apps/graphics/pdcurs34/nuttx and system/termcurses: This commit fixes two issues:

1. A memory corruption issue that occurs from a paste operation that would overflow the fixed buffer size for keyboard processing.

2. A stall in getch() processing when there are cached keycodes in the termcurses emulation (tcurses_vt100.c).

graphics/pdcurs34/nuttx/pdckbd.c

@@ -167,12 +167,20 @@ bool PDC_check_key(void)
     fd_set rfds;
     struct timeval tv;
 
+    /* Test the registered tcurs interface for cached characters */
+
+    ret = termcurses_checkkey(termstate->tcurs);
+    if (ret)
+      {
+        return true;
+      }
+
     /* Watch stdin (fd 0) to see when it has input. */
 
     FD_ZERO(&rfds);
     FD_SET(termstate->in_fd, &rfds);
 
-    /* Wait up to five seconds. */
+    /* Do not wait. */
 
     tv.tv_sec = 0;
     tv.tv_usec = 0;

include/system/termcurses.h

@@ -117,6 +117,10 @@ struct termcurses_ops_s
   /* Get a keycode value */
 
   CODE int (*getkeycode)(FAR struct termcurses_s *dev, int *specialkey, int *keymodifers);
+
+  /* Check for cached keycode value */
+
+  CODE bool (*checkkey)(FAR struct termcurses_s *dev);
 };
 
 struct termcurses_dev_s
@@ -229,6 +233,16 @@ int termcurses_getwinsize(FAR struct termcurses_s *term, FAR struct winsize *win
 int termcurses_getkeycode(FAR struct termcurses_s *term, FAR int *specialkey,
                           FAR int *keymodifiers);
 
+/************************************************************************************
+ * Name: termcurses_checkkey
+ *
+ * Description:
+ *   Check if there is a key waiting to be processed.
+ *
+ ************************************************************************************/
+
+bool termcurses_checkkey(FAR struct termcurses_s *term);
+
 #undef EXTERN
 #ifdef __cplusplus
 }

system/termcurses/tcurses_vt100.c

@@ -107,6 +107,7 @@ static int tcurses_vt100_setattributes(FAR struct termcurses_s *dev,
               unsigned long attrib);
 static int tcurses_vt100_getkeycode(FAR struct termcurses_s *dev,
               FAR int *specialkey, FAR int *keymodifers);
+static bool tcurses_vt100_checkkey(FAR struct termcurses_s *dev);
 
 /************************************************************************************
  * Private Data
@@ -120,7 +121,8 @@ static const struct termcurses_ops_s g_vt100_ops =
   tcurses_vt100_getwinsize,
   tcurses_vt100_setcolors,
   tcurses_vt100_setattributes,
-  tcurses_vt100_getkeycode
+  tcurses_vt100_getkeycode,
+  tcurses_vt100_checkkey
 };
 
 /* VT100 terminal codes */
@@ -831,7 +833,7 @@ static int tcurses_vt100_getkeycode(FAR struct termcurses_s *dev, FAR int *speci
         {
           /* Get next bytes from input stream */
 
-          priv->keycount = read(fd, priv->keybuf, sizeof(priv->keybuf));
+          priv->keycount = read(fd, priv->keybuf, sizeof(priv->keybuf)-1);
           if (priv->keycount <= 0)
             {
               return -1;
@@ -1047,6 +1049,48 @@ static int tcurses_vt100_getkeycode(FAR struct termcurses_s *dev, FAR int *speci
   return keycode;
 }
 
+/************************************************************************************
+ * Check if a key is cached for processing.
+ *
+ ************************************************************************************/
+
+static bool tcurses_vt100_checkkey(FAR struct termcurses_s *dev)
+{
+  FAR struct tcurses_vt100_s  *priv;
+  int                         ret;
+  int                         fd;
+  fd_set                      rfds;
+  struct                      timeval tv;
+
+  priv = (FAR struct tcurses_vt100_s *) dev;
+  fd   = priv->in_fd;
+
+  /* Test for queued characters */
+
+  if (priv->keycount > 0)
+    {
+      return true;
+    }
+
+  /* Watch stdin (fd 0) to see when it has input. */
+
+  FD_ZERO(&rfds);
+  FD_SET(fd, &rfds);
+
+  /* Wait up to 1000us for next character after ESC */
+
+  tv.tv_sec = 0;
+  tv.tv_usec = 0;
+
+  ret = select(1, &rfds, NULL, NULL, &tv);
+  if (ret > 0)
+    {
+      return true;
+    }
+
+  return false;
+}
+
 /************************************************************************************
  * Public Functions
  ************************************************************************************/

system/termcurses/termcurses.c

@@ -272,3 +272,25 @@ int termcurses_getkeycode(FAR struct termcurses_s *term, FAR int *specialkey,
 
   return -1;
 }
+
+/************************************************************************************
+ * Name: termcurses_checkkey
+ *
+ * Description:
+ *   Check if there is a key waiting to be processed.
+ *
+ ************************************************************************************/
+
+bool termcurses_checkkey(FAR struct termcurses_s *term)
+{
+  FAR struct termcurses_dev_s *dev = (FAR struct termcurses_dev_s *) term;
+
+  /* Call the dev function */
+
+  if (dev->ops->checkkey)
+    {
+      return dev->ops->checkkey(term);
+    }
+
+  return 0;
+}