bug#6579: 23.2; (require 'dbus) without dbus being available makes Emacs unresponsive, maxing out CPU and eating memory

[David Engster]

This was observed on GNU/Linux (Archlinux), but I also witnessed this
under OS X.

* Stop dbus or do not start it in the first place.

* emacs -Q

* evaluate (require 'dbus) in the scratch buffer

Emacs now consumes 100% CPU and is quickly eating memory until there is
no more. Pressing C-g (or any other key) doesn't have any effect.

Attaching gdb to Emacs in this situation usually shows different
backtraces; here is one example:

(gdb) bt full
#0  0x081c0ef7 in set_internal (symbol=23, newval=138692810, buf=0x0,
# bindflag=1) at data.c:1180
        voide = 0
        valcontents = 138692810
        innercontents = -1074816364
        tem1 = -1074816364
        current_alist_element = 0
#1  0x081d801a in unbind_to (count=2, value=138692810) at eval.c:3409
        this_binding = {
          symbol = 138811818, 
          old_value = 138692810, 
          func = 0, 
          unused = 0
        }
        quitf = 138692810
        gcpro1 = {
          next = 0x85bf188, 
          var = 0x14c7ebde, 
          nvars = 140243341
        }
        gcpro2 = {
          next = 0x81d7e0b, 
          var = 0x8468c12, 
          nvars = 138692858
        }
#2  0x082384f7 in update_compositions (from=37, to=38, check_mask=3) at
composite.c:605
        count = 2
        prop = 0
        start = 38
        end = 38
        min_pos = 37
        max_pos = 38
#3  0x08181024 in insert (string=0xbfef9337 "o\001", nbytes=1) at
insdel.c:727
        len = 1
        opoint = 37
#4  0x0818118f in insert_char (c=111) at insdel.c:762
        str = "o\001\000\000"
        len = 1
#5  0x081f0b26 in printchar (ch=111, fun=138692858) at print.c:337
        multibyte_p = 1
        str = "o\000\000\000"
        len = 1
#6  0x081f5ae7 in print_object (obj=348447145, printcharfun=138692858,
escapeflag=1) at print.c:1720
        len = 2
        c = 111
        i_byte = 23
        gcpro1 = {
          next = 0x84448ca, 
          var = 0x14c7ed16, 
          nvars = 138839264
        }
        str = 0x14c778cc "Failed to connect to socket
        /var/run/dbus/system_bus_socket: Connection refused"
        need_nonhex = 0
        multibyte = 0
        size_byte = 79
        buf =
        
"`\225\357\277K\177F\bh\225\357\277\354\r\034\bK\177F\b{`,\t\372HD\b\000\000\000\000\000\000\000\000ȭD\b"
#7  0x081f49ba in print (obj=348447129, printcharfun=138692858,
escapeflag=1) at print.c:1304
No locals.
#8  0x081f2d52 in Fprin1 (object=348447129, printcharfun=138692858) at
# print.c:750
        old = 0x844adc8
        old_point = -1
        start_point = -1
        old_point_byte = -1
        start_point_byte = -1
        specpdl_count = 2
        free_print_buffer = 0
        multibyte = 1
        original = 138692858
#9  0x081f44b8 in print_error_message (data=348647862, stream=138692858,
context=0xbfef9726 "", caller=138692810) at print.c:1105
        obj = 348447129
        errname = 138895850
        errmsg = 136789105
        file_error = 138692810
        tail = 348647846
        gcpro1 = {
          next = 0x0, 
          var = 0xb6a08847, 
          nvars = 1
        }
        i = 0
#10 0x08156045 in cmd_error_internal (data=348647862, context=0xbfef9726 "")
at keyboard.c:1305
        sf = 0x9168410
---Type <return> to continue, or q <return> to quit---
#11 0x08155e99 in cmd_error (data=348647862) at keyboard.c:1234
        old_level = 138692810
        old_length = 138692810
        macroerror = "\000\000)\000\000\000\275\031+\b", '\000' <repeats 12
        times>"\312,
        
HD\b\344\234ￔ\232\357\277\002\000\000\000Pa\025\b\000\000\000\000\000\000\000"
#12 0x081d4f19 in internal_condition_case (bfun=0x81563d1 <command_loop_1>,
handlers=138730794, hfun=0x8155dab <cmd_error>) at eval.c:1480
        val = 138939926
        c = {
          tag = 138692810, 
          val = 348647862, 
          next = 0xbfef98a8, 
          gcpro = 0x0, 
          jmp = {{
              __jmpbuf = {0, -1074815772, -1074816364, -1074816920,
1352025123, -1255756980}, 
              __mask_was_saved = 0, 
              __saved_mask = {
                __val = {3220150368, 3220150304, 0, 3077898242, 3078043896,
134547426, 3065788424, 3078041532, 3063912900, 36, 3220150056, 3077961474,
100, 3065237492, 3064330609, 3065244704, 3220149964, 36, 3065237492,
138616160, 
                  138616288, 3063930392, 3065788424, 135734916, 4294967295,
3078041532, 134547426, 1, 3220150384, 3077978728, 3078044336, 3060471368}
              }
            }}, 
          backlist = 0x0, 
          handlerlist = 0x0, 
          lisp_eval_depth = 0, 
          pdlcount = 2, 
          poll_suppress_count = 1, 
          interrupt_input_blocked = 0, 
          byte_stack = 0x0
        }
        h = {
          handler = 138730794, 
          var = 138692810, 
          chosen_clause = 138692858, 
          tag = 0xbfef9794, 
          next = 0x0
        }
#13 0x08156127 in command_loop_2 () at keyboard.c:1360
        val = 0
#14 0x081d4a4e in internal_catch (tag=138727866, func=0x8156102
<command_loop_2>, arg=138692810) at eval.c:1226
        c = {
          tag = 138727866, 
          val = 138692810, 
          next = 0x0, 
          gcpro = 0x0, 
          jmp = {{
              __jmpbuf = {-1074815632, -1074815772, -1074816364,
-1074816648, 1351189539, -1255351476}, 
              __mask_was_saved = 0, 
              __saved_mask = {
                __val = {0 <repeats 16 times>, 3064348398, 0, 0, 0,
138858107, 3220150648, 136057552, 138860226, 138858107, 138692810,
138718664, 140838948, 136705628, 14, 22, 192}
              }
            }}, 
          backlist = 0x0, 
          handlerlist = 0x0, 
          lisp_eval_depth = 0, 
          pdlcount = 2, 
          poll_suppress_count = 1, 
          interrupt_input_blocked = 0, 
          byte_stack = 0x0
        }
#15 0x081560e0 in command_loop () at keyboard.c:1339
No locals.
#16 0x081559ca in recursive_edit_1 () at keyboard.c:954
        count = 1
        val = -1074816504
#17 0x08155b35 in Frecursive_edit () at keyboard.c:1016
        count = 0
        buffer = 138692810
#18 0x0815431b in main (argc=2, argv=0xbfef9e14) at emacs.c:1833
        dummy = 0
        stack_bottom_variable = 0 '\000'
        do_initial_setlocale = 1
        skip_args = 0
        rlim = {
          rlim_cur = 8388608, 
          rlim_max = 18446744073709551615
        }
        no_loadup = 0
        junk = 0x0
        dname_arg = 0x0


----------------------

Configuration:

In GNU Emacs 23.2.1 (i686-pc-linux-gnu, GTK+ Version 2.20.1)
 of 2010-05-08 on pidsley.hoetzel.info
Windowing system distributor `The X.Org Foundation', version 11.0.10801902
configured using `configure  '--prefix=/usr' '--sysconfdir=/etc' 
'--libexecdir=/usr/lib' '--localstatedir=/var' '--mandir=/usr/share/man' 
'--without-sound' '-with-x-toolkit=gtk' 'CFLAGS=-march=i686 -mtune=generic -O2 
-pipe -fno-optimize-sibling-calls' 'LDFLAGS=-Wl,--hash-style=gnu 
-Wl,--as-needed''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t