maint: work even if argc == INT_MAX

GCC 7 warned about undefined behavior in this unlikely case.
Problem reported by Jim Meyering in: http://bugs.gnu.org/23825
* src/md5sum.c (main):
* src/paste.c (main):
* src/yes.c (main):
Avoid undefined behavior when argc == INT_MAX.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/md5sum.c b/src/md5sum.c
index 39132e340..3ed1b65e7 100644
--- a/src/md5sum.c
+++ b/src/md5sum.c
@@ -864,12 +864,13 @@ main (int argc, char **argv)
   if (!O_BINARY && binary < 0)
     binary = 0;
 
+  char **operand_lim = argv + argc;
   if (optind == argc)
-    argv[argc++] = bad_cast ("-");
+    *operand_lim++ = bad_cast ("-");
 
-  for (; optind < argc; ++optind)
+  for (char **operandp = argv + optind; operandp < operand_lim; operandp++)
     {
-      char *file = argv[optind];
+      char *file = *operandp;
 
       if (do_check)
         ok &= digest_check (file);