get rid of argp dependency

src/lib/utils/arg.h

@@ -0,0 +1,97 @@
+/*
+ * ebusd - daemon for communication with eBUS heating systems.
+ * Copyright (C) 2023 John Baier <ebusd@ebusd.eu>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIB_UTILS_ARGS_H_
+#define LIB_UTILS_ARGS_H_
+
+namespace ebusd {
+
+/** \file lib/utils/args.h */
+
+/** the available arg flags. */
+enum ArgFlag {
+  af_optional = 1<<0,  //!< optional argument value
+  af_noHelp = 1<<1,  //!< do not include -?/--help option
+  af_noVersion = 1<<2,  //!< do not include -V/--version option
+};
+
+/** Definition of a single argument. */
+typedef struct argDef {
+  const char* name;  //!< the (long) name of the argument, or nullptr for a group header
+  int key;  //!< the argument key, also used as short name if alphabetic or the question mark
+  const char* valueName;  //!< the optional argument value name
+  int flags;  //!< flags for the argument, bit combination of @a ArgFlag
+  const char* help;  //!< help text (mandatory)
+  int unused;  //!< currently unused (kept for compatibility to argp)
+} argDef;
+
+struct argParseOpt;
+
+/**
+ * Function to be called for each argument.
+ * @param key the argument key as defined.
+ * @param arg the argument value, or nullptr.
+ * @param parseOpt ppointer to the @a argParseOpt structure.
+ * @return 0 on success, non-zero otherwise.
+ */
+typedef int (*parse_function_t)(int key, char *arg, const struct argParseOpt *parseOpt);
+
+/** Options for child definitions. */
+typedef struct argParseChildOpt {
+  const argDef *argDefs;  //!< pointer to the argument defintions (last one needs to have nullptr help as end sign)
+  parse_function_t parser;  //!< parse function to use
+} argParseChildOpt;
+
+/** Options to pass to @a argParse(). */
+typedef struct argParseOpt {
+  const argDef *argDefs;  //!< pointer to the argument defintions (last one needs to have nullptr help as end sign)
+  parse_function_t parser;  //!< parse function to use
+  int flags;  //!< flags for the parser, bit combination of @a ArgFlag
+  const char* name;  //!< name of the program parsed
+  const char* positional;  //!< help text for optional positional argument
+  const char* help;  //!< help text for the program (second line of help output)
+  const char* suffix;  //!< optional help suffix text
+  const argParseChildOpt *childOpts;  //!< optional child definitions
+  void* userArg;  //!< optional user argument
+} argParseOpt;
+
+/**
+ * Parse the arguments given in @a argv.
+ * @param parseOpt pointer to the @a argParseOpt structure.
+ * @param argc the argument count (including the full program name in index 0).
+ * @param argv the argument values (including the full program name in index 0).
+ * @param argIndex optional pointer for storing the index to the first non-argument found in argv.
+ * @return 0 on success, '!' for an invalid argument value, ':' for a missing argument value,
+ * '?' when "-?" was given, or the result of the parse function if non-zero.
+ */
+int argParse(const argParseOpt *parseOpt, int argc, char **argv, int *argIndex);
+
+/**
+ * Print the help text.
+ * @param parseOpt ppointer to the @a argParseOpt structure.
+ */
+void argHelp(const argParseOpt *parseOpt);
+
+/**
+ * Convenience macro to print an error message to stderr.
+*/
+#define argParseError(argParseOpt, message) fprintf(stderr, "%s\n", message);
+
+}  // namespace ebusd
+
+#endif  // LIB_UTILS_ARGS_H_