letopt: command-line argument handling

src/letopt.c

@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define INCLUDED_FROM_LETOPT_C_
+#include "letopt.h"
+#undef INCLUDED_FROM_LETOPT_C_
+
+extern_letopt_state_init();
+extern_letopt_get_number_arg();
+extern_letopt_get_string_arg();
+extern_letopt_get_long_opt_arg();
+
+#undef extern_letopt_state_init
+#undef extern_letopt_get_number_arg
+#undef extern_letopt_get_string_arg
+#undef extern_letopt_get_long_opt_arg
+
+struct letopt_state
+letopt_state_init (int    argc,
+                   char **argv)
+{
+	struct letopt_state state = {
+		.v = argv,
+		.c = argc
+	};
+
+	if (state.c > 1 &&
+	    !(state.q = calloc((size_t)state.c, sizeof *state.q)))
+		state.e = errno ? errno : ENOMEM;
+
+	return state;
+}
+
+bool
+letopt_get_number_arg (struct letopt_state *const state,
+                       int64_t *const             dest,
+                       const int64_t              min,
+                       const int64_t              max)
+{
+	if (!*state->p) {
+		state->e = EINVAL;
+		return false;
+	}
+
+	errno = 0;
+
+	char *end = state->p;
+	int64_t n = _Generic(n
+		, long: strtol
+		, long long: strtoll
+	)(state->p, &end, 0);
+
+	int e = errno;
+	if (!e) {
+		if (*end) {
+			e = EINVAL;
+		} else if (n < min || n > max) {
+			e = ERANGE;
+		} else {
+			*dest = n;
+			return true;
+		}
+	}
+
+	state->e = e;
+	return false;
+}
+
+bool
+letopt_get_string_arg (struct letopt_state *const state,
+                       char const **const         dest)
+{
+	if (!*state->p) {
+		state->e = EINVAL;
+		return false;
+	}
+
+	*dest = state->p;
+	return true;
+}
+
+int
+letopt_get_long_opt_arg (struct letopt_state *const state,
+                         const size_t               len)
+{
+	do {
+		if (!state->p[len]) {
+			if (++state->i >= state->c)
+				break;
+			state->p = state->v[state->i];
+		} else {
+			if (state->p[len] != '=')
+				return EAGAIN;
+			state->p += len + 1U;
+		}
+
+		if (*state->p)
+			return 0;
+	} while(0);
+
+	state->e = EINVAL;
+	return EINVAL;
+}