import less(1)

[unleashed/tickless.git] / bin / less / screen.c

/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * 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, see the README file.
 */

/*
 * Routines which deal with the characteristics of the terminal.
 * Uses termcap to be as terminal-independent as possible.
 */

#include <sys/ioctl.h>

#include <err.h>
#include <term.h>
#include <termios.h>

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

#define DEFAULT_TERM            "unknown"

/*
 * Strings passed to tputs() to do various terminal functions.
 */
static char
        *sc_home,               /* Cursor home */
        *sc_addline,            /* Add line, scroll down following lines */
        *sc_lower_left,         /* Cursor to last line, first column */
        *sc_return,             /* Cursor to beginning of current line */
        *sc_move,               /* General cursor positioning */
        *sc_clear,              /* Clear screen */
        *sc_eol_clear,          /* Clear to end of line */
        *sc_eos_clear,          /* Clear to end of screen */
        *sc_s_in,               /* Enter standout (highlighted) mode */
        *sc_s_out,              /* Exit standout mode */
        *sc_u_in,               /* Enter underline mode */
        *sc_u_out,              /* Exit underline mode */
        *sc_b_in,               /* Enter bold mode */
        *sc_b_out,              /* Exit bold mode */
        *sc_bl_in,              /* Enter blink mode */
        *sc_bl_out,             /* Exit blink mode */
        *sc_visual_bell,        /* Visual bell (flash screen) sequence */
        *sc_backspace,          /* Backspace cursor */
        *sc_s_keypad,           /* Start keypad mode */
        *sc_e_keypad,           /* End keypad mode */
        *sc_init,               /* Startup terminal initialization */
        *sc_deinit;             /* Exit terminal de-initialization */

static int init_done = 0;

int auto_wrap;                  /* Terminal does \r\n when write past margin */
int ignaw;                      /* Terminal ignores \n immediately after wrap */
int erase_char;                 /* The user's erase char */
int erase2_char;                /* The user's other erase char */
int kill_char;                  /* The user's line-kill char */
int werase_char;                /* The user's word-erase char */
int sc_width, sc_height;        /* Height & width of screen */
int bo_s_width, bo_e_width;     /* Printing width of boldface seq */
int ul_s_width, ul_e_width;     /* Printing width of underline seq */
int so_s_width, so_e_width;     /* Printing width of standout seq */
int bl_s_width, bl_e_width;     /* Printing width of blink seq */
int can_goto_line;              /* Can move cursor to any line */
int missing_cap = 0;            /* Some capability is missing */
static int above_mem;           /* Memory retained above screen */
static int below_mem;           /* Memory retained below screen */

static int attrmode = AT_NORMAL;
extern int binattr;

static char *cheaper(char *, char *, char *);
static void tmodes(char *, char *, char **, char **, char *, char *);

extern int quiet;               /* If VERY_QUIET, use visual bell for bell */
extern int no_back_scroll;
extern int swindow;
extern int no_init;
extern int no_keypad;
extern volatile sig_atomic_t sigs;
extern int wscroll;
extern int screen_trashed;
extern int tty;
extern int top_scroll;
extern int oldbot;
extern int hilite_search;

/*
 * Change terminal to "raw mode", or restore to "normal" mode.
 * "Raw mode" means
 *      1. An outstanding read will complete on receipt of a single keystroke.
 *      2. Input is not echoed.
 *      3. On output, \n is mapped to \r\n.
 *      4. \t is NOT expanded into spaces.
 *      5. Signal-causing characters such as ctrl-C (interrupt),
 *         etc. are NOT disabled.
 * It doesn't matter whether an input \n is mapped to \r, or vice versa.
 */
void
raw_mode(int on)
{
        static int curr_on = 0;
        struct termios s;
        static struct termios save_term;
        static int saved_term = 0;

        if (on == curr_on)
                return;
        erase2_char = '\b'; /* in case OS doesn't know about erase2 */

        if (on) {
                /*
                 * Get terminal modes.
                 */
                (void) tcgetattr(tty, &s);

                /*
                 * Save modes and set certain variables dependent on modes.
                 */
                if (!saved_term) {
                        save_term = s;
                        saved_term = 1;
                }

                erase_char = s.c_cc[VERASE];
#ifdef VERASE2
                erase2_char = s.c_cc[VERASE2];
#endif
                kill_char = s.c_cc[VKILL];
#ifdef VWERASE
                werase_char = s.c_cc[VWERASE];
#endif

                /*
                 * Set the modes to the way we want them.
                 */
                s.c_lflag &= ~(ICANON | ECHO | ECHOE | ECHOK | ECHONL);

#ifndef TAB3
#define TAB3    0       /* Its a lie, but TAB3 isn't defined by POSIX. */
#endif
                s.c_oflag |= (TAB3 | OPOST | ONLCR);
                s.c_oflag &= ~(OCRNL | ONOCR | ONLRET);
                s.c_cc[VMIN] = 1;
                s.c_cc[VTIME] = 0;
#ifdef VLNEXT
                s.c_cc[VLNEXT] = 0;
#endif
#ifdef VDSUSP
                s.c_cc[VDSUSP] = 0;
#endif
        } else {
                /*
                 * Restore saved modes.
                 */
                s = save_term;
        }
        (void) tcsetattr(tty, TCSASOFT | TCSADRAIN, &s);
        curr_on = on;
}

/*
 * Some glue to prevent calling termcap functions if tgetent() failed.
 */
static int hardcopy;

/*
 * Get size of the output screen.
 */
static void
scrsize(void)
{
        int sys_height = 0, sys_width = 0, n;
        struct winsize w;
        char *s;

#define DEF_SC_WIDTH    80
#define DEF_SC_HEIGHT   24

        if (ioctl(2, TIOCGWINSZ, &w) == 0) {
                if (w.ws_row > 0)
                        sys_height = w.ws_row;
                if (w.ws_col > 0)
                        sys_width = w.ws_col;
        }

        if (sys_height > 0)
                sc_height = sys_height;
        else if ((s = lgetenv("LINES")) != NULL)
                sc_height = atoi(s);
        else if (!hardcopy && (n = lines) > 0)
                sc_height = n;
        if (sc_height <= 0)
                sc_height = DEF_SC_HEIGHT;

        if (sys_width > 0)
                sc_width = sys_width;
        else if ((s = lgetenv("COLUMNS")) != NULL)
                sc_width = atoi(s);
        else if (!hardcopy && (n = columns) > 0)
                sc_width = n;
        if (sc_width <= 0)
                sc_width = DEF_SC_WIDTH;
}

/*
 * Return the characters actually input by a "special" key.
 */
char *
special_key_str(int key)
{
        char *s;
        static char ctrlk[] = { CONTROL('K'), 0 };

        if (hardcopy)
                return (NULL);

        switch (key) {
        case SK_RIGHT_ARROW:
                s = key_right;
                break;
        case SK_LEFT_ARROW:
                s = key_left;
                break;
        case SK_UP_ARROW:
                s = key_up;
                break;
        case SK_DOWN_ARROW:
                s = key_down;
                break;
        case SK_PAGE_UP:
                s = key_ppage;
                break;
        case SK_PAGE_DOWN:
                s = key_npage;
                break;
        case SK_HOME:
                s = key_home;
                break;
        case SK_END:
                s = key_end;
                break;
        case SK_DELETE:
                s = key_dc;
                if (s == NULL) {
                        s = "\177\0";
                }
                break;
        case SK_CONTROL_K:
                s = ctrlk;
                break;
        default:
                return (NULL);
        }
        return (s);
}

/*
 * Get terminal capabilities via termcap.
 */
void
get_term(void)
{
        char *t1, *t2;
        char *term;
        int  err;

        /*
         * Find out what kind of terminal this is.
         */
        if ((term = lgetenv("TERM")) == NULL)
                term = DEFAULT_TERM;
        hardcopy = 0;

        if (setupterm(term, 1, &err) < 0) {
                if (err == 1)
                        hardcopy = 1;
                else
                        errx(1, "%s: unknown terminal type", term);
        }
        if (hard_copy == 1)
                hardcopy = 1;

        /*
         * Get size of the screen.
         */
        scrsize();
        pos_init();

        auto_wrap = hardcopy ? 0 : auto_right_margin;
        ignaw = hardcopy ? 0 : eat_newline_glitch;
        above_mem = hardcopy ? 0 : memory_above;
        below_mem = hardcopy ? 0 : memory_below;

        /*
         * Assumes termcap variable "sg" is the printing width of:
         * the standout sequence, the end standout sequence,
         * the underline sequence, the end underline sequence,
         * the boldface sequence, and the end boldface sequence.
         */
        if (hardcopy || (so_s_width = magic_cookie_glitch) < 0)
                so_s_width = 0;
        so_e_width = so_s_width;

        bo_s_width = bo_e_width = so_s_width;
        ul_s_width = ul_e_width = so_s_width;
        bl_s_width = bl_e_width = so_s_width;

        if (so_s_width > 0 || so_e_width > 0)
                /*
                 * Disable highlighting by default on magic cookie terminals.
                 * Turning on highlighting might change the displayed width
                 * of a line, causing the display to get messed up.
                 * The user can turn it back on with -g,
                 * but she won't like the results.
                 */
                hilite_search = 0;

        /*
         * Get various string-valued capabilities.
         */

        sc_s_keypad = keypad_xmit;
        if (hardcopy || sc_s_keypad == NULL)
                sc_s_keypad = "";
        sc_e_keypad = keypad_local;
        if (hardcopy || sc_e_keypad == NULL)
                sc_e_keypad = "";

        sc_init = enter_ca_mode;
        if (hardcopy || sc_init == NULL)
                sc_init = "";

        sc_deinit = exit_ca_mode;
        if (hardcopy || sc_deinit == NULL)
                sc_deinit = "";

        sc_eol_clear = clr_eol;
        if (hardcopy || sc_eol_clear == NULL || *sc_eol_clear == '\0') {
                missing_cap = 1;
                sc_eol_clear = "";
        }

        sc_eos_clear = clr_eos;
        if (below_mem &&
            (hardcopy || sc_eos_clear == NULL || *sc_eos_clear == '\0')) {
                missing_cap = 1;
                sc_eos_clear = "";
        }

        sc_clear = clear_screen;
        if (hardcopy || sc_clear == NULL || *sc_clear == '\0') {
                missing_cap = 1;
                sc_clear = "\n\n";
        }

        sc_move = cursor_address;
        if (hardcopy || sc_move == NULL || *sc_move == '\0') {
                /*
                 * This is not an error here, because we don't
                 * always need sc_move.
                 * We need it only if we don't have home or lower-left.
                 */
                sc_move = "";
                can_goto_line = 0;
        } else {
                can_goto_line = 1;
        }

        tmodes(enter_standout_mode, exit_standout_mode, &sc_s_in, &sc_s_out,
            "", "");
        tmodes(enter_underline_mode, exit_underline_mode, &sc_u_in, &sc_u_out,
            sc_s_in, sc_s_out);
        tmodes(enter_bold_mode, exit_attribute_mode, &sc_b_in, &sc_b_out,
            sc_s_in, sc_s_out);
        tmodes(enter_blink_mode, exit_attribute_mode, &sc_bl_in, &sc_bl_out,
            sc_s_in, sc_s_out);

        sc_visual_bell = flash_screen;
        if (hardcopy || sc_visual_bell == NULL)
                sc_visual_bell = "";

        sc_backspace = "\b";

        /*
         * Choose between using "ho" and "cm" ("home" and "cursor move")
         * to move the cursor to the upper left corner of the screen.
         */
        t1 = cursor_home;
        if (hardcopy || t1 == NULL)
                t1 = "";
        if (*sc_move == '\0') {
                t2 = "";
        } else {
                t2 = estrdup(tparm(sc_move, 0, 0, 0, 0, 0, 0, 0, 0, 0));
        }
        sc_home = cheaper(t1, t2, "|\b^");

        /*
         * Choose between using "ll" and "cm"  ("lower left" and "cursor move")
         * to move the cursor to the lower left corner of the screen.
         */
        t1 = cursor_to_ll;
        if (hardcopy || t1 == NULL)
                t1 = "";
        if (*sc_move == '\0') {
                t2 = "";
        } else {
                t2 = estrdup(tparm(sc_move, sc_height-1,
                    0, 0, 0, 0, 0, 0, 0, 0));
        }
        sc_lower_left = cheaper(t1, t2, "\r");

        /*
         * Get carriage return string.
         */
        sc_return = carriage_return;
        if (hardcopy || sc_return == NULL)
                sc_return = "\r";

        /*
         * Choose between using insert_line or scroll_reverse
         * to add a line at the top of the screen.
         */
        t1 = insert_line;
        if (hardcopy || t1 == NULL)
                t1 = "";
        t2 = scroll_reverse;
        if (hardcopy || t2 == NULL)
                t2 = "";
        if (above_mem)
                sc_addline = t1;
        else
                sc_addline = cheaper(t1, t2, "");
        if (*sc_addline == '\0') {
                /*
                 * Force repaint on any backward movement.
                 */
                no_back_scroll = 1;
        }
}

/*
 * Return the cost of displaying a termcap string.
 * We use the trick of calling tputs, but as a char printing function
 * we give it inc_costcount, which just increments "costcount".
 * This tells us how many chars would be printed by using this string.
 * {{ Couldn't we just use strlen? }}
 */
static int costcount;

static int
inc_costcount(int c)
{
        costcount++;
        return (c);
}

static int
cost(char *t)
{
        costcount = 0;
        (void) tputs(t, sc_height, inc_costcount);
        return (costcount);
}

/*
 * Return the "best" of the two given termcap strings.
 * The best, if both exist, is the one with the lower
 * cost (see cost() function).
 */
static char *
cheaper(char *t1, char *t2, char *def)
{
        if (*t1 == '\0' && *t2 == '\0') {
                missing_cap = 1;
                return (def);
        }
        if (*t1 == '\0')
                return (t2);
        if (*t2 == '\0')
                return (t1);
        if (cost(t1) < cost(t2))
                return (t1);
        return (t2);
}

static void
tmodes(char *incap, char *outcap, char **instr, char **outstr,
    char *def_instr, char *def_outstr)
{
        if (hardcopy) {
                *instr = "";
                *outstr = "";
                return;
        }

        *instr = incap;
        *outstr = outcap;

        if (*instr == NULL) {
                /* Use defaults. */
                *instr = def_instr;
                *outstr = def_outstr;
                return;
        }

        if (*outstr == NULL)
                /* No specific out capability; use exit_attribute_mode. */
                *outstr = exit_attribute_mode;
        if (*outstr == NULL)
                /* Don't even have that, use an empty string */
                *outstr = "";
}

/*
 * Below are the functions which perform all the
 * terminal-specific screen manipulation.
 */

/*
 * Initialize terminal
 */
void
init(void)
{
        if (!no_init)
                (void) tputs(sc_init, sc_height, putchr);
        if (!no_keypad)
                (void) tputs(sc_s_keypad, sc_height, putchr);
        if (top_scroll) {
                int i;

                /*
                 * This is nice to terminals with no alternate screen,
                 * but with saved scrolled-off-the-top lines.  This way,
                 * no previous line is lost, but we start with a whole
                 * screen to ourself.
                 */
                for (i = 1; i < sc_height; i++)
                        (void) putchr('\n');
        } else
                line_left();
        init_done = 1;
}

/*
 * Deinitialize terminal
 */
void
deinit(void)
{
        if (!init_done)
                return;
        if (!no_keypad)
                (void) tputs(sc_e_keypad, sc_height, putchr);
        if (!no_init)
                (void) tputs(sc_deinit, sc_height, putchr);
        init_done = 0;
}

/*
 * Home cursor (move to upper left corner of screen).
 */
void
home(void)
{
        (void) tputs(sc_home, 1, putchr);
}

/*
 * Add a blank line (called with cursor at home).
 * Should scroll the display down.
 */
void
add_line(void)
{
        (void) tputs(sc_addline, sc_height, putchr);
}

/*
 * Move cursor to lower left corner of screen.
 */
void
lower_left(void)
{
        (void) tputs(sc_lower_left, 1, putchr);
}

/*
 * Move cursor to left position of current line.
 */
void
line_left(void)
{
        (void) tputs(sc_return, 1, putchr);
}

/*
 * Goto a specific line on the screen.
 */
void
goto_line(int slinenum)
{
        (void) tputs(tparm(sc_move, slinenum, 0, 0, 0, 0, 0, 0, 0, 0), 1,
            putchr);
}

/*
 * Output the "visual bell", if there is one.
 */
void
vbell(void)
{
        if (*sc_visual_bell == '\0')
                return;
        (void) tputs(sc_visual_bell, sc_height, putchr);
}

/*
 * Make a noise.
 */
static void
beep(void)
{
        (void) putchr(CONTROL('G'));
}

/*
 * Ring the terminal bell.
 */
void
ring_bell(void)
{
        if (quiet == VERY_QUIET)
                vbell();
        else
                beep();
}

/*
 * Clear the screen.
 */
void
do_clear(void)
{
        (void) tputs(sc_clear, sc_height, putchr);
}

/*
 * Clear from the cursor to the end of the cursor's line.
 * {{ This must not move the cursor. }}
 */
void
clear_eol(void)
{
        (void) tputs(sc_eol_clear, 1, putchr);
}

/*
 * Clear the current line.
 * Clear the screen if there's off-screen memory below the display.
 */
static void
clear_eol_bot(void)
{
        if (below_mem)
                (void) tputs(sc_eos_clear, 1, putchr);
        else
                (void) tputs(sc_eol_clear, 1, putchr);
}

/*
 * Clear the bottom line of the display.
 * Leave the cursor at the beginning of the bottom line.
 */
void
clear_bot(void)
{
        /*
         * If we're in a non-normal attribute mode, temporarily exit
         * the mode while we do the clear.  Some terminals fill the
         * cleared area with the current attribute.
         */
        if (oldbot)
                lower_left();
        else
                line_left();

        if (attrmode == AT_NORMAL)
                clear_eol_bot();
        else
        {
                int saved_attrmode = attrmode;

                at_exit();
                clear_eol_bot();
                at_enter(saved_attrmode);
        }
}

void
at_enter(int attr)
{
        attr = apply_at_specials(attr);

        /* The one with the most priority is last.  */
        if (attr & AT_UNDERLINE)
                (void) tputs(sc_u_in, 1, putchr);
        if (attr & AT_BOLD)
                (void) tputs(sc_b_in, 1, putchr);
        if (attr & AT_BLINK)
                (void) tputs(sc_bl_in, 1, putchr);
        if (attr & AT_STANDOUT)
                (void) tputs(sc_s_in, 1, putchr);

        attrmode = attr;
}

void
at_exit(void)
{
        /* Undo things in the reverse order we did them.  */
        if (attrmode & AT_STANDOUT)
                (void) tputs(sc_s_out, 1, putchr);
        if (attrmode & AT_BLINK)
                (void) tputs(sc_bl_out, 1, putchr);
        if (attrmode & AT_BOLD)
                (void) tputs(sc_b_out, 1, putchr);
        if (attrmode & AT_UNDERLINE)
                (void) tputs(sc_u_out, 1, putchr);

        attrmode = AT_NORMAL;
}

void
at_switch(int attr)
{
        int new_attrmode = apply_at_specials(attr);
        int ignore_modes = AT_ANSI;

        if ((new_attrmode & ~ignore_modes) != (attrmode & ~ignore_modes)) {
                at_exit();
                at_enter(attr);
        }
}

int
is_at_equiv(int attr1, int attr2)
{
        attr1 = apply_at_specials(attr1);
        attr2 = apply_at_specials(attr2);

        return (attr1 == attr2);
}

int
apply_at_specials(int attr)
{
        if (attr & AT_BINARY)
                attr |= binattr;
        if (attr & AT_HILITE)
                attr |= AT_STANDOUT;
        attr &= ~(AT_BINARY|AT_HILITE);

        return (attr);
}

/*
 * Output a plain backspace, without erasing the previous char.
 */
void
putbs(void)
{
        (void) tputs(sc_backspace, 1, putchr);
}