Re: Bug that needs fixing

[Stefan Monnier]

SM> I've finally had time to take a look at it on my Mac OS X system and I can
SM> indeed reproduce it.  The patch below seems to fix it, but it's maybe a bit
SM> naive, I don't know.
SM> Does someone see something wrong with such a patch?
>> 
>> It does solve the problem, but I have some doubts: What happens when
>> it was a real error. Maybe at least some IPV6 check should be in, e.g.
>> by including a colon in the r.e. 

> This case the patch doesn't work, indeed.

> First of all, I had to adapt the regexp of Stefan a little bit. My ftp
> client responds this:

> magdalene:~> ftp 192.168.0.9
> ftp: connect: No route to host

> When I apply the (modified) patch from Stefan, ange-ftp is locked in
> `ange-ftp-wait-not-busy', as suspected.

>> Even better would be to check that it is followed by 'Trying', but the
>> current implementation of ange-ftp doesn't allow for multi-line
>> regexps AFAIK.

> One could play with `ange-ftp-multi-msgs'. Unfortunately, I cannot
> test this due to my ftp client restrictions ...

The problem is that none of the existing mechanisms in ange-ftp handle the
situation where a message can be an error or not depending on
subsequent messages.  The ange-ftp-multi-msgs is only useful for messages
which always span several lines.

Can someone test(&fix) the patch below?  Also could someone try and convince
himself that it is harmless?


        Stefan


--- ange-ftp.el 04 jui 2005 14:42:05 -0400      1.67
+++ ange-ftp.el 21 jui 2005 16:40:49 -0400      
@@ -743,6 +743,21 @@
   :group 'ange-ftp
   :type 'regexp)
 
+(defcustom ange-ftp-potential-error-msgs
+  ;; On Mac OS X we sometimes get things like:
+  ;; 
+  ;;     ftp> open ftp.nluug.nl
+  ;;     Trying 2001:610:1:80aa:192:87:102:36...
+  ;;     ftp: connect to address 2001:610:1:80aa:192:87:102:36: No route to 
host
+  ;;     Trying 192.87.102.36...
+  ;;     Connected to ftp.nluug.nl.
+  "^ftp: connect to address .*: No route to host"
+  "*Regular expression matching ftp messages that can indicate serious errors.
+These mean that something went wrong, but they may be followed by more
+messages indicating that the error was somehow corrected."
+  :group 'ange-ftp
+  :type 'regexp)
+
 (defcustom ange-ftp-gateway-fatal-msgs
   "No route to host\\|Connection closed\\|No such host\\|Login incorrect"
   "*Regular expression matching login failure messages from rlogin/telnet."
@@ -1071,6 +1086,7 @@
 (defvar ange-ftp-xfer-size nil)
 (defvar ange-ftp-process-string nil)
 (defvar ange-ftp-process-result-line nil)
+(defvar ange-ftp-pending-error-line nil)
 (defvar ange-ftp-process-busy nil)
 (defvar ange-ftp-process-result nil)
 (defvar ange-ftp-process-multi-skip nil)
@@ -1544,6 +1560,7 @@
        ((string-match ange-ftp-good-msgs line)
         (setq ange-ftp-process-busy nil
               ange-ftp-process-result t
+               ange-ftp-pending-error-line nil
               ange-ftp-process-result-line line))
        ;; Check this before checking for errors.
        ;; Otherwise the last line of these three seems to be an error:
@@ -1558,6 +1575,12 @@
               ange-ftp-process-result-line line))
        (ange-ftp-process-multi-skip
         t)
+        ((string-match ange-ftp-potential-error-msgs line)
+         ;; This looks like an error, but we have to keep reading the output
+         ;; to see if it was fixed or not.  E.g. it may indicate that IPv6
+         ;; failed, but maybe a subsequent IPv4 fallback succeeded.
+         (set (make-local-variable 'ange-ftp-pending-error-line) line)
+         t)
        (t
         (setq ange-ftp-process-busy nil
               ange-ftp-process-result-line line))))
@@ -1651,12 +1674,20 @@
                          (string-match "\n" ange-ftp-process-string))
                (let ((line (substring ange-ftp-process-string
                                       0
-                                      (match-beginning 0))))
+                                      (match-beginning 0)))
+                      (seen-prompt nil))
                  (setq ange-ftp-process-string (substring 
ange-ftp-process-string
                                                           (match-end 0)))
                  (while (string-match "^ftp> *" line)
+                    (setq seen-prompt t)
                    (setq line (substring line (match-end 0))))
-                 (ange-ftp-process-handle-line line proc)))
+                  (if (and seen-prompt ange-ftp-pending-error-line)
+                      ;; If we've seen a potential error message and it
+                      ;; hasn't been cancelled by a good message before
+                      ;; seeing a propt, then the error was real.
+                      (setq ange-ftp-process-busy nil
+                            ange-ftp-process-result-line 
ange-ftp-pending-error-line)
+                    (ange-ftp-process-handle-line line proc))))
 
              ;; has the ftp client finished?  if so then do some clean-up
              ;; actions.
@@ -1988,7 +2019,7 @@
   (make-local-variable 'comint-password-prompt-regexp)
   ;; This is a regexp that can't match anything.
   ;; ange-ftp has its own ways of handling passwords.
-  (setq comint-password-prompt-regexp "^a\\'z")
+  (setq comint-password-prompt-regexp "\\`a\\`")
   (make-local-variable 'paragraph-start)
   (setq paragraph-start comint-prompt-regexp)
   (run-mode-hooks 'internal-ange-ftp-mode-hook))
@@ -4543,9 +4574,9 @@
   (setq ange-ftp-ls-cache-file nil)    ;Stop confusing Dired.
   0)
 
-;;; This is turned off because it has nothing properly to do
-;;; with dired.  It could be reasonable to adapt this to
-;;; replace ange-ftp-copy-file.
+;; This is turned off because it has nothing properly to do
+;; with dired.  It could be reasonable to adapt this to
+;; replace ange-ftp-copy-file.
 
 ;;;;; ------------------------------------------------------------
 ;;;;; Noddy support for async copy-file within dired.