added -y/--side-by-side option

[dfdiff.git] / contrib / less-4 / decode.c

/*
 * Copyright (C) 1984-2007  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * Routines to decode user commands.
 *
 * This is all table driven.
 * A command table is a sequence of command descriptors.
 * Each command descriptor is a sequence of bytes with the following format:
 *      <c1><c2>...<cN><0><action>
 * The characters c1,c2,...,cN are the command string; that is,
 * the characters which the user must type.
 * It is terminated by a null <0> byte.
 * The byte after the null byte is the action code associated
 * with the command string.
 * If an action byte is OR-ed with A_EXTRA, this indicates
 * that the option byte is followed by an extra string.
 *
 * There may be many command tables.
 * The first (default) table is built-in.
 * Other tables are read in from "lesskey" files.
 * All the tables are linked together and are searched in order.
 */

#include "less.h"
#include "cmd.h"
#include "lesskey.h"

extern int erase_char, erase2_char, kill_char;
extern int secure;

#define SK(k) \
        SK_SPECIAL_KEY, (k), 6, 1, 1, 1
/*
 * Command table is ordered roughly according to expected
 * frequency of use, so the common commands are near the beginning.
 */

static unsigned char cmdtable[] =
{
        '\r',0,                         A_F_LINE,
        '\n',0,                         A_F_LINE,
        'e',0,                          A_F_LINE,
        'j',0,                          A_F_LINE,
        SK(SK_DOWN_ARROW),0,            A_F_LINE,
        CONTROL('E'),0,                 A_F_LINE,
        CONTROL('N'),0,                 A_F_LINE,
        'k',0,                          A_B_LINE,
        'y',0,                          A_B_LINE,
        CONTROL('Y'),0,                 A_B_LINE,
        SK(SK_CONTROL_K),0,             A_B_LINE,
        CONTROL('P'),0,                 A_B_LINE,
        SK(SK_UP_ARROW),0,              A_B_LINE,
        'J',0,                          A_FF_LINE,
        'K',0,                          A_BF_LINE,
        'Y',0,                          A_BF_LINE,
        'd',0,                          A_F_SCROLL,
        CONTROL('D'),0,                 A_F_SCROLL,
        'u',0,                          A_B_SCROLL,
        CONTROL('U'),0,                 A_B_SCROLL,
        ' ',0,                          A_F_SCREEN,
        'f',0,                          A_F_SCREEN,
        CONTROL('F'),0,                 A_F_SCREEN,
        CONTROL('V'),0,                 A_F_SCREEN,
        SK(SK_PAGE_DOWN),0,             A_F_SCREEN,
        'b',0,                          A_B_SCREEN,
        CONTROL('B'),0,                 A_B_SCREEN,
        ESC,'v',0,                      A_B_SCREEN,
        SK(SK_PAGE_UP),0,               A_B_SCREEN,
        'z',0,                          A_F_WINDOW,
        'w',0,                          A_B_WINDOW,
        ESC,' ',0,                      A_FF_SCREEN,
        'F',0,                          A_F_FOREVER,
        'R',0,                          A_FREPAINT,
        'r',0,                          A_REPAINT,
        CONTROL('R'),0,                 A_REPAINT,
        CONTROL('L'),0,                 A_REPAINT,
        ESC,'u',0,                      A_UNDO_SEARCH,
        'g',0,                          A_GOLINE,
        SK(SK_HOME),0,                  A_GOLINE,
        '<',0,                          A_GOLINE,
        ESC,'<',0,                      A_GOLINE,
        'p',0,                          A_PERCENT,
        '%',0,                          A_PERCENT,
        ESC,'[',0,                      A_LSHIFT,
        ESC,']',0,                      A_RSHIFT,
        ESC,'(',0,                      A_LSHIFT,
        ESC,')',0,                      A_RSHIFT,
        SK(SK_RIGHT_ARROW),0,           A_RSHIFT,
        SK(SK_LEFT_ARROW),0,            A_LSHIFT,
        '{',0,                          A_F_BRACKET|A_EXTRA,    '{','}',0,
        '}',0,                          A_B_BRACKET|A_EXTRA,    '{','}',0,
        '(',0,                          A_F_BRACKET|A_EXTRA,    '(',')',0,
        ')',0,                          A_B_BRACKET|A_EXTRA,    '(',')',0,
        '[',0,                          A_F_BRACKET|A_EXTRA,    '[',']',0,
        ']',0,                          A_B_BRACKET|A_EXTRA,    '[',']',0,
        ESC,CONTROL('F'),0,             A_F_BRACKET,
        ESC,CONTROL('B'),0,             A_B_BRACKET,
        'G',0,                          A_GOEND,
        ESC,'>',0,                      A_GOEND,
        '>',0,                          A_GOEND,
        SK(SK_END),0,                   A_GOEND,
        'P',0,                          A_GOPOS,

        '0',0,                          A_DIGIT,
        '1',0,                          A_DIGIT,
        '2',0,                          A_DIGIT,
        '3',0,                          A_DIGIT,
        '4',0,                          A_DIGIT,
        '5',0,                          A_DIGIT,
        '6',0,                          A_DIGIT,
        '7',0,                          A_DIGIT,
        '8',0,                          A_DIGIT,
        '9',0,                          A_DIGIT,
        '.',0,                          A_DIGIT,

        '=',0,                          A_STAT,
        CONTROL('G'),0,                 A_STAT,
        ':','f',0,                      A_STAT,
        '/',0,                          A_F_SEARCH,
        '?',0,                          A_B_SEARCH,
        ESC,'/',0,                      A_F_SEARCH|A_EXTRA,     '*',0,
        ESC,'?',0,                      A_B_SEARCH|A_EXTRA,     '*',0,
        'n',0,                          A_AGAIN_SEARCH,
        ESC,'n',0,                      A_T_AGAIN_SEARCH,
        'N',0,                          A_REVERSE_SEARCH,
        ESC,'N',0,                      A_T_REVERSE_SEARCH,
        'm',0,                          A_SETMARK,
        '\'',0,                         A_GOMARK,
        CONTROL('X'),CONTROL('X'),0,    A_GOMARK,
        'E',0,                          A_EXAMINE,
        ':','e',0,                      A_EXAMINE,
        CONTROL('X'),CONTROL('V'),0,    A_EXAMINE,
        ':','n',0,                      A_NEXT_FILE,
        ':','p',0,                      A_PREV_FILE,
        't',0,                          A_NEXT_TAG,
        'T',0,                          A_PREV_TAG,
        ':','x',0,                      A_INDEX_FILE,
        ':','d',0,                      A_REMOVE_FILE,
        '-',0,                          A_OPT_TOGGLE,
        ':','t',0,                      A_OPT_TOGGLE|A_EXTRA,   't',0,
        's',0,                          A_OPT_TOGGLE|A_EXTRA,   'o',0,
        '_',0,                          A_DISP_OPTION,
        '|',0,                          A_PIPE,
        'v',0,                          A_VISUAL,
        '!',0,                          A_SHELL,
        '+',0,                          A_FIRSTCMD,

        'H',0,                          A_HELP,
        'h',0,                          A_HELP,
        SK(SK_F1),0,                    A_HELP,
        'V',0,                          A_VERSION,
        'q',0,                          A_QUIT,
        'Q',0,                          A_QUIT,
        ':','q',0,                      A_QUIT,
        ':','Q',0,                      A_QUIT,
        'Z','Z',0,                      A_QUIT
};

static unsigned char edittable[] =
{
        '\t',0,                         EC_F_COMPLETE,  /* TAB */
        '\17',0,                        EC_B_COMPLETE,  /* BACKTAB */
        SK(SK_BACKTAB),0,               EC_B_COMPLETE,  /* BACKTAB */
        ESC,'\t',0,                     EC_B_COMPLETE,  /* ESC TAB */
        CONTROL('L'),0,                 EC_EXPAND,      /* CTRL-L */
        CONTROL('V'),0,                 EC_LITERAL,     /* BACKSLASH */
        CONTROL('A'),0,                 EC_LITERAL,     /* BACKSLASH */
        ESC,'l',0,                      EC_RIGHT,       /* ESC l */
        SK(SK_RIGHT_ARROW),0,           EC_RIGHT,       /* RIGHTARROW */
        ESC,'h',0,                      EC_LEFT,        /* ESC h */
        SK(SK_LEFT_ARROW),0,            EC_LEFT,        /* LEFTARROW */
        ESC,'b',0,                      EC_W_LEFT,      /* ESC b */
        ESC,SK(SK_LEFT_ARROW),0,        EC_W_LEFT,      /* ESC LEFTARROW */
        SK(SK_CTL_LEFT_ARROW),0,        EC_W_LEFT,      /* CTRL-LEFTARROW */
        ESC,'w',0,                      EC_W_RIGHT,     /* ESC w */
        ESC,SK(SK_RIGHT_ARROW),0,       EC_W_RIGHT,     /* ESC RIGHTARROW */
        SK(SK_CTL_RIGHT_ARROW),0,       EC_W_RIGHT,     /* CTRL-RIGHTARROW */
        ESC,'i',0,                      EC_INSERT,      /* ESC i */
        SK(SK_INSERT),0,                EC_INSERT,      /* INSERT */
        ESC,'x',0,                      EC_DELETE,      /* ESC x */
        SK(SK_DELETE),0,                EC_DELETE,      /* DELETE */
        ESC,'X',0,                      EC_W_DELETE,    /* ESC X */
        ESC,SK(SK_DELETE),0,            EC_W_DELETE,    /* ESC DELETE */
        SK(SK_CTL_DELETE),0,            EC_W_DELETE,    /* CTRL-DELETE */
        SK(SK_CTL_BACKSPACE),0,         EC_W_BACKSPACE, /* CTRL-BACKSPACE */
        ESC,'\b',0,                     EC_W_BACKSPACE, /* ESC BACKSPACE */
        ESC,'0',0,                      EC_HOME,        /* ESC 0 */
        SK(SK_HOME),0,                  EC_HOME,        /* HOME */
        ESC,'$',0,                      EC_END,         /* ESC $ */
        SK(SK_END),0,                   EC_END,         /* END */
        ESC,'k',0,                      EC_UP,          /* ESC k */
        SK(SK_UP_ARROW),0,              EC_UP,          /* UPARROW */
        ESC,'j',0,                      EC_DOWN,        /* ESC j */
        SK(SK_DOWN_ARROW),0,            EC_DOWN,        /* DOWNARROW */
};

/*
 * Structure to support a list of command tables.
 */
struct tablelist
{
        struct tablelist *t_next;
        char *t_start;
        char *t_end;
};

/*
 * List of command tables and list of line-edit tables.
 */
static struct tablelist *list_fcmd_tables = NULL;
static struct tablelist *list_ecmd_tables = NULL;
static struct tablelist *list_var_tables = NULL;
static struct tablelist *list_sysvar_tables = NULL;


/*
 * Expand special key abbreviations in a command table.
 */
        static void
expand_special_keys(table, len)
        char *table;
        int len;
{
        register char *fm;
        register char *to;
        register int a;
        char *repl;
        int klen;

        for (fm = table;  fm < table + len; )
        {
                /*
                 * Rewrite each command in the table with any
                 * special key abbreviations expanded.
                 */
                for (to = fm;  *fm != '\0'; )
                {
                        if (*fm != SK_SPECIAL_KEY)
                        {
                                *to++ = *fm++;
                                continue;
                        }
                        /*
                         * After SK_SPECIAL_KEY, next byte is the type
                         * of special key (one of the SK_* contants),
                         * and the byte after that is the number of bytes,
                         * N, reserved by the abbreviation (including the
                         * SK_SPECIAL_KEY and key type bytes).
                         * Replace all N bytes with the actual bytes
                         * output by the special key on this terminal.
                         */
                        repl = special_key_str(fm[1]);
                        klen = fm[2] & 0377;
                        fm += klen;
                        if (repl == NULL || (int) strlen(repl) > klen)
                                repl = "\377";
                        while (*repl != '\0')
                                *to++ = *repl++;
                }
                *to++ = '\0';
                /*
                 * Fill any unused bytes between end of command and 
                 * the action byte with A_SKIP.
                 */
                while (to <= fm)
                        *to++ = A_SKIP;
                fm++;
                a = *fm++ & 0377;
                if (a & A_EXTRA)
                {
                        while (*fm++ != '\0')
                                continue;
                }
        }
}

/*
 * Initialize the command lists.
 */
        public void
init_cmds()
{
        /*
         * Add the default command tables.
         */
        add_fcmd_table((char*)cmdtable, sizeof(cmdtable));
        add_ecmd_table((char*)edittable, sizeof(edittable));
#if USERFILE
        /*
         * For backwards compatibility,
         * try to add tables in the OLD system lesskey file.
         */
#ifdef BINDIR
        add_hometable(NULL, BINDIR "/.sysless", 1);
#endif
        /*
         * Try to add the tables in the system lesskey file.
         */
        add_hometable("LESSKEY_SYSTEM", LESSKEYFILE_SYS, 1);
        /*
         * Try to add the tables in the standard lesskey file "$HOME/.less".
         */
        add_hometable("LESSKEY", LESSKEYFILE, 0);
#endif
}

/*
 * Add a command table.
 */
        static int
add_cmd_table(tlist, buf, len)
        struct tablelist **tlist;
        char *buf;
        int len;
{
        register struct tablelist *t;

        if (len == 0)
                return (0);
        /*
         * Allocate a tablelist structure, initialize it, 
         * and link it into the list of tables.
         */
        if ((t = (struct tablelist *) 
                        calloc(1, sizeof(struct tablelist))) == NULL)
        {
                return (-1);
        }
        expand_special_keys(buf, len);
        t->t_start = buf;
        t->t_end = buf + len;
        t->t_next = *tlist;
        *tlist = t;
        return (0);
}

/*
 * Add a command table.
 */
        public void
add_fcmd_table(buf, len)
        char *buf;
        int len;
{
        if (add_cmd_table(&list_fcmd_tables, buf, len) < 0)
                error("Warning: some commands disabled", NULL_PARG);
}

/*
 * Add an editing command table.
 */
        public void
add_ecmd_table(buf, len)
        char *buf;
        int len;
{
        if (add_cmd_table(&list_ecmd_tables, buf, len) < 0)
                error("Warning: some edit commands disabled", NULL_PARG);
}

/*
 * Add an environment variable table.
 */
        static void
add_var_table(tlist, buf, len)
        struct tablelist **tlist;
        char *buf;
        int len;
{
        if (add_cmd_table(tlist, buf, len) < 0)
                error("Warning: environment variables from lesskey file unavailable", NULL_PARG);
}

/*
 * Search a single command table for the command string in cmd.
 */
        static int
cmd_search(cmd, table, endtable, sp)
        char *cmd;
        char *table;
        char *endtable;
        char **sp;
{
        register char *p;
        register char *q;
        register int a;

        *sp = NULL;
        for (p = table, q = cmd;  p < endtable;  p++, q++)
        {
                if (*p == *q)
                {
                        /*
                         * Current characters match.
                         * If we're at the end of the string, we've found it.
                         * Return the action code, which is the character
                         * after the null at the end of the string
                         * in the command table.
                         */
                        if (*p == '\0')
                        {
                                a = *++p & 0377;
                                while (a == A_SKIP)
                                        a = *++p & 0377;
                                if (a == A_END_LIST)
                                {
                                        /*
                                         * We get here only if the original
                                         * cmd string passed in was empty ("").
                                         * I don't think that can happen,
                                         * but just in case ...
                                         */
                                        return (A_UINVALID);
                                }
                                /*
                                 * Check for an "extra" string.
                                 */
                                if (a & A_EXTRA)
                                {
                                        *sp = ++p;
                                        a &= ~A_EXTRA;
                                }
                                return (a);
                        }
                } else if (*q == '\0')
                {
                        /*
                         * Hit the end of the user's command,
                         * but not the end of the string in the command table.
                         * The user's command is incomplete.
                         */
                        return (A_PREFIX);
                } else
                {
                        /*
                         * Not a match.
                         * Skip ahead to the next command in the
                         * command table, and reset the pointer
                         * to the beginning of the user's command.
                         */
                        if (*p == '\0' && p[1] == A_END_LIST)
                        {
                                /*
                                 * A_END_LIST is a special marker that tells 
                                 * us to abort the cmd search.
                                 */
                                return (A_UINVALID);
                        }
                        while (*p++ != '\0')
                                continue;
                        while (*p == A_SKIP)
                                p++;
                        if (*p & A_EXTRA)
                                while (*++p != '\0')
                                        continue;
                        q = cmd-1;
                }
        }
        /*
         * No match found in the entire command table.
         */
        return (A_INVALID);
}

/*
 * Decode a command character and return the associated action.
 * The "extra" string, if any, is returned in sp.
 */
        static int
cmd_decode(tlist, cmd, sp)
        struct tablelist *tlist;
        char *cmd;
        char **sp;
{
        register struct tablelist *t;
        register int action = A_INVALID;

        /*
         * Search thru all the command tables.
         * Stop when we find an action which is not A_INVALID.
         */
        for (t = tlist;  t != NULL;  t = t->t_next)
        {
                action = cmd_search(cmd, t->t_start, t->t_end, sp);
                if (action != A_INVALID)
                        break;
        }
        if (action == A_UINVALID)
                action = A_INVALID;
        return (action);
}

/*
 * Decode a command from the cmdtables list.
 */
        public int
fcmd_decode(cmd, sp)
        char *cmd;
        char **sp;
{
        return (cmd_decode(list_fcmd_tables, cmd, sp));
}

/*
 * Decode a command from the edittables list.
 */
        public int
ecmd_decode(cmd, sp)
        char *cmd;
        char **sp;
{
        return (cmd_decode(list_ecmd_tables, cmd, sp));
}

/*
 * Get the value of an environment variable.
 * Looks first in the lesskey file, then in the real environment.
 */
        public char *
lgetenv(var)
        char *var;
{
        int a;
        char *s;

        a = cmd_decode(list_var_tables, var, &s);
        if (a == EV_OK)
                return (s);
        s = getenv(var);
        if (s != NULL && *s != '\0')
                return (s);
        a = cmd_decode(list_sysvar_tables, var, &s);
        if (a == EV_OK)
                return (s);
        return (NULL);
}

#if USERFILE
/*
 * Get an "integer" from a lesskey file.
 * Integers are stored in a funny format: 
 * two bytes, low order first, in radix KRADIX.
 */
        static int
gint(sp)
        char **sp;
{
        int n;

        n = *(*sp)++;
        n += *(*sp)++ * KRADIX;
        return (n);
}

/*
 * Process an old (pre-v241) lesskey file.
 */
        static int
old_lesskey(buf, len)
        char *buf;
        int len;
{
        /*
         * Old-style lesskey file.
         * The file must end with either 
         *     ...,cmd,0,action
         * or  ...,cmd,0,action|A_EXTRA,string,0
         * So the last byte or the second to last byte must be zero.
         */
        if (buf[len-1] != '\0' && buf[len-2] != '\0')
                return (-1);
        add_fcmd_table(buf, len);
        return (0);
}

/* 
 * Process a new (post-v241) lesskey file.
 */
        static int
new_lesskey(buf, len, sysvar)
        char *buf;
        int len;
        int sysvar;
{
        char *p;
        register int c;
        register int n;

        /*
         * New-style lesskey file.
         * Extract the pieces.
         */
        if (buf[len-3] != C0_END_LESSKEY_MAGIC ||
            buf[len-2] != C1_END_LESSKEY_MAGIC ||
            buf[len-1] != C2_END_LESSKEY_MAGIC)
                return (-1);
        p = buf + 4;
        for (;;)
        {
                c = *p++;
                switch (c)
                {
                case CMD_SECTION:
                        n = gint(&p);
                        add_fcmd_table(p, n);
                        p += n;
                        break;
                case EDIT_SECTION:
                        n = gint(&p);
                        add_ecmd_table(p, n);
                        p += n;
                        break;
                case VAR_SECTION:
                        n = gint(&p);
                        add_var_table((sysvar) ? 
                                &list_sysvar_tables : &list_var_tables, p, n);
                        p += n;
                        break;
                case END_SECTION:
                        return (0);
                default:
                        /*
                         * Unrecognized section type.
                         */
                        return (-1);
                }
        }
}

/*
 * Set up a user command table, based on a "lesskey" file.
 */
        public int
lesskey(filename, sysvar)
        char *filename;
        int sysvar;
{
        register char *buf;
        register POSITION len;
        register long n;
        register int f;

        if (secure)
                return (1);
        /*
         * Try to open the lesskey file.
         */
        filename = shell_unquote(filename);
        f = open(filename, OPEN_READ);
        free(filename);
        if (f < 0)
                return (1);

        /*
         * Read the file into a buffer.
         * We first figure out the size of the file and allocate space for it.
         * {{ Minimal error checking is done here.
         *    A garbage .less file will produce strange results.
         *    To avoid a large amount of error checking code here, we
         *    rely on the lesskey program to generate a good .less file. }}
         */
        len = filesize(f);
        if (len == NULL_POSITION || len < 3)
        {
                /*
                 * Bad file (valid file must have at least 3 chars).
                 */
                close(f);
                return (-1);
        }
        if ((buf = (char *) calloc((int)len, sizeof(char))) == NULL)
        {
                close(f);
                return (-1);
        }
        if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
        {
                free(buf);
                close(f);
                return (-1);
        }
        n = read(f, buf, (unsigned int) len);
        close(f);
        if (n != len)
        {
                free(buf);
                return (-1);
        }

        /*
         * Figure out if this is an old-style (before version 241)
         * or new-style lesskey file format.
         */
        if (buf[0] != C0_LESSKEY_MAGIC || buf[1] != C1_LESSKEY_MAGIC ||
            buf[2] != C2_LESSKEY_MAGIC || buf[3] != C3_LESSKEY_MAGIC)
                return (old_lesskey(buf, (int)len));
        return (new_lesskey(buf, (int)len, sysvar));
}

/*
 * Add the standard lesskey file "$HOME/.less"
 */
        public void
add_hometable(envname, def_filename, sysvar)
        char *envname;
        char *def_filename;
        int sysvar;
{
        char *filename;
        PARG parg;

        if (envname != NULL && (filename = lgetenv(envname)) != NULL)
                filename = save(filename);
        else if (sysvar)
                filename = save(def_filename);
        else
                filename = homefile(def_filename);
        if (filename == NULL)
                return;
        if (lesskey(filename, sysvar) < 0)
        {
                parg.p_string = filename;
                error("Cannot use lesskey file \"%s\"", &parg);
        }
        free(filename);
}
#endif

/*
 * See if a char is a special line-editing command.
 */
        public int
editchar(c, flags)
        int c;
        int flags;
{
        int action;
        int nch;
        char *s;
        char usercmd[MAX_CMDLEN+1];
        
        /*
         * An editing character could actually be a sequence of characters;
         * for example, an escape sequence sent by pressing the uparrow key.
         * To match the editing string, we use the command decoder
         * but give it the edit-commands command table
         * This table is constructed to match the user's keyboard.
         */
        if (c == erase_char || c == erase2_char)
                return (EC_BACKSPACE);
        if (c == kill_char)
                return (EC_LINEKILL);
                
        /*
         * Collect characters in a buffer.
         * Start with the one we have, and get more if we need them.
         */
        nch = 0;
        do {
                if (nch > 0)
                        c = getcc();
                usercmd[nch] = c;
                usercmd[nch+1] = '\0';
                nch++;
                action = ecmd_decode(usercmd, &s);
        } while (action == A_PREFIX);
        
        if (flags & EC_NORIGHTLEFT)
        {
                switch (action)
                {
                case EC_RIGHT:
                case EC_LEFT:
                        action = A_INVALID;
                        break;
                }
        }
#if CMD_HISTORY
        if (flags & EC_NOHISTORY) 
        {
                /*
                 * The caller says there is no history list.
                 * Reject any history-manipulation action.
                 */
                switch (action)
                {
                case EC_UP:
                case EC_DOWN:
                        action = A_INVALID;
                        break;
                }
        }
#endif
#if TAB_COMPLETE_FILENAME
        if (flags & EC_NOCOMPLETE) 
        {
                /*
                 * The caller says we don't want any filename completion cmds.
                 * Reject them.
                 */
                switch (action)
                {
                case EC_F_COMPLETE:
                case EC_B_COMPLETE:
                case EC_EXPAND:
                        action = A_INVALID;
                        break;
                }
        }
#endif
        if ((flags & EC_PEEK) || action == A_INVALID)
        {
                /*
                 * We're just peeking, or we didn't understand the command.
                 * Unget all the characters we read in the loop above.
                 * This does NOT include the original character that was 
                 * passed in as a parameter.
                 */
                while (nch > 1) 
                {
                        ungetcc(usercmd[--nch]);
                }
        } else
        {
                if (s != NULL)
                        ungetsc(s);
        }
        return action;
}