangles the example
lisp code, and the link to the info node should not be in e.g. the
html page.

Add a simple test to make sure the switch from defvar to defcustom did
not break something obvious.

doc/notmuch-emacs.rst

@@ -238,6 +238,27 @@ Display of messages can be controlled by the following variables
 :index:`notmuch-show-header-line`
        |docstring::notmuch-show-header-line|
 
+:index:`notmuch-multipart/alternative-discouraged`
+
+   Which mime types to hide by default for multipart messages.
+
+   Can either be a list of mime types (as strings) or a function
+   mapping a plist representing the current message to such a list.
+   The following example function would discourage `text/html` and
+   `multipart/related` generally, but discourage `text/plain` should
+   the message be sent from `whatever@example.com`.
+
+   .. code:: lisp
+
+      (defun my--determine-discouraged (msg)
+        (let* ((headers (plist-get msg :headers))
+               (from (or (plist-get headers :From) "")))
+          (cond
+           ((string-match "whatever@example.com" from)
+            (list "text/plain"))
+           (t
+            (list "text/html" "multipart/related")))))
+
 .. _show-copy:
 
 Copy to kill-ring

emacs/notmuch-lib.el

@@ -567,12 +567,20 @@ Take wildcards into account."
 	   (string= (downcase t1)
 		    (downcase t2))))))
 
-(defvar notmuch-multipart/alternative-discouraged
+(defcustom notmuch-multipart/alternative-discouraged
   '(;; Avoid HTML parts.
     "text/html"
     ;; multipart/related usually contain a text/html part and some
     ;; associated graphics.
-    "multipart/related"))
+    "multipart/related")
+  "Which mime types to hide by default for multipart messages.
+
+Can either be a list of mime types (as strings) or a function
+mapping a plist representing the current message to such a list.
+See Info node `(notmuch-emacs) notmuch-show' for a sample function."
+  :group 'notmuch-show
+  :type '(radio (repeat :tag "MIME Types" string)
+		(function :tag "Function")))
 
 (defun notmuch-multipart/alternative-determine-discouraged (msg)
   "Return the discouraged alternatives for the specified message."

test/T450-emacs-show.sh

@@ -209,6 +209,10 @@ test_emacs '(notmuch-show "id:'$gen_msg_id'")
 output=$(head -1 OUTPUT.raw|cut -f1-4 -d' ')
 test_expect_equal "$output" "Notmuch Test Suite <test_suite@notmuchmail.org>"
 
+test_begin_subtest "multipart/alternative hides html by default"
+test_emacs '(notmuch-show "id:cf0c4d610911171136h1713aa59w9cf9aa31f052ad0a@mail.gmail.com")
+	    (test-visible-output)'
+test_expect_equal_file $EXPECTED/notmuch-show-multipart-alternative OUTPUT
 
 # switching to the crypto corpus, using gpg from here on:
 add_gnupg_home

test/emacs-show.expected-output/notmuch-show-multipart-alternative

@@ -0,0 +1,62 @@
+Alex Botero-Lowry <alex.boterolowry@gmail.com> (2009-11-17) (attachment inbox)
+Subject: [notmuch] preliminary FreeBSD support
+To: notmuch@notmuchmail.org
+Date: Tue, 17 Nov 2009 11:36:14 -0800
+
+[ multipart/mixed ]
+[ multipart/alternative ]
+[ text/plain ]
+I saw the announcement this morning, and was very excited, as I had been
+hoping sup would be turned into a library,
+since I like the concept more than the UI (I'd rather an emacs interface).
+
+I did a preliminary compile which worked out fine, but
+sysconf(_SC_SC_GETPW_R_SIZE_MAX) returns -1 on
+FreeBSD, so notmuch_config_open segfaulted.
+
+Attached is a patch that supplies a default buffer size of 64 in cases where
+-1 is returned.
+
+http://www.opengroup.org/austin/docs/austin_328.txt - seems to indicate this
+is acceptable behavior,
+and
+http://mail-index.netbsd.org/pkgsrc-bugs/2006/06/07/msg016808.htmlspecifically
+uses 64 as the
+buffer size.
+[ text/html (hidden) ]
+[ 0001-Deal-with-situation-where-sysconf-_SC_GETPW_R_SIZE_M.patch: application/octet-stream (as text/x-diff) ]
+From e3bc4bbd7b9d0d086816ab5f8f2d6ffea1dd3ea4 Mon Sep 17 00:00:00 2001
+From: Alexander Botero-Lowry <alex.boterolowry@gmail.com>
+Date: Tue, 17 Nov 2009 11:30:39 -0800
+Subject: [PATCH] Deal with situation where sysconf(_SC_GETPW_R_SIZE_MAX) returns -1
+
+---
+ notmuch-config.c |    2 ++
+ 1 files changed, 2 insertions(+), 0 deletions(-)
+
+diff --git a/notmuch-config.c b/notmuch-config.c
+index 248149c..e7220d8 100644
+--- a/notmuch-config.c
++++ b/notmuch-config.c
+@@ -77,6 +77,7 @@ static char *
+ get_name_from_passwd_file (void *ctx)
+ {
+     long pw_buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
++    if (pw_buf_size == -1) pw_buf_size = 64;
+     char *pw_buf = talloc_zero_size (ctx, pw_buf_size);
+     struct passwd passwd, *ignored;
+     char *name;
+@@ -101,6 +102,7 @@ static char *
+ get_username_from_passwd_file (void *ctx)
+ {
+     long pw_buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
++    if (pw_buf_size == -1) pw_buf_size = 64;
+     char *pw_buf = talloc_zero_size (ctx, pw_buf_size);
+     struct passwd passwd, *ignored;
+     char *name;
+-- 
+1.6.5.2
+
+[ text/plain ]
+[ 4-line signature. Click/Enter to show. ]
+ Carl Worth <cworth@cworth.org> (2009-11-17) (inbox unread)