Factor some things out elsewhere

bin/can2dump.c

@@ -3,6 +3,7 @@
 #include <string.h>
 #include <stdarg.h>
 #include <getopt.h>
+#include <sysexits.h>
 #include <inttypes.h>
 #include <fcntl.h>
 
@@ -19,6 +20,10 @@ enum timestamp_type {
     TIMESTAMP_DATE
 };
 
+struct optvalues {
+    enum timestamp_type tstype;
+};
+
 char *hexagram_arglist_can2dump(void) {
     return "[--timestamp=|adzA|] ifname [file.can] [candump.txt]";
 }
@@ -35,10 +40,59 @@ static int usage(int argc, char **argv, const char *message, ...) {
 
     fprintf(stderr, "usage: hexagram %s %s\n", argv[0], hexagram_arglist_can2dump());
 
-    return 1;
+    return EX_USAGE;
+}
+
+static int parseopts(struct optvalues *v,
+                     struct option opts[],
+                     int *argc,
+                     char **argv[]) {
+    int ch, index;
+
+    while ((ch = getopt_long(*argc, *argv, "t:", opts, &index)) >= 0) {
+        switch (ch) {
+            case 't':
+                switch (optarg[0]) {
+                    case 'a': v->tstype = TIMESTAMP_ABSOLUTE; break;
+                    case 'd': v->tstype = TIMESTAMP_DELTA;    break;
+                    case 'z': v->tstype = TIMESTAMP_ZERO;     break;
+                    case 'A': v->tstype = TIMESTAMP_DATE;     break;
+
+                    default:
+                        return usage(*argc, *argv, "Invalid timestamp type");
+                }
+
+                break;
+
+            default:
+                if (ch == '?') {
+                    return usage(*argc, *argv, NULL);
+                } else {
+                    return usage(*argc, *argv, "Unknown flag '%c'", ch);
+                }
+
+                break;
+        }
+    }
+
+    *argc -= optind;
+    *argv += optind;
+
+    return 0;
 }
 
 int hexagram_main_can2dump(int argc, char **argv) {
+    static struct option opts[] = {
+        { "timestamp", required_argument, NULL, 't' },
+        { NULL,        0,                 NULL, 0   }
+    };
+
+    struct optvalues values = {
+        .tstype = TIMESTAMP_NONE
+    };
+
+    int status;
+
     hexagram_capture *capture;
     const char *ifname;
     FILE *fh;
@@ -46,41 +100,13 @@ int hexagram_main_can2dump(int argc, char **argv) {
     struct timeval timestamp;
     struct can_frame frame;
 
-    static struct option opts[] = {
+    int argn    = argc;
-        { "timestamp", required_argument, NULL, 't' },
+    char **args = argv;
-        { NULL,        0,                 NULL, 0   }
-    };
 
-    enum timestamp_type tstype = TIMESTAMP_NONE;
+    if ((status = parseopts(&values, opts, &argn, &args)) != 0) {
-
+        return status;
-    int argn;
-    char **args;
-
-    int ch;
-
-    while ((ch = getopt_long(argc, argv, "t:", opts, NULL)) >= 0) {
-        switch (ch) {
-            case 't':
-                switch (optarg[0]) {
-                    case 'a': tstype = TIMESTAMP_ABSOLUTE; break;
-                    case 'd': tstype = TIMESTAMP_DELTA;    break;
-                    case 'z': tstype = TIMESTAMP_ZERO;     break;
-                    case 'A': tstype = TIMESTAMP_DATE;     break;
-
-                    default:
-                        return usage(argc, argv, "Invalid timestamp type");
-                }
-
-                break;
-
-            default:
-                return usage(argc, argv, "Unknown flag '%c'", ch);
-        }
     }
 
-    argn = argc - optind;
-    args = argv + optind;
-
     if (argn == 0) {
         return usage(argc, argv, "No CAN interface name provided");
     }
@@ -95,24 +121,20 @@ int hexagram_main_can2dump(int argc, char **argv) {
         }
 
         fh = stdout;
-    } else if (argn == 2) {
+    } else if (argn > 1) {
-        if ((capture = hexagram_capture_open_file(args[1], O_RDONLY)) == NULL) {
-            perror("hexagram_capture_open_file()");
-
-            goto error_capture_open;
-        }
-
-        fh = stdout;
-    } else if (argn == 3) {
         if ((capture = hexagram_capture_open_file(args[1], O_RDONLY)) == NULL) {
             perror("hexagram_capture_open_file()");
 
             goto error_capture_open;
         }
+    }
 
+    if (argn == 3) {
         if ((fh = fopen(args[2], "w")) == NULL) {
             goto error_fopen;
         }
+    } else if (argn == 2) {
+        fh = stdout;
     } else {
         return usage(argc, argv, NULL);
     }
@@ -120,8 +142,10 @@ int hexagram_main_can2dump(int argc, char **argv) {
     while (hexagram_capture_read(capture, &timestamp, &frame) >= 0) {
         uint8_t i;
 
-        switch (tstype) {
+        switch (values.tstype) {
             case TIMESTAMP_NONE:
+                fprintf(fh, " ");
+
                 break;
 
             case TIMESTAMP_ABSOLUTE: