utils: poll: also use stdin if no path set and stdin is not a tty

README.md

@@ -96,6 +96,19 @@ See their help output for usage.
 * `osp3-dump` - dump the device's serial output.
 * `osp3-poll` - poll the device's serial output for complete log entries.
 
+While `osp3-poll` reads from the serial port by default, it can also read from standard input.
+For example:
+
+```sh
+osp3-dump | osp3-poll
+````
+
+Or, more usefully, if you have UDP logging over wifi configured:
+
+```sh
+netcat -u -l -p 6000 | osp3-poll
+```
+
 
 ## C API
 

utils/osp3-poll.c

@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <osp3.h>
 
 #ifdef __APPLE__
@@ -25,6 +26,7 @@
 // Much bigger than anything an OSP3 should produce.
 #define OSP3_LINE_LEN_MAX 1024
 
+static int path_set = 0;
 static const char* path = PATH_DEFAULT;
 static unsigned int baud = OSP3_BAUD_DEFAULT;
 static unsigned int timeout_ms = TIMEOUT_MS_DEFAULT;
@@ -72,6 +74,7 @@ static void parse_args(int argc, char** argv) {
         print_usage(0);
         break;
       case 'p':
+        path_set = 1;
         path = optarg;
         break;
       case 'b':
@@ -226,7 +229,7 @@ int main(int argc, char** argv) {
 
   parse_args(argc, argv);
 
-  if (path != NULL && strlen(path) > 0 && strcmp(path, "-")) {
+  if (path_set || (isatty(0) && path != NULL && strlen(path) > 0 && strcmp(path, "-"))) {
     signal(SIGINT, shandle);
     if ((dev = osp3_open_device(path, baud)) == NULL) {
       perror("Failed to open ODROID Smart Power 3 connection");