[O] [RFC] [PATCH] org-table: introduce an upper bound on the number of lines `org-table-convert-region-max-lines' will attempt.

[Aaron Ecay]

* lisp/org-table.el (org-table-convert-region-max-lines): New
defcustom.
(org-table-convert-region): Use it.

This is useful primarily for babel results.  If a large table-like
object is returned by a code block, this function will become bogged
down in trying to read it, and hang emacs (necessitating a C-g).  This
situation most commonly arises when a :results none header has been
ommitted.  With the patch, the user will not experience a hang, but
rather an error message.
---
 lisp/org-table.el | 95 +++++++++++++++++++++++++++++++------------------------
 1 file changed, 54 insertions(+), 41 deletions(-)

diff --git a/lisp/org-table.el b/lisp/org-table.el
index 06a1008..bf88d11 100644
--- a/lisp/org-table.el
+++ b/lisp/org-table.el
@@ -366,6 +366,16 @@ available parameters."
   :group 'org-table-import-export
   :type 'string)

+(defcustom org-table-convert-region-max-lines 999
+  "Max lines that `org-table-convert-region' will attempt to process.
+
+The function can be slow on larger regions; this safety feature
+prevents it from hanging emacs."
+  :group 'org-table-import-export
+  :type 'integer
+  :version "24.5"
+  :package-version '(Org . "8.4"))
+
 (defconst org-table-auto-recalculate-regexp "^[ \t]*| *# *\\(|\\|$\\)"
   "Detects a table line marked for automatic recalculation.")
 (defconst org-table-recalculate-regexp "^[ \t]*| *[#*] *\\(|\\|$\\)"
@@ -566,49 +576,52 @@ nil      When nil, the command tries to be smart and 
figure out the
   (let* ((beg (min beg0 end0))
         (end (max beg0 end0))
         re)
-    (if (equal separator '(64))
-       (setq separator (read-regexp "Regexp for field separator")))
-    (goto-char beg)
-    (beginning-of-line 1)
-    (setq beg (point-marker))
-    (goto-char end)
-    (if (bolp) (backward-char 1) (end-of-line 1))
-    (setq end (point-marker))
-    ;; Get the right field separator
-    (unless separator
+    (if (> (count-lines beg end) org-table-convert-region-max-lines)
+       (user-error "Region is longer than `org-table-convert-region-max-lines' 
(%s) lines; not converting"
+                   org-table-convert-region-max-lines)
+      (if (equal separator '(64))
+         (setq separator (read-regexp "Regexp for field separator")))
       (goto-char beg)
-      (setq separator
+      (beginning-of-line 1)
+      (setq beg (point-marker))
+      (goto-char end)
+      (if (bolp) (backward-char 1) (end-of-line 1))
+      (setq end (point-marker))
+      ;; Get the right field separator
+      (unless separator
+       (goto-char beg)
+       (setq separator
+             (cond
+              ((not (re-search-forward "^[^\n\t]+$" end t)) '(16))
+              ((not (re-search-forward "^[^\n,]+$" end t)) '(4))
+              (t 1))))
+      (goto-char beg)
+      (if (equal separator '(4))
+         (while (< (point) end)
+           ;; parse the csv stuff
            (cond
-            ((not (re-search-forward "^[^\n\t]+$" end t)) '(16))
-            ((not (re-search-forward "^[^\n,]+$" end t)) '(4))
-            (t 1))))
-    (goto-char beg)
-    (if (equal separator '(4))
-       (while (< (point) end)
-         ;; parse the csv stuff
-         (cond
-          ((looking-at "^") (insert "| "))
-          ((looking-at "[ \t]*$") (replace-match " |") (beginning-of-line 2))
-          ((looking-at "[ \t]*\"\\([^\"\n]*\\)\"")
-           (replace-match "\\1")
-           (if (looking-at "\"") (insert "\"")))
-          ((looking-at "[^,\n]+") (goto-char (match-end 0)))
-          ((looking-at "[ \t]*,") (replace-match " | "))
-          (t (beginning-of-line 2))))
-      (setq re (cond
-               ((equal separator '(4)) "^\\|\"?[ \t]*,[ \t]*\"?")
-               ((equal separator '(16)) "^\\|\t")
-               ((integerp separator)
-                (if (< separator 1)
-                    (user-error "Number of spaces in separator must be >= 1")
-                  (format "^ *\\| *\t *\\| \\{%d,\\}" separator)))
-               ((stringp separator)
-                (format "^ *\\|%s" separator))
-               (t (error "This should not happen"))))
-      (while (re-search-forward re end t)
-       (replace-match "| " t t)))
-    (goto-char beg)
-    (org-table-align)))
+            ((looking-at "^") (insert "| "))
+            ((looking-at "[ \t]*$") (replace-match " |") (beginning-of-line 2))
+            ((looking-at "[ \t]*\"\\([^\"\n]*\\)\"")
+             (replace-match "\\1")
+             (if (looking-at "\"") (insert "\"")))
+            ((looking-at "[^,\n]+") (goto-char (match-end 0)))
+            ((looking-at "[ \t]*,") (replace-match " | "))
+            (t (beginning-of-line 2))))
+       (setq re (cond
+                 ((equal separator '(4)) "^\\|\"?[ \t]*,[ \t]*\"?")
+                 ((equal separator '(16)) "^\\|\t")
+                 ((integerp separator)
+                  (if (< separator 1)
+                      (user-error "Number of spaces in separator must be >= 1")
+                    (format "^ *\\| *\t *\\| \\{%d,\\}" separator)))
+                 ((stringp separator)
+                  (format "^ *\\|%s" separator))
+                 (t (error "This should not happen"))))
+       (while (re-search-forward re end t)
+         (replace-match "| " t t)))
+      (goto-char beg)
+      (org-table-align))))

 ;;;###autoload
 (defun org-table-import (file arg)
--
2.0.4