system/termcurses: Add terminate operation into the termcurses_ops_s interface

The existing implementation of the termcurses_deinitterm calls
termcurses_setcolors with some hard-coded values, leading to different
terminal emulators' behavior. Instead, a reset call needs to be made to
the implementation to roll back changes.

A new operation (terminate) has been added to the termcurses_ops interface
to achieve this functionality.

The vt100's terminate implementation ensures that default foreground and
background colors are applied portably across different terminals emulators.

include/system/termcurses.h

@@ -110,6 +110,10 @@ struct termcurses_ops_s
   /* Check for cached keycode value */
 
   CODE bool (*checkkey)(FAR struct termcurses_s *dev);
+
+  /* Terminate  */
+
+  CODE int (*terminate)(FAR struct termcurses_s *dev);
 };
 
 struct termcurses_dev_s
@@ -157,7 +161,7 @@ extern "C"
  ****************************************************************************/
 
 int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
-                        FAR struct termcurses_s **dev);
+                        FAR struct termcurses_s **term);
 
 /****************************************************************************
  * Name: termcurses_deinitterm
@@ -168,7 +172,7 @@ int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
  *
  ****************************************************************************/
 
-int termcurses_deinitterm(FAR struct termcurses_s *dev);
+int termcurses_deinitterm(FAR struct termcurses_s *term);
 
 /****************************************************************************
  * Name: termcurses_moveyx

system/termcurses/tcurses_vt100.c

@@ -93,6 +93,7 @@ static int tcurses_vt100_setattributes(FAR struct termcurses_s *dev,
 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);
+static int tcurses_vt100_terminate(FAR struct termcurses_s *dev);
 
 /************************************************************************************
  * Private Data
@@ -107,7 +108,8 @@ static const struct termcurses_ops_s g_vt100_ops =
   tcurses_vt100_setcolors,
   tcurses_vt100_setattributes,
   tcurses_vt100_getkeycode,
-  tcurses_vt100_checkkey
+  tcurses_vt100_checkkey,
+  tcurses_vt100_terminate
 };
 
 /* VT100 terminal codes */
@@ -129,6 +131,10 @@ static const char *g_setnoblink     = ";25";
 static const char *g_setunderline   = ";4";
 static const char *g_setnounderline = ";24";
 
+/* Set default background and foreground colors. */
+
+static const char *g_setdefcolors   = "\x1b[39;m\x1b[49;m";
+
 struct keycodes_s
 {
 #ifdef CONFIG_TERMCURSES_INCLUDE_TERMINFO_NAME
@@ -1479,3 +1485,28 @@ FAR struct termcurses_s *tcurses_vt100_initialize(int in_fd, int out_fd)
 
   return (FAR struct termcurses_s *) priv;
 }
+
+/************************************************************************************
+ * Name: tcurses_vt100_terminate
+ *
+ * Description:
+ *   Terminates a specific instance of the VT100 TermCurses handler.
+ *
+ ************************************************************************************/
+
+static int tcurses_vt100_terminate(FAR struct termcurses_s *dev)
+{
+  FAR struct tcurses_vt100_s *priv;
+  int  fd;
+
+  priv = (FAR struct tcurses_vt100_s *) dev;
+  fd   = priv->out_fd;
+
+  /* Set default foreground and background colors.
+   * (Ignore the return result.)
+   */
+
+  write(fd, g_setdefcolors, strlen(g_setdefcolors));
+
+  return OK;
+}

system/termcurses/termcurses.c

@@ -62,7 +62,7 @@ static struct termcurses_dev_s *g_termcurses_devices[] =
  ************************************************************************************/
 
 int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
-                        FAR struct termcurses_s **dev)
+                        FAR struct termcurses_s **term)
 {
   FAR struct termcurses_dev_s *pnext;
   int c;
@@ -94,11 +94,11 @@ int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
         {
           /* Allocate a new structure for this termcurses */
 
-          if (*dev == NULL)
+          if (*term == NULL)
             {
               /* Call the termcurses_dev init function */
 
-              *dev = pnext->ops->init(in_fd, out_fd);
+              *term = pnext->ops->init(in_fd, out_fd);
             }
 
           return OK;
@@ -111,7 +111,7 @@ int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
 
   /* Not found! */
 
-  *dev = NULL;
+  *term = NULL;
   return -ENOSYS;
 }
 
@@ -124,26 +124,24 @@ int termcurses_initterm(FAR const char *term_type, int in_fd, int out_fd,
  *
  ************************************************************************************/
 
-int termcurses_deinitterm(FAR struct termcurses_s *dev)
+int termcurses_deinitterm(FAR struct termcurses_s *term)
 {
-  struct termcurses_colors_s colors;
+  FAR struct termcurses_dev_s *dev = (FAR struct termcurses_dev_s *) term;
+  int result = OK;
 
-  /* Ensure terminal has default color scheme */
+  /* Call the dev function */
 
-  colors.fg_red     = 255;
+  if (dev->ops->terminate)
-  colors.fg_green   = 255;
+    {
-  colors.fg_blue    = 255;
+      result = dev->ops->terminate(term);
-  colors.bg_red     = 0;
+    }
-  colors.bg_green   = 0;
-  colors.bg_blue    = 0;
-  colors.color_mask = 0xff;
-  termcurses_setcolors(dev, &colors);
 
-  /* For now, simply free the memory */
+  /* Free the memory if termination is successful. */
 
-  free(dev);
+  if (result == OK)
+    free(dev);
 
-  return OK;
+  return result;
 }
 
 /************************************************************************************