args: Convert nng_opts_parse into a header only library using `nng_ar…

…gs_parse`. The API is identical, except that some names have changed, and this is now a header library in `nng/args.h` - so the core library does not need to carry this code in binaries. Being a header library also means it is not necessary to link against NNG, and it does not include any parts of NNG; it only depends on a standard C99 or C11 environment.
nanomsg · Jan 5, 2025 · f77e5a5 · f77e5a5
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diff --git a/docs/ref/SUMMARY.md b/docs/ref/SUMMARY.md
@@ -38,7 +38,7 @@
 
   - [ID Map](./api/id_map.md)
 
-  - [Command Options](./api/cmd_opts.md)
+  - [Arguments Parser](./api/args.md)
 
 - [Protocols](./proto/index.md)
 

diff --git a/docs/ref/api/cmd_opts.md → docs/ref/api/args.md b/docs/ref/api/cmd_opts.md → docs/ref/api/args.md
@@ -1,31 +1,39 @@
-# Command Options
+# Command Arguments
 
-Some _NNG_ utilities need to parse command line options,
-and the supplementary function here allows applications that
-need the same support to benefit from this.
+Some NNG utilities need to parse command line options,
+and for this purpose a header library is supplied.
 
-To make use of this, the supplemental header `<nng/supplemental/util/options.h>`
-must be included.
+To make use of this, the header `<nng/args.h>` must be included.
 
-## Parse Command Line Options
+> [!TIP]
+> The functionality described here is entirely contained in the
+> `nng/args.h` header file, and may be used without previously
+> initializing the library with [`nng_init`], and may even be used
+> in programs that are not linked against the NNG library.
+
+## Parse Command Line Arguments
 
 ```c
-typedef 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_arg_spec {
+    const char *a_name;  // Long style name (may be NULL for short only)
+    int         a_short; // Short option (no clustering!)
+    int         a_val;   // Value stored on a good parse (>0)
+    bool        a_arg;   // Option takes an argument if true
 } nng_optspec;
 
-int nng_opts_parse(int argc, char *const *argv,
+#define NNG_ARG_END     (-1)
+#define NNG_ARG_INVAL   (-2)
+#define NNG_ARG_AMBIG   (-3)
+#define NNG_ARG_MISSING (-4)
+
+int nng_args_parse(int argc, char *const *argv,
                    const nng_optspec *spec, int *val, char **arg, int *idx);
 ```
 
-The {{i:`nng_opts_parse`}} function is a intended to facilitate parsing
+The {{i:`nng_args_parse`}} function is intended to facilitate parsing
 {{i:command-line arguments}}.
 This function exists largely to stand in for {{i:`getopt`}} from POSIX systems,
-but it is available everywhere that _NNG_ is, and it includes
-some capabilities missing from `getopt`.
+but it is available on all platforms, and it includes some capabilities missing from `getopt`.
 
 The function parses arguments from
 `main`{{footnote: Parsing argument strings from other sources can be done as well,
@@ -34,7 +42,7 @@ although usually then _idx_ will be initialized to zero.}}
 starting at the index referenced by _idx_.
 (New invocations typically set the value pointed to by _idx_ to 1.)
 
-Options are parsed as specified by _spec_ (see [Option Specification](#option-specification).)
+Options are parsed as specified by _spec_ (see [Argument Specification](#argument-specification).)
 The value of the parsed option will be stored at the address indicated by
 _val_, and the value of _idx_ will be incremented to reflect the next
 option to parse.
@@ -52,23 +60,23 @@ returned.
 
 This function may return the following errors:
 
-- [`NNG_EAMBIGUOUS`]: Parsed option matches more than one specification.
-- [`NNG_ENOARG`]: Option requires an argument, but one is not present.
-- [`NNG_EINVAL`]: An invalid (unknown) argument is present.
+- [`NNG_ARG_AMBIGU`]: Parsed option matches more than one specification.
+- [`NNG_ARG_MISSING`]: Option requires an argument, but one is not present.
+- [`NNG_ARG_INVAL`]: An invalid (unknown) argument is present in _argv_.
 
 ### Option Specification
 
-The calling program must first create an array of {{i:`nng_optspec`}} structures
+The calling program must first create an array of {{i:`nng_arg_spec`}} structures
 describing the options to be supported.
 This structure has the following members:
 
-- `o_name`:
+- `a_name`:
 
   The long style name for the option, such as "verbose".
   This will be parsed as a [long option](#long-options) on the command line when it is prefixed with two dashes.
   It may be `NULL` if only a [short option](#short-options) is to be supported.
 
-- `o_short`:
+- `a_short`:
 
   This is a single letter (at present only ASCII letters are supported).
   These options appear as just a single letter, and are prefixed with a single dash on the command line.
@@ -81,10 +89,10 @@ This structure has the following members:
   This value is assigned by the application program, and must be non-zero for a valid option.
   If this is zero, then it indicates the end of the specifications, and the
   rest of this structure is ignored.
-  The value will be returned to the caller in _val_ by `nng_opts_parse` when
+  The value will be returned to the caller in _val_ by `nng_args_parse` when
   this option is parsed from the command line.
 
-- `o_arg`:
+- `a_arg`:
 
   This value should be set to `true` if the option should take an argument.
 
@@ -112,7 +120,7 @@ same element of _argv_, or may appear in the next _argv_ element.
 ### Prefix Matching
 
 When using long options, the parser will match if it is equal to a prefix
-of the `o_name` member of a option specification, provided that it do so
+of the `a_name` member of a option specification, provided that it do so
 unambiguously (meaning it must not match any other option specification.)
 
 ## Example
@@ -124,26 +132,26 @@ The following program fragment demonstrates this function.
     char *logfile; // options to be set
     bool verbose;
 
-    static nng_optspec specs[] = {
+    static nng_arg_spec specs[] = {
         {
-            .o_name = "logfile",
-            .o_short = 'D',
-            .o_val = OPT_LOGFILE,
-            .o_arg = true,
+            .a_name = "logfile",
+            .a_short = 'D',
+            .a_val = OPT_LOGFILE,
+            .a_arg = true,
         }, {
-            .o_name = "verbose",
-            .o_short = 'V',
-            .o_val = OPT_VERBOSE,
-            .o_arg = false,
+            .a_name = "verbose",
+            .a_short = 'V',
+            .a_val = OPT_VERBOSE,
+            .a_arg = false,
         }, {
-            .o_val = 0; // Terminate array
+            .a_val = 0; // Terminate array
         }
     };
 
     for (int idx = 1;;) {
         int rv, opt;
         char *arg;
-        rv = nng_opts_parse(argc, argv, specs, &opt, &arg, &idx);
+        rv = nng_args_parse(argc, argv, specs, &opt, &arg, &idx);
         if (rv != 0) {
             break;
         }
@@ -156,8 +164,18 @@ The following program fragment demonstrates this function.
             break;
         }
     }
-    if (rv != -1) {
-        printf("Options error: %s\n", nng_strerror(rv));
+    if (rv != NNG_ARG_END) {
+        switch (rv) {
+        case NNG_ARG_AMBIG:
+            printf("Options error: ambiguous option\n");
+            break;
+        case NNG_ARG_MISSING:
+            printf("Options error: required option argument missing\n");
+            break;
+        case NNG_ARG_INVAL:
+            printf("Options error: unknown option present\n");
+            break;
+        }
         exit(1);
     }
 ```

diff --git a/docs/ref/api/errors.md b/docs/ref/api/errors.md
@@ -65,8 +65,6 @@ future locale-specific strings may be presented instead.
 | `NNG_EWRITEONLY`<a name="NNG_EWRITEONLY"></a>     | 25                      | Write only resource. A read operation failed because the object only supports writes.                                                             |
 | `NNG_ECRYPTO`<a name="NNG_ECRYPTO"></a>           | 26                      | Cryptographic error. Usually indicates an invalid key was used for TLS.                                                                           |
 | `NNG_EPEERAUTH`<a name="NNG_EPEERAUTH"></a>       | 27                      | Peer could not be authenticated.                                                                                                                  |
-| `NNG_ENOARG`<a name="NNG_ENOARG"></a>             | 28                      | Option requires argument. A command-line option was supplied without an argument. Only used with [`nng_opts_parse`].                              |
-| `NNG_EAMBIGUOUS`<a name="NNG_EAMBIGUOUS"></a>     | 29                      | Ambiguous option. The command line option could not be unambiguously resolved. Only used with [`nng_opts_parse`].                                 |
 | `NNG_EBADTYPE`<a name="NNG_EBADTYPE"></a>         | 30                      | Incorrect type. A type-specific function was used for an object of the wrong type.                                                                |
 | `NNG_ECONNSHUT`<a name="NNG_ECONNSHUT"></a>       | 31                      | Connection shutdown. The connection was shut down and cannot be used.                                                                             |
 | `NNG_ESTOPPED`<a name="NNG_ESTOPPED"></a>         | 1000                    | Operation stopped. The operation was stopped with [`nng_aio_stop`] or [`nng_aio_close`].                                                          |

diff --git a/docs/ref/migrate/nanomsg.md b/docs/ref/migrate/nanomsg.md
@@ -101,7 +101,7 @@ There are some exceptions. Be aware that the numeric values are _not_ the same.
 | -------------- | ---------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------- |
 | `EINTR`        | [`NNG_EINTR`]                                                                            |                                                                                    |
 | `ENOMEM`       | [`NNG_ENOMEM`]                                                                           |                                                                                    |
-| `EINVAL`       | [`NNG_EINVAL`], [`NNG_EADDRINVAL`], [`NNG_EBADTYPE`], [`NNG_EAMBIGUOUS`]                 | NNG discrimates between different types of errors.                                 |
+| `EINVAL`       | [`NNG_EINVAL`], [`NNG_EADDRINVAL`], [`NNG_EBADTYPE`]                                     | NNG discrimates between different types of errors.                                 |
 | `EBUSY`        | [`NNG_EBUSY`]                                                                            |                                                                                    |
 | `ETIMEDOUT`    | [`NNG_ETIMEDOUT`]                                                                        |                                                                                    |
 | `ECONNREFUSED` | [`NNG_ECONNREFUSED`]                                                                     |                                                                                    |

diff --git a/docs/ref/migrate/nng1.md b/docs/ref/migrate/nng1.md
@@ -88,14 +88,16 @@ suboptimal in terms of performance.
 Modern code should use one of [`nng_sendmsg`], [`nng_recvmsg`], [`nng_socket_send`], or [`nng_socket_recv`] to get the maximum performance benefit.
 Working directly with [`nng_msg`] structures gives more control, reduces copies, and reduces allocation activity.
 
-## New AIO Error Code NNG_ESTOPPED
+## Error Code Changes
 
 When an operation fails with [`NNG_ESTOPPED`], it means that the associated [`nni_aio`] object has
 been permanently stopped and must not be reused. Applications must watch for this error code, and
 not resubmit an operation that returns it. This is particularly important for callbacks that automatically
 resubmit operations. Failure to observe this rule will lead to an infinite loop
 as any further operations on the object will fail immediately with `NNG_ESTOPPED`.
 
+The error codes `NNG_EAMBIGUOUS` and `NNG_ENOARG` have been removed.
+
 ## AIO Provider API changes
 
 The API used for providers for asynchronous I/O operations has changed slightly.
@@ -365,6 +367,12 @@ and is presently only supported for IPC when Named Pipes are used.
 Planned future changes to switch to UNIX domain sockets may eliminate
 support for security descriptors altogether in NNG.
 
+## Command Line Argument Parser Changes
+
+The supplemental function `nng_opts_parse` and supporting definitions have moved.
+This functionality is now supplied by a header only library, available in `nng/args.h`.
+See [`nng_args_parse`] for more information.
+
 ## ZeroTier Support Removed
 
 The Layer 2 special ZeroTier transport has been removed.

diff --git a/docs/ref/xref.md b/docs/ref/xref.md
@@ -193,7 +193,7 @@
 [`nng_dialer_get_tls`]: /TODO.md
 [`nng_listener_set_tls`]: /TODO.md
 [`nng_listener_get_tls`]: /TODO.md
-[`nng_opts_parse`]: /api/cmd_opts.md#parse-command-line-options
+[`nng_args_parse`]: /api/args.md#parse-command-line-arguments
 [`nng_aio_finish`]: /TODO.md
 [`nng_aio_reset`]: /TODO.md
 [`nng_aio_start`]: /TODO.md
@@ -272,8 +272,6 @@
 [`NNG_EWRITEONLY`]: /api/errors.md#NNG_EWRITEONLY
 [`NNG_ECRYPTO`]: /api/errors.md#NNG_ECRYPTO
 [`NNG_EPEERAUTH`]: /api/errors.md#NNG_EPEERAUTH
-[`NNG_ENOARG`]: /api/errors.md#NNG_ENOARG
-[`NNG_EAMBIGUOUS`]: /api/errors.md#NNG_EAMBIGUOUS
 [`NNG_EBADTYPE`]: /api/errors.md#NNG_EBADTYPE
 [`NNG_ECONNSHUT`]: /api/errors.md#NNG_ECONNSHUT
 [`NNG_EINTERNAL`]: /api/errors.md#NNG_EINTERNAL