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Don't lose top specpdl entry when memory is exhausted.

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* eval.c (grow_specpdl): Increment specpdl top by 1 and check for
specpdl overflow here, to simplify callers; all callers changed.
Always reserve an unused entry at the stack top; this avoids
losing the top entry's information when memory is exhausted.
This commit is contained in:
Paul Eggert 2013-07-12 17:24:38 -07:00
parent c04bbd85c9
commit 5e301d7651
2 changed files with 41 additions and 23 deletions
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8
src/ChangeLog
View file

@ -1,3 +1,11 @@
2013-07-13 Paul Eggert <eggert@cs.ucla.edu>
Don't lose top specpdl entry when memory is exhausted.
* eval.c (grow_specpdl): Increment specpdl top by 1 and check for
specpdl overflow here, to simplify callers; all callers changed.
Always reserve an unused entry at the stack top; this avoids
losing the top entry's information when memory is exhausted.
2013-07-12 Paul Eggert <eggert@cs.ucla.edu>
Clean up errno reporting and fix some errno-reporting bugs.

56
src/eval.c
View file

@ -1996,38 +1996,52 @@ If LEXICAL is t, evaluate using lexical scoping. */)
return unbind_to (count, eval_sub (form));
}
/* Grow the specpdl stack by one entry.
The caller should have already initialized the entry.
Signal an error on stack overflow.
Make sure that there is always one unused entry past the top of the
stack, so that the just-initialized entry is safely unwound if
memory exhausted and an error is signaled here. Also, allocate a
never-used entry just before the bottom of the stack; sometimes its
address is taken. */
static void
grow_specpdl (void)
{
ptrdiff_t count = SPECPDL_INDEX ();
ptrdiff_t max_size = min (max_specpdl_size, PTRDIFF_MAX - 1000);
union specbinding *pdlvec = specpdl - 1;
ptrdiff_t pdlvecsize = specpdl_size + 1;
if (max_size <= specpdl_size)
specpdl_ptr++;
if (specpdl_ptr == specpdl + specpdl_size)
{
if (max_specpdl_size < 400)
max_size = max_specpdl_size = 400;
ptrdiff_t count = SPECPDL_INDEX ();
ptrdiff_t max_size = min (max_specpdl_size, PTRDIFF_MAX - 1000);
union specbinding *pdlvec = specpdl - 1;
ptrdiff_t pdlvecsize = specpdl_size + 1;
if (max_size <= specpdl_size)
signal_error ("Variable binding depth exceeds max-specpdl-size", Qnil);
{
if (max_specpdl_size < 400)
max_size = max_specpdl_size = 400;
if (max_size <= specpdl_size)
signal_error ("Variable binding depth exceeds max-specpdl-size",
Qnil);
}
pdlvec = xpalloc (pdlvec, &pdlvecsize, 1, max_size + 1, sizeof *specpdl);
specpdl = pdlvec + 1;
specpdl_size = pdlvecsize - 1;
specpdl_ptr = specpdl + count;
}
pdlvec = xpalloc (pdlvec, &pdlvecsize, 1, max_size + 1, sizeof *specpdl);
specpdl = pdlvec + 1;
specpdl_size = pdlvecsize - 1;
specpdl_ptr = specpdl + count;
}
void
record_in_backtrace (Lisp_Object function, Lisp_Object *args, ptrdiff_t nargs)
{
eassert (nargs >= UNEVALLED);
if (specpdl_ptr == specpdl + specpdl_size)
grow_specpdl ();
specpdl_ptr->bt.kind = SPECPDL_BACKTRACE;
specpdl_ptr->bt.debug_on_exit = false;
specpdl_ptr->bt.function = function;
specpdl_ptr->bt.args = args;
specpdl_ptr->bt.nargs = nargs;
specpdl_ptr++;
grow_specpdl ();
}
/* Eval a sub-expression of the current expression (i.e. in the same
@ -3113,8 +3127,6 @@ specbind (Lisp_Object symbol, Lisp_Object value)
CHECK_SYMBOL (symbol);
sym = XSYMBOL (symbol);
if (specpdl_ptr == specpdl + specpdl_size)
grow_specpdl ();
start:
switch (sym->redirect)
@ -3127,7 +3139,7 @@ specbind (Lisp_Object symbol, Lisp_Object value)
specpdl_ptr->let.kind = SPECPDL_LET;
specpdl_ptr->let.symbol = symbol;
specpdl_ptr->let.old_value = SYMBOL_VAL (sym);
++specpdl_ptr;
grow_specpdl ();
if (!sym->constant)
SET_SYMBOL_VAL (sym, value);
else
@ -3162,7 +3174,7 @@ specbind (Lisp_Object symbol, Lisp_Object value)
if (NILP (Flocal_variable_p (symbol, Qnil)))
{
specpdl_ptr->let.kind = SPECPDL_LET_DEFAULT;
++specpdl_ptr;
grow_specpdl ();
Fset_default (symbol, value);
return;
}
@ -3170,7 +3182,7 @@ specbind (Lisp_Object symbol, Lisp_Object value)
else
specpdl_ptr->let.kind = SPECPDL_LET;
specpdl_ptr++;
grow_specpdl ();
set_internal (symbol, value, Qnil, 1);
break;
}
@ -3181,12 +3193,10 @@ specbind (Lisp_Object symbol, Lisp_Object value)
void
record_unwind_protect (Lisp_Object (*function) (Lisp_Object), Lisp_Object arg)
{
if (specpdl_ptr == specpdl + specpdl_size)
grow_specpdl ();
specpdl_ptr->unwind.kind = SPECPDL_UNWIND;
specpdl_ptr->unwind.func = function;
specpdl_ptr->unwind.arg = arg;
specpdl_ptr++;
grow_specpdl ();
}
Lisp_Object