[Emacs-diffs] emacs/src ralloc.c

[Jason Rumney]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Jason Rumney <jasonr>   08/12/24 11:37:12

Modified files:
        src            : ralloc.c 

Log message:
        Add comments to explain checks and aborts, to assist future debugging.

CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/emacs/src/ralloc.c?cvsroot=emacs&r1=1.70&r2=1.71

Patches:
Index: ralloc.c
===================================================================
RCS file: /sources/emacs/emacs/src/ralloc.c,v
retrieving revision 1.70
retrieving revision 1.71
diff -u -b -r1.70 -r1.71
--- ralloc.c    24 Dec 2008 11:20:36 -0000      1.70
+++ ralloc.c    24 Dec 2008 11:37:12 -0000      1.71
@@ -402,6 +402,11 @@
 
   while (p != NIL_BLOC)
     {
+      /* Consistency check. Don't return inconsistent blocs.
+        Don't abort here, as callers might be expecting this,  but
+        callers that always expect a bloc to be returned should abort
+        if one isn't to avoid a memory corruption bug that is
+        difficult to track down.  */
       if (p->variable == ptr && p->data == *ptr)
        return p;
 
@@ -981,7 +986,7 @@
 
   dead_bloc = find_bloc (ptr);
   if (dead_bloc == NIL_BLOC)
-    abort ();
+    abort (); /* Double free? PTR not originally used to allocate?  */
 
   free_bloc (dead_bloc);
   *ptr = 0;
@@ -1025,7 +1030,7 @@
 
   bloc = find_bloc (ptr);
   if (bloc == NIL_BLOC)
-    abort ();
+    abort (); /* Already freed? PTR not originally used to allocate?  */
 
   if (size < bloc->size)
     {
@@ -1246,7 +1251,7 @@
     }
 
   if (bloc == NIL_BLOC || bloc->variable != old)
-    abort ();
+    abort (); /* Already freed? OLD not originally used to allocate?  */
 
   /* Update variable to point to the new location.  */
   bloc->variable = new;