Re: Weird bug with approximate completion

[Sven Wischnowsky <wischnow@xxxxxxxxxxxxxxxxxxxxxxx>]

Peter Stephenson wrote:

> I'm getting a weird bug with approximate completion:  the shell exits with
> an out-of-memory error.  One command that did this (there were more) was
> % echo ~/bin/comp/set<TAB>
> where the real file is ~/bin/comp/_setopt.
> 
> It looks like zhalloc() is being called with one argument and getting
> another much larger one.  It could be specific to AIX 3.2, and related to
> the fact that my stack backtrace is now 97 frames deep (but another time it
> was `only' 88).  No fewer then 12 of those (10 in the other case) are
> runshfunc(), because of the effect of wrappers.  The limits are all large,
> e.g. stacksize is 32MB.  Maybe it would be nice to flatten out the
> hierarchy for calls to shell functions a bit.
> 
> But it's strange it only happens when correcting, so I can't be sure it
> isn't a shell problem.  I couldn't get it to happen as such on HPUX or
> IRIX, but I did see something weird with correction on IRIX, lots of 255
> characters appeared (which isn't even German).  So maybe there is some
> corruption coming from the shell.  Looks rather subtle though.  In that
> case it may be useful to know that the call to zhalloc() that goes wrong is
> always from
> 
> 		p = (char *)ncalloc(lpl + lsl + 3);
> 
> in make complistflags() around line 6192.  The arguments lpl and lsl
> themselves seem to be sensible, so it's nothing simple.  One clue might be
> that I don't use pattern matching much apart from correction, and this is
> in a (ispattern & 1) section (fairly innocuous looking, however, and
> ordinary glob completion doesn't seem to do this).

Problem #1 (patched):
  `rpre' should be set to the expanded prefix even if called from a
  completion widget

Problem #2:
  sticking it after the first slash will make the completion code use
  `/users/foo/(#a...)bin/comp' as the expanded prefix and make it
  search in that directory -- which doesn't exists, so it will
  generate no matches; should we have some special casing in the
  C-code or in the shell code here?

Problem #3 (patched):
  due to #2, with automatic correction, the `(#a...)' should not be
  put at the beginning of the string if it starts with `~'; this would
  lead to `(#a1)~/bin/comp/set' which matches files in the current
  directory whose name is only one character long (in a certain sense
  this is correct)

I couldn't reproduce your bug, though (and for me the line you quoted
is line number 6239). The bugs fixed by the patch made this fail for
me, but I didn't get any strange allocation behaviour. The 255 you
mention, btw, suggest a memory problem, too, since (at least with
debugging) newly allocated memory is filled with `-1's.

Bye
 Sven

diff -u os/Zle/zle_tricky.c Src/Zle/zle_tricky.c
--- os/Zle/zle_tricky.c	Wed Mar  3 12:51:36 1999
+++ Src/Zle/zle_tricky.c	Wed Mar  3 17:09:41 1999
@@ -6067,7 +6067,7 @@
     noreal = !delit;
     for (p = lpre; *p && *p != String && *p != Tick; p++);
     tt = ic && !ispar ? lpre + 1 : lpre;
-    rpre = (*p || (!incompfunc && (*lpre == Tilde || *lpre == Equals))) ?
+    rpre = (*p || *lpre == Tilde || *lpre == Equals) ?
 	(noreal = 0, getreal(tt)) :
 	dupstring(tt);
 
@@ -6086,6 +6086,7 @@
 	    if (!s1)
 		s1 = p;
 	}
+    rsl = strlen(rsuf);
     for (s2 = NULL, sf2 = t = 0, p = rsuf; *p && (!t || !sf2); p++)
 	if (itok(*p))
 	    t |= sf2 ? 4 : 2;
diff -u -r oc/Core/_main_complete Completion/Core/_main_complete
--- oc/Core/_main_complete	Wed Mar  3 13:00:41 1999
+++ Completion/Core/_main_complete	Wed Mar  3 16:41:18 1999
@@ -104,7 +104,7 @@
 	# original string as a possible match, let it not be shown in
 	# the list, and probably display the `CCPROMPT'.
 
-        (( $+CCORIG )) && builtin compadd -n - "$PREFIX$SUFFIX"
+        (( $+CCORIG )) && builtin compadd -nQ - "$PREFIX$SUFFIX"
 
 	# If you always want to see the list of possible corrections,
 	# set `compstate[list]=list' here.
@@ -145,7 +145,11 @@
       # ignored prefix).
 
       compadd() {
-        PREFIX="(#a${_comp_correct})$PREFIX"
+        if [[ "$PREFIX" = \~*/* ]]; then
+	  PREFIX="${PREFIX%%/*}/(#a${_comp_correct})${PREFIX#*/}"
+	else
+          PREFIX="(#a${_comp_correct})$PREFIX"
+	fi
 	if (( $+CCPROMPT )); then
 	  builtin compadd -X "$CCPROMPT" -J _correct "$@"
 	else
@@ -153,7 +157,11 @@
 	fi
       }
       compgen() {
-        PREFIX="(#a${_comp_correct})$PREFIX"
+        if [[ "$PREFIX" = \~*/* ]]; then
+	  PREFIX="${PREFIX%%/*}/(#a${_comp_correct})${PREFIX#*/}"
+	else
+          PREFIX="(#a${_comp_correct})$PREFIX"
+	fi
 	if (( $+CCPROMPT )); then
 	  builtin compgen "$@" -X "$CCPROMPT" -J _correct
 	else

--
Sven Wischnowsky                         wischnow@xxxxxxxxxxxxxxxxxxxxxxx