From 39b5db3b1bb51088830bdf2d5e50940d462573d2 Mon Sep 17 00:00:00 2001
From: Paul Eggert
Date: Fri, 30 Sep 2011 22:57:41 -0700
Subject: * bytecode.c (unmark_byte_stack, exec_byte_code): use ptrdiff_t, not
 int.

(exec_byte_code): Use tighter memory-full test, one that checks
for alloca overflow.  Do not compute the address of the object
just before an array.
---
 src/bytecode.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

(limited to 'src/bytecode.c')

diff --git a/src/bytecode.c b/src/bytecode.c
index b6ac6c51bed..4a414b41712 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -318,7 +318,7 @@ unmark_byte_stack (void)
     {
       if (stack->byte_string_start != SDATA (stack->byte_string))
 	{
-	  int offset = stack->pc - stack->byte_string_start;
+	  ptrdiff_t offset = stack->pc - stack->byte_string_start;
 	  stack->byte_string_start = SDATA (stack->byte_string);
 	  stack->pc = stack->byte_string_start + offset;
 	}
@@ -446,7 +446,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
 #ifdef BYTE_CODE_SAFE
   ptrdiff_t const_length;
   Lisp_Object *stacke;
-  int bytestr_length;
+  ptrdiff_t bytestr_length;
 #endif
   struct byte_stack stack;
   Lisp_Object *top;
@@ -486,13 +486,14 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   stack.byte_string = bytestr;
   stack.pc = stack.byte_string_start = SDATA (bytestr);
   stack.constants = vector;
-  top = (Lisp_Object *) alloca (XFASTINT (maxdepth)
+  if (MAX_ALLOCA / sizeof (Lisp_Object) <= XFASTINT (maxdepth))
+    memory_full (SIZE_MAX);
+  top = (Lisp_Object *) alloca ((XFASTINT (maxdepth) + 1)
                                          * sizeof (Lisp_Object));
 #if BYTE_MAINTAIN_TOP
-  stack.bottom = top;
+  stack.bottom = top + 1;
   stack.top = NULL;
 #endif
-  top -= 1;
   stack.next = byte_stack_list;
   byte_stack_list = &stack;
 
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