Re: append-to-file can crash Emacs

[Alex Schroeder]

Eli Zaretskii <eliz@is.elta.co.il> writes:

> On 22 Apr 2001, Alex Schroeder wrote:
> 
> > In GNU Emacs 20.7.1 (i686-pc-linux-gnu, X toolkit)
> >  of Sun Apr  8 2001 on snail
> > 
> > The code I attached crashes my Emacs.
> 
> Is it possible to see a crash traceback?

Hm, I never did this before.  Does the following help?
I am sorry, it is quite verbose because I don't know what you might be
looking for.

First, the elisp code I executed, second a log of some gdb dabbling of
mine.  Feel free to ask more detailed questions.  :)

Alex.

(require 'cl)
(defun command-cookies (file)
  (interactive "FWrite cookie files: ")
  (setq file (or file "~/tmp/commands"))
  (my-append-string-to-file "%\n%\n" file)
  (loop with i = 1
        for num from 1
        when (> num 99) do (setq num 1 i (1+ i))
        for s being the symbols
        when (commandp s) do
        (my-append-string-to-file
         (concat (describe-function s)
                 "\n\nInvoke with:\n\n"
                 (with-temp-buffer
                   (where-is s t)
                   (buffer-string))
                 "\n%\n")
         (concat file "-" i))))

(defun my-append-string-to-file (str file)
  "Append string STR to FILE."
  (with-temp-buffer
    (insert str)
    (append-to-file (point-min) (point-max) file)))


alex@snail:/usr/local/src/emacs-20.7 > gdb src/emacs
GNU gdb 4.18
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rranty" for details.
This GDB was configured as "i386-suse-linux"...
(gdb) run
Starting program: /usr/local/src/emacs-20.7/src/emacs 

Program received signal SIGSEGV, Segmentation fault.
0x8101d5d in print (obj=1073731385, 
    printcharfun=404767956, escapeflag=1)
    at print.c:1283
1283              if (!NULL_INTERVAL_P (XSTRING (obj)->intervals))
(gdb) backtrace
#0  0x8101d5d in print (obj=1073731385, 
    printcharfun=404767956, escapeflag=1)
    at print.c:1283
#1  0x810095a in Fprin1 (object=1073731385, 
    printcharfun=404767956) at print.c:860
#2  0x8101992 in print_error_message (
    data=1479519540, stream=404767956) at print.c:1071
#3  0x809a4c8 in cmd_error_internal (data=1479519540, 
    context=0xbfffedb8 "") at keyboard.c:1038
#4  0x809a417 in cmd_error (data=1479519540)
    at keyboard.c:989
#5  0x80f3bbf in internal_condition_case (
    bfun=0x809a730 <command_loop_1>, 
    handlers=404768412, hfun=0x809a370 <cmd_error>)
    at eval.c:1140
#6  0x809a5de in command_loop_2 () at keyboard.c:1093
#7  0x80f36f7 in internal_catch (tag=404768388, 
    func=0x809a5c0 <command_loop_2>, arg=404767908)
    at eval.c:925
#8  0x809a583 in command_loop () at keyboard.c:1072
#9  0x809a151 in recursive_edit_1 () at keyboard.c:821
#10 0x809a269 in Frecursive_edit () at keyboard.c:869
#11 0x80992d2 in main (argc=1, argv=0xbffff324, 
    envp=0xbffff32c) at emacs.c:1361
(gdb) list
1278              int need_nonhex = 0;
1279    
1280              GCPRO1 (obj);
1281    
1282    #ifdef USE_TEXT_PROPERTIES
1283              if (!NULL_INTERVAL_P (XSTRING (obj)->intervals))
1284                {
1285                  PRINTCHAR ('#');
1286                  PRINTCHAR ('(');
1287                }
(gdb) source src/.gdbinit
Warning: /usr/local/src/emacs-20.7/../lwlib: Datei oder Verzeichnis nicht 
gefunden.
DISPLAY = :0
TERM = xterm
Breakpoint 1 at 0x80981a6: file emacs.c, line 284.
Breakpoint 2 at 0x8088b12: file xterm.c, line 5335.
(gdb) xtype obj
The history is empty.
(gdb) pr obj
The history is empty.
(gdb) p obj
$1 = 1073731385
(gdb) pr

Program received signal SIGSEGV, Segmentation fault.
0x8101d5d in print (obj=1073731385, 
    printcharfun=404825844, escapeflag=1)
    at print.c:1283
1283              if (!NULL_INTERVAL_P (XSTRING (obj)->intervals))
The program being debugged stopped while in a function called from GDB.
When the function (debug_print) is done executing, GDB will silently
stop (instead of continuing to evaluate the expression containing
the function call).
(gdb) xtype
Lisp_String
0
(gdb) xstring
$2 = (struct Lisp_String *) 0xfffd739
Cannot access memory at address 0xfffd739.
(gdb)