Re: Util/helpfiles - problem with provided example

[Peter Stephenson <pws@xxxxxxx>]

Peter Stephenson wrote:
> Edited down to bare essentials:
> 
> Michael Prokop wrote:
> > man () {
> >        man $1                                     # this is the original
> >   }
> > $ man zsh
> 
> > Segmentation fault
> 
> This isn't very nice.  Should we turn on --enable-max-function-depth by
> default?  The default for --enable-max-function-depth=yes is 4096 which
> isn't going to hurt most people.  Or should we make it configurable
> internally with a sensible default?

Here's a patch which turns it on by default.

Index: configure.ac
===================================================================
RCS file: /cvsroot/zsh/zsh/configure.ac,v
retrieving revision 1.18
diff -u -r1.18 configure.ac
--- configure.ac	8 Jun 2004 13:34:12 -0000	1.18
+++ configure.ac	29 Jul 2004 15:39:00 -0000
@@ -301,12 +301,14 @@
 AH_TEMPLATE([MAX_FUNCTION_DEPTH],
 [Define for function depth limits])
 AC_ARG_ENABLE(max-function-depth,
-[  --enable-max-function-depth=MAX   limit function depth to MAX],
+[  --enable-max-function-depth=MAX   limit function depth to MAX, default 4096],
 [if test x$enableval = xyes; then
   AC_DEFINE(MAX_FUNCTION_DEPTH, 4096)
-else
+elif test x$enableval != xno; then
   AC_DEFINE_UNQUOTED(MAX_FUNCTION_DEPTH, $enableval)
-fi])
+fi],
+[AC_DEFINE(MAX_FUNCTION_DEPTH, 4096)]
+)
 
 dnl Do you want to look for pcre support?
 AC_ARG_ENABLE(pcre,
Index: INSTALL
===================================================================
RCS file: /cvsroot/zsh/zsh/INSTALL,v
retrieving revision 1.17
diff -u -r1.17 INSTALL
--- INSTALL	2 Jul 2004 15:59:11 -0000	1.17
+++ INSTALL	29 Jul 2004 15:39:01 -0000
@@ -330,6 +330,19 @@
 `make uninstall' or `make uninstall.fns', although the version-specific
 directory and its contents will be deleted.
 
+Function depth
+--------------
+
+Shell functions may be called recursively.  In order to detect infinite
+recursion the shell has a limit on the depth to which functions may be
+called:  note that this is a single limit for all functions, not a limit
+for each function called recursively.  The default for the limit is 4096.
+The limit may be altered to the value MAX by passing the option
+--enable-max-function-depth=MAX to configure.  Alternatively, the limit may
+be disabled with --disable-max-function-depth.  However, this is not
+recommended as it is likely to cause the shell to crash on an infinite
+recursion.
+
 Support for large files and integers
 ------------------------------------
 
-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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