[PATCH v2 3/8] emacs: Remove broken `notmuch-get-bodypart-content' API

[Austin Clements <amdragon@mit.edu>]

`notmuch-get-bodypart-content' could do two very different things,
depending on conditions: for text/* parts other than text/html, it
would return the part content as a multibyte Lisp string *after*
charset conversion, while for other parts (including text/html), it
would return binary part content without charset conversion.

This commit completes the split of `notmuch-get-bodypart-content' into
two different and explicit APIs: `notmuch-get-bodypart-binary' and
`notmuch-get-bodypart-text'.  It updates all callers to use one or the
other depending on what's appropriate.
---
 emacs/notmuch-lib.el  | 37 ++++++++++++++++++++++++++++---------
 emacs/notmuch-show.el |  8 ++++----
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/emacs/notmuch-lib.el b/emacs/notmuch-lib.el
index d4b6684..a0a95d8 100644
--- a/emacs/notmuch-lib.el
+++ b/emacs/notmuch-lib.el
@@ -545,9 +545,25 @@ (defun notmuch-get-bodypart-binary (msg part process-crypto)
 	(apply #'call-process notmuch-command nil '(t nil) nil args)
 	(buffer-string)))))
 
-(defun notmuch-get-bodypart-content (msg part process-crypto)
-  (or (plist-get part :content)
-      (notmuch-get-bodypart-binary msg part process-crypto)))
+(defun notmuch-get-bodypart-text (msg part process-crypto)
+  "Return the text content of PART in MSG.
+
+This returns the content of the given part as a multibyte Lisp
+string after performing content transfer decoding and any
+necessary charset decoding.  It is an error to use this for
+non-text/* parts."
+  (let ((content (plist-get part :content)))
+    (when (not content)
+      ;; Use show --format=sexp to fetch decoded content
+      (let* ((args `("show" "--format=sexp" "--include-html"
+		     ,(format "--part=%s" (plist-get part :id))
+		     ,@(when process-crypto '("--decrypt"))
+		     ,(notmuch-id-to-query (plist-get msg :id))))
+	     (npart (apply #'notmuch-call-notmuch-sexp args)))
+	(setq content (plist-get npart :content))
+	(when (not content)
+	  (error "Internal error: No :content from %S" args))))
+    content))
 
 ;; Workaround: The call to `mm-display-part' below triggers a bug in
 ;; Emacs 24 if it attempts to use the shr renderer to display an HTML
@@ -568,18 +584,21 @@ (defun notmuch-mm-display-part-inline (msg part content-type process-crypto)
 current buffer, if possible."
   (let ((display-buffer (current-buffer)))
     (with-temp-buffer
-      ;; In case there is :content, the content string is already converted
-      ;; into emacs internal format. `gnus-decoded' is a fake charset,
-      ;; which means no further decoding (to be done by mm- functions).
-      (let* ((charset (if (plist-member part :content)
-			  'gnus-decoded
+      ;; In case we already have :content, use it and tell mm-* that
+      ;; it's already been charset-decoded by using the fake
+      ;; `gnus-decoded' charset.  Otherwise, we'll fetch the binary
+      ;; part content and let mm-* decode it.
+      (let* ((have-content (plist-member part :content))
+	     (charset (if have-content 'gnus-decoded
 			(plist-get part :content-charset)))
 	     (handle (mm-make-handle (current-buffer) `(,content-type (charset . ,charset)))))
 	;; If the user wants the part inlined, insert the content and
 	;; test whether we are able to inline it (which includes both
 	;; capability and suitability tests).
 	(when (mm-inlined-p handle)
-	  (insert (notmuch-get-bodypart-content msg part process-crypto))
+	  (if have-content
+	      (insert (notmuch-get-bodypart-text msg part process-crypto))
+	    (insert (notmuch-get-bodypart-binary msg part process-crypto)))
 	  (when (mm-inlinable-p handle)
 	    (set-buffer display-buffer)
 	    (mm-display-part handle)
diff --git a/emacs/notmuch-show.el b/emacs/notmuch-show.el
index b3e339e..f29428a 100644
--- a/emacs/notmuch-show.el
+++ b/emacs/notmuch-show.el
@@ -702,7 +702,7 @@ (defun notmuch-show-insert-part-text/plain (msg part content-type nth depth butt
   (let ((start (if button
 		   (button-start button)
 		 (point))))
-    (insert (notmuch-get-bodypart-content msg part notmuch-show-process-crypto))
+    (insert (notmuch-get-bodypart-text msg part notmuch-show-process-crypto))
     (save-excursion
       (save-restriction
 	(narrow-to-region start (point-max))
@@ -711,9 +711,9 @@ (defun notmuch-show-insert-part-text/plain (msg part content-type nth depth butt
 
 (defun notmuch-show-insert-part-text/calendar (msg part content-type nth depth button)
   (insert (with-temp-buffer
-	    (insert (notmuch-get-bodypart-content msg part notmuch-show-process-crypto))
-	    ;; notmuch-get-bodypart-content provides "raw", non-converted
-	    ;; data. Replace CRLF with LF before icalendar can use it.
+	    (insert (notmuch-get-bodypart-text msg part notmuch-show-process-crypto))
+	    ;; notmuch-get-bodypart-text does no newline conversion.
+	    ;; Replace CRLF with LF before icalendar can use it.
 	    (goto-char (point-min))
 	    (while (re-search-forward "\r\n" nil t)
 	      (replace-match "\n" nil nil))
-- 
2.1.3