nvttest: Enable specifying device

Also check that the device file exists.

nvttest/nvttest.c

@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include <fcntl.h>
 
@@ -20,6 +21,7 @@
 static const char help_text[] =
     "Usage: nvttest OPTIONS...\n"
     "OPTIONS:\n"
+    "  -D name    : Specify device name (/dev/name, default /dev/ttyNVT0)\n"
     "  -d         : Enable debug\n"
     "  -n loops   : Test loops per thread\n"
     "  -q         : Quiet\n"
@@ -28,7 +30,7 @@ static const char help_text[] =
     ;
 /**INDENT-ON**/
 
-static const char *dev = "/dev/ttyNVT0";
+static char     dev[64] = "/dev/ttyNVT0";
 
 typedef struct {
     int             nthread;
@@ -126,18 +128,22 @@ int main(int argc, char **argv)
     topts_t         topts = { }, *popts;
     pthread_t      *ptids;
     int             debug, quiet;
+    struct stat     st;
 
     debug = quiet = 0;
     nthr = 1;
     topts.nloop = 1;
 
-    while ((opt = getopt(argc, argv, "dn:qrt:")) != -1)
+    while ((opt = getopt(argc, argv, "D:dn:qrt:")) != -1)
     {
         switch (opt)
         {
         default:               /* '?' */
             _usage(1);
             break;
+        case 'D':
+            snprintf(dev, sizeof(dev), "/dev/%s", optarg);
+            break;
         case 'd':
             debug += 1;
             break;
@@ -156,6 +162,12 @@ int main(int argc, char **argv)
         }
     }
 
+    if (stat(dev, &st) || !S_ISCHR(st.st_mode))
+    {
+        fprintf(stderr, "Invalid device file: '%s'\n", dev);
+        exit(EXIT_FAILURE);
+    }
+
     nvt_log_level(quiet, debug);
     nvt_log_dest(NVT_LOG_STDOUT);