Bugreport: completion hanging at ubo<Tab> - endless loop

[Michael Prokop <news@michael-prokop.at>]

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Hi,

in http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=353863
Sebastien Desreux reported a bug about zsh with its
completion system in a specific situation.

To trigger the bug (at least 4.3.10 and 4.3.11 in Debian are
known to be affected by this bug):

  zsh -f
  autoload -Uz compinit; compinit; alias ubox=ls
  ubo<tab>

Then the zsh process is hanging in an endless loop, eating CPU.

I've just stepped down the problem in gdb, it seems to be hanging in
this code forever (I've extracted the relevant parts that
repeat-and-repeat-again out of my gdb session, hope this helps):

,---- [ gdb session - the relevant parts / the endless loop ]
| get_comp_string (lst=4) at ../../../Src/Zle/zle_tricky.c:1487
|                             nnb = tt + nclen;
|                             nnb = tt + nclen;
|                 for (tt = s; tt < s + zlemetacs_qsub - wb;) {
|                     if (*tt == Inbrack) {
|                     } else if (i && *tt == Outbrack) {
|                         int nclen = MB_METACHARLEN(tt);
| mb_metacharlenconv (s=0x23aaf32 "", wcp=0x0) at ../../Src/utils.c:4439
|             if (!isset(MULTIBYTE)) {
|             if (itok(*s)) {
|             return mb_metacharlenconv_r(s, wcp, &mb_shiftstate);
| mb_metacharlenconv_r (s=0x23aaf32 "", wcp=0x0, mbsp=0x6b1f30) at ../../Src/utils.c:4389
|         {
|                 ret = mbrtowc(&wc, &inchar, 1, mbsp);
|         {
|             for (ptr = s; *ptr; ) {
|             if (wcp)
|             if (ptr > s) {
|             memset(mbsp, 0, sizeof(*mbsp));
|             if (ptr > s) {
|         }
| get_comp_string (lst=4) at ../../../Src/Zle/zle_tricky.c:1486
|                         if (itype_end(tt, IIDENT, 1) == tt)
|                         int nclen = MB_METACHARLEN(tt);
|                         if (itype_end(tt, IIDENT, 1) == tt)
| itype_end (ptr=0x23aaf32 "", itype=128, once=1) at ../../Src/utils.c:3491
|         {
|             if (isset(MULTIBYTE) &&
|                 (itype != IIDENT || !isset(POSIXIDENTIFIERS))) {
|                 mb_metacharinit();
| mb_metacharinit () at ../../Src/utils.c:449
|             memset(&mb_shiftstate, 0, sizeof(mb_shiftstate));
| mb_metacharinit () at ../../Src/utils.c:450
|         }
| itype_end (ptr=0x23aaf32 "", itype=128, once=1) at ../../Src/utils.c:3498
|                     int len = mb_metacharlenconv(ptr, &wc);
|                 while (*ptr) {
|         }
`----

regards,
-mika-
-- 
http://michael-prokop.at/  || http://adminzen.org/
http://grml-solutions.com/ || http://grml.org/

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