Re: readonly bug

[Zoltan Hidvegi <hzoli@cs.elte.hu>]

Peter Stephenson wrote:
> haven't time to check this out further just now:
> (there was some IFS stuff around to make this useful but it turns out that's
> not necessary)
> 
> % readonly vers=foo
> % vers=(${=ZSH_VERSION})
> Segmentation fault (core dumped)

Unfortunately read-only variables are not handled very well in most places.
Here is a fix.  After that zsh prints error message when you attempt to
change a read-only variable.  Patch applies to both zsh-3.0.2 and zsh-3.1.0

It makes createparam() fail and return NULL when you attempt to crearte an
existing non-local parameter.

Zoltan


*** Src/builtin.c	1997/01/05 23:33:32	3.1.1.10
--- Src/builtin.c	1997/01/07 16:27:56
***************
*** 1842,1847 ****
--- 1842,1851 ----
  	    }
  	} else {
  	    if (bit) {
+ 		if (pm->flags & PM_READONLY) {
+ 		    on |= ~off & PM_READONLY;
+ 		    pm->flags &= ~PM_READONLY;
+ 		}
  		if (!asg->value)
  		    asg->value = dupstring(getsparam(asg->name));
  		unsetparam(asg->name);
***************
*** 1850,1857 ****
  		    addlinknode(locallist, ztrdup(asg->name));
  		} LASTALLOC;
  	    }
! 	    /* create a new node for a parameter with the flags in `on' minus the readonly flag */
  	    pm = createparam(ztrdup(asg->name), on & ~PM_READONLY);
  	    pm->ct = auxlen;
  	    if (func != BIN_EXPORT)
  		pm->level = locallevel;
--- 1854,1863 ----
  		    addlinknode(locallist, ztrdup(asg->name));
  		} LASTALLOC;
  	    }
! 	    /* create a new node for a parameter with the *
! 	     * flags in `on' minus the readonly flag      */
  	    pm = createparam(ztrdup(asg->name), on & ~PM_READONLY);
+ 	    DPUTS(!pm, "BUG: parameter not created");
  	    pm->ct = auxlen;
  	    if (func != BIN_EXPORT)
  		pm->level = locallevel;
*** Src/exec.c	1997/01/06 20:41:03	3.1.1.6
--- Src/exec.c	1997/01/07 16:09:45
***************
*** 1806,1813 ****
  
      if (removelist) {
  	/* remove temporary parameters */
! 	while ((s = (char *) ugetnode(removelist)))
! 	    unsetparam(s);
      }
  
      if (restorelist) {
--- 1806,1818 ----
  
      if (removelist) {
  	/* remove temporary parameters */
! 	while ((s = (char *) ugetnode(removelist))) {
! 	    if ((pm = (Param) paramtab->getnode(paramtab, s)) &&
! 		!(pm->flags & PM_SPECIAL)) {
! 		pm->flags &= ~PM_READONLY;
! 		unsetparam_pm(pm, 0);
! 	    }
! 	}
      }
  
      if (restorelist) {
*** params.c	1997/01/05 21:07:31	3.1.1.7
--- params.c	1997/01/07 16:56:19
***************
*** 173,187 ****
  	spec = oldpm && (oldpm->flags & PM_SPECIAL);
  
  	if ((oldpm && oldpm->level == locallevel) || spec) {
  	    pm = oldpm;
  	    pm->ct = 0;
  	    oldpm = pm->old;
! 	    pm->flags = (flags & (PM_EXPORTED | PM_LEFT | PM_RIGHT_B | PM_RIGHT_Z |
! 				  PM_LOWER | PM_UPPER | PM_READONLY | PM_TAGGED)) |
  		(pm->flags & (PM_SCALAR | PM_INTEGER | PM_ARRAY | PM_SPECIAL));
! 	    if (pm->ename && (altpm = (Param) paramtab->getnode(paramtab, pm->ename))) {
! 		altpm->flags &= ~(PM_UNSET | PM_EXPORTED | PM_LEFT | PM_RIGHT_B |
! 				  PM_RIGHT_Z | PM_LOWER | PM_UPPER | PM_READONLY | PM_TAGGED);
  	    }
  	} else {
  	    pm = (Param) zcalloc(sizeof *pm);
--- 173,192 ----
  	spec = oldpm && (oldpm->flags & PM_SPECIAL);
  
  	if ((oldpm && oldpm->level == locallevel) || spec) {
+ 	    if (oldpm && !(oldpm->flags & PM_UNSET))
+ 		return NULL;
  	    pm = oldpm;
  	    pm->ct = 0;
  	    oldpm = pm->old;
! 	    pm->flags = (flags & (PM_EXPORTED | PM_LEFT | PM_RIGHT_B |
! 				  PM_RIGHT_Z | PM_LOWER | PM_UPPER |
! 				  PM_READONLY | PM_TAGGED | PM_UNIQUE)) |
  		(pm->flags & (PM_SCALAR | PM_INTEGER | PM_ARRAY | PM_SPECIAL));
! 	    if (pm->ename &&
! 		(altpm = (Param) paramtab->getnode(paramtab, pm->ename))) {
! 		altpm->flags &= ~(PM_UNSET | PM_UNIQUE | PM_UPPER | PM_LEFT |
! 				  PM_RIGHT_B | PM_RIGHT_Z | PM_LOWER |
! 				  PM_READONLY | PM_TAGGED | PM_EXPORTED);
  	    }
  	} else {
  	    pm = (Param) zcalloc(sizeof *pm);
***************
*** 771,776 ****
--- 776,782 ----
  
      MUSTUSEHEAP("setstrvalue");
      if (v->pm->flags & PM_READONLY) {
+ 	zerr("read-only variable: %s", v->pm->nam, 0);
  	zsfree(val);
  	return;
      }
***************
*** 847,854 ****
  {
      char buf[DIGBUFSIZE];
  
!     if (v->pm->flags & PM_READONLY)
  	return;
      switch (PM_TYPE(v->pm->flags)) {
      case PM_SCALAR:
      case PM_ARRAY:
--- 853,862 ----
  {
      char buf[DIGBUFSIZE];
  
!     if (v->pm->flags & PM_READONLY) {
! 	zerr("read-only variable: %s", v->pm->nam, 0);
  	return;
+     }
      switch (PM_TYPE(v->pm->flags)) {
      case PM_SCALAR:
      case PM_ARRAY:
***************
*** 880,885 ****
--- 888,894 ----
  setarrvalue(Value v, char **val)
  {
      if (v->pm->flags & PM_READONLY) {
+ 	zerr("read-only variable: %s", v->pm->nam, 0);
  	freearray(val);
  	return;
      }
***************
*** 1060,1065 ****
--- 1069,1075 ----
      }
      if (!(v = getvalue(&s, 1))) {
  	pm = createparam(t, PM_INTEGER);
+ 	DPUTS(!pm, "BUG: parameter not created");
  	pm->u.val = val;
  	return pm;
      }
***************
*** 1088,1095 ****
      Param oldpm, altpm;
      int spec;
  
!     if ((pm->flags & PM_READONLY) && pm->level <= locallevel)
  	return;
      spec = (pm->flags & PM_SPECIAL) && !pm->level;
      switch (PM_TYPE(pm->flags)) {
      case PM_SCALAR:
--- 1098,1107 ----
      Param oldpm, altpm;
      int spec;
  
!     if ((pm->flags & PM_READONLY) && pm->level <= locallevel) {
! 	zerr("read-only variable: %s", pm->nam, 0);
  	return;
+     }
      spec = (pm->flags & PM_SPECIAL) && !pm->level;
      switch (PM_TYPE(pm->flags)) {
      case PM_SCALAR: