add arg parser

Signed-off-by: AGentooCat <agentoocat@mail.i2p>

config.mk

@@ -21,7 +21,7 @@ PROJ_LD =
 
 # set the source files to be built for the program/library
 # dont prefix src/ or src/lib/
-PROG_SRCS=main.c
+PROG_SRCS=main.c args.c
 LIB_SRCS=
 
 # what the program depends on (-l<ib>)

src/args.c

@@ -0,0 +1,41 @@
+#include "args.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <err.h>
+
+#define EMSG "failed to parse args: "
+
+_Noreturn void print_help(char *argv0, int code) {
+    errx(code,
+"itoomail " VERSION ", written by AGentooCat\n"
+"USAGE: %s <-c config>\n"
+"    -c <config> : config file to use", argv0);
+}
+
+struct Args parse_args(int argc, char **argv) {
+    struct Args args;
+
+    memset(&args, 0, sizeof(args));
+    int opt;
+
+    while ((opt = getopt(argc, argv, ":c:h")) != -1) switch (opt) {
+	case 'c':
+	    if (!(args.config = strdup(optarg)))
+		err(1, EMSG "couldn't allocate memory");
+	    break;
+
+	case 'h':
+	    print_help(argv[0], 0);
+	case ':':
+	    errx(1, "missing argument to \"-%c\"", optopt);
+	case '?':
+	    errx(1, "unknown argument to \"-%c\"", optopt);
+    }
+
+    if (!args.config)
+	errx(1, "no config file given");
+
+    return args;
+}

src/args.h

@@ -0,0 +1,12 @@
+#ifndef ARGS_H
+#define ARGS_H
+
+#include <stdlib.h>
+
+struct Args {
+    char *config;
+};
+
+struct Args parse_args(int argc, char **argv);
+
+#endif

src/main.c

@@ -1,5 +1,7 @@
 #include <stdio.h>
+#include "args.h"
 
 int main(int argc, char **argv) {
-    fprintf(stderr, "Hello world! argc=%d argv=%p\n", argc, argv);
+    struct Args args = parse_args(argc, argv);
+    fprintf(stderr, "Hello world! config=%s\n", args.config);
 }