Explicitly set an action variable to say which action to perform, instead of inferring it from other settings like whether a watch PID was set (#12).

src/include/options.h

@@ -23,6 +23,16 @@ extern "C" {
 struct opts_s;
 typedef struct opts_s *opts_t;
 
+/*
+ * Overall program actions to select.
+ */
+typedef enum {
+	PV_ACTION_NOTHING,		/* do nothing, and exit */
+	PV_ACTION_TRANSFER,		/* transfer data */
+	PV_ACTION_STORE_AND_FORWARD,	/* store to file, then output from it */
+	PV_ACTION_WATCHFD		/* watch process file descriptors */
+} pvaction_t;
+
 /*
  * Structure describing run-time options.
  *
@@ -58,7 +68,7 @@ struct opts_s {
 	unsigned int argv_length;      /* allocated array size */
 	unsigned int watchfd_count;	       /* number of watchfd items */
 	unsigned int watchfd_length;	       /* allocated array size */
-	bool do_nothing;               /* exit-without-doing-anything flag */
+	pvaction_t action;	       /* the program action to perform */
 	bool progress;                 /* progress bar flag */
 	bool timer;                    /* timer flag */
 	bool eta;                      /* ETA flag */

src/main/main.c

@@ -308,7 +308,7 @@ int main(int argc, char **argv)
 	}
 
 	/* Early exit if necessary, such as with "-h". */
-	if (opts->do_nothing) {
+	if (PV_ACTION_NOTHING == opts->action) {
 		debug("%s", "nothing to do - exiting with status 0");
 		opts_free(opts);
 		return 0;
@@ -465,7 +465,7 @@ int main(int argc, char **argv)
 	pv_state_stop_at_size_set(state, opts->stop_at_size);
 
 	/* Total size calculation, in normal transfer mode. */
-	if (0 == opts->watch_pid) {
+	if (PV_ACTION_TRANSFER == opts->action) {
 		/*
 		 * If no size was given, try to calculate the total size.
 		 */
@@ -533,22 +533,30 @@ int main(int argc, char **argv)
 	pv_sig_init(state);
 
 	/* Run the appropriate main loop. */
-	if (0 == opts->watch_pid && NULL == opts->store_and_forward_file) {
+	switch (opts->action) {
+	case PV_ACTION_NOTHING:
+		break;
+	case PV_ACTION_TRANSFER:
 		/* Normal "transfer data" mode. */
 		pv_remote_init();
 		retcode = pv_main_loop(state);
 		pv_remote_fini();
-	} else if (0 == opts->watch_pid && NULL != opts->store_and_forward_file) {
+		break;
+	case PV_ACTION_STORE_AND_FORWARD:
 		/* Store-and-forward transfer mode. */
 		pv_remote_init();
 		retcode = pv__store_and_forward(state, opts, can_have_eta);
 		pv_remote_fini();
-	} else if (0 != opts->watch_pid && -1 == opts->watch_fd) {
-		/* "Watch all file descriptors of another process" mode. */
-		retcode = pv_watchpid_loop(state);
-	} else if (0 != opts->watch_pid && -1 != opts->watch_fd) {
-		/* "Watch a specific file descriptor of another process" mode. */
-		retcode = pv_watchfd_loop(state);
+		break;
+	case PV_ACTION_WATCHFD:
+		if (-1 == opts->watch_fd) {
+			/* "Watch all file descriptors of another process" mode. */
+			retcode = pv_watchpid_loop(state);
+		} else if (-1 != opts->watch_fd) {
+			/* "Watch a specific file descriptor of another process" mode. */
+			retcode = pv_watchfd_loop(state);
+		}
+		break;
 	}
 
 	/* Clear up the PID file, if one was written. */

src/main/options.c

@@ -410,6 +410,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 
 	numopts = 0;
 
+	opts->action = PV_ACTION_TRANSFER;
 	opts->interval = 1;
 	opts->delay_start = 0;
 	opts->watch_pid = 0;
@@ -507,10 +508,6 @@ opts_t opts_parse(unsigned int argc, char **argv)
 				return NULL;
 				/*@+mustfreefresh@ */
 			}
-			if (!opts_add_watchfd(opts, (pid_t) check_pid, check_fd)) {
-				opts_free(opts);
-				return NULL;
-			}
 			break;
 		default:
 			break;
@@ -522,11 +519,11 @@ opts_t opts_parse(unsigned int argc, char **argv)
 		switch (c) {
 		case 'h':
 			display_help();
-			opts->do_nothing = true;
+			opts->action = PV_ACTION_NOTHING;
 			return opts;	    /* early return */
 		case 'V':
 			display_version();
-			opts->do_nothing = true;
+			opts->action = PV_ACTION_NOTHING;
 			return opts;	    /* early return */
 		case 'p':
 			opts->progress = true;
@@ -683,6 +680,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 				opts_free(opts);
 				return NULL;
 			}
+			opts->action = PV_ACTION_STORE_AND_FORWARD;
 			break;
 		case 'R':
 			opts->remote = (pid_t) pv_getnum_count(optarg, false);
@@ -718,6 +716,11 @@ opts_t opts_parse(unsigned int argc, char **argv)
 			(void) sscanf(optarg, "%u:%d", &parse_pid, &parse_fd);
 			opts->watch_pid = (pid_t) parse_pid;
 			opts->watch_fd = parse_fd;
+			if (!opts_add_watchfd(opts, (pid_t) parse_pid, parse_fd)) {
+				opts_free(opts);
+				return NULL;
+			}
+			opts->action = PV_ACTION_WATCHFD;
 			break;
 		case 'o':
 			opts->output = pv_strdup(optarg);
@@ -766,7 +769,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 	if (NULL == opts)
 		return NULL;
 
-	if (0 != opts->watch_pid) {
+	if (PV_ACTION_WATCHFD == opts->action) {
 		if (opts->linemode || opts->null_terminated_lines || opts->stop_at_size
 		    || (opts->skip_errors > 0) || (opts->buffer_size > 0)
 		    || (opts->rate_limit > 0)) {
@@ -796,6 +799,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 			/*@+mustfreefresh@ */
 		}
 
+		/* TODO: accept additional args as pid[:fd] */
 		if (optind < (int) argc) {
 			/*@-mustfreefresh@ *//* see above */
 			fprintf(stderr, "%s: %s\n", opts->program_name,
@@ -847,7 +851,5 @@ opts_t opts_parse(unsigned int argc, char **argv)
 		}
 	}
 
-	/* TODO: set an enum to say which mode to use (nothing, PV, watchfd) */
-
 	return opts;
 }