apps: use sizeof array in snprintf

Signed-off-by: Petro Karashchenko <petro.karashchenko@gmail.com>
diff --git a/examples/ws2812esp32rmt/ws2812esp32rmt_main.c b/examples/ws2812esp32rmt/ws2812esp32rmt_main.c
index 4f1c7f9..892c135 100644
--- a/examples/ws2812esp32rmt/ws2812esp32rmt_main.c
+++ b/examples/ws2812esp32rmt/ws2812esp32rmt_main.c
@@ -157,15 +157,15 @@
 
   uint32_t n_leds = atoi(argv[2]);
 
-  char dev_name[50];
-  snprintf(dev_name, 50, "/dev/rmt%d", ch_idx);
-  fd = open(dev_name, O_WRONLY);
+  char devname[50];
+  snprintf(devname, sizeof(devname), "/dev/rmt%d", ch_idx);
+  fd = open(devname, O_WRONLY);
   if (fd < 0)
     {
       fprintf(stderr,
               "%s: open %s failed: %d\n",
               argv[0],
-              dev_name,
+              devname,
               errno);
       goto errout_with_dev;
     }
diff --git a/graphics/nxwm/src/cnxterm.cxx b/graphics/nxwm/src/cnxterm.cxx
index d84fd1b..2df27c3 100644
--- a/graphics/nxwm/src/cnxterm.cxx
+++ b/graphics/nxwm/src/cnxterm.cxx
@@ -331,7 +331,7 @@
       // Construct the driver name using this minor number
 
       char devname[32];
-      snprintf(devname, 32, "/dev/nxterm%d", m_minor);
+      snprintf(devname, sizeof(devname), "/dev/nxterm%d", m_minor);
 
       unlink(devname);
       m_nxterm = 0;
@@ -460,7 +460,7 @@
   // Construct the driver name using this minor number
 
   char devname[32];
-  snprintf(devname, 32, "/dev/nxterm%d", g_nxtermvars.minor);
+  snprintf(devname, sizeof(devname), "/dev/nxterm%d", g_nxtermvars.minor);
 
   // Increment the minor number while it is protect by the semaphore
 
diff --git a/graphics/twm4nx/apps/cnxterm.cxx b/graphics/twm4nx/apps/cnxterm.cxx
index d3cbd99..67a964c 100644
--- a/graphics/twm4nx/apps/cnxterm.cxx
+++ b/graphics/twm4nx/apps/cnxterm.cxx
@@ -330,7 +330,7 @@
       // Construct the driver name using this minor number
 
       char devname[32];
-      snprintf(devname, 32, "/dev/nxterm%d", m_minor);
+      snprintf(devname, sizeof(devname), "/dev/nxterm%d", m_minor);
 
       unlink(devname);
       m_NxTerm = 0;
@@ -373,7 +373,7 @@
   // Construct the driver name using this minor number
 
   char devname[32];
-  snprintf(devname, 32, "/dev/nxterm%d", GNxTermVars.minor);
+  snprintf(devname, sizeof(devname), "/dev/nxterm%d", GNxTermVars.minor);
 
   // Increment the minor number while it is protect by the semaphore
 
diff --git a/testing/sensortest/sensortest.c b/testing/sensortest/sensortest.c
index 8544d67..ca309aa 100644
--- a/testing/sensortest/sensortest.c
+++ b/testing/sensortest/sensortest.c
@@ -350,7 +350,7 @@
       goto name_err;
     }
 
-  snprintf(devname, PATH_MAX, DEVNAME_FMT, name);
+  snprintf(devname, sizeof(devname), DEVNAME_FMT, name);
   fd = open(devname, O_RDONLY | O_NONBLOCK);
   if (fd < 0)
     {