Tried to improve getopt()

[Gregory Pietsch]

Here's my latest patch, correcting what Eric Blake said were mistakes. 
Also, I did this with the -abuZ options of diff, so you might want to 
run the resulting file through indent before reposting it:

--- getopt.c.old    2012-08-26 19:24:27.466130300 -0400
+++ getopt.c    2012-08-27 11:21:00.777353500 -0400
@@ -71,6 +71,14 @@
  value of ordering.  In the case of RETURN_IN_ORDER, only `--' can cause
  getopt() and friends to return EOF with optind != argc.

+2012-08-26: Tried to make the error handling more sus4-like. The functions
+return a colon if getopt() and friends detect a missing argument and the
+first character of shortopts/optstring starts with a colon (`:'). If 
getopt()
+and friends detect a missing argument and shortopts/optstring does not 
start
+with a colon, the function returns a question mark (`?'). If it was a 
missing
+argument to a short option, optopt is set to the character in question. The
+colon goes after the ordering character (`+' or `-').
+
  COPYRIGHT NOTICE AND DISCLAIMER:

  Copyright (C) 1997 Gregory Pietsch
@@ -185,6 +193,7 @@
    int has_arg = -1;
    char *cp = 0;
    int arg_next = 0;
+  int initial_colon = 0;

    /* first, deal with silly parameters and easy stuff */
    if (argc == 0 || argv == 0 || (shortopts == 0 && longopts == 0)
@@ -209,6 +218,13 @@
    else
      ordering = (getenv ("POSIXLY_CORRECT") != 0) ? REQUIRE_ORDER : 
PERMUTE;

+  /* check for initial colon in shortopts */
+  if (shortopts != 0 && *shortopts == ':')
+    {
+      ++shortopts;
+      initial_colon = 1;
+    }
+
    /*
     * based on ordering, find our next option, if we're at the beginning of
     * one
@@ -359,12 +375,18 @@
          {
            fprintf (stderr, "%s: argument required for option `", argv[0]);
            if (longopt_match >= 0)
+        {
          fprintf (stderr, "--%s'\n", longopts[longopt_match].name);
+          data->optopt = initial_colon ? ':' : '\?';
+        }
            else
+        {
          fprintf (stderr, "-%c'\n", *cp);
+          data->optopt = *cp;
+        }
          }
        data->optind++;
-      return (data->optopt = ':');
+      return initial_colon ? ':' : '\?';
      }
        else
      {