Handle scroll-error-top-bottom in follow.el and view.el (bug#21893)

* lisp/follow.el (follow-scroll-up-arg, follow-scroll-up-window):
Use scroll-up-command instead of scroll-up.
(follow-scroll-down-arg, follow-scroll-down-window):
Use scroll-down-command instead of scroll-down.
(follow-scroll-up, follow-scroll-down): Handle scroll-error-top-bottom.

* lisp/view.el (view-scroll-lines): Use scroll-down-command
instead of scroll-down and scroll-up-command instead of scroll-up.
(view-really-at-end): Handle scroll-error-top-bottom.

2 files changed, 18 insertions, 11 deletions

diff --git a/lisp/follow.el b/lisp/follow.el
index acc2b26c550..faac87986bb 100644
--- a/lisp/follow.el
+++ b/lisp/follow.el
@@ -557,7 +557,7 @@ This is an internal function for `follow-scroll-up' and
   (let ((opoint (point))  (owin (selected-window)))
     (while
         ;; If we are too near EOB, try scrolling the previous window.
-        (condition-case nil (progn (scroll-up arg) nil)
+        (condition-case nil (progn (scroll-up-command arg) nil)
           (end-of-buffer
            (condition-case nil (progn (follow-previous-window) t)
              (error
@@ -576,7 +576,7 @@ If ARG is nil, scroll the size of the current window.
 This is an internal function for `follow-scroll-down' and
 `follow-scroll-down-window'."
   (let ((opoint (point)))
-    (scroll-down arg)
+    (scroll-down-command arg)
     (unless (and scroll-preserve-screen-position
                  (get this-command 'scroll-command))
       (goto-char opoint))
@@ -596,7 +596,7 @@ Negative ARG means scroll downward.
 Works like `scroll-up' when not in Follow mode."
   (interactive "P")
   (cond ((not follow-mode)
-         (scroll-up arg))
+         (scroll-up-command arg))
         ((eq arg '-)
          (follow-scroll-down-window))
         (t (follow-scroll-up-arg arg))))
@@ -616,7 +616,7 @@ Negative ARG means scroll upward.
 Works like `scroll-down' when not in Follow mode."
   (interactive "P")
   (cond ((not follow-mode)
-         (scroll-down arg))
+         (scroll-down-command arg))
         ((eq arg '-)
          (follow-scroll-up-window))
         (t (follow-scroll-down-arg arg))))
@@ -635,13 +635,16 @@ Negative ARG means scroll downward.
 Works like `scroll-up' when not in Follow mode."
   (interactive "P")
   (cond ((not follow-mode)
-         (scroll-up arg))
+         (scroll-up-command arg))
         (arg (follow-scroll-up-arg arg))
         (t
          (let* ((windows (follow-all-followers))
                 (end (window-end (car (reverse windows)))))
            (if (eq end (point-max))
-               (signal 'end-of-buffer nil)
+               (if (or (null scroll-error-top-bottom)
+                       (eobp))
+                   (signal 'end-of-buffer nil)
+                 (goto-char (point-max)))
              (select-window (car windows))
              ;; `window-end' might return nil.
              (if end
@@ -663,14 +666,17 @@ Negative ARG means scroll upward.
 Works like `scroll-down' when not in Follow mode."
   (interactive "P")
   (cond ((not follow-mode)
-         (scroll-down arg))
+         (scroll-down-command arg))
         (arg (follow-scroll-down-arg arg))
         (t
          (let* ((windows (follow-all-followers))
                 (win (car (reverse windows)))
                 (start (window-start (car windows))))
            (if (eq start (point-min))
-               (signal 'beginning-of-buffer nil)
+               (if (or (null scroll-error-top-bottom)
+                       (bobp))
+                   (signal 'beginning-of-buffer nil)
+                 (goto-char (point-min)))
              (select-window win)
              (goto-char start)
              (vertical-motion (- (- (window-height win)
diff --git a/lisp/view.el b/lisp/view.el
index a765be02c1e..e4489b391a9 100644
--- a/lisp/view.el
+++ b/lisp/view.el
@@ -743,18 +743,19 @@ invocations return to earlier marks."
     (setq backward (not backward) lines (- lines)))
   (when (and maxdefault lines (> lines (view-window-size)))
     (setq lines nil))
-  (cond (backward (scroll-down lines))
+  (cond (backward (scroll-down-command lines))
         ((view-really-at-end)
          (if view-scroll-auto-exit
              (View-quit)
            (ding)
            (view-end-message)))
-        (t (scroll-up lines)
+        (t (scroll-up-command lines)
            (if (view-really-at-end) (view-end-message)))))
 
 (defun view-really-at-end ()
   ;; Return true if buffer end visible.  Maybe revert buffer and test.
-  (and (pos-visible-in-window-p (point-max))
+  (and (or (null scroll-error-top-bottom) (eobp))
+       (pos-visible-in-window-p (point-max))
        (let ((buf (current-buffer))
              (bufname (buffer-name))
              (file (buffer-file-name)))