NSH: Add a break command; if-then-else and looping behavior can not be configured out of the build for small systems that need minimal scripting capability

ChangeLog.txt

@@ -796,4 +796,9 @@
 	  a command to be on the same line as the then and else tokens like:
 	  "if true; then echo true; else echo false; fi".  Much more like bash!
 	  (2014-1-17).
-
+	* apps/nshlib/Kconfig, README.txt, nsh.h, nsh_command.c, and
+	  nsh_script.c:  Add an option to conditionally compile out support for
+	  loop and for if-then-else-fi sequence (2014-1-17).  
+	* apps/nshlib/nsh.h, nsh_command.c, and nsh_parse.c:  Add a break
+	  command that can be executed with a loop to terminate the loop
+	  immediately (2014-1-17).

nshlib/Kconfig

@@ -345,6 +345,27 @@ config NSH_DISABLESCRIPT
 		if-then[-else]-fi construct.  This would only be set on systems
 		where a minimal footprint is a necessity and scripting is not.
 
+if !NSH_DISABLESCRIPT
+
+config NSH_DISABLE_ITEF
+	bool "Disable if-then-else-fi"
+	default n
+	---help---
+		This can be set to 'y' to suppress support for if-then-else-fi
+		sequences in scripts.  This would only be set on systems where
+		some minimal scripting is required but if-then-else-fi is not.
+
+config NSH_DISABLE_LOOPS
+	bool "Disable loops"
+	default n
+	---help---
+		This can be set to 'y' to suppress support for while-do-done and
+		until-do-done sequences in scripts.  This would only be set on
+		systems where some minimal scripting is required but looping
+		is not.
+
+endif # !NSH_DISABLESCRIPT
+
 config NSH_DISABLEBG
 	bool "Disable background commands"
 	default n

nshlib/README.txt

@@ -7,6 +7,7 @@ apps/nshlib
   - Console/NSH Front End
   - Command Overview
   - Conditional Command Execution
+  - Looping
   - Built-In Variables
   - Current Working Directory
     Environment Variables
@@ -121,6 +122,12 @@ Looping
         Execute <cmd-sequence> as long as <test-cmd> has a non-zero exit
         status.
 
+  A break command is also supported.  The break command is only valid
+  within the body of the a while or until loop, between the do and done
+  tokens. If the break command is executed within the body of a loop, the
+  loop will immediately terminate and execution will continue with the
+  next command immediately following the done token.
+
 Built-In Variables
 ^^^^^^^^^^^^^^^^^^
 
@@ -1094,6 +1101,20 @@ NSH-Specific Configuration Settings
       if-then[-else]-fi construct.  This would only be set on systems
       where a minimal footprint is a necessity and scripting is not.
 
+  * CONFIG_NSH_DISABLE_ITEF
+
+     If scripting is enabled, then then this option can be selected to
+     suppress support for if-then-else-fi sequences in scripts.  This would
+     only be set on systems where some minimal scripting is required but
+     if-then-else-fi is not.
+
+  * CONFIG_NSH_DISABLE_LOOPS
+
+     If scripting is enabled, then then this option can be selected
+     suppress support for while-do-done and until-do-done sequences in
+     scripts.  This would only be set on systems where some minimal
+     scripting is required but looping is not.
+
   * CONFIG_NSH_DISABLEBG
       This can be set to 'y' to suppress support for background
       commands.  This setting disables the 'nice' command prefix and

nshlib/nsh.h

@@ -453,6 +453,8 @@
 /****************************************************************************
  * Public Types
  ****************************************************************************/
+
+#ifndef CONFIG_NSH_DISABLE_ITEF
 /* State when parsing and if-then-else sequence */
 
 enum nsh_itef_e
@@ -472,7 +474,9 @@ struct nsh_itef_s
   uint8_t   ie_unused   : 4;
   uint8_t   ie_state    : 2;   /* If-then-else state (see enum nsh_itef_e) */
 };
+#endif
 
+#ifndef CONFIG_NSH_DISABLE_LOOPS
 /* State when parsing and while-do-done or until-do-done sequence */
 
 enum nsh_lp_e
@@ -490,8 +494,12 @@ struct nsh_loop_s
   uint8_t   lp_enable   : 1;   /* Loop command processing is enabled */
   uint8_t   lp_unused   : 5;
   uint8_t   lp_state    : 2;   /* Loop state (see enume nsh_lp_e) */
+#ifndef CONFIG_NSH_DISABLE_ITEF
+  uint8_t   lp_iendx;          /* Saved if-then-else-fi index */
+#endif
   long      lp_topoffs;        /* Top of loop file offset */
 };
+#endif
 
 /* These structure provides the overall state of the parser */
 
@@ -510,19 +518,27 @@ struct nsh_parser_s
 
 #ifndef CONFIG_NSH_DISABLESCRIPT
   FILE    *np_stream;   /* Stream of current script */
+#ifndef CONFIG_NSH_DISABLE_LOOPS
   long     np_foffs;    /* File offset to the beginning of a line */
 #ifndef NSH_DISABLE_SEMICOLON
   uint16_t np_loffs;    /* Byte offset to the beginning of a command */
   bool     np_jump;     /* "Jump" to the top of the loop */
 #endif
-  uint8_t  np_iendx;    /* Current index into np_iestate[] */
   uint8_t  np_lpndx;    /* Current index into np_lpstate[] */
+#endif
+#ifndef CONFIG_NSH_DISABLE_ITEF
+  uint8_t  np_iendx;    /* Current index into np_iestate[] */
+#endif
 
   /* This is a stack of parser state information. */
 
+#ifndef CONFIG_NSH_DISABLE_ITEF
   struct nsh_itef_s np_iestate[CONFIG_NSH_NESTDEPTH];
+#endif
+#ifndef CONFIG_NSH_DISABLE_LOOPS
   struct nsh_loop_s np_lpstate[CONFIG_NSH_NESTDEPTH];
 #endif
+#endif
 };
 
 struct nsh_vtbl_s; /* Defined in nsh_console.h */
@@ -643,6 +659,9 @@ void nsh_usbtrace(void);
 
 /* Shell command handlers */
 
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
+  int cmd_break(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv);
+#endif 
 #ifndef CONFIG_NSH_DISABLE_ECHO
   int cmd_echo(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv);
 #endif

nshlib/nsh_command.c

@@ -119,6 +119,10 @@ static const struct cmdmap_s g_cmdmap[] =
 #  endif
 #endif
 
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
+  { "break",     cmd_break,   1, 1, NULL },
+#endif 
+
 #if CONFIG_NFILE_DESCRIPTORS > 0
 # ifndef CONFIG_NSH_DISABLE_CAT
   { "cat",      cmd_cat,      2, CONFIG_NSH_MAXARGUMENTS, "<path> [<path> [<path> ...]]" },
@@ -465,6 +469,7 @@ static inline void help_usage(FAR struct nsh_vtbl_s *vtbl)
   nsh_output(vtbl, "  <cmd> [> <file>|>> <file>]\n\n");
 #endif
 #ifndef CONFIG_NSH_DISABLESCRIPT
+#ifndef CONFIG_NSH_DISABLE_ITEF
   nsh_output(vtbl, "OR\n");
   nsh_output(vtbl, "  if <cmd>\n");
   nsh_output(vtbl, "  then\n");
@@ -472,6 +477,8 @@ static inline void help_usage(FAR struct nsh_vtbl_s *vtbl)
   nsh_output(vtbl, "  else\n");
   nsh_output(vtbl, "    [sequence of <cmd>]\n");
   nsh_output(vtbl, "  fi\n\n");
+#endif
+#ifndef CONFIG_NSH_DISABLE_LOOPS
   nsh_output(vtbl, "OR\n");
   nsh_output(vtbl, "  while <cmd>\n");
   nsh_output(vtbl, "  do\n");
@@ -483,6 +490,7 @@ static inline void help_usage(FAR struct nsh_vtbl_s *vtbl)
   nsh_output(vtbl, "    [sequence of <cmd>]\n");
   nsh_output(vtbl, "  done\n\n");
 #endif
+#endif
 }
 #endif
 

nshlib/nsh_parse.c

@@ -160,14 +160,22 @@ static FAR char *nsh_argument(FAR struct nsh_vtbl_s *vtbl, char **saveptr,
                FAR NSH_MEMLIST_TYPE *memlist);
 
 #ifndef CONFIG_NSH_DISABLESCRIPT
+#ifndef CONFIG_NSH_DISABLE_LOOPS
 static bool nsh_loop_enabled(FAR struct nsh_vtbl_s *vtbl);
+#endif
+#ifndef CONFIG_NSH_DISABLE_ITEF
 static bool nsh_itef_enabled(FAR struct nsh_vtbl_s *vtbl);
+#endif
 static bool nsh_cmdenabled(FAR struct nsh_vtbl_s *vtbl);
+#ifndef CONFIG_NSH_DISABLE_LOOPS
 static int nsh_loop(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
                     FAR char **saveptr, FAR NSH_MEMLIST_TYPE *memlist);
+#endif
+#ifndef CONFIG_NSH_DISABLE_ITEF
 static int nsh_itef(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
                     FAR char **saveptr, FAR NSH_MEMLIST_TYPE *memlist);
 #endif
+#endif
 
 #ifndef CONFIG_NSH_DISABLEBG
 static int nsh_nice(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
@@ -396,6 +404,7 @@ static int nsh_saveresult(FAR struct nsh_vtbl_s *vtbl, bool result)
   struct nsh_parser_s *np = &vtbl->np;
 
 #ifndef CONFIG_NSH_DISABLESCRIPT
+#ifndef CONFIG_NSH_DISABLE_LOOPS
   /* Check if we are waiting for the condition associated with a while
    * token.
    *
@@ -427,16 +436,20 @@ static int nsh_saveresult(FAR struct nsh_vtbl_s *vtbl, bool result)
       np->np_lpstate[np->np_lpndx].lp_enable = (result != OK);
       return OK;
     }
+  else
+#endif
 
+#ifndef CONFIG_NSH_DISABLE_ITEF
   /* Check if we are waiting for the condition associated with an if token */
 
-  else if (np->np_iestate[np->np_iendx].ie_state == NSH_ITEF_IF)
+  if (np->np_iestate[np->np_iendx].ie_state == NSH_ITEF_IF)
     {
       np->np_fail = false;
       np->np_iestate[np->np_iendx].ie_ifcond = result;
       return OK;
     }
   else
+#endif
 #endif
     {
       np->np_fail = result;
@@ -1369,7 +1382,7 @@ static FAR char *nsh_argument(FAR struct nsh_vtbl_s *vtbl, FAR char **saveptr,
  * Name: nsh_loop_enabled
  ****************************************************************************/
 
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
 static bool nsh_loop_enabled(FAR struct nsh_vtbl_s *vtbl)
 {
   FAR struct nsh_parser_s *np = &vtbl->np;
@@ -1388,13 +1401,15 @@ static bool nsh_loop_enabled(FAR struct nsh_vtbl_s *vtbl)
 
   return true;
 }
+#else
+#  define nsh_loop_enabled(vtbl) true
 #endif
 
 /****************************************************************************
  * Name: nsh_itef_enabled
  ****************************************************************************/
 
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_ITEF)
 static bool nsh_itef_enabled(FAR struct nsh_vtbl_s *vtbl)
 {
   FAR struct nsh_parser_s *np = &vtbl->np;
@@ -1420,6 +1435,8 @@ static bool nsh_itef_enabled(FAR struct nsh_vtbl_s *vtbl)
 
   return ret;
 }
+#else
+#  define nsh_itef_enabled(vtbl) true
 #endif
 
 /****************************************************************************
@@ -1442,7 +1459,7 @@ static bool nsh_cmdenabled(FAR struct nsh_vtbl_s *vtbl)
  * Name: nsh_loop
  ****************************************************************************/
 
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
 static int nsh_loop(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
                     FAR char **saveptr, FAR NSH_MEMLIST_TYPE *memlist)
 {
@@ -1476,7 +1493,10 @@ static int nsh_loop(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
 
           /* Verify that "while" or "until" is valid in this context */
 
-          if (np->np_iestate[np->np_iendx].ie_state == NSH_ITEF_IF ||
+          if (
+#ifndef CONFIG_NSH_DISABLE_ITEF
+              np->np_iestate[np->np_iendx].ie_state == NSH_ITEF_IF ||
+#endif
               np->np_lpstate[np->np_lpndx].lp_state == NSH_LOOP_WHILE ||
               np->np_lpstate[np->np_lpndx].lp_state == NSH_LOOP_UNTIL ||
               np->np_stream == NULL || np->np_foffs < 0)
@@ -1509,6 +1529,9 @@ static int nsh_loop(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
           np->np_lpndx++;
           np->np_lpstate[np->np_lpndx].lp_state   = state;
           np->np_lpstate[np->np_lpndx].lp_enable  = enable;
+#ifndef CONFIG_NSH_DISABLE_ITEF
+          np->np_lpstate[np->np_lpndx].lp_iendx   = np->np_iendx;
+#endif
           np->np_lpstate[np->np_lpndx].lp_topoffs = offset;
         }
 
@@ -1516,14 +1539,9 @@ static int nsh_loop(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
 
       else if (strcmp(cmd, "do") == 0)
         {
-          /* Get the cmd following the "do" -- there shouldn't be one */
+          /* Get the cmd following the "do" -- there may or may not be one */
 
           *ppcmd = nsh_argument(vtbl, saveptr, memlist);
-          if (*ppcmd)
-            {
-              nsh_output(vtbl, g_fmtarginvalid, "do");
-              goto errout;
-            }
 
           /* Verify that "do" is valid in this context */
 
@@ -1632,7 +1650,7 @@ errout:
  * Name: nsh_itef
  ****************************************************************************/
 
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_ITEF)
 static int nsh_itef(FAR struct nsh_vtbl_s *vtbl, FAR char **ppcmd,
                     FAR char **saveptr, FAR NSH_MEMLIST_TYPE *memlist)
 {
@@ -1982,6 +2000,7 @@ static int nsh_parse_command(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
   cmd = nsh_argument(vtbl, &saveptr, &memlist);
 
 #ifndef CONFIG_NSH_DISABLESCRIPT
+#ifndef CONFIG_NSH_DISABLE_LOOPS
   /* Handle while-do-done and until-do-done loops */
 
   if (nsh_loop(vtbl, &cmd, &saveptr, &memlist) != 0)
@@ -1989,7 +2008,9 @@ static int nsh_parse_command(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
       NSH_MEMLIST_FREE(&memlist);
       return nsh_saveresult(vtbl, true);
     }
+#endif
 
+#ifndef CONFIG_NSH_DISABLE_ITEF
   /* Handle if-then-else-fi */
 
   if (nsh_itef(vtbl, &cmd, &saveptr, &memlist) != 0)
@@ -1997,6 +2018,8 @@ static int nsh_parse_command(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
       NSH_MEMLIST_FREE(&memlist);
       return nsh_saveresult(vtbl, true);
     }
+
+#endif
 #endif
 
   /* Handle nice */
@@ -2137,7 +2160,7 @@ int nsh_parse(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
   return nsh_parse_command(vtbl, cmdline);
 
 #else
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
   FAR struct nsh_parser_s *np = &vtbl->np;
 #endif
   FAR char *start   = cmdline;
@@ -2151,13 +2174,13 @@ int nsh_parse(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
    * at the top of the loop.
    */
 
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
   for (np->np_jump = false; !np->np_jump; )
 #else
   for (;;)
 #endif
     {
-#ifndef CONFIG_NSH_DISABLESCRIPT
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
       /* Save the offset on the line to the start of the command */
 
       np->np_loffs = (uint16_t)(working - cmdline);
@@ -2241,3 +2264,34 @@ int nsh_parse(FAR struct nsh_vtbl_s *vtbl, FAR char *cmdline)
 #endif
 #endif
 }
+
+/****************************************************************************
+ * Name: cmd_break
+ ****************************************************************************/
+
+#if !defined(CONFIG_NSH_DISABLESCRIPT) && !defined(CONFIG_NSH_DISABLE_LOOPS)
+int cmd_break(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv)
+{
+  FAR struct nsh_parser_s *np = &vtbl->np;
+
+  /* Break outside of a loop is ignored */
+
+  if (np->np_lpstate[np->np_lpndx].lp_state == NSH_LOOP_DO)
+    {
+#ifndef CONFIG_NSH_DISABLE_ITEF
+      /* Yes... pop the original if-then-else-if state */
+
+      np->np_iendx = np->np_lpstate[np->np_lpndx].lp_iendx;
+#endif
+      /* Disable all command processing until 'done' is encountered.  */
+
+      np->np_lpstate[np->np_lpndx].lp_enable = false;
+    }
+
+  /* No syntax errors are detected(?).  Break is a nop everywhere except
+   * the supported context.
+   */
+
+  return OK;
+}
+#endif 

nshlib/nsh_script.c

@@ -129,10 +129,11 @@ int nsh_script(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
 
       do
         {
-          /* Get the next line of input from the file */
+          /* Flush any output generated by the previous line */
 
           fflush(stdout);
 
+#ifndef CONFIG_NSH_DISABLE_LOOPS
           /* Get the current file position.  This is used to control
            * looping.  If a loop begins in the next line, then this file
            * offset will be needed to locate the top of the loop in the
@@ -146,6 +147,7 @@ int nsh_script(FAR struct nsh_vtbl_s *vtbl, FAR const char *cmd,
             {
               nsh_output(vtbl, g_fmtcmdfailed, "loop", "ftell", NSH_ERRNO);
             }
+#endif
 
           /* Now read the next line from the script file */