nanobox.c

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+/* vi: set sw=4 ts=4: */
+/*
+ * nanobox:A small 'nano' clone
+ * Copyright (C) 2000, 2001 Sterling Huxley <sterling@europa.com>
+ * Copyright (C) 2019 Michele Bini <michele.bini@gmail.com>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+/*
+ * Things To Do:
+ *	add help command
+ *	if mark[] values were line numbers rather than pointers
+ *      it would be easier to change the mark when add/delete lines
+ *	More intelligence in refresh()
+ *	filter text through an external command
+ *	An "ex" line oriented mode- maybe using "cmdedit"
+ */
+
+//config:config NANO
+//config:	bool "nano"
+//config:	default y
+//config:	help
+//config:	  'nano' is a text editor. This is a clone attempt.
+//config:
+//config:config FEATURE_NANO_MAX_LEN
+//config:	int "Maximum screen width"
+//config:	range 256 16384
+//config:	default 4096
+//config:	depends on NANO
+//config:	help
+//config:	  Contrary to what you may think, this is not eating much.
+//config:	  Make it smaller than 4k only if you are very limited on memory.
+//config:
+//config:config FEATURE_NANO_8BIT
+//config:	bool "Allow to display 8-bit chars (otherwise shows dots)"
+//config:	default n
+//config:	depends on NANO
+//config:	help
+//config:	  If your terminal can display characters with high bit set,
+//config:	  you may want to enable this. Note: nano is not Unicode-capable.
+//config:	  If your terminal combines several 8-bit bytes into one character
+//config:	  (as in Unicode mode), this will not work properly.
+//config:
+//config:config FEATURE_NANO_UTF8
+//config:	bool "Allow editing utf-8 files"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Allow input of utf8 characters. (EXPERIMENTAL)
+//config:
+//config:config FEATURE_NANO_UTF8_MIXED
+//config:	bool "Allow editing of utf-8 files containing invalid character sequences"
+//config:	default y
+//config:	depends on NANO_UTF8
+//config:	help
+//config:	  Allow input of utf8 characters. (EXPERIMENTAL)
+//config:
+//config:config FEATURE_NANO_COLON
+//config:	bool "Enable \":\" colon commands (no \"ex\" mode)"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Enable a limited set of colon commands. This does not
+//config:	  provide an "ex" mode.
+//config:
+//config:config FEATURE_NANO_YANKMARK
+//config:	bool "Enable yank/put commands and mark cmds"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  This will enable you to use yank and put, as well as mark.
+//config:
+//config:config FEATURE_NANO_SEARCH
+//config:	bool "Enable search and replace cmds"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Select this if you wish to be able to do search and replace.
+//config:
+//config:config FEATURE_NANO_REGEX_SEARCH
+//config:	bool "Enable regex in search and replace"
+//config:	default n   # Uses GNU regex, which may be unavailable. FIXME
+//config:	depends on FEATURE_NANO_SEARCH
+//config:	help
+//config:	  Use extended regex search.
+//config:
+//config:config FEATURE_NANO_USE_SIGNALS
+//config:	bool "Catch signals"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Selecting this option will make nano signal aware. This will support
+//config:	  SIGWINCH to deal with Window Changes, catch ^Z and ^C and alarms.
+//config:
+//config:config FEATURE_NANO_READONLY
+//config:	bool "Enable -R option and \"view\" mode"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Enable the read-only command line option, which allows the user to
+//config:	  open a file in read-only mode.
+//config:
+//config:config FEATURE_NANO_SETOPTS
+//config:	bool "Enable settable options, ai ic showmatch"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Enable the editor to set some (ai, ic, showmatch) options.
+//config:	  Consider removing this option! FIXME
+//config:
+//config:config FEATURE_NANO_SET
+//config:	bool "Support :set"
+//config:	default y
+//config:	depends on NANO
+//config:
+//config:config FEATURE_NANO_WIN_RESIZE
+//config:	bool "Handle window resize"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Behave nicely with terminals that get resized.
+//config:
+//config:config FEATURE_NANO_ASK_TERMINAL
+//config:	bool "Use 'tell me cursor position' ESC sequence to measure window"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  If terminal size can't be retrieved and $LINES/$COLUMNS are not set,
+//config:	  this option makes nano perform a last-ditch effort to find it:
+//config:	  position cursor to 999,999 and ask terminal to report real
+//config:	  cursor position using "ESC [ 6 n" escape sequence, then read stdin.
+//config:	  This is not clean but helps a lot on serial lines and such.
+//config:
+//config:config FEATURE_NANO_UNDO
+//config:	bool "Support undo command \"u\""
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Support the 'u' command to undo insertion, deletion, and replacement
+//config:	  of text.
+//config:
+//config:config FEATURE_NANO_UNDO_QUEUE
+//config:	bool "Enable undo operation queuing"
+//config:	default y
+//config:	depends on FEATURE_NANO_UNDO
+//config:	help
+//config:	  The nano undo functions can use an intermediate queue to greatly lower
+//config:	  malloc() calls and overhead. When the maximum size of this queue is
+//config:	  reached, the contents of the queue are committed to the undo stack.
+//config:	  This increases the size of the undo code and allows some undo
+//config:	  operations (especially un-typing/backspacing) to be far more useful.
+//config:
+//config:config FEATURE_NANO_UNDO_QUEUE_MAX
+//config:	int "Maximum undo character queue size"
+//config:	default 256
+//config:	range 32 65536
+//config:	depends on FEATURE_NANO_UNDO_QUEUE
+//config:	help
+//config:	  This option sets the number of bytes used at runtime for the queue.
+//config:	  Smaller values will create more undo objects and reduce the amount
+//config:	  of typed or backspaced characters that are grouped into one undo
+//config:	  operation; larger values increase the potential size of each undo
+//config:	  and will generally malloc() larger objects and less frequently.
+//config:	  Unless you want more (or less) frequent "undo points" while typing,
+//config:	  you should probably leave this unchanged.
+//config:
+//config:config FEATURE_NANO_HIGHLIGHT
+//config:	bool "Support syntax highlighting"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Support syntax highlighting.
+//config:
+//config:config FEATURE_NANO_HIGHLIGHT_LANGUAGE_C
+//config:	bool "Support syntax highlighting for C language"
+//config:	default y
+//config:	depends on NANO
+//config:	help
+//config:	  Support syntax highlighting for the C language
+//config:
+
+//applet:IF_NANO(APPLET(nano, BB_DIR_BIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_NANO) += nano.o
+
+//usage:#define nano_trivial_usage
+//usage:       "[OPTIONS] [FILE]..."
+//usage:#define nano_full_usage "\n\n"
+//usage:       "Edit FILE\n"
+//usage:	IF_FEATURE_NANO_COLON(
+//usage:     "\n	-c CMD	Initial command to run ($EXINIT also available)"
+//usage:	)
+//usage:	IF_FEATURE_NANO_READONLY(
+//usage:     "\n	-R	Read-only"
+//usage:	)
+//usage:     "\n	-H	List available features"
+
+// #include "libbb.h"
+
+/* Should be after libbb.h: on some systems regex.h needs sys/types.h: */
+#if ENABLE_FEATURE_NANO_REGEX_SEARCH
+# include <regex.h>
+#endif
+
+/* the CRASHME code is unmaintained, and doesn't currently build */
+#define ENABLE_FEATURE_NANO_CRASHME 0
+
+
+#if ENABLE_LOCALE_SUPPORT
+
+#if ENABLE_FEATURE_NANO_8BIT
+//FIXME: this does not work properly for Unicode anyway
+# define Isprint(c) (isprint)(c)
+#else
+# define Isprint(c) isprint_asciionly(c)
+#endif
+
+#else
+
+/* 0x9b is Meta-ESC */
+#if ENABLE_FEATURE_NANO_8BIT
+# define Isprint(c) ((unsigned char)(c) >= ' ' && (c) != 0x7f && (unsigned char)(c) != 0x9b)
+#else
+# define Isprint(c) ((unsigned char)(c) >= ' ' && (unsigned char)(c) < 0x7f)
+#endif
+
+#endif
+
+
+enum {
+	MAX_TABSTOP = 32, // sanity limit
+	// User input len. Need not be extra big.
+	// Lines in file being edited *can* be bigger than this.
+	MAX_INPUT_LEN = 128,
+	// Sanity limits. We have only one buffer of this size.
+	MAX_SCR_COLS = CONFIG_FEATURE_NANO_MAX_LEN,
+	MAX_SCR_ROWS = CONFIG_FEATURE_NANO_MAX_LEN,
+};
+
+/* VT102 ESC sequences.
+ * See "Xterm Control Sequences"
+ * http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
+ */
+/* Inverse/Normal text */
+#define ESC_BOLD_TEXT "\033[7m"
+#define ESC_NORM_TEXT "\033[0m"
+/* Bell */
+#define ESC_BELL "\007"
+/* Clear-to-end-of-line */
+#define ESC_CLEAR2EOL "\033[K"
+/* Clear-to-end-of-screen.
+ * (We use default param here.
+ * Full sequence is "ESC [ <num> J",
+ * <num> is 0/1/2 = "erase below/above/all".)
+ */
+#define ESC_CLEAR2EOS "\033[J"
+/* Cursor to given coordinate (1,1: top left) */
+#define ESC_SET_CURSOR_POS "\033[%u;%uH"
+//UNUSED
+// /* Cursor up and down */
+//#define ESC_CURSOR_UP "\033[A"
+//#define ESC_CURSOR_DOWN "\n"
+
+#if ENABLE_FEATURE_NANO_YANKMARK
+// cmds modifying text[]
+// vda: removed "aAiIs" as they switch us into insert mode
+// and remembering input for replay after them makes no sense
+static const char modifying_cmds[] ALIGN1 = "cCdDJoOpPrRxX<>~";
+#endif
+
+enum {
+	YANKONLY = FALSE,
+	YANKDEL = TRUE,
+	FORWARD = 1,	// code depends on "1"  for array index
+	BACK = -1,	// code depends on "-1" for array index
+	LIMITED = 0,	// how much of text[] in char_search
+	FULL = 1,	// how much of text[] in char_search
+};
+
+
+/* nano.c expects chars to be unsigned. */
+/* busybox build system provides that, but it's better */
+/* to audit and fix the source */
+
+struct globals {
+	/* many references - keep near the top of globals */
+	char *text, *end;       // pointers to the user data in memory
+	char *dot;              // where all the action takes place
+	int text_size;		// size of the allocated buffer
+
+	/* the rest */
+	smallint nano_setops;
+#define NANO_AUTOINDENT 1
+#define NANO_SHOWMATCH  2
+#define NANO_IGNORECASE 4
+#define NANO_ERR_METHOD 8
+#define autoindent (nano_setops & NANO_AUTOINDENT)
+#define showmatch  (nano_setops & NANO_SHOWMATCH )
+#define ignorecase (nano_setops & NANO_IGNORECASE)
+
+#if ENABLE_FEATURE_NANO_READONLY
+	smallint readonly_mode;
+#define SET_READONLY_FILE(flags)        ((flags) |= 0x01)
+#define SET_READONLY_MODE(flags)        ((flags) |= 0x02)
+#define UNSET_READONLY_FILE(flags)      ((flags) &= 0xfe)
+#else
+#define SET_READONLY_FILE(flags)        ((void)0)
+#define SET_READONLY_MODE(flags)        ((void)0)
+#define UNSET_READONLY_FILE(flags)      ((void)0)
+#endif
+
+	smallint editing;        // >0 while we are editing a file
+	                         // [code audit says "can be 0, 1 or 2 only"]
+	int modified_count;      // buffer contents changed if !0
+	int last_modified_count; // = -1;
+	int save_argc;           // how many file names on cmd line
+	unsigned rows, columns;	 // the terminal screen is this size
+#if ENABLE_FEATURE_NANO_ASK_TERMINAL
+	int get_rowcol_error;
+#endif
+	int crow, ccol;          // cursor is on Crow x Ccol
+	int offset;              // chars scrolled off the screen to the left
+	int have_status_msg;     // is default edit status needed?
+	                         // [don't make smallint!]
+	int last_status_cksum;   // hash of current status line
+	char *current_filename;
+	char *screenbegin;       // index into text[], of top line on the screen
+	char *screen;            // pointer to the virtual screen buffer
+	int screensize;          //            and its size
+	int tabstop;
+	int last_forward_char;   // last char searched for with 'f' (int because of Unicode)
+	char erase_char;         // the users erase character
+	char last_input_char;    // last char read from user
+
+#if ENABLE_FEATURE_NANO_USE_SIGNALS || ENABLE_FEATURE_NANO_CRASHME
+	int my_pid;
+#endif
+#if ENABLE_FEATURE_NANO_SEARCH
+	char *last_search_pattern; // last pattern from a '/' or '?' search
+#endif
+
+	/* former statics */
+#if ENABLE_FEATURE_NANO_YANKMARK
+	char *edit_file__cur_line;
+#endif
+	int refresh__old_offset;
+	int format_edit_status__tot;
+
+	/* a few references only */
+#if ENABLE_FEATURE_NANO_YANKMARK
+	// char *reg[28];          // named register a-z, "D", and "U" 0-25,26,27
+	char *clipboard;
+	char *mark[28];         // user marks points somewhere in text[]-  a-z and previous context ''
+	char *context_start, *context_end;
+#endif
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+	sigjmp_buf restart;     // catch_sig()
+#endif
+	struct termios term_orig; // remember what the cooked mode was
+#if ENABLE_FEATURE_NANO_COLON
+	char *initial_cmds[3];  // currently 2 entries, NULL terminated
+#endif
+	// Should be just enough to hold a key sequence,
+	// but CRASHME mode uses it as generated command buffer too
+#if ENABLE_FEATURE_NANO_CRASHME
+	char readbuffer[128];
+#else
+	char readbuffer[KEYCODE_BUFFER_SIZE];
+#endif
+#define STATUS_BUFFER_LEN  200
+	char status_buffer[STATUS_BUFFER_LEN]; // messages to the user
+	char get_input_line__buf[MAX_INPUT_LEN];
+	char search__buf[MAX_INPUT_LEN];
+
+	char scr_out_buf[MAX_SCR_COLS + MAX_TABSTOP * 2];
+#if ENABLE_FEATURE_NANO_UNDO
+// undo_push() operations
+#define UNDO_INS         0
+#define UNDO_DEL         1
+#define UNDO_INS_CHAIN   2
+#define UNDO_DEL_CHAIN   3
+// UNDO_*_QUEUED must be equal to UNDO_xxx ORed with UNDO_QUEUED_FLAG
+#define UNDO_QUEUED_FLAG 4
+#define UNDO_INS_QUEUED  4
+#define UNDO_DEL_QUEUED  5
+#define UNDO_USE_SPOS   32
+#define UNDO_EMPTY      64
+// Pass-through flags for functions that can be undone
+#define NO_UNDO          0
+#define ALLOW_UNDO       1
+#define ALLOW_UNDO_CHAIN 2
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+#define ALLOW_UNDO_QUEUED 3
+	char undo_queue_state;
+	int undo_q;
+	char *undo_queue_spos;	// Start position of queued operation
+	char undo_queue[CONFIG_FEATURE_NANO_UNDO_QUEUE_MAX];
+# else
+// If undo queuing disabled, don't invoke the missing queue logic
+#define ALLOW_UNDO_QUEUED 1
+# endif
+
+	struct undo_object {
+		struct undo_object *prev;	// Linking back avoids list traversal (LIFO)
+		int start;		// Offset where the data should be restored/deleted
+		int length;		// total data size
+		uint8_t u_type;		// 0=deleted, 1=inserted, 2=swapped
+		char undo_text[1];	// text that was deleted (if deletion)
+	} *undo_stack_tail;
+#endif /* ENABLE_FEATURE_NANO_UNDO */
+};
+#define G (*ptr_to_globals)
+#define text           (G.text          )
+#define text_size      (G.text_size     )
+#define end            (G.end           )
+#define dot            (G.dot           )
+#define clipboard      (G.clipboard     )
+
+#define nano_setops               (G.nano_setops          )
+#define editing                 (G.editing            )
+#define modified_count          (G.modified_count     )
+#define last_modified_count     (G.last_modified_count)
+#define save_argc               (G.save_argc          )
+#define rows                    (G.rows               )
+#define columns                 (G.columns            )
+#define crow                    (G.crow               )
+#define ccol                    (G.ccol               )
+#define offset                  (G.offset             )
+#define status_buffer           (G.status_buffer      )
+#define have_status_msg         (G.have_status_msg    )
+#define last_status_cksum       (G.last_status_cksum  )
+#define current_filename        (G.current_filename   )
+#define screen                  (G.screen             )
+#define screensize              (G.screensize         )
+#define screenbegin             (G.screenbegin        )
+#define tabstop                 (G.tabstop            )
+#define last_forward_char       (G.last_forward_char  )
+#define erase_char              (G.erase_char         )
+#define last_input_char         (G.last_input_char    )
+#if ENABLE_FEATURE_NANO_READONLY
+#define readonly_mode           (G.readonly_mode      )
+#else
+#define readonly_mode           0
+#endif
+#define adding2q                (G.adding2q           )
+#define lmc_len                 (G.lmc_len            )
+#define ioq                     (G.ioq                )
+#define ioq_start               (G.ioq_start          )
+#define my_pid                  (G.my_pid             )
+#define last_search_pattern     (G.last_search_pattern)
+
+#define edit_file__cur_line     (G.edit_file__cur_line)
+#define refresh__old_offset     (G.refresh__old_offset)
+#define format_edit_status__tot (G.format_edit_status__tot)
+
+#define mark           (G.mark          )
+#define context_start  (G.context_start )
+#define context_end    (G.context_end   )
+#define restart        (G.restart       )
+#define term_orig      (G.term_orig     )
+#define initial_cmds   (G.initial_cmds  )
+#define readbuffer     (G.readbuffer    )
+#define scr_out_buf    (G.scr_out_buf   )
+#define last_modifying_cmd  (G.last_modifying_cmd )
+#define get_input_line__buf (G.get_input_line__buf)
+#define search__buf    (G.search__buf)
+
+#if ENABLE_FEATURE_NANO_UNDO
+#define undo_stack_tail  (G.undo_stack_tail )
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+#define undo_queue_state (G.undo_queue_state)
+#define undo_q           (G.undo_q          )
+#define undo_queue       (G.undo_queue      )
+#define undo_queue_spos  (G.undo_queue_spos )
+# endif
+#endif
+
+#define INIT_G() do { \
+	SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
+	last_modified_count = -1; \
+	/* "" but has space for 2 chars: */ \
+	IF_FEATURE_NANO_SEARCH(last_search_pattern = xzalloc(2);) \
+} while (0)
+
+
+static void edit_file(char *);	// edit one file
+static void do_cmd(int);	// execute a command
+static int next_tabstop(int);
+static void sync_cursor(char *, int *, int *);	// synchronize the screen cursor to dot
+static char *begin_line(char *);	// return pointer to cur line B-o-l
+static char *end_line(char *);	// return pointer to cur line E-o-l
+static char *prev_line(char *);	// return pointer to prev line B-o-l
+static char *next_line(char *);	// return pointer to next line B-o-l
+static char *end_screen(void);	// get pointer to last char on screen
+static int count_lines(char *, char *);	// count line from start to stop
+static char *move_to_col(char *, int);	// move "p" to column l
+static void dot_left(void);	// move dot left- dont leave line
+static void dot_right(void);	// move dot right- dont leave line
+static void dot_begin(void);	// move dot to B-o-l
+static void dot_next(void);	// move dot to next line B-o-l
+static void dot_prev(void);	// move dot to prev line B-o-l
+static void dot_scroll(int, int);	// move the screen up or down
+static void dot_skip_over_ws(void);	// move dot pat WS
+static char *bound_dot(char *);	// make sure  text[0] <= P < "end"
+static char *new_screen(int, int);	// malloc virtual screen memory
+#if !ENABLE_FEATURE_NANO_UNDO
+#define char_insert(a,b,c) char_insert(a,b)
+#endif
+static char *char_insert(char *, char, int);	// insert the char c at 'p'
+// might reallocate text[]! use p += stupid_insert(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+static uintptr_t stupid_insert(char *, char);	// stupidly insert the char c at 'p'
+static char *find_pair(char *, char);	// find matching pair ()  []  {}
+#if !ENABLE_FEATURE_NANO_UNDO
+#define text_hole_delete(a,b,c) text_hole_delete(a,b)
+#endif
+static char *text_hole_delete(char *, char *, int);	// at "p", delete a 'size' byte hole
+// might reallocate text[]! use p += text_hole_make(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+static uintptr_t text_hole_make(char *, int);	// at "p", make a 'size' byte hole
+#if !ENABLE_FEATURE_NANO_UNDO
+#define yank_delete(a,b,c,d,e) yank_delete(a,b,c,d)
+#endif
+static char *yank_delete(char *, char *, int, int, int);	// yank text[] into register then delete
+static void show_help(void);	// display some help info
+static void rawmode(void);	// set "raw" mode on tty
+static void cookmode(void);	// return to "cooked" mode on tty
+// sleep for 'h' 1/100 seconds, return 1/0 if stdin is (ready for read)/(not ready)
+static int mysleep(int);
+static int get_one_char(void);	// read 1 char from stdin
+// file_insert might reallocate text[]!
+static int file_insert(const char *, char *, int);
+static int file_write(char *, char *, char *);
+static void place_cursor(int, int);
+static void screen_erase(void);
+static void clear_to_eol(void);
+static void clear_to_eos(void);
+static void go_bottom_and_clear_to_eol(void);
+static void standout_start(void);	// send "start reverse video" sequence
+static void standout_end(void);	// send "end reverse video" sequence
+static void show_status_line(void);	// put a message on the bottom line
+static void status_line(const char *, ...);     // print to status buf
+static void status_line_bold(const char *, ...);
+static void status_line_bold_errno(const char *fn);
+static void not_implemented(const char *); // display "Not implemented" message
+static int format_edit_status(void);	// format file status on status line
+static void redraw(int);	// force a full screen refresh
+static char* format_line(char* /*, int*/);
+static void refresh(int);	// update the terminal from screen[]
+
+static void indicate_error(void);       // beep to indicate error
+static void Hit_Return(void);
+
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+static void winch_sig(int);	// catch window size changes
+static void suspend_sig(int);	// catch ctrl-Z
+static void catch_sig(int);     // catch ctrl-C and alarm time-outs
+#endif
+#define end_cmd_q() ((void)0)
+#if ENABLE_FEATURE_NANO_SETOPTS
+static void showmatching(char *);	// show the matching pair ()  []  {}
+#endif
+#if ENABLE_FEATURE_NANO_YANKMARK || (ENABLE_FEATURE_NANO_COLON && ENABLE_FEATURE_NANO_SEARCH) || ENABLE_FEATURE_NANO_CRASHME
+// might reallocate text[]! use p += string_insert(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+# if !ENABLE_FEATURE_NANO_UNDO
+#define string_insert(a,b,c) string_insert(a,b)
+# endif
+static uintptr_t string_insert(char *, const char *, int);	// insert the string at 'p'
+#endif
+#if ENABLE_FEATURE_NANO_YANKMARK
+static char *text_yank(char *, char *);	// save copy of "p" into a register
+static void check_context(char);	// remember context for '' command
+static int yank_append = 0;
+static int previous_yank_position = -1;
+#endif
+#if ENABLE_FEATURE_NANO_UNDO
+static void flush_undo_data(void);
+static void undo_push(char *, unsigned int, unsigned char);	// Push an operation on the undo stack
+static void undo_pop(void);	// Undo the last operation
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+static void undo_queue_commit(void);	// Flush any queued objects to the undo stack
+# else
+# define undo_queue_commit() ((void)0)
+# endif
+#else
+#define flush_undo_data()   ((void)0)
+#define undo_queue_commit() ((void)0)
+#endif
+
+#if ENABLE_FEATURE_NANO_CRASHME
+static void crash_dummy();
+static void crash_test();
+static int crashme = 0;
+#endif
+
+#if ENABLE_FEATURE_NANO_HIGHLIGHT
+#endif
+
+static void write1(const char *out)
+{
+	fputs(out, stdout);
+}
+
+int nano_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int nano_main(int argc, char **argv)
+{
+	int c;
+
+	INIT_G();
+
+#if ENABLE_FEATURE_NANO_UNDO
+	/* undo_stack_tail = NULL; - already is */
+#if ENABLE_FEATURE_NANO_UNDO_QUEUE
+	undo_queue_state = UNDO_EMPTY;
+	/* undo_q = 0; - already is  */
+#endif
+#endif
+
+#if ENABLE_FEATURE_NANO_USE_SIGNALS || ENABLE_FEATURE_NANO_CRASHME
+	my_pid = getpid();
+#endif
+#if ENABLE_FEATURE_NANO_CRASHME
+	srand((long) my_pid);
+#endif
+#ifdef NO_SUCH_APPLET_YET
+	/* If we aren't "nano", we are "view" */
+	if (ENABLE_FEATURE_NANO_READONLY && applet_name[2]) {
+		SET_READONLY_MODE(readonly_mode);
+	}
+#endif
+
+	// autoindent is not default in vi 7.3
+	nano_setops = /*NANO_AUTOINDENT |*/ NANO_SHOWMATCH | NANO_IGNORECASE;
+	//  1-  process $HOME/.exrc file (not inplemented yet)
+	//  2-  process EXINIT variable from environment
+	//  3-  process command line args
+#if ENABLE_FEATURE_NANO_COLON
+	{
+		char *p = getenv("EXINIT");
+		if (p && *p)
+			initial_cmds[0] = xstrndup(p, MAX_INPUT_LEN);
+	}
+#endif
+	while ((c = getopt(argc, argv, "hCRH" IF_FEATURE_NANO_COLON("c:"))) != -1) {
+		switch (c) {
+#if ENABLE_FEATURE_NANO_CRASHME
+		case 'C':
+			crashme = 1;
+			break;
+#endif
+#if ENABLE_FEATURE_NANO_READONLY
+		case 'R':		// Read-only flag
+			SET_READONLY_MODE(readonly_mode);
+			break;
+#endif
+#if ENABLE_FEATURE_NANO_COLON
+		case 'c':		// cmd line nano command
+			if (*optarg)
+				initial_cmds[initial_cmds[0] != NULL] = xstrndup(optarg, MAX_INPUT_LEN);
+			break;
+#endif
+		case 'H':
+			show_help();
+			/* fall through */
+		default:
+			bb_show_usage();
+			return 1;
+		}
+	}
+
+	// The argv array can be used by the ":next"  and ":rewind" commands
+	argv += optind;
+	argc -= optind;
+
+	//----- This is the main file handling loop --------------
+	save_argc = argc;
+	optind = 0;
+	// "Save cursor, use alternate screen buffer, clear screen"
+	write1("\033[?1049h");
+	while (1) {
+		edit_file(argv[optind]); /* param might be NULL */
+		if (++optind >= argc)
+			break;
+	}
+	// "Use normal screen buffer, restore cursor"
+	write1("\033[?1049l");
+	//-----------------------------------------------------------
+
+	return 0;
+}
+
+/* read text from file or create an empty buf */
+/* will also update current_filename */
+static int init_text_buffer(char *fn)
+{
+	int rc;
+
+	/* allocate/reallocate text buffer */
+	free(text);
+	text_size = 10240;
+	screenbegin = dot = end = text = xzalloc(text_size);
+
+	if (fn != current_filename) {
+		free(current_filename);
+		current_filename = xstrdup(fn);
+	}
+	rc = file_insert(fn, text, 1);
+	if (rc < 0) {
+		// file doesnt exist. Start empty buf with dummy line
+		char_insert(text, '\n', NO_UNDO);
+	}
+
+	flush_undo_data();
+	modified_count = 0;
+	last_modified_count = -1;
+#if ENABLE_FEATURE_NANO_YANKMARK
+	/* init the marks */
+	memset(mark, 0, sizeof(mark));
+#endif
+	return rc;
+}
+
+#if ENABLE_FEATURE_NANO_WIN_RESIZE
+static int query_screen_dimensions(void)
+{
+	int err = get_terminal_width_height(STDIN_FILENO, &columns, &rows);
+	if (rows > MAX_SCR_ROWS)
+		rows = MAX_SCR_ROWS;
+	if (columns > MAX_SCR_COLS)
+		columns = MAX_SCR_COLS;
+	return err;
+}
+#else
+# define query_screen_dimensions() (0)
+#endif
+
+static void edit_file(char *fn)
+{
+#if ENABLE_FEATURE_NANO_YANKMARK
+#define cur_line edit_file__cur_line
+#endif
+	int c;
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+	int sig;
+#endif
+
+	editing = 1;	// 0 = exit, 1 = one file, 2 = multiple files
+	rawmode();
+	rows = 24;
+	columns = 80;
+	IF_FEATURE_NANO_ASK_TERMINAL(G.get_rowcol_error =) query_screen_dimensions();
+#if ENABLE_FEATURE_NANO_ASK_TERMINAL
+	if (G.get_rowcol_error /* TODO? && no input on stdin */) {
+		uint64_t k;
+		write1("\033[999;999H" "\033[6n");
+		fflush_all();
+		k = read_key(STDIN_FILENO, readbuffer, /*timeout_ms:*/ 100);
+		if ((int32_t)k == KEYCODE_CURSOR_POS) {
+			uint32_t rc = (k >> 32);
+			columns = (rc & 0x7fff);
+			if (columns > MAX_SCR_COLS)
+				columns = MAX_SCR_COLS;
+			rows = ((rc >> 16) & 0x7fff);
+			if (rows > MAX_SCR_ROWS)
+				rows = MAX_SCR_ROWS;
+		}
+	}
+#endif
+	new_screen(rows, columns);	// get memory for virtual screen
+	init_text_buffer(fn);
+
+#if ENABLE_FEATURE_NANO_YANKMARK
+	mark[26] = mark[27] = text;	// init "previous context"
+#endif
+
+	last_forward_char = last_input_char = '\0';
+	crow = 0;
+	ccol = 0;
+
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+	signal(SIGINT, catch_sig);
+	signal(SIGWINCH, winch_sig);
+	signal(SIGTSTP, suspend_sig);
+	sig = sigsetjmp(restart, 1);
+	if (sig != 0) {
+		screenbegin = dot = text;
+	}
+#endif
+
+	tabstop = 8;
+	offset = 0;			// no horizontal offset
+	c = '\0';
+
+	redraw(FALSE);			// dont force every col re-draw
+	//------This is the main Nano cmd handling loop -----------------------
+	while (editing > 0) {
+#if ENABLE_FEATURE_NANO_CRASHME
+		if (crashme > 0) {
+			if ((end - text) > 1) {
+				crash_dummy();	// generate a random command
+			} else {
+				crashme = 0;
+				string_insert(text, "\n\n#####  Ran out of text to work on.  #####\n\n", NO_UNDO); // insert the string
+				dot = text;
+				refresh(FALSE);
+			}
+		}
+#endif
+		last_input_char = c = get_one_char();	// get a cmd from user
+		do_cmd(c);		// execute the user command
+
+		// poll to see if there is input already waiting. if we are
+		// not able to display output fast enough to keep up, skip
+		// the display update until we catch up with input.
+		if (!readbuffer[0] && mysleep(0) == 0) {
+			// no input pending - so update output
+			refresh(FALSE);
+			show_status_line();
+		}
+#if ENABLE_FEATURE_NANO_CRASHME
+		if (crashme > 0)
+			crash_test();	// test editor variables
+#endif
+	}
+	//-------------------------------------------------------------------
+
+	go_bottom_and_clear_to_eol();
+	cookmode();
+#undef cur_line
+}
+
+static void Hit_Return(void)
+{
+	int c;
+
+	standout_start();
+	write1("[Hit return to continue]");
+	standout_end();
+	while ((c = get_one_char()) != '\n' && c != '\r')
+		continue;
+	redraw(TRUE);		// force redraw all
+}
+
+static int next_tabstop(int col)
+{
+	return col + ((tabstop - 1) - (col % tabstop));
+}
+
+#if ENABLE_FEATURE_NANO_UTF8
+static int utf8_char_len(unsigned char c)
+{
+	return
+		(c & 0x40) ?
+			((c & 0x20) ?
+				((c & 0x10) ?
+					((c & 0x8) ? 1 : 4)
+				: 3)
+			: 2)
+		: 1;
+}
+#endif
+
+//----- Synchronize the cursor to Dot --------------------------
+static NOINLINE void sync_cursor(char *d, int *row, int *col)
+{
+	char *beg_cur;	// begin and end of "d" line
+	char *tp;
+	int cnt, ro, co;
+
+	beg_cur = begin_line(d);	// first char of cur line
+
+	if (beg_cur < screenbegin) {
+		// "d" is before top line on screen
+		// how many lines do we have to move
+		cnt = count_lines(beg_cur, screenbegin);
+ sc1:
+		screenbegin = beg_cur;
+		if (cnt > (rows - 1) / 2) {
+			// we moved too many lines. put "dot" in middle of screen
+			for (cnt = 0; cnt < (rows - 1) / 2; cnt++) {
+				screenbegin = prev_line(screenbegin);
+			}
+		}
+	} else {
+		char *end_scr;	// begin and end of screen
+		end_scr = end_screen();	// last char of screen
+		if (beg_cur > end_scr) {
+			// "d" is after bottom line on screen
+			// how many lines do we have to move
+			cnt = count_lines(end_scr, beg_cur);
+			if (cnt > (rows - 1) / 2)
+				goto sc1;	// too many lines
+			for (ro = 0; ro < cnt - 1; ro++) {
+				// move screen begin the same amount
+				screenbegin = next_line(screenbegin);
+				// now, move the end of screen
+				end_scr = next_line(end_scr);
+				end_scr = end_line(end_scr);
+			}
+		}
+	}
+	// "d" is on screen- find out which row
+	tp = screenbegin;
+	for (ro = 0; ro < rows - 1; ro++) {	// drive "ro" to correct row
+		if (tp == beg_cur)
+			break;
+		tp = next_line(tp);
+	}
+
+	// find out what col "d" is on
+	co = 0;
+	while (tp < d) { // drive "co" to correct column
+		if (*tp == '\n') //vda || *tp == '\0')
+			break;
+		if (*tp == '\t') {
+			// handle tabs like real nano
+			if (d == tp) {
+				break;
+			}
+			co = next_tabstop(co);
+		} else if ((unsigned char)*tp < ' ' || *tp == 0x7f) {
+			co++; // display as ^X, use 2 columns
+#if ENABLE_FEATURE_NANO_UTF8
+		} else if (*tp & 0x80) {
+#if ENABLE_FEATURE_NANO_UTF8_MIXED
+			char *tp_orig = tp;
+			int char_len = utf8_char_len(*tp) - 1;
+			do {
+				tp++;
+				if ((*tp & 0xC0) != 0x80) {
+					tp = tp_orig;
+					break;
+				}
+				if (!(--char_len > 0)) break;
+				if (!(tp < d)) {
+					tp = tp_orig;
+					break;
+				}
+			} while (1);
+#else
+			int char_len = utf8_char_len(*tp) - 1;
+			do { tp++; } while (tp < d && (--char_len > 0));
+#endif
+#endif
+		}
+		co++;
+		tp++;
+	}
+
+	// "co" is the column where "dot" is.
+	// The screen has "columns" columns.
+	// The currently displayed columns are  0+offset -- columns+ofset
+	// |-------------------------------------------------------------|
+	//               ^ ^                                ^
+	//        offset | |------- columns ----------------|
+	//
+	// If "co" is already in this range then we do not have to adjust offset
+	//      but, we do have to subtract the "offset" bias from "co".
+	// If "co" is outside this range then we have to change "offset".
+	// If the first char of a line is a tab the cursor will try to stay
+	//  in column 7, but we have to set offset to 0.
+
+	if (co < 0 + offset) {
+		offset = co;
+	}
+	if (co >= columns + offset) {
+		offset = co - columns + 1;
+	}
+	// if the first char of the line is a tab, and "dot" is sitting on it
+	//  force offset to 0.
+	if (d == beg_cur && *d == '\t') {
+		offset = 0;
+	}
+	co -= offset;
+
+	*row = ro;
+	*col = co;
+}
+
+//----- Text Movement Routines ---------------------------------
+static char *begin_line(char *p) // return pointer to first char cur line
+{
+	if (p > text) {
+		p = memrchr(text, '\n', p - text);
+		if (!p)
+			return text;
+		return p + 1;
+	}
+	return p;
+}
+
+static char *end_line(char *p) // return pointer to NL of cur line
+{
+	if (p < end - 1) {
+		p = memchr(p, '\n', end - p - 1);
+		if (!p)
+			return end - 1;
+	}
+	return p;
+}
+
+static char *prev_line(char *p) // return pointer first char prev line
+{
+	p = begin_line(p);	// goto beginning of cur line
+	if (p > text && p[-1] == '\n')
+		p--;			// step to prev line
+	p = begin_line(p);	// goto beginning of prev line
+	return p;
+}
+
+static char *next_line(char *p) // return pointer first char next line
+{
+	p = end_line(p);
+	if (p < end - 1 && *p == '\n')
+		p++;			// step to next line
+	return p;
+}
+
+//----- Text Information Routines ------------------------------
+static char *end_screen(void)
+{
+	char *q;
+	int cnt;
+
+	// find new bottom line
+	q = screenbegin;
+	for (cnt = 0; cnt < rows - 2; cnt++)
+		q = next_line(q);
+	q = end_line(q);
+	return q;
+}
+
+// count line from start to stop
+static int count_lines(char *start, char *stop)
+{
+	char *q;
+	int cnt;
+
+	if (stop < start) { // start and stop are backwards- reverse them
+		q = start;
+		start = stop;
+		stop = q;
+	}
+	cnt = 0;
+	stop = end_line(stop);
+	while (start <= stop && start <= end - 1) {
+		start = end_line(start);
+		if (*start == '\n')
+			cnt++;
+		start++;
+	}
+	return cnt;
+}
+
+//----- Dot Movement Routines ----------------------------------
+static void dot_left(void)
+{
+	undo_queue_commit();
+#if 0
+	// Vi-like movement
+	if (dot > text && dot[-1] != '\n')
+	 	dot--;
+#else
+	if (dot > text) dot--;
+#if ENABLE_FEATURE_NANO_UTF8
+        if (*dot & 0x80) {
+		char *utf8_char_start = dot;
+#if ENABLE_FEATURE_NANO_UTF8_MIXED
+                do {
+			if (*utf8_char_start & 0x40) break;
+			if (utf8_char_start <= text) goto unrecognized_utf8_code;
+			utf8_char_start--;
+			if (!(*utf8_char_start & 0x80)) goto unrecognized_utf8_code;
+			if (dot - utf8_char_start > 3) goto unrecognized_utf8_code;
+		} while (1);
+		if (utf8_char_len(*utf8_char_start) == (dot - utf8_char_start + 1)) {
+			dot = utf8_char_start;
+                }
+#else
+                do {
+			if (*utf8_char_start & 0x40) break;
+			if (utf8_char_start <= text) goto unrecognized_utf8_code;
+			utf8_char_start--;
+		} while (1);
+		dot = utf8_char_start;
+#endif
+ unrecognized_utf8_code: ;
+	}
+#endif
+#endif
+}
+
+static void dot_right(void)
+{
+	undo_queue_commit();
+#if 0
+	// Vi-like movement
+	if (dot < end - 1 && *dot != '\n')
+		dot++;
+#else
+#if ENABLE_FEATURE_NANO_UTF8
+	if (*dot & 0x80) {
+#if ENABLE_FEATURE_NANO_UTF8_MIXED
+		char *orig_dot = dot;
+		int char_len = utf8_char_len(*dot);
+		while (dot < end - 1 && --char_len > 0) {
+			dot++;
+			if (*dot & 0xC0 != 0x80) {
+				dot = orig_dot;
+				break;
+			}
+		}
+#else
+		int char_len = utf8_char_len(*dot);
+		while (dot < end - 1 && --char_len > 0) dot++;
+#endif
+	}
+#endif
+	if (dot < end - 1) dot++;
+#endif
+}
+
+static void dot_begin(void)
+{
+	undo_queue_commit();
+	dot = begin_line(dot);	// return pointer to first char cur line
+}
+
+static char *move_to_col(char *p, int l)
+{
+	int co;
+
+	p = begin_line(p);
+	co = 0;
+	while (co < l && p < end) {
+		if (*p == '\n') //vda || *p == '\0')
+			break;
+		if (*p == '\t') {
+			co = next_tabstop(co);
+		} else if (*p < ' ' || *p == 127) {
+			co++; // display as ^X, use 2 columns
+		}
+		co++;
+		p++;
+	}
+	return p;
+}
+
+static void dot_next(void)
+{
+	undo_queue_commit();
+	dot = next_line(dot);
+}
+
+static void dot_prev(void)
+{
+	undo_queue_commit();
+	dot = prev_line(dot);
+}
+
+static void dot_scroll(int cnt, int dir)
+{
+	char *q;
+
+	undo_queue_commit();
+	for (; cnt > 0; cnt--) {
+		if (dir < 0) {
+			// scroll Backwards
+			// ctrl-Y scroll up one line
+			screenbegin = prev_line(screenbegin);
+		} else {
+			// scroll Forwards
+			// ctrl-E scroll down one line
+			screenbegin = next_line(screenbegin);
+		}
+	}
+	// make sure "dot" stays on the screen so we dont scroll off
+	if (dot < screenbegin)
+		dot = screenbegin;
+	q = end_screen();	// find new bottom line
+	if (dot > q)
+		dot = begin_line(q);	// is dot is below bottom line?
+	dot_skip_over_ws();
+}
+
+static void dot_skip_over_ws(void)
+{
+	// skip WS
+	while (isspace(*dot) && *dot != '\n' && dot < end - 1)
+		dot++;
+}
+
+static char *bound_dot(char *p) // make sure  text[0] <= P < "end"
+{
+	if (p >= end && end > text) {
+		p = end - 1;
+		indicate_error();
+	}
+	if (p < text) {
+		p = text;
+		indicate_error();
+	}
+	return p;
+}
+
+//----- Helper Utility Routines --------------------------------
+
+//----------------------------------------------------------------
+//----- Char Routines --------------------------------------------
+/* Chars that are part of a word-
+ *    0123456789_ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
+ * Chars that are Not part of a word (stoppers)
+ *    !"#$%&'()*+,-./:;<=>?@[\]^`{|}~
+ * Chars that are WhiteSpace
+ *    TAB NEWLINE VT FF RETURN SPACE
+ * DO NOT COUNT NEWLINE AS WHITESPACE
+ */
+
+static char *new_screen(int ro, int co)
+{
+	int li;
+
+	free(screen);
+	screensize = ro * co + 8;
+	screen = xmalloc(screensize);
+	// initialize the new screen. assume this will be a empty file.
+	screen_erase();
+	//   non-existent text[] lines start with a tilde (~).
+	for (li = 1; li < ro - 1; li++) {
+		screen[(li * co) + 0] = '~';
+	}
+	return screen;
+}
+
+#if ENABLE_FEATURE_NANO_SEARCH
+
+# if ENABLE_FEATURE_NANO_REGEX_SEARCH
+
+# else
+
+#  if ENABLE_FEATURE_NANO_SETOPTS
+static int mycmp(const char *s1, const char *s2, int len)
+{
+	if (ignorecase) {
+		return strncasecmp(s1, s2, len);
+	}
+	return strncmp(s1, s2, len);
+}
+#  else
+#   define mycmp strncmp
+#  endif
+
+# endif
+
+#endif /* FEATURE_NANO_SEARCH */
+
+#define CTRL_CODE(x) (1+x-'A')
+
+static char *char_insert(char *p, char c, int undo) // insert the char c at 'p'
+{
+	switch (c) {
+	case CTRL_CODE('V'):
+		p += stupid_insert(p, '^');	// use ^ to indicate literal next
+		refresh(FALSE);	// show the ^
+		c = get_one_char();
+		*p = c;
+#if ENABLE_FEATURE_NANO_UNDO
+		switch (undo) {
+			case ALLOW_UNDO:
+				undo_push(p, 1, UNDO_INS);
+				break;
+			case ALLOW_UNDO_CHAIN:
+				undo_push(p, 1, UNDO_INS_CHAIN);
+				break;
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+			case ALLOW_UNDO_QUEUED:
+				undo_push(p, 1, UNDO_INS_QUEUED);
+				break;
+# endif
+		}
+#else
+		modified_count++;
+#endif /* ENABLE_FEATURE_NANO_UNDO */
+		p++;
+                break;
+#if 0
+  // Vi specific
+	case 27:	// Is this an ESC?
+		cmd_mode = 0;
+		undo_queue_commit();
+		end_cmd_q();	// stop adding to q
+		last_status_cksum = 0;	// force status update
+		if ((p[-1] != '\n') && (dot > text)) {
+			p--;
+		}
+                break;
+#endif
+        case 8: case 127:
+ backspace:
+		if (p > text) {
+			p--;
+			p = text_hole_delete(p, p, ALLOW_UNDO_QUEUED);	// shrink buffer 1 char
+		}
+		break;
+	default:
+                if (c == erase_char) goto backspace;
+		// insert a char into text[]
+		if (c == 13)
+			c = '\n';	// translate \r to \n
+#if ENABLE_FEATURE_NANO_UNDO
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+		if (c == '\n')
+			undo_queue_commit();
+# endif
+		switch (undo) {
+			case ALLOW_UNDO:
+				undo_push(p, 1, UNDO_INS);
+				break;
+			case ALLOW_UNDO_CHAIN:
+				undo_push(p, 1, UNDO_INS_CHAIN);
+				break;
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+			case ALLOW_UNDO_QUEUED:
+				undo_push(p, 1, UNDO_INS_QUEUED);
+				break;
+# endif
+		}
+#else
+		modified_count++;
+#endif /* ENABLE_FEATURE_NANO_UNDO */
+		p += 1 + stupid_insert(p, c);	// insert the char
+#if 0&&ENABLE_FEATURE_NANO_UTF8
+		// Causes segfault!
+                if (c & 0x80) {
+			int utf8_len = utf8_char_len(c);
+			while (--utf8_len > 0) {
+	                    c = get_one_char();
+	                    p += 1 + stupid_insert(p, c); // this may break undo? FIXME
+			}
+			c = 0;
+                }
+#endif
+#if ENABLE_FEATURE_NANO_SETOPTS
+		if (showmatch && strchr(")]}", c) != NULL) {
+			showmatching(p - 1);
+		}
+		if (autoindent && c == '\n') {	// auto indent the new line
+			char *q;
+			size_t len;
+			q = prev_line(p);	// use prev line as template
+			len = strspn(q, " \t"); // space or tab
+			if (len) {
+				uintptr_t bias;
+				bias = text_hole_make(p, len);
+				p += bias;
+				q += bias;
+#if ENABLE_FEATURE_NANO_UNDO
+				undo_push(p, len, UNDO_INS);
+#endif
+				memcpy(p, q, len);
+				p += len;
+			}
+		}
+#endif
+	}
+	return p;
+}
+
+// might reallocate text[]! use p += stupid_insert(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+static uintptr_t stupid_insert(char *p, char c) // stupidly insert the char c at 'p'
+{
+	uintptr_t bias;
+	bias = text_hole_make(p, 1);
+	p += bias;
+	*p = c;
+	return bias;
+}
+
+// find matching char of pair  ()  []  {}
+// will crash if c is not one of these
+static char *find_pair(char *p, const char c)
+{
+	const char *braces = "()[]{}";
+	char match;
+	int dir, level;
+
+	dir = strchr(braces, c) - braces;
+	dir ^= 1;
+	match = braces[dir];
+	dir = ((dir & 1) << 1) - 1; /* 1 for ([{, -1 for )\} */
+
+	// look for match, count levels of pairs  (( ))
+	level = 1;
+	for (;;) {
+		p += dir;
+		if (p < text || p >= end)
+			return NULL;
+		if (*p == c)
+			level++;	// increase pair levels
+		if (*p == match) {
+			level--;	// reduce pair level
+			if (level == 0)
+				return p; // found matching pair
+		}
+	}
+}
+
+#if ENABLE_FEATURE_NANO_SETOPTS
+// show the matching char of a pair,  ()  []  {}
+static void showmatching(char *p)
+{
+	char *q, *save_dot;
+
+	// we found half of a pair
+	q = find_pair(p, *p);	// get loc of matching char
+	if (q == NULL) {
+		indicate_error();	// no matching char
+	} else {
+		// "q" now points to matching pair
+		save_dot = dot;	// remember where we are
+		dot = q;		// go to new loc
+		refresh(FALSE);	// let the user see it
+		mysleep(40);	// give user some time
+		dot = save_dot;	// go back to old loc
+		refresh(FALSE);
+	}
+}
+#endif /* FEATURE_NANO_SETOPTS */
+
+#if ENABLE_FEATURE_NANO_UNDO
+static void flush_undo_data(void)
+{
+	struct undo_object *undo_entry;
+
+	while (undo_stack_tail) {
+		undo_entry = undo_stack_tail;
+		undo_stack_tail = undo_entry->prev;
+		free(undo_entry);
+	}
+}
+
+// Undo functions and hooks added by Jody Bruchon (jody@jodybruchon.com)
+static void undo_push(char *src, unsigned int length, uint8_t u_type)	// Add to the undo stack
+{
+	struct undo_object *undo_entry;
+
+	// "u_type" values
+	// UNDO_INS: insertion, undo will remove from buffer
+	// UNDO_DEL: deleted text, undo will restore to buffer
+	// UNDO_{INS,DEL}_CHAIN: Same as above but also calls undo_pop() when complete
+	// The CHAIN operations are for handling multiple operations that the user
+	// performs with a single action, i.e. REPLACE mode or find-and-replace commands
+	// UNDO_{INS,DEL}_QUEUED: If queuing feature is enabled, allow use of the queue
+	// for the INS/DEL operation. The raw values should be equal to the values of
+	// UNDO_{INS,DEL} ORed with UNDO_QUEUED_FLAG
+
+#if ENABLE_FEATURE_NANO_UNDO_QUEUE
+	// This undo queuing functionality groups multiple character typing or backspaces
+	// into a single large undo object. This greatly reduces calls to malloc() for
+	// single-character operations while typing and has the side benefit of letting
+	// an undo operation remove chunks of text rather than a single character.
+	switch (u_type) {
+	case UNDO_EMPTY:	// Just in case this ever happens...
+		return;
+	case UNDO_DEL_QUEUED:
+		if (length != 1)
+			return;	// Only queue single characters
+		switch (undo_queue_state) {
+		case UNDO_EMPTY:
+			undo_queue_state = UNDO_DEL;
+		case UNDO_DEL:
+			undo_queue_spos = src;
+			undo_q++;
+			undo_queue[CONFIG_FEATURE_NANO_UNDO_QUEUE_MAX - undo_q] = *src;
+			// If queue is full, dump it into an object
+			if (undo_q == CONFIG_FEATURE_NANO_UNDO_QUEUE_MAX)
+				undo_queue_commit();
+			return;
+		case UNDO_INS:
+			// Switch from storing inserted text to deleted text
+			undo_queue_commit();
+			undo_push(src, length, UNDO_DEL_QUEUED);
+			return;
+		}
+		break;
+	case UNDO_INS_QUEUED:
+		if (length != 1)
+			return;
+		switch (undo_queue_state) {
+		case UNDO_EMPTY:
+			undo_queue_state = UNDO_INS;
+			undo_queue_spos = src;
+		case UNDO_INS:
+			undo_q++;	// Don't need to save any data for insertions
+			if (undo_q == CONFIG_FEATURE_NANO_UNDO_QUEUE_MAX)
+				undo_queue_commit();
+			return;
+		case UNDO_DEL:
+			// Switch from storing deleted text to inserted text
+			undo_queue_commit();
+			undo_push(src, length, UNDO_INS_QUEUED);
+			return;
+		}
+		break;
+	}
+#else
+	// If undo queuing is disabled, ignore the queuing flag entirely
+	u_type = u_type & ~UNDO_QUEUED_FLAG;
+#endif
+
+	// Allocate a new undo object
+	if (u_type == UNDO_DEL || u_type == UNDO_DEL_CHAIN) {
+		// For UNDO_DEL objects, save deleted text
+		if ((src + length) == end)
+			length--;
+		// If this deletion empties text[], strip the newline. When the buffer becomes
+		// zero-length, a newline is added back, which requires this to compensate.
+		undo_entry = xzalloc(offsetof(struct undo_object, undo_text) + length);
+		memcpy(undo_entry->undo_text, src, length);
+	} else {
+		undo_entry = xzalloc(sizeof(*undo_entry));
+	}
+	undo_entry->length = length;
+#if ENABLE_FEATURE_NANO_UNDO_QUEUE
+	if ((u_type & UNDO_USE_SPOS) != 0) {
+		undo_entry->start = undo_queue_spos - text;	// use start position from queue
+	} else {
+		undo_entry->start = src - text;	// use offset from start of text buffer
+	}
+	u_type = (u_type & ~UNDO_USE_SPOS);
+#else
+	undo_entry->start = src - text;
+#endif
+	undo_entry->u_type = u_type;
+
+	// Push it on undo stack
+	undo_entry->prev = undo_stack_tail;
+	undo_stack_tail = undo_entry;
+	modified_count++;
+}
+
+static void undo_pop(void)	// Undo the last operation
+{
+	int repeat;
+	char *u_start, *u_end;
+	struct undo_object *undo_entry;
+
+	// Commit pending undo queue before popping (should be unnecessary)
+	undo_queue_commit();
+
+	undo_entry = undo_stack_tail;
+	// Check for an empty undo stack
+	if (!undo_entry) {
+		status_line("Already at oldest change");
+		return;
+	}
+
+	switch (undo_entry->u_type) {
+	case UNDO_DEL:
+	case UNDO_DEL_CHAIN:
+		// make hole and put in text that was deleted; deallocate text
+		u_start = text + undo_entry->start;
+		text_hole_make(u_start, undo_entry->length);
+		memcpy(u_start, undo_entry->undo_text, undo_entry->length);
+		status_line("Undo [%d] %s %d chars at position %d",
+			modified_count, "restored",
+			undo_entry->length, undo_entry->start
+		);
+		break;
+	case UNDO_INS:
+	case UNDO_INS_CHAIN:
+		// delete what was inserted
+		u_start = undo_entry->start + text;
+		u_end = u_start - 1 + undo_entry->length;
+		text_hole_delete(u_start, u_end, NO_UNDO);
+		status_line("Undo [%d] %s %d chars at position %d",
+			modified_count, "deleted",
+			undo_entry->length, undo_entry->start
+		);
+		break;
+	}
+	repeat = 0;
+	switch (undo_entry->u_type) {
+	// If this is the end of a chain, lower modification count and refresh display
+	case UNDO_DEL:
+	case UNDO_INS:
+		dot = (text + undo_entry->start);
+		refresh(FALSE);
+		break;
+	case UNDO_DEL_CHAIN:
+	case UNDO_INS_CHAIN:
+		repeat = 1;
+		break;
+	}
+	// Deallocate the undo object we just processed
+	undo_stack_tail = undo_entry->prev;
+	free(undo_entry);
+	modified_count--;
+	// For chained operations, continue popping all the way down the chain.
+	if (repeat) {
+		undo_pop();	// Follow the undo chain if one exists
+	}
+}
+
+#if ENABLE_FEATURE_NANO_UNDO_QUEUE
+static void undo_queue_commit(void)	// Flush any queued objects to the undo stack
+{
+	// Pushes the queue object onto the undo stack
+	if (undo_q > 0) {
+		// Deleted character undo events grow from the end
+		undo_push(undo_queue + CONFIG_FEATURE_NANO_UNDO_QUEUE_MAX - undo_q,
+			undo_q,
+			(undo_queue_state | UNDO_USE_SPOS)
+		);
+		undo_queue_state = UNDO_EMPTY;
+		undo_q = 0;
+	}
+}
+#endif
+
+#endif /* ENABLE_FEATURE_NANO_UNDO */
+
+// open a hole in text[]
+// might reallocate text[]! use p += text_hole_make(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+static uintptr_t text_hole_make(char *p, int size)	// at "p", make a 'size' byte hole
+{
+	uintptr_t bias = 0;
+
+	if (size <= 0)
+		return bias;
+	end += size;		// adjust the new END
+	if (end >= (text + text_size)) {
+		char *new_text;
+		text_size += end - (text + text_size) + 10240;
+		new_text = xrealloc(text, text_size);
+		bias = (new_text - text);
+		screenbegin += bias;
+		dot         += bias;
+		end         += bias;
+		p           += bias;
+#if ENABLE_FEATURE_NANO_YANKMARK
+		{
+			int i;
+			for (i = 0; i < ARRAY_SIZE(mark); i++)
+				if (mark[i])
+					mark[i] += bias;
+		}
+#endif
+		text = new_text;
+	}
+	memmove(p + size, p, end - size - p);
+	memset(p, ' ', size);	// clear new hole
+	return bias;
+}
+
+//  close a hole in text[]
+//  "undo" value indicates if this operation should be undo-able
+static char *text_hole_delete(char *p, char *q, int undo) // delete "p" through "q", inclusive
+{
+	char *src, *dest;
+	int cnt, hole_size;
+
+	// move forwards, from beginning
+	// assume p <= q
+	src = q + 1;
+	dest = p;
+	if (q < p) {		// they are backward- swap them
+		src = p + 1;
+		dest = q;
+	}
+	hole_size = q - p + 1;
+	cnt = end - src;
+#if ENABLE_FEATURE_NANO_UNDO
+	switch (undo) {
+		case NO_UNDO:
+			break;
+		case ALLOW_UNDO:
+			undo_push(p, hole_size, UNDO_DEL);
+			break;
+		case ALLOW_UNDO_CHAIN:
+			undo_push(p, hole_size, UNDO_DEL_CHAIN);
+			break;
+# if ENABLE_FEATURE_NANO_UNDO_QUEUE
+		case ALLOW_UNDO_QUEUED:
+			undo_push(p, hole_size, UNDO_DEL_QUEUED);
+			break;
+# endif
+	}
+	modified_count--;
+#endif
+	if (src < text || src > end)
+		goto thd0;
+	if (dest < text || dest >= end)
+		goto thd0;
+	modified_count++;
+	if (src >= end)
+		goto thd_atend;	// just delete the end of the buffer
+	memmove(dest, src, cnt);
+ thd_atend:
+	end = end - hole_size;	// adjust the new END
+	if (dest >= end)
+		dest = end - 1;	// make sure dest in below end-1
+	if (end <= text)
+		dest = end = text;	// keep pointers valid
+ thd0:
+	return dest;
+}
+
+// copy text into register, then delete text.
+// if dist <= 0, do not include, or go past, a NewLine
+//
+static char *yank_delete(char *start, char *stop, int dist, int yf, int undo)
+{
+	char *p;
+
+	// make sure start <= stop
+	if (start > stop) {
+		// they are backwards, reverse them
+		p = start;
+		start = stop;
+		stop = p;
+	}
+	if (dist <= 0) {
+		// we cannot cross NL boundaries
+		p = start;
+		if (*p == '\n')
+			return p;
+		// dont go past a NewLine
+		for (; p + 1 <= stop; p++) {
+			if (p[1] == '\n') {
+				stop = p;	// "stop" just before NewLine
+				break;
+			}
+		}
+	}
+	p = start;
+#if ENABLE_FEATURE_NANO_YANKMARK
+	text_yank(start, stop);
+#endif
+	if (yf == YANKDEL) {
+		p = text_hole_delete(start, stop, undo);
+	}					// delete lines
+	return p;
+}
+
+static void show_help(void)
+{
+	puts("These features are available:"
+#if ENABLE_FEATURE_NANO_SEARCH
+	"\n\tPattern searches with / and ?"
+#endif
+#if ENABLE_FEATURE_NANO_YANKMARK
+	"\n\tLine marking with 'x"
+	"\n\tNamed buffers with \"x"
+#endif
+#if ENABLE_FEATURE_NANO_READONLY
+	//not implemented: "\n\tReadonly if nano is called as \"view\""
+	//redundant: usage text says this too: "\n\tReadonly with -R command line arg"
+#endif
+#if ENABLE_FEATURE_NANO_SET
+	"\n\tSome colon mode commands with :"
+#endif
+#if ENABLE_FEATURE_NANO_SETOPTS
+	"\n\tSettable options with \":set\""
+#endif
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+	"\n\tSignal catching- ^C"
+	"\n\tJob suspend and resume with ^Z"
+#endif
+#if ENABLE_FEATURE_NANO_WIN_RESIZE
+	"\n\tAdapt to window re-sizes"
+#endif
+	);
+}
+
+#if ENABLE_FEATURE_NANO_YANKMARK \
+ || (ENABLE_FEATURE_NANO_COLON && ENABLE_FEATURE_NANO_SEARCH) \
+ || ENABLE_FEATURE_NANO_CRASHME
+// might reallocate text[]! use p += string_insert(p, ...),
+// and be careful to not use pointers into potentially freed text[]!
+static uintptr_t string_insert(char *p, const char *s, int undo) // insert the string at 'p'
+{
+	uintptr_t bias;
+	int i;
+
+	i = strlen(s);
+#if ENABLE_FEATURE_NANO_UNDO
+	switch (undo) {
+		case ALLOW_UNDO:
+			undo_push(p, i, UNDO_INS);
+			break;
+		case ALLOW_UNDO_CHAIN:
+			undo_push(p, i, UNDO_INS_CHAIN);
+			break;
+	}
+#endif
+	bias = text_hole_make(p, i);
+	p += bias;
+	memcpy(p, s, i);
+#if ENABLE_FEATURE_NANO_YANKMARK
+	{
+		int cnt;
+		for (cnt = 0; *s != '\0'; s++) {
+			if (*s == '\n')
+				cnt++;
+		}
+		status_line("Put %d lines (%d chars)", cnt, i);
+	}
+#endif
+	return bias;
+}
+#endif
+
+#if ENABLE_FEATURE_NANO_YANKMARK
+static char *text_yank(char *p, char *q)	// copy text into a register
+{
+	int cnt = q - p;
+	if (cnt < 0) {		// they are backwards- reverse them
+		p = q;
+		cnt = -cnt;
+	}
+	if (yank_append) {
+                int l = strlen(clipboard);
+		clipboard = xrealloc(clipboard, l + cnt + 2);
+		memcpy(clipboard + l, p, cnt + 1);
+		clipboard[l + cnt + 1] = 0;
+	} else {
+		free(clipboard);	//  if already a yank register, free it
+		clipboard = xstrndup(p, cnt + 1);
+	}
+	return p;
+}
+
+static void check_context(char cmd)
+{
+	// A context is defined to be "modifying text"
+	// Any modifying command establishes a new context.
+
+	if (dot < context_start || dot > context_end) {
+		if (strchr(modifying_cmds, cmd) != NULL) {
+			// we are trying to modify text[]- make this the current context
+			mark[27] = mark[26];	// move cur to prev
+			mark[26] = dot;	// move local to cur
+			context_start = prev_line(prev_line(dot));
+			context_end = next_line(next_line(dot));
+			//loiter= start_loiter= now;
+		}
+	}
+}
+
+#endif /* FEATURE_NANO_YANKMARK */
+
+//----- Set terminal attributes --------------------------------
+static void rawmode(void)
+{
+	// no TERMIOS_CLEAR_ISIG: leave ISIG on - allow signals
+	set_termios_to_raw(STDIN_FILENO, &term_orig, TERMIOS_RAW_CRNL);
+	erase_char = term_orig.c_cc[VERASE];
+}
+
+static void cookmode(void)
+{
+	fflush_all();
+	tcsetattr_stdin_TCSANOW(&term_orig);
+}
+
+#if ENABLE_FEATURE_NANO_USE_SIGNALS
+//----- Come here when we get a window resize signal ---------
+static void winch_sig(int sig UNUSED_PARAM)
+{
+	int save_errno = errno;
+	// FIXME: do it in main loop!!!
+	signal(SIGWINCH, winch_sig);
+	query_screen_dimensions();
+	new_screen(rows, columns);	// get memory for virtual screen
+	redraw(TRUE);		// re-draw the screen
+	errno = save_errno;
+}
+
+//----- Come here when we get a continue signal -------------------
+static void cont_sig(int sig UNUSED_PARAM)
+{
+	int save_errno = errno;
+	rawmode(); // terminal to "raw"
+	last_status_cksum = 0; // force status update
+	redraw(TRUE); // re-draw the screen
+
+	signal(SIGTSTP, suspend_sig);
+	signal(SIGCONT, SIG_DFL);
+	//kill(my_pid, SIGCONT); // huh? why? we are already "continued"...
+	errno = save_errno;
+}
+
+//----- Come here when we get a Suspend signal -------------------
+static void suspend_sig(int sig UNUSED_PARAM)
+{
+	int save_errno = errno;
+	go_bottom_and_clear_to_eol();
+	cookmode(); // terminal to "cooked"
+
+	signal(SIGCONT, cont_sig);
+	signal(SIGTSTP, SIG_DFL);
+	kill(my_pid, SIGTSTP);
+	errno = save_errno;
+}
+
+//----- Come here when we get a signal ---------------------------
+static void catch_sig(int sig)
+{
+	signal(SIGINT, catch_sig);
+	siglongjmp(restart, sig);
+}
+#endif /* FEATURE_NANO_USE_SIGNALS */
+
+static int mysleep(int hund)	// sleep for 'hund' 1/100 seconds or stdin ready
+{
+	struct pollfd pfd[1];
+
+	if (hund != 0)
+		fflush_all();
+
+	pfd[0].fd = STDIN_FILENO;
+	pfd[0].events = POLLIN;
+	return safe_poll(pfd, 1, hund*10) > 0;
+}
+
+static int get_one_char(void) // read (maybe cursor) key from stdin
+{
+	int c;
+
+	fflush_all();
+
+	// Wait for input. TIMEOUT = -1 makes read_key wait even
+	// on nonblocking stdin.
+	// Note: read_key sets errno to 0 on success.
+ again:
+	c = read_key(STDIN_FILENO, readbuffer, /*timeout:*/ -1);
+	if (c == -1) { // EOF/error
+		if (errno == EAGAIN) // paranoia
+			goto again;
+		go_bottom_and_clear_to_eol();
+		cookmode(); // terminal to "cooked"
+		bb_error_msg_and_die("can't read user input");
+	}
+	return c;
+}
+
+// Get input line (uses "status line" area)
+static char *get_input_line(const char *prompt, const char *value)
+{
+	// char [MAX_INPUT_LEN]
+#define buf get_input_line__buf
+
+	int c;
+	int i;
+	int selected = 0;
+
+	int prompt_len = strlen(prompt);
+	strcpy(buf, prompt);
+        strncat(buf, value, sizeof(buf));
+	last_status_cksum = 0;	// force status update
+	go_bottom_and_clear_to_eol();
+	write1(buf);      // write out the :, /, or ? prompt
+	if (value != NULL && value[0]) {
+		place_cursor(rows - 1, prompt_len);
+		selected = 1;
+	}
+
+	i = strlen(buf);
+	while (i < MAX_INPUT_LEN) {
+		c = get_one_char();
+		if (selected) {
+			switch (c) {
+			case 0: case 27: case '\n': case '\r':
+				break;
+			case KEYCODE_RIGHT: case KEYCODE_END:
+				place_cursor(rows - 1, i = strlen(buf));
+				selected = 0;
+				c = 0;
+				break;
+			default:
+				strcpy(buf, prompt);
+				i = prompt_len;
+				clear_to_eol();
+				selected = 0;
+			}
+		}
+		switch (c) {
+		case 27:
+			get_one_char();
+			// fallthrough
+		case 0:
+			break;
+		case '\n': case '\r':
+			goto end_of_input;
+		case 8: case 127:
+ backspace_2:
+			if (i > prompt_len) {
+				// erase prev char
+				buf[--i] = '\0';
+				write1("\b \b");
+			}
+			break;
+		default:
+			if (c == erase_char) goto backspace_2;
+#if 0 // ENABLE_FEATURE_NANO_UTF8 this shouldn't actually be needed as handling is equivalent here, this may change if more complex line editing is required
+			char_len = utf8_char_len(c);
+			do {
+#endif
+				buf[i] = c;
+				buf[++i] = '\0';
+				bb_putchar(c);
+#if 0 // ENABLE_FEATURE_NANO_UTF8 ditto
+			} while (--char_len > 0);
+#endif
+		}
+	}
+ end_of_input:
+	refresh(FALSE);
+	return buf + prompt_len;
+#undef buf
+}
+
+// might reallocate text[]!
+static int file_insert(const char *fn, char *p, int initial)
+{
+	int cnt = -1;
+	int fd, size;
+	struct stat statbuf;
+
+	if (p < text)
+		p = text;
+	if (p > end)
+		p = end;
+
+	fd = open(fn, O_RDONLY);
+	if (fd < 0) {
+		if (!initial)
+			status_line_bold_errno(fn);
+		return cnt;
+	}
+
+	/* Validate file */
+	if (fstat(fd, &statbuf) < 0) {
+		status_line_bold_errno(fn);
+		goto fi;
+	}
+	if (!S_ISREG(statbuf.st_mode)) {
+		status_line_bold("'%s' is not a regular file", fn);
+		goto fi;
+	}
+	size = (statbuf.st_size < INT_MAX ? (int)statbuf.st_size : INT_MAX);
+	p += text_hole_make(p, size);
+	cnt = full_read(fd, p, size);
+	if (cnt < 0) {
+		status_line_bold_errno(fn);
+		p = text_hole_delete(p, p + size - 1, NO_UNDO);	// un-do buffer insert
+	} else if (cnt < size) {
+		// There was a partial read, shrink unused space
+		p = text_hole_delete(p + cnt, p + size - 1, NO_UNDO);
+		status_line_bold("can't read '%s'", fn);
+	}
+ fi:
+	close(fd);
+
+#if ENABLE_FEATURE_NANO_READONLY
+	if (initial
+	 && ((access(fn, W_OK) < 0) ||
+		/* root will always have access()
+		 * so we check fileperms too */
+		!(statbuf.st_mode & (S_IWUSR | S_IWGRP | S_IWOTH))
+	    )
+	) {
+		SET_READONLY_FILE(readonly_mode);
+	}
+#endif
+	return cnt;
+}
+
+static int file_write(char *fn, char *first, char *last)
+{
+	int fd, cnt, charcnt;
+
+	if (fn == 0) {
+		status_line_bold("No current filename");
+		return -2;
+	}
+	/* By popular request we do not open file with O_TRUNC,
+	 * but instead ftruncate() it _after_ successful write.
+	 * Might reduce amount of data lost on power fail etc.
+	 */
+	fd = open(fn, (O_WRONLY | O_CREAT), 0666);
+	if (fd < 0)
+		return -1;
+	cnt = last - first + 1;
+	charcnt = full_write(fd, first, cnt);
+	ftruncate(fd, charcnt);
+	if (charcnt == cnt) {
+		// good write
+		//modified_count = FALSE;
+	} else {
+		charcnt = 0;
+	}
+	close(fd);
+	return charcnt;
+}
+
+//----- Terminal Drawing ---------------------------------------
+// The terminal is made up of 'rows' line of 'columns' columns.
+// classically this would be 24 x 80.
+//  screen coordinates
+//  0,0     ...     0,79
+//  1,0     ...     1,79
+//  .       ...     .
+//  .       ...     .
+//  22,0    ...     22,79
+//  23,0    ...     23,79   <- status line
+
+//----- Move the cursor to row x col (count from 0, not 1) -------
+static void place_cursor(int row, int col)
+{
+	char cm1[sizeof(ESC_SET_CURSOR_POS) + sizeof(int)*3 * 2];
+
+	if (row < 0) row = 0;
+	if (row >= rows) row = rows - 1;
+	if (col < 0) col = 0;
+	if (col >= columns) col = columns - 1;
+
+	sprintf(cm1, ESC_SET_CURSOR_POS, row + 1, col + 1);
+	write1(cm1);
+}
+
+//----- Erase from cursor to end of line -----------------------
+static void clear_to_eol(void)
+{
+	write1(ESC_CLEAR2EOL);
+}
+
+static void go_bottom_and_clear_to_eol(void)
+{
+	place_cursor(rows - 1, 0);
+	clear_to_eol();
+}
+
+//----- Erase from cursor to end of screen -----------------------
+static void clear_to_eos(void)
+{
+	write1(ESC_CLEAR2EOS);
+}
+
+//----- Start standout mode ------------------------------------
+static void standout_start(void)
+{
+	write1(ESC_BOLD_TEXT);
+}
+
+//----- End standout mode --------------------------------------
+static void standout_end(void)
+{
+	write1(ESC_NORM_TEXT);
+}
+
+static void indicate_error(void)
+{
+#if ENABLE_FEATURE_NANO_CRASHME
+	if (crashme > 0)
+		return;			// generate a random command
+#endif
+	write1(ESC_BELL);
+}
+
+//----- Screen[] Routines --------------------------------------
+//----- Erase the Screen[] memory ------------------------------
+static void screen_erase(void)
+{
+	memset(screen, ' ', screensize);	// clear new screen
+}
+
+static int bufsum(char *buf, int count)
+{
+	int sum = 0;
+	char *e = buf + count;
+
+	while (buf < e)
+		sum += (unsigned char) *buf++;
+	return sum;
+}
+
+//----- Draw the status line at bottom of the screen -------------
+static void show_status_line(void)
+{
+	int cnt = 0, cksum = 0;
+
+	// either we already have an error or status message, or we
+	// create one.
+	if (!have_status_msg) {
+		cnt = format_edit_status();
+		cksum = bufsum(status_buffer, cnt);
+	}
+	if (have_status_msg || ((cnt > 0 && last_status_cksum != cksum))) {
+		last_status_cksum = cksum;		// remember if we have seen this line
+		go_bottom_and_clear_to_eol();
+		write1(status_buffer);
+		if (have_status_msg) {
+			if (((int)strlen(status_buffer) - (have_status_msg - 1)) >
+					(columns - 1) ) {
+				have_status_msg = 0;
+				Hit_Return();
+			}
+			have_status_msg = 0;
+		}
+		place_cursor(crow, ccol);  // put cursor back in correct place
+	}
+	fflush_all();
+}
+
+//----- format the status buffer, the bottom line of screen ------
+// format status buffer, with STANDOUT mode
+static void status_line_bold(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	strcpy(status_buffer, ESC_BOLD_TEXT);
+	vsprintf(status_buffer + sizeof(ESC_BOLD_TEXT)-1, format, args);
+	strcat(status_buffer, ESC_NORM_TEXT);
+	va_end(args);
+
+	have_status_msg = 1 + sizeof(ESC_BOLD_TEXT) + sizeof(ESC_NORM_TEXT) - 2;
+}
+
+static void status_line_bold_errno(const char *fn)
+{
+	status_line_bold("'%s' %s", fn, strerror(errno));
+}
+
+// format status buffer
+static void status_line(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vsprintf(status_buffer, format, args);
+	va_end(args);
+
+	have_status_msg = 1;
+}
+
+// copy s to buf, convert unprintable
+static void print_literal(char *buf, const char *s)
+{
+	char *d;
+	unsigned char c;
+
+	buf[0] = '\0';
+	if (!s[0])
+		s = "(NULL)";
+
+	d = buf;
+	for (; *s; s++) {
+		int c_is_no_print;
+
+		c = *s;
+		c_is_no_print = (c & 0x80) && !Isprint(c);
+		if (c_is_no_print) {
+			strcpy(d, ESC_NORM_TEXT);
+			d += sizeof(ESC_NORM_TEXT)-1;
+			c = '.';
+		}
+		if (c < ' ' || c == 0x7f) {
+			*d++ = '^';
+			c |= '@'; /* 0x40 */
+			if (c == 0x7f)
+				c = '?';
+		}
+		*d++ = c;
+		*d = '\0';
+		if (c_is_no_print) {
+			strcpy(d, ESC_BOLD_TEXT);
+			d += sizeof(ESC_BOLD_TEXT)-1;
+		}
+		if (*s == '\n') {
+			*d++ = '$';
+			*d = '\0';
+		}
+		if (d - buf > MAX_INPUT_LEN - 10) // paranoia
+			break;
+	}
+}
+
+static void not_implemented(const char *s)
+{
+	char buf[MAX_INPUT_LEN];
+
+	print_literal(buf, s);
+	status_line_bold("\'%s\' is not implemented", buf);
+}
+
+#define NANO_DEBUG 0
+#if NANO_DEBUG
+static char last_key_code = 0;
+#endif
+
+// show file status on status line
+static int format_edit_status(void)
+{
+#define tot format_edit_status__tot
+
+	int cur, percent, ret, trunc_at;
+
+	// modified_count is now a counter rather than a flag.  this
+	// helps reduce the amount of line counting we need to do.
+	// (this will cause a mis-reporting of modified status
+	// once every MAXINT editing operations.)
+
+	// it would be nice to do a similar optimization here -- if
+	// we haven't done a motion that could have changed which line
+	// we're on, then we shouldn't have to do this count_lines()
+	cur = count_lines(text, dot);
+
+	// count_lines() is expensive.
+	// Call it only if something was changed since last time
+	// we were here:
+	if (modified_count != last_modified_count) {
+		tot = cur + count_lines(dot, end - 1) - 1;
+		last_modified_count = modified_count;
+	}
+
+	//    current line         percent
+	//   -------------    ~~ ----------
+	//    total lines            100
+	if (tot > 0) {
+		percent = (100 * cur) / tot;
+	} else {
+		cur = tot = 0;
+		percent = 100;
+	}
+
+	trunc_at = columns < STATUS_BUFFER_LEN-1 ?
+		columns : STATUS_BUFFER_LEN-1;
+
+	ret = snprintf(status_buffer, trunc_at+1,
+#if ENABLE_FEATURE_NANO_READONLY
+		" %s%s%s %d/%d %d%%"
+#else
+		" %s%s %d/%d %d%%"
+#endif
+#if 0
+		"  %02x %02x %02x %02x %02x"
+#endif
+#if NANO_DEBUG
+		"  %08x"
+#endif
+#if 0
+		" %ld"
+#endif
+		"   ^X=Exit ^O=Save ^W=Search ^K=Cut ^U=Paste M-u Undo",
+		(current_filename != NULL ? current_filename : "No file"),
+#if ENABLE_FEATURE_NANO_READONLY
+		(readonly_mode ? " [Readonly]" : ""),
+#endif
+		(modified_count ? " [Modified]" : ""),
+		cur, tot, percent
+#if 0
+                (dot < end) ? dot[0] : 0,
+                (dot + 1 < end) ? dot[1] : 0,
+                (dot + 2 < end) ? dot[2] : 0,
+                (dot + 3 < end) ? dot[3] : 0,
+                (dot + 4 < end) ? dot[4] : 0,
+                (dot + 5 < end) ? dot[5] : 0,
+#endif
+#if NANO_DEBUG
+		last_key_code,
+#endif
+#if 0
+                dot - text
+#endif
+                );
+
+	if (ret >= 0 && ret < trunc_at)
+		return ret;  /* it all fit */
+
+	return trunc_at;  /* had to truncate */
+#undef tot
+}
+
+//----- Force refresh of all Lines -----------------------------
+static void redraw(int full_screen)
+{
+	place_cursor(0, 0);
+	clear_to_eos();
+	screen_erase();		// erase the internal screen buffer
+	last_status_cksum = 0;	// force status update
+	refresh(full_screen);	// this will redraw the entire display
+	show_status_line();
+}
+
+//----- Format a text[] line into a buffer ---------------------
+static char* format_line(char *src /*, int li*/)
+{
+	unsigned char c;
+	int co;
+	int ofs = offset;
+	char *dest = scr_out_buf; // [MAX_SCR_COLS + MAX_TABSTOP * 2]
+
+	c = '~'; // char in col 0 in non-existent lines is '~'
+	co = 0;
+	while (co < columns + tabstop) {
+		// have we gone past the end?
+		if (src < end) {
+			c = *src++;
+			if (c == '\n')
+				break;
+#if 0 && ENABLE_FEATURE_NANO_UTF8
+			// breaks redraw!
+			if (c & 0x80) {
+				do {
+					dest[co++] = c;
+					if (src < end) {
+						c = *src++;
+					}
+				} while (c & 0x80);
+                                goto continue_printing;
+                        }
+			if (!Isprint(c)) {
+				c = '.';
+			}
+#else
+			if ((c & 0x80) && !Isprint(c)) {
+				c = '.';
+			}
+#endif
+			if (c < ' ' || c == 0x7f) {
+				if (c == '\t') {
+					c = ' ';
+					//      co %    8     !=     7
+					while ((co % tabstop) != (tabstop - 1)) {
+						dest[co++] = c;
+					}
+				} else {
+					dest[co++] = '^';
+					if (c == 0x7f)
+						c = '?';
+					else
+						c += '@'; // Ctrl-X -> 'X'
+				}
+			}
+		}
+ continue_printing:
+		dest[co++] = c;
+		// discard scrolled-off-to-the-left portion,
+		// in tabstop-sized pieces
+		if (ofs >= tabstop && co >= tabstop) {
+			memmove(dest, dest + tabstop, co);
+			co -= tabstop;
+			ofs -= tabstop;
+		}
+		if (src >= end)
+			break;
+	}
+	// check "short line, gigantic offset" case
+	if (co < ofs)
+		ofs = co;
+	// discard last scrolled off part
+	co -= ofs;
+	dest += ofs;
+	// fill the rest with spaces
+	if (co < columns)
+		memset(&dest[co], ' ', columns - co);
+	return dest;
+}
+
+//----- Refresh the changed screen lines -----------------------
+// Copy the source line from text[] into the buffer and note
+// if the current screenline is different from the new buffer.
+// If they differ then that line needs redrawing on the terminal.
+//
+static void refresh(int full_screen)
+{
+#define old_offset refresh__old_offset
+
+	int li, changed;
+	char *tp, *sp;		// pointer into text[] and screen[]
+
+	if (ENABLE_FEATURE_NANO_WIN_RESIZE IF_FEATURE_NANO_ASK_TERMINAL(&& !G.get_rowcol_error) ) {
+		unsigned c = columns, r = rows;
+		query_screen_dimensions();
+		full_screen |= (c - columns) | (r - rows);
+	}
+	sync_cursor(dot, &crow, &ccol);	// where cursor will be (on "dot")
+	tp = screenbegin;	// index into text[] of top line
+
+	// compare text[] to screen[] and mark screen[] lines that need updating
+	for (li = 0; li < rows - 1; li++) {
+		int cs, ce;				// column start & end
+		char *out_buf;
+		// format current text line
+		out_buf = format_line(tp /*, li*/);
+
+		// skip to the end of the current text[] line
+		if (tp < end) {
+			char *t = memchr(tp, '\n', end - tp);
+			if (!t) t = end - 1;
+			tp = t + 1;
+		}
+
+		// see if there are any changes between virtual screen and out_buf
+		changed = FALSE;	// assume no change
+		cs = 0;
+		ce = columns - 1;
+		sp = &screen[li * columns];	// start of screen line
+		if (full_screen) {
+			// force re-draw of every single column from 0 - columns-1
+			goto re0;
+		}
+		// compare newly formatted buffer with virtual screen
+		// look forward for first difference between buf and screen
+		for (; cs <= ce; cs++) {
+			if (out_buf[cs] != sp[cs]) {
+				changed = TRUE;	// mark for redraw
+				break;
+			}
+		}
+
+		// look backward for last difference between out_buf and screen
+		for (; ce >= cs; ce--) {
+			if (out_buf[ce] != sp[ce]) {
+				changed = TRUE;	// mark for redraw
+				break;
+			}
+		}
+		// now, cs is index of first diff, and ce is index of last diff
+
+		// if horz offset has changed, force a redraw
+		if (offset != old_offset) {
+ re0:
+			changed = TRUE;
+		}
+
+		// make a sanity check of columns indexes
+		if (cs < 0) cs = 0;
+		if (ce > columns - 1) ce = columns - 1;
+		if (cs > ce) { cs = 0; ce = columns - 1; }
+		// is there a change between virtual screen and out_buf
+		if (changed) {
+			// copy changed part of buffer to virtual screen
+			memcpy(sp+cs, out_buf+cs, ce-cs+1);
+			place_cursor(li, cs);
+			// write line out to terminal
+			fwrite(&sp[cs], ce - cs + 1, 1, stdout);
+		}
+	}
+
+	place_cursor(crow, ccol);
+
+	old_offset = offset;
+#undef old_offset
+}
+
+static int save_file(void)
+{
+	int cnt;
+	if (ENABLE_FEATURE_NANO_READONLY && readonly_mode) {
+		status_line_bold("'%s' is read only", current_filename);
+		return 0;
+	}
+	cnt = file_write(current_filename, text, end - 1);
+	if (cnt < 0) {
+		if (cnt == -1)
+			status_line_bold("Write error: %s", strerror(errno));
+		return 0;
+	}
+	if (cnt != (end - 1 - text + 1)) {
+		status_line_bold("File truncated: %s", strerror(errno));
+		return 0;
+	}
+	modified_count = 0;
+	return 1;
+}
+
+static int get_filename(void)
+{
+	char *p = get_input_line("Save to file: ", current_filename);
+	if (p == NULL || p[0] == 0) return 0;
+	free(current_filename);
+	current_filename = xstrdup(p);
+	return 1;
+}
+
+//---------------------------------------------------------------------
+//----- the Ascii Chart -----------------------------------------------
+//
+//  00 nul   01 soh   02 stx   03 etx   04 eot   05 enq   06 ack   07 bel
+//  08 bs    09 ht    0a nl    0b vt    0c np    0d cr    0e so    0f si
+//  10 dle   11 dc1   12 dc2   13 dc3   14 dc4   15 nak   16 syn   17 etb
+//  18 can   19 em    1a sub   1b esc   1c fs    1d gs    1e rs    1f us
+//  20 sp    21 !     22 "     23 #     24 $     25 %     26 &     27 '
+//  28 (     29 )     2a *     2b +     2c ,     2d -     2e .     2f /
+//  30 0     31 1     32 2     33 3     34 4     35 5     36 6     37 7
+//  38 8     39 9     3a :     3b ;     3c <     3d =     3e >     3f ?
+//  40 @     41 A     42 B     43 C     44 D     45 E     46 F     47 G
+//  48 H     49 I     4a J     4b K     4c L     4d M     4e N     4f O
+//  50 P     51 Q     52 R     53 S     54 T     55 U     56 V     57 W
+//  58 X     59 Y     5a Z     5b [     5c \     5d ]     5e ^     5f _
+//  60 `     61 a     62 b     63 c     64 d     65 e     66 f     67 g
+//  68 h     69 i     6a j     6b k     6c l     6d m     6e n     6f o
+//  70 p     71 q     72 r     73 s     74 t     75 u     76 v     77 w
+//  78 x     79 y     7a z     7b {     7c |     7d }     7e ~     7f del
+//---------------------------------------------------------------------
+
+//----- Execute a Nano Command -----------------------------------
+static void do_cmd(int c)
+{
+	char *p, *q, *save_dot;
+	char buf[12];
+
+//	c1 = c; // quiet the compiler
+//	cnt = yf = 0; // quiet the compiler
+//	p = q = save_dot = buf; // quiet the compiler
+	memset(buf, '\0', sizeof(buf));
+
+#if NANO_DEBUG
+	last_key_code = c;
+#endif
+	// show_status_line(); // isn't this called twice per character?
+
+	/* if this is a cursor key, skip these checks */
+	switch (c) {
+#if ENABLE_FEATURE_NANO_INSERT
+		// Unsupported yet, should insert file at point
+		case KEYCODE_INSERT:
+#endif
+	default:
+		if (1 <= c || Isprint(c)) {
+			dot = char_insert(dot, c, ALLOW_UNDO_QUEUED);
+			break;
+		}
+		buf[0] = c;
+		buf[1] = '\0';
+		not_implemented(buf);
+		end_cmd_q();
+		break;
+		//case 0x01:	// soh
+		//case 0x09:	// ht
+		//case 0x0b:	// vt
+		//case 0x0e:	// so
+		//case 0x0f:	// si
+		//case 0x10:	// dle
+		//case 0x11:	// dc1
+		//case 0x13:	// dc3
+#if ENABLE_FEATURE_NANO_CRASHME
+	case 0x14:			// dc4  ctrl-T
+		crashme = (crashme == 0) ? 1 : 0;
+		break;
+#endif
+		//case 0x16:	// syn
+		//case 0x17:	// etb
+		//case 0x18:	// can
+		//case 0x1c:	// fs
+		//case 0x1d:	// gs
+		//case 0x1e:	// rs
+		//case 0x1f:	// us
+		//case '!':	// !-
+		//case '#':	// #-
+		//case '&':	// &-
+		//case '(':	// (-
+		//case ')':	// )-
+		//case '*':	// *-
+		//case '=':	// =-
+		//case '@':	// @-
+		//case 'F':	// F-
+		//case 'K':	// K-
+		//case 'Q':	// Q-
+		//case 'S':	// S-
+		//case 'T':	// T-
+		//case 'V':	// V-
+		//case '[':	// [-
+		//case '\\':	// \-
+		//case ']':	// ]-
+		//case '_':	// _-
+		//case '`':	// `-
+		//case 'v':	// v-
+	case 0x00:			// nul- ignore
+		break;
+	case 2:			// ctrl-B  scroll up   full screen
+	case KEYCODE_PAGEUP:	// Cursor Key Page Up
+		dot_scroll(rows - 2, -1);
+		break;
+	case 4:			// ctrl-D  scroll down half screen
+		dot_scroll((rows - 2) / 2, 1);
+		break;
+	case 5:			// ctrl-E  scroll down one line
+		dot_scroll(1, 1);
+		break;
+	case 6:			// ctrl-F  scroll down full screen
+	case KEYCODE_PAGEDOWN:	// Cursor Key Page Down
+		dot_scroll(rows - 2, 1);
+		break;
+	case 7:			// ctrl-G  show current status
+		last_status_cksum = 0;	// force status update
+		break;
+	case KEYCODE_LEFT:	// cursor key Left
+		dot_left();
+		break;
+	case 8:
+	case 0x7f:
+		undo_queue_commit();
+		save_dot = dot;
+		dot_left();
+		if (dot != save_dot) {
+			dot = text_hole_delete(dot, save_dot-1, ALLOW_UNDO);
+		}
+		break;
+	case 10:			// Newline ^J
+	case KEYCODE_DOWN:	// cursor key Down
+		dot_next();		// go to next B-o-l
+		// try stay in same col
+		dot = move_to_col(dot, ccol + offset);
+		break;
+	case 12:			// ctrl-L  force redraw whole screen
+	case 18:			// ctrl-R  force redraw
+		place_cursor(0, 0);
+		clear_to_eos();
+		//mysleep(10); // why???
+		screen_erase();	// erase the internal screen buffer
+		last_status_cksum = 0;	// force status update
+		refresh(TRUE);	// this will redraw the entire display
+		break;
+	case CTRL_CODE('K'):
+#if ENABLE_FEATURE_NANO_YANKMARK
+		if (yank_append && (dot - text) != previous_yank_position) {
+			yank_append = 0;
+		}
+#endif
+		save_dot = begin_line(dot);
+		dot = end_line(dot);
+		dot = yank_delete(save_dot, dot, 1, YANKDEL, ALLOW_UNDO);
+#if ENABLE_FEATURE_NANO_YANKMARK
+		yank_append = 1;
+		previous_yank_position = dot - text;
+#endif
+		break;
+	case CTRL_CODE('O'):
+		undo_queue_commit();
+		if (get_filename()) save_file();
+		break;
+#if ENABLE_FEATURE_NANO_YANKMARK
+	case CTRL_CODE('U'):
+		if (clipboard == NULL) {
+			status_line_bold("Nothing in clipboard");
+			break;
+		}
+		dot += string_insert(dot, clipboard, ALLOW_UNDO);	// insert the string
+		yank_append = 0;
+		break;
+#endif
+	case CTRL_CODE('X'):
+		undo_queue_commit();
+		if (modified_count != 0) {
+			go_bottom_and_clear_to_eol();
+			write1("Save? [y/n]");
+			switch (get_one_char()) {
+			case 'n': case 'N':
+				// modified_count = 0;
+				break;
+			case 'y': case 'Y':
+				if ((current_filename != NULL || get_filename()) && save_file()) break;
+				// fallthrough
+			default:
+				goto continue_editing;
+                        }
+		}
+		editing = 0;
+ continue_editing:
+		break;
+#if ENABLE_FEATURE_NANO_SEARCH
+	case CTRL_CODE('W'):
+#define buf search__buf
+		p = get_input_line("Search: ", buf);
+		strcpy(buf, p);
+		q = dot + 1 < end ? strstr(dot+1, p) : NULL;
+		if (q != NULL) {
+			dot = q;
+		} else {
+			// This may scan parts of the buffer twice but is still correct and much simpler to implement.
+			q = strstr(text, p);
+			if (q != NULL) {
+				status_line_bold("Search wrapped!", p);
+				dot = q;
+			} else {
+				status_line_bold("String not found: %s", p);
+			}
+		}
+#undef buf
+		break;
+#endif
+	case 25:			// ctrl-Y  scroll up one line
+		dot_scroll(1, -1);
+		break;
+	case KEYCODE_RIGHT:	// Cursor Key Right
+		dot_right();
+		break;
+	case 27:
+		switch (get_one_char()) {
+#if ENABLE_FEATURE_NANO_UNDO
+		case 'u':	// u- undo last operation
+			undo_pop();
+			break;
+#endif
+		}
+		break;
+	case KEYCODE_END:		// Cursor Key End
+		dot = end_line(dot);
+		break;
+	case KEYCODE_DELETE:
+		undo_queue_commit();
+		save_dot = dot;
+		dot_right();
+		if (dot != save_dot) {
+			dot = text_hole_delete(save_dot, dot-1, ALLOW_UNDO);
+		}
+		break;
+	case KEYCODE_UP:		// cursor key Up
+		dot_prev();
+		dot = move_to_col(dot, ccol + offset);	// try stay in same col
+		break;
+	case KEYCODE_HOME:	// Cursor Key Home
+		dot_begin();
+		break;
+		// The Fn keys could point to do_macro which could translate them
+#if 0
+	case KEYCODE_FUN1:	// Function Key F1
+	case KEYCODE_FUN2:	// Function Key F2
+	case KEYCODE_FUN3:	// Function Key F3
+	case KEYCODE_FUN4:	// Function Key F4
+	case KEYCODE_FUN5:	// Function Key F5
+	case KEYCODE_FUN6:	// Function Key F6
+	case KEYCODE_FUN7:	// Function Key F7
+	case KEYCODE_FUN8:	// Function Key F8
+	case KEYCODE_FUN9:	// Function Key F9
+	case KEYCODE_FUN10:	// Function Key F10
+	case KEYCODE_FUN11:	// Function Key F11
+	case KEYCODE_FUN12:	// Function Key F12
+		break;
+#endif
+	}
+
+	// if text[] just became empty, add back an empty line
+#if 0
+        // I tried disabling this by two newlines are added instead!
+	if (end == text) {
+		char_insert(text, '\n', NO_UNDO);	// start empty buf with dummy line
+		dot = text;
+	}
+#endif
+	// it is OK for dot to exactly equal to end, otherwise check dot validity
+	if (dot != end) {
+		dot = bound_dot(dot);	// make sure "dot" is valid
+	}
+#if ENABLE_FEATURE_NANO_YANKMARK
+	check_context(c);	// update the current context
+#endif
+}
+
+/* NB!  the CRASHME code is unmaintained, and doesn't currently build */
+#if ENABLE_FEATURE_NANO_CRASHME
+static int totalcmds = 0;
+static int Mp = 85;             // Movement command Probability
+static int Np = 90;             // Non-movement command Probability
+static int Dp = 96;             // Delete command Probability
+static int Ip = 97;             // Insert command Probability
+static int Yp = 98;             // Yank command Probability
+static int Pp = 99;             // Put command Probability
+static int M = 0, N = 0, I = 0, D = 0, Y = 0, P = 0, U = 0;
+static const char chars[20] = "\t012345 abcdABCD-=.$";
+static const char *const words[20] = {
+	"this", "is", "a", "test",
+	"broadcast", "the", "emergency", "of",
+	"system", "quick", "brown", "fox",
+	"jumped", "over", "lazy", "dogs",
+	"back", "January", "Febuary", "March"
+};
+static const char *const lines[20] = {
+	"You should have received a copy of the GNU General Public License\n",
+	"char c, cm, *cmd, *cmd1;\n",
+	"generate a command by percentages\n",
+	"Numbers may be typed as a prefix to some commands.\n",
+	"Quit, discarding changes!\n",
+	"Forced write, if permission originally not valid.\n",
+	"In general, any ex or ed command (such as substitute or delete).\n",
+	"I have tickets available for the Blazers vs LA Clippers for Monday, Janurary 1 at 1:00pm.\n",
+	"Please get w/ me and I will go over it with you.\n",
+	"The following is a list of scheduled, committed changes.\n",
+	"1.   Launch Norton Antivirus (Start, Programs, Norton Antivirus)\n",
+	"Reminder....Town Meeting in Central Perk cafe today at 3:00pm.\n",
+	"Any question about transactions please contact Sterling Huxley.\n",
+	"I will try to get back to you by Friday, December 31.\n",
+	"This Change will be implemented on Friday.\n",
+	"Let me know if you have problems accessing this;\n",
+	"Sterling Huxley recently added you to the access list.\n",
+	"Would you like to go to lunch?\n",
+	"The last command will be automatically run.\n",
+	"This is too much english for a computer geek.\n",
+};
+static char *multilines[20] = {
+	"You should have received a copy of the GNU General Public License\n",
+	"char c, cm, *cmd, *cmd1;\n",
+	"generate a command by percentages\n",
+	"Numbers may be typed as a prefix to some commands.\n",
+	"Quit, discarding changes!\n",
+	"Forced write, if permission originally not valid.\n",
+	"In general, any ex or ed command (such as substitute or delete).\n",
+	"I have tickets available for the Blazers vs LA Clippers for Monday, Janurary 1 at 1:00pm.\n",
+	"Please get w/ me and I will go over it with you.\n",
+	"The following is a list of scheduled, committed changes.\n",
+	"1.   Launch Norton Antivirus (Start, Programs, Norton Antivirus)\n",
+	"Reminder....Town Meeting in Central Perk cafe today at 3:00pm.\n",
+	"Any question about transactions please contact Sterling Huxley.\n",
+	"I will try to get back to you by Friday, December 31.\n",
+	"This Change will be implemented on Friday.\n",
+	"Let me know if you have problems accessing this;\n",
+	"Sterling Huxley recently added you to the access list.\n",
+	"Would you like to go to lunch?\n",
+	"The last command will be automatically run.\n",
+	"This is too much english for a computer geek.\n",
+};
+
+// create a random command to execute
+static void crash_dummy()
+{
+	static int sleeptime;   // how long to pause between commands
+	char c, cm, *cmd, *cmd1;
+	int i, cnt, thing, rbi, startrbi, percent;
+
+	// "dot" movement commands
+	cmd1 = " \n\r\002\004\005\006\025\0310^$-+wWeEbBhjklHL";
+
+	// is there already a command running?
+	if (readbuffer[0] > 0)
+		goto cd1;
+ cd0:
+	readbuffer[0] = 'X';
+	startrbi = rbi = 1;
+	sleeptime = 0;          // how long to pause between commands
+	memset(readbuffer, '\0', sizeof(readbuffer));
+	// generate a command by percentages
+	percent = (int) lrand48() % 100;        // get a number from 0-99
+	if (percent < Mp) {     //  Movement commands
+		// available commands
+		cmd = cmd1;
+		M++;
+	} else if (percent < Np) {      //  non-movement commands
+		cmd = "mz<>\'\"";       // available commands
+		N++;
+	} else if (percent < Dp) {      //  Delete commands
+		cmd = "dx";             // available commands
+		D++;
+	} else if (percent < Ip) {      //  Inset commands
+		cmd = "iIaAsrJ";        // available commands
+		I++;
+	} else if (percent < Yp) {      //  Yank commands
+		cmd = "yY";             // available commands
+		Y++;
+	} else if (percent < Pp) {      //  Put commands
+		cmd = "pP";             // available commands
+		P++;
+	} else {
+		// We do not know how to handle this command, try again
+		U++;
+		goto cd0;
+	}
+	// randomly pick one of the available cmds from "cmd[]"
+	i = (int) lrand48() % strlen(cmd);
+	cm = cmd[i];
+	if (strchr(":\024", cm))
+		goto cd0;               // dont allow colon or ctrl-T commands
+	readbuffer[rbi++] = cm; // put cmd into input buffer
+
+	// now we have the command-
+	// there are 1, 2, and multi char commands
+	// find out which and generate the rest of command as necessary
+	if (strchr("dmryz<>\'\"", cm)) {        // 2-char commands
+		cmd1 = " \n\r0$^-+wWeEbBhjklHL";
+		if (cm == 'm' || cm == '\'' || cm == '\"') {    // pick a reg[]
+			cmd1 = "abcdefghijklmnopqrstuvwxyz";
+		}
+		thing = (int) lrand48() % strlen(cmd1); // pick a movement command
+		c = cmd1[thing];
+		readbuffer[rbi++] = c;  // add movement to input buffer
+	}
+	if (strchr("iIaAsc", cm)) {     // multi-char commands
+		if (cm == 'c') {
+			// change some thing
+			thing = (int) lrand48() % strlen(cmd1); // pick a movement command
+			c = cmd1[thing];
+			readbuffer[rbi++] = c;  // add movement to input buffer
+		}
+		thing = (int) lrand48() % 4;    // what thing to insert
+		cnt = (int) lrand48() % 10;     // how many to insert
+		for (i = 0; i < cnt; i++) {
+			if (thing == 0) {       // insert chars
+				readbuffer[rbi++] = chars[((int) lrand48() % strlen(chars))];
+			} else if (thing == 1) {        // insert words
+				strcat(readbuffer, words[(int) lrand48() % 20]);
+				strcat(readbuffer, " ");
+				sleeptime = 0;  // how fast to type
+			} else if (thing == 2) {        // insert lines
+				strcat(readbuffer, lines[(int) lrand48() % 20]);
+				sleeptime = 0;  // how fast to type
+			} else {        // insert multi-lines
+				strcat(readbuffer, multilines[(int) lrand48() % 20]);
+				sleeptime = 0;  // how fast to type
+			}
+		}
+		strcat(readbuffer, "\033");
+	}
+	readbuffer[0] = strlen(readbuffer + 1);
+ cd1:
+	totalcmds++;
+	if (sleeptime > 0)
+		mysleep(sleeptime);      // sleep 1/100 sec
+}
+
+// test to see if there are any errors
+static void crash_test()
+{
+	static time_t oldtim;
+
+	time_t tim;
+	char d[2], msg[80];
+
+	msg[0] = '\0';
+	if (end < text) {
+		strcat(msg, "end<text ");
+	}
+	if (end > textend) {
+		strcat(msg, "end>textend ");
+	}
+	if (dot < text) {
+		strcat(msg, "dot<text ");
+	}
+	if (dot > end) {
+		strcat(msg, "dot>end ");
+	}
+	if (screenbegin < text) {
+		strcat(msg, "screenbegin<text ");
+	}
+	if (screenbegin > end - 1) {
+		strcat(msg, "screenbegin>end-1 ");
+	}
+
+	if (msg[0]) {
+		printf("\n\n%d: \'%c\' %s\n\n\n%s[Hit return to continue]%s",
+			totalcmds, last_input_char, msg, ESC_BOLD_TEXT, ESC_NORM_TEXT);
+		fflush_all();
+		while (safe_read(STDIN_FILENO, d, 1) > 0) {
+			if (d[0] == '\n' || d[0] == '\r')
+				break;
+		}
+	}
+	tim = time(NULL);
+	if (tim >= (oldtim + 3)) {
+		sprintf(status_buffer,
+				"Tot=%d: M=%d N=%d I=%d D=%d Y=%d P=%d U=%d size=%d",
+				totalcmds, M, N, I, D, Y, P, U, end - text + 1);
+		oldtim = tim;
+	}
+}
+#endif