code review 198044: Avoid overflow of include and define buffers in 5a/6a/8...

src/cmd/5a/lex.c

 // Inferno utils/5a/lex.c
 // http://code.google.com/p/inferno-os/source/browse/utils/5a/lex.c
 //
 //      Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //      Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
 //      Portions Copyright © 1997-1999 Vita Nuova Limited
 //      Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
 //      Portions Copyright © 2004,2006 Bruce Ellis
 //      Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
 //      Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
@@ skipping 41 matching lines @@
 void
 main(int argc, char *argv[])
 {
         char *p;
         int nout, nproc, i, c;
 
         thechar = '5';
         thestring = "arm";
 
         ensuresymb(NSYMB);
-        Dlist = alloc(sizeof(char *));
-        include = alloc(sizeof(char *));
         memset(debug, 0, sizeof(debug));
         cinit();
         outfile = 0;
-        include[ninclude++] = ".";
+        setinclude(".");
         ARGBEGIN {
         default:
                 c = ARGC();
                 if(c >= 0 || c < sizeof(debug))
                         debug[c] = 1;
                 break;
 
         case 'o':
                 outfile = ARGF();
                 break;
 
         case 'D':
                 p = ARGF();
                 if(p) {
-                        Dlist = allocn(Dlist, nDlist*sizeof(char *), sizeof(char *));
+                        if (nDlist%8 == 0)·
+                                Dlist = allocn(Dlist, nDlist*sizeof(char *), 
+                                        8*sizeof(char *));
                         Dlist[nDlist++] = p;
                 }
                 break;
 
         case 'I':
                 p = ARGF();
                 setinclude(p);
                 break;
         case 't':
                 thechar = 't';
@@ skipping 645 matching lines @@
                 Bputc(&obuf, h->line>>8);
                 Bputc(&obuf, h->line>>16);
                 Bputc(&obuf, h->line>>24);
                 zaddr(&nullgen, 0);
                 zaddr(&g, 0);
         }
 }
 
 #include "../cc/lexbody"
 #include "../cc/macbody"