usr/src/usr.bin/more/decode.c

/*
 * Copyright (c) 1988 Mark Nudleman
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mark Nudleman.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)decode.c    5.1 (Berkeley) %G%";
#endif /* not lint */

/*
 * 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.
 *
 * The default commands are described by cmdtable.
 * User-defined commands are read into usertable.
 */

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

/*
 * Command table is ordered roughly according to expected
 * frequency of use, so the common commands are near the beginning.
 */
static char cmdtable[] =
{
        '\r',0,                         A_F_LINE,
        '\n',0,                         A_F_LINE,
        'e',0,                          A_F_LINE,
        'j',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,
        CONTROL('K'),0,                 A_B_LINE,
        CONTROL('P'),0,                 A_B_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,
        'b',0,                          A_B_SCREEN,
        CONTROL('B'),0,                 A_B_SCREEN,
        CONTROL('['),'v',0,             A_B_SCREEN,
        'R',0,                          A_FREPAINT,
        'r',0,                          A_REPAINT,
        CONTROL('R'),0,                 A_REPAINT,
        CONTROL('L'),0,                 A_REPAINT,
        'g',0,                          A_GOLINE,
        '<',0,                          A_GOLINE,
        CONTROL('['),'<',0,             A_GOLINE,
        'p',0,                          A_PERCENT,
        '%',0,                          A_PERCENT,
        'G',0,                          A_GOEND,
        CONTROL('['),'>',0,             A_GOEND,
        '>',0,                          A_GOEND,

        '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_STAT,
        CONTROL('G'),0,                 A_STAT,
        '/',0,                          A_F_SEARCH,
        '?',0,                          A_B_SEARCH,
        'n',0,                          A_AGAIN_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,
        ':','n',0,                      A_NEXT_FILE,
        ':','p',0,                      A_PREV_FILE,
        '-',0,                          A_TOGGLE_OPTION,
        '_',0,                          A_DISP_OPTION,
        'v',0,                          A_VISUAL,
        '!',0,                          A_SHELL,
        '+',0,                          A_FIRSTCMD,

        'H',0,                          A_HELP,
        'h',0,                          A_HELP,
        'V',0,                          A_VERSION,
        'q',0,                          A_QUIT,
        ':','q',0,                      A_QUIT,
        'Z','Z',0,                      A_QUIT
};

char *cmdendtable = cmdtable + sizeof(cmdtable);

static char usertable[MAX_USERCMD];
char *userendtable = usertable;

static char kbuf[MAX_CMDLEN+1];
static char *kp = kbuf;

/*
 * Decode a command character and return the associated action.
 */
        public int
cmd_decode(c)
        int c;
{
        register int action = A_INVALID;

        /*
         * Append the new command character to the command string in kbuf.
         */
        *kp++ = c;
        *kp = '\0';

#if USERFILE
        /*
         * Look first for any user-defined commands.
         */
        action = cmd_search(usertable, userendtable);
#endif
        /*
         * If didn't find user-defined command,
         * try the normal default commands.
         */
        if (action == A_INVALID)
                action = cmd_search(cmdtable, cmdendtable);

        if (action != A_PREFIX)
                /*
                 * This is not a prefix character.
                 */
                noprefix();

        return (action);
}

/*
 * Indicate that we're not in a prefix command
 * by resetting the command buffer pointer.
 */
        public void
noprefix()
{
        kp = kbuf;
}

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

        for (p = table, q = kbuf;  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')
                                return (p[1]);
                } 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 user's command.
                         */
                        while (*p++ != '\0') ;
                        q = kbuf-1;
                }
        }
        /*
         * No match found in the entire command table.
         */
        return (A_INVALID);
}

/*
 * Initialize the user command table.
 */
        public void
init_cmd()
{
#if USERFILE
        char *filename;
        char *homedir;
        int f;
        int n;
        extern char *getenv();

        /*
         * Try to open "$HOME/.less"
         * If we can't, return without doing anything.
         */
        homedir = getenv("HOME");
        if (homedir == NULL)
                return;
        filename = calloc(strlen(homedir)+7, sizeof(char));
        if (filename == NULL)
                return;
        sprintf(filename, "%s/%s", homedir, ".less");
        f = open(filename, 0);
        free(filename);
        if (f < 0)
                return;

        /*
         * Read the file into the user table.
         * {{ 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. }}
         */
        n = read(f, (char *)usertable, MAX_USERCMD);
        if (n < 3 || usertable[n-2] != '\0')
        {
                /*
                 * Several error cases are lumped together here:
                 * - Cannot read user file (n < 0).
                 * - User file is too short (a valid file must
                 *   have at least 3 chars: one char command string,
                 *   the terminating null byte, and the action byte).
                 * - The final entry in the user file is bad (it
                 *   doesn't have a null byte in the proper place).
                 * Many other error cases are not caught, such as
                 * invalid format in any except the last entry,
                 * invalid action codes, command strings too long, etc.
                 */
                error("invalid user key file");
                n = 0;
        }
        userendtable = usertable + n;
        close(f);
#endif
}