Use texi2dvi for processing LaTeX to pdf

* lisp/org-latex.el (org-latex-to-pdf-process): Use texi2dvi if available.
(org-export-latex-get-error): New function.
(org-export-as-pdf): Give an indication of the errors that happened
during processing.

lisp/org-latex.el

@@ -456,8 +456,10 @@ allowed.  The default we use here encompasses both."
   :group 'org-export)
 
 (defcustom org-latex-to-pdf-process
-  '("pdflatex -interaction nonstopmode -output-directory %o %f"
-    "pdflatex -interaction nonstopmode -output-directory %o %f")
+  (if (executable-find "texi2dvi")
+      '("texi2dvi -p -b -c -V %f")
+    '("pdflatex -interaction nonstopmode -output-directory %o %f"
+      "pdflatex -interaction nonstopmode -output-directory %o %f"))
   "Commands to process a LaTeX file to a PDF file.
 This is a list of strings, each of them will be given to the shell
 as a command.  %f in the command will be replaced by the full file name, %b
@@ -468,6 +470,9 @@ pdflatex, maybe mixed with a call to bibtex.  Org does not have a clever
 mechanism to detect which of these commands have to be run to get to a stable
 result, and it also does not do any error checking.
 
+By default, Org used texi2dvi to do the processing, if that command
+is on the system.  If not, it uses 2 pdflatex runs.
+
 Alternatively, this may be a Lisp function that does the processing, so you
 could use this to apply the machinery of AUCTeX or the Emacs LaTeX mode.
 This function should accept the file name as its single argument."
@@ -871,16 +876,40 @@ when PUB-DIR is set, use this as the publishing directory."
 		     t t cmd)))
 	(shell-command cmd outbuf outbuf)))
     (message (concat "Processing LaTeX file " file "...done"))
+    (setq errors (org-export-latex-get-error outbuf))
     (if (not (file-exists-p pdffile))
-	(error (concat "PDF file " pdffile " was not produced"))
+	(error (concat "PDF file " pdffile " was not produced"
+		       (if errors (concat ":" errors "") "")))
       (set-window-configuration wconfig)
       (when org-export-pdf-remove-logfiles
 	(dolist (ext org-export-pdf-logfiles)
 	  (setq file (concat base "." ext))
 	  (and (file-exists-p file) (delete-file file))))
-      (message "Exporting to PDF...done")
+      (message (concat
+		"Exporting to PDF...done"
+		(if errors
+		    (concat ", with some errors:" errors)
+		  "")))
       pdffile)))
 
+(defun org-export-latex-get-error (buf)
+  "Collect the kinds of errors that remain in pdflatex processing."
+  (with-current-buffer buf
+    (save-excursion
+      (goto-char (point-max))
+      (when (re-search-backward "^[ \t]*This is pdf.*?TeX.*?Version" nil t)
+	;; OK, we are at the location of the final run
+	(let ((pos (point)) (errors "") (case-fold-search t))
+	  (if (re-search-forward "Reference.*?undefined" nil t)
+	      (setq errors (concat errors " [undefined reference]")))
+	  (goto-char pos)
+	  (if (re-search-forward "Citation.*?undefined" nil t)
+	      (setq errors (concat errors " [undefined citation]")))
+	  (goto-char pos)
+	  (if (re-search-forward "Undefined control sequence" nil t)
+	      (setq errors (concat errors " [undefined control sequence]")))
+	  (and (org-string-nw-p errors) errors))))))
+
 ;;;###autoload
 (defun org-export-as-pdf-and-open (arg)
   "Export as LaTeX, then process through to PDF, and open."