code review 7965043: cmd/5l, cmd/6l, cmd/8l: fix segfault on reading LOCALS ...

src/cmd/5l/obj.c

 // Inferno utils/5l/obj.c
 // http://code.google.com/p/inferno-os/source/browse/utils/5l/obj.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 118 matching lines @@
         flagcount("v", "print link trace", &debug['v']);
         flagcount("w", "disable DWARF generation", &debug['w']);
         flagcount("shared", "generate shared object", &flag_shared);
         // TODO: link mode flag
 ········
         flagparse(&argc, &argv, usage);
 
         if(argc != 1)
                 usage();
 
-        if(linkmode != LinkInternal) {
+        if(linkmode == LinkExternal) {
                 diag("only -linkmode=internal is supported");
                 errorexit();
+        } else if(linkmode == LinkAuto) {
+                linkmode = LinkInternal;
         }
 
         libinit();
 
         if(HEADTYPE == -1)
                 HEADTYPE = headtype(goos);
         switch(HEADTYPE) {
         default:
                 diag("unknown -H option");
                 errorexit();
@@ skipping 633 matching lines @@
 appendp(Prog *q)
 {
         Prog *p;
 
         p = prg();
         p->link = q->link;
         q->link = p;
         p->line = q->line;
         return p;
 }