tftpd: switch to getopt_long()

Switch to using getopt_long(); include a version in case the platform
lacks it.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

lib/getopt_long.c

@@ -0,0 +1,150 @@
+/*
+ * getopt_long.c
+ *
+ * getopt_long(), or at least a common subset thereof:
+ *
+ * - Option reordering is not supported
+ * - -W foo is not supported
+ * - First optstring character "-" not supported.
+ */
+
+#include "config.h"
+
+char *optarg;
+int optind, opterr, optopt;
+
+static struct getopt_private_state {
+    const char *optptr;
+    const char *last_optstring;
+    char *const *last_argv;
+} pvt;
+
+static inline const char *option_matches(const char *arg_str,
+					 const char *opt_name)
+{
+    while (*arg_str != '\0' && *arg_str != '=') {
+	if (*arg_str++ != *opt_name++)
+	    return NULL;
+    }
+
+    if (*opt_name)
+	return NULL;
+
+    return arg_str;
+}
+
+int getopt_long(int argc, char *const *argv, const char *optstring,
+		const struct option *longopts, int *longindex)
+{
+    const char *carg;
+    const char *osptr;
+    int opt;
+
+    /* getopt() relies on a number of different global state
+       variables, which can make this really confusing if there is
+       more than one use of getopt() in the same program.  This
+       attempts to detect that situation by detecting if the
+       "optstring" or "argv" argument have changed since last time
+       we were called; if so, reinitialize the query state. */
+
+    if (optstring != pvt.last_optstring || argv != pvt.last_argv ||
+	optind < 1 || optind > argc) {
+	/* optind doesn't match the current query */
+	pvt.last_optstring = optstring;
+	pvt.last_argv = argv;
+	optind = 1;
+	pvt.optptr = NULL;
+    }
+
+    carg = argv[optind];
+
+    /* First, eliminate all non-option cases */
+
+    if (!carg || carg[0] != '-' || !carg[1])
+	return -1;
+
+    if (carg[1] == '-') {
+	const struct option *lo;
+	const char *opt_end = NULL;
+
+	optind++;
+
+	/* Either it's a long option, or it's -- */
+	if (!carg[2]) {
+	    /* It's -- */
+	    return -1;
+	}
+
+	for (lo = longopts; lo->name; lo++) {
+	    if ((opt_end = option_matches(carg+2, lo->name)))
+		break;
+	}
+	if (!opt_end)
+	    return '?';
+
+	if (longindex)
+	    *longindex = lo-longopts;
+
+	if (*opt_end == '=') {
+	    if (lo->has_arg)
+		optarg = (char *)opt_end+1;
+	    else
+		return '?';
+	} else if (lo->has_arg == 1) {
+	    if (!(optarg = argv[optind]))
+		return '?';
+	    optind++;
+	}
+
+	if (lo->flag) {
+	    *lo->flag = lo->val;
+	    return 0;
+	} else {
+	    return lo->val;
+	}
+    }
+
+    if ((uintptr_t) (pvt.optptr - carg) > (uintptr_t) strlen(carg)) {
+	/* Someone frobbed optind, change to new opt. */
+	pvt.optptr = carg + 1;
+    }
+
+    opt = *pvt.optptr++;
+
+    if (opt != ':' && (osptr = strchr(optstring, opt))) {
+	if (osptr[1] == ':') {
+	    if (*pvt.optptr) {
+		/* Argument-taking option with attached
+		   argument */
+		optarg = (char *)pvt.optptr;
+		optind++;
+	    } else {
+		/* Argument-taking option with non-attached
+		   argument */
+		if (argv[optind + 1]) {
+		    optarg = (char *)argv[optind+1];
+		    optind += 2;
+		} else {
+		    /* Missing argument */
+		    optind++;
+		    return (optstring[0] == ':')
+			? ':' : '?';
+		}
+	    }
+	    return opt;
+	} else {
+	    /* Non-argument-taking option */
+	    /* pvt.optptr will remember the exact position to
+	       resume at */
+	    if (!*pvt.optptr)
+		optind++;
+	    return opt;
+	}
+    } else {
+	/* Unknown option */
+	optopt = opt;
+	if (!*pvt.optptr)
+	    optind++;
+	return '?';
+    }
+}