From: Austin Clements <amdragon@MIT.EDU>
To: notmuch@notmuchmail.org
Subject: [PATCH 2/4] emacs: Fix exception when fetching empty or unconfigured
	settings
Date: Thu, 20 Feb 2014 14:16:35 -0500
Message-Id: <1392923797-17045-3-git-send-email-amdragon@mit.edu>
In-Reply-To: <1392923797-17045-1-git-send-email-amdragon@mit.edu>
References: <1392923797-17045-1-git-send-email-amdragon@mit.edu>
Cc: bjonnh-nm@bjonnh.net
Precedence: list

When "notmuch config" is called with the name of an empty or
unconfigured setting, it prints nothing (not even a new line).
Previously, `notmuch-config-get' assumed it would always print a
newline.  As a result, when `notmuch-config-get' was called with the
name of an empty of unconfigured setting, it would attempt to
(substring "" 0 -1) to strip the newline, which would fail with a
(args-out-of-range "" 0 -1) exception.

Fix this by only stripping the newline if there actually is one.
---
 emacs/notmuch-lib.el | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index fa35fa9..09110b5 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -198,8 +198,13 @@ on the command line, and then retry your notmuch command")))
 
 (defun notmuch-config-get (item)
   "Return a value from the notmuch configuration."
-  ;; Trim off the trailing newline
-  (substring (notmuch-command-to-string "config" "get" item) 0 -1))
+  (let* ((val (notmuch-command-to-string "config" "get" item))
+	 (len (length val)))
+    ;; Trim off the trailing newline (if the value is empty or not
+    ;; configured, there will be no newline)
+    (if (and (> len 0) (= (aref val (- len 1)) ?\n))
+	(substring val 0 -1)
+      val)))
 
 (defun notmuch-database-path ()
   "Return the database.path value from the notmuch configuration."
-- 
1.8.4.rc3