Extract patch information from a buffer rather than files

piem-am will become a command that works with mboxes outside of -b4.
In this context, it's easier and cleaner to deal with a buffer than
temporary files.

2 files changed, 16 insertions, 14 deletions

diff --git a/piem-b4.el b/piem-b4.el
index a5530e3..487b548 100644
--- a/piem-b4.el
+++ b/piem-b4.el
@@ -121,9 +121,12 @@
                              (read-directory-name "Git repository: ")))
                (`(,cover ,mbox-file)
                 (piem-b4--get-am-files mid coderepo args))
-               (info (piem-series-info cover mbox-file))
                (default-directory coderepo))
-    (piem-am mbox-file info coderepo)))
+    (piem-am mbox-file
+             (with-temp-buffer
+               (insert-file-contents (or cover mbox-file))
+               (piem-extract-mbox-info))
+             coderepo)))
 
 (define-infix-argument piem-b4-am:--outdir ()
   :description "Output directory"
diff --git a/piem.el b/piem.el
index 7b51d34..80e8a35 100644
--- a/piem.el
+++ b/piem.el
@@ -242,18 +242,17 @@ the following information about the patch series:
 
 ;;;; Patch handling
 
-(defun piem-series-info (cover patches)
-  "Collect information for a patch series.
-COVER is an mbox with the cover letter, and PATCHES is an
-am-ready mbox.  If the series does not have a cover letter (e.g.,
-a one-patch series), COVER may be nil."
-  (with-temp-buffer
-    (insert-file-contents (or cover patches))
-    (let ((info (save-restriction
-                  (message-narrow-to-head)
-                  (list :date (message-fetch-field "date")
-                        :from (message-fetch-field "from")
-                        :subject (message-fetch-field "subject")))))
+(defun piem-extract-mbox-info (&optional buffer)
+  "Collect information from message in BUFFER.
+If BUFFER is nil, the current buffer is used.  Any message after
+the first will be ignored."
+  (with-current-buffer (or buffer (current-buffer))
+    (let ((info (save-excursion
+                  (save-restriction
+                    (message-narrow-to-head)
+                    (list :date (message-fetch-field "date")
+                          :from (message-fetch-field "from")
+                          :subject (message-fetch-field "subject"))))))
       (when (re-search-forward (rx line-start "base-commit: "
                                    (group (>= 40 hex-digit))
                                    line-end)