Add nng_opts_parse() API for handling command line options.

We have implemented this alternative to getopt() so that we can
create nngcat.  The reason we did not just use getopt() is that
getopt() does not understand long options (which nanocat uses, and
we want to preserve for compatibility) and getopt() is not available
on Windows (and possibly other non-POSIX platforms.)

This function handles long and short options, but does not have support
for option clustering.  It also is threadsafe & reentrant, unlike getopt.

1 files changed, 48 insertions, 0 deletions

diff --git a/src/supplemental/util/options.h b/src/supplemental/util/options.h
new file mode 100644
index 00000000..02b3a9d4
--- /dev/null
+++ b/src/supplemental/util/options.h
@@ -0,0 +1,48 @@
+//
+// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2018 Capitar IT Group BV <info@capitar.com>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#ifndef NNG_SUPPLEMENTAL_UTIL_OPTIONS_H
+#define NNG_SUPPLEMENTAL_UTIL_OPTIONS_H
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// This is a relatively simple "options parsing" library, used to
+// parse command line options.  We would use getopt(3), but there are
+// two problems with getopt(3).  First, it isn't available on all
+// platforms (especially Win32), and second, it doesn't support long
+// options.  We *exclusively* support long options.  POSIX style
+// short option clustering is *NOT* supported.
+
+struct nng_optspec {
+	const char *o_name;  // Long style name (may be NULL for short only)
+	int         o_short; // Short option (no clustering!)
+	int         o_val;   // Value stored on a good parse (>0)
+	bool        o_arg;   // Option takes an argument if true
+};
+
+typedef struct nng_optspec nng_optspec;
+
+// Call with *optidx set to 1 to start parsing for a standard program.
+// The val will store the value of the matched "o_val", optarg will be
+// set to match the option string, and optidx will be increment appropriately.
+// Returns -1 when the end of options is reached, 0 on success, or
+// NNG_EINVAL if the option parse is invalid for any reason.
+NNG_DECL int nng_opts_parse(int argc, const char **argv,
+    const nng_optspec *opts, int *val, const char **optarg, int *optidx);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // NNG_SUPPLEMENTAL_UTIL_OPTIONS_H
\ No newline at end of file