(forward-paragraph): If moving back we find nothing

but separator lines till buffer beg, just stay there.
Exit outer loop if at beg or end of buffer.

1 files changed, 29 insertions, 22 deletions

diff --git a/lisp/textmodes/paragraphs.el b/lisp/textmodes/paragraphs.el
index c6885617015..fd5edc09a7e 100644
--- a/lisp/textmodes/paragraphs.el
+++ b/lisp/textmodes/paragraphs.el
@@ -75,35 +75,42 @@ to which the end of the previous line belongs, or the end of the buffer."
               (concat paragraph-separate "\\|^"
                       fill-prefix-regexp "[ \t]*$")
             paragraph-separate)))
-    (while (< arg 0)
+    (while (and (< arg 0) (not (bobp)))
       (if (and (not (looking-at paragraph-separate))
                (re-search-backward "^\n" (max (1- (point)) (point-min)) t))
           nil
+        ;; Move back over paragraph-separating lines.
         (forward-char -1) (beginning-of-line)
         (while (and (not (bobp)) (looking-at paragraph-separate))
           (forward-line -1))
-        (end-of-line)
-        ;; Search back for line that starts or separates paragraphs.
-        (if (if fill-prefix-regexp
-                ;; There is a fill prefix; it overrides paragraph-start.
-                (progn
-                 (while (progn (beginning-of-line)
-                               (and (not (bobp))
-                                    (not (looking-at paragraph-separate))
-                                    (looking-at fill-prefix-regexp)))
-                   (forward-line -1))
-                 (not (bobp)))
-              (re-search-backward paragraph-start nil t))
-            ;; Found one.
-            (progn
-              (while (and (not (eobp)) (looking-at paragraph-separate))
-                (forward-line 1))
-              (if (eq (char-after (- (point) 2)) ?\n)
-                  (forward-line -1)))
-          ;; No starter or separator line => use buffer beg.
-          (goto-char (point-min))))
+        (if (bobp)
+            nil
+          ;; Go to end of the previous (non-separating) line.
+          (end-of-line)
+          ;; Search back for line that starts or separates paragraphs.
+          (if (if fill-prefix-regexp
+                  ;; There is a fill prefix; it overrides paragraph-start.
+                  (progn
+                   (while (progn (beginning-of-line)
+                                 (and (not (bobp))
+                                      (not (looking-at paragraph-separate))
+                                      (looking-at fill-prefix-regexp)))
+                     (forward-line -1))
+                   (not (bobp)))
+                (re-search-backward paragraph-start nil t))
+              ;; Found one.
+              (progn
+                ;; Move forward over paragraph separators.
+                ;; We know this cannot reach the place we started
+                ;; because we know we moved back over a non-separator.
+                (while (and (not (eobp)) (looking-at paragraph-separate))
+                  (forward-line 1))
+                (if (eq (char-after (- (point) 2)) ?\n)
+                    (forward-line -1)))
+            ;; No starter or separator line => use buffer beg.
+            (goto-char (point-min)))))
       (setq arg (1+ arg)))
-    (while (> arg 0)
+    (while (and (> arg 0) (not (eobp)))
       (beginning-of-line)
       (while (prog1 (and (not (eobp))
                          (looking-at paragraph-separate))