/*      $NetBSD: hack.pager.c,v 1.21 2011/09/01 07:18:50 plunky Exp $   */

/*
 * Copyright (c) 1985, Stichting Centrum voor Wiskunde en Informatica,
 * Amsterdam
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Stichting Centrum voor Wiskunde en
 * Informatica, nor the names of its contributors may be used to endorse or
 * promote products derived from this software without specific prior
 * written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982 Jay Fenlason <hack@gnu.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author 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 ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* This file contains the command routine dowhatis() and a pager. */
/*
 * Also readmail() and doshell(), and generally the things that contact the
 * outside world.
 */

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include "hack.h"
#include "extern.h"

static void intruph(int);
static void page_more(FILE *, int);
static int page_file(const char *, boolean);
static int child(int);

int
dowhatis(void)
{
        FILE           *fp;
        char            bufr[BUFSZ + 6];
        char           *buf = &bufr[6], *ep, q;

        if (!(fp = fopen(DATAFILE, "r")))
                pline("Cannot open data file!");
        else {
                pline("Specify what? ");
                q = readchar();
                if (q != '\t')
                        while (fgets(buf, BUFSZ, fp))
                                if (*buf == q) {
                                        ep = strchr(buf, '\n');
                                        if (ep)
                                                *ep = 0;
                                        /* else: bad data file */
                                        else {
                                                pline("Bad data file!");
                                                (void) fclose(fp);
                                                return(0);
                                        }
                                        /* Expand tab 'by hand' */
                                        if (buf[1] == '\t') {
                                                buf = bufr;
                                                buf[0] = q;
                                                (void) strncpy(buf + 1, "       ", 7);
                                        }
                                        pline("%s", buf);
                                        if (ep[-1] == ';') {
                                                pline("More info? ");
                                                if (readchar() == 'y') {
                                                        page_more(fp, 1);       /* does fclose() */
                                                        return (0);
                                                }
                                        }
                                        (void) fclose(fp);      /* kopper@psuvax1 */
                                        return (0);
                                }
                pline("I've never heard of such things.");
                (void) fclose(fp);
        }
        return (0);
}

/* make the paging of a file interruptible */
static int      got_intrup;

static void
intruph(int n __unused)
{
        got_intrup++;
}

/* simple pager, also used from dohelp() */
/* strip: nr of chars to be stripped from each line (0 or 1) */
static void
page_more(FILE *fp, int strip)
{
        char           *bufr, *ep;
        sig_t           prevsig = signal(SIGINT, intruph);

        set_pager(0);
        bufr = alloc(CO);
        bufr[CO - 1] = 0;
        while (fgets(bufr, CO - 1, fp) && (!strip || *bufr == '\t') && !got_intrup) {
                ep = strchr(bufr, '\n');
                if (ep)
                        *ep = 0;
                if (page_line(bufr + strip)) {
                        set_pager(2);
                        goto ret;
                }
        }
        set_pager(1);
ret:
        free(bufr);
        (void) fclose(fp);
        (void) signal(SIGINT, prevsig);
        got_intrup = 0;
}

static boolean  whole_screen = TRUE;
#define PAGMIN  12              /* minimum # of lines for page below level
                                 * map */

void
set_whole_screen(void)
{                               /* called in termcap as soon as LI is known */
        whole_screen = (LI - ROWNO - 2 <= PAGMIN || !CD);
}

#ifdef NEWS
int
readnews(void)
{
        int             ret;

        whole_screen = TRUE;    /* force a docrt(), our first */
        ret = page_file(NEWS, TRUE);
        set_whole_screen();
        return (ret);           /* report whether we did docrt() */
}
#endif  /* NEWS */

/* mode:  0: open  1: wait+close  2: close */
void
set_pager(int mode)
{
        static boolean  so;
        if (mode == 0) {
                if (!whole_screen) {
                        /* clear topline */
                        clrlin();
                        /* use part of screen below level map */
                        curs(1, ROWNO + 4);
                } else {
                        cls();
                }
                so = flags.standout;
                flags.standout = 1;
        } else {
                if (mode == 1) {
                        curs(1, LI);
                        more();
                }
                flags.standout = so;
                if (whole_screen)
                        docrt();
                else {
                        curs(1, ROWNO + 4);
                        cl_eos();
                }
        }
}

int
page_line(const char *s)        /* returns 1 if we should quit */
{
        if (cury == LI - 1) {
                if (!*s)
                        return (0);     /* suppress blank lines at top */
                putchar('\n');
                cury++;
                cmore("q\033");
                if (morc) {
                        morc = 0;
                        return (1);
                }
                if (whole_screen)
                        cls();
                else {
                        curs(1, ROWNO + 4);
                        cl_eos();
                }
        }
        puts(s);
        cury++;
        return (0);
}

/*
 * Flexible pager: feed it with a number of lines and it will decide
 * whether these should be fed to the pager above, or displayed in a
 * corner.
 * Call:
 *      cornline(0, title or 0) : initialize
 *      cornline(1, text)       : add text to the chain of texts
 *      cornline(2, morcs)      : output everything and cleanup
 *      cornline(3, 0)          : cleanup
 */

void
cornline(int mode, const char *text)
{
        static struct line {
                struct line    *next_line;
                char           *line_text;
        }              *texthead, *texttail;
        static int      maxlen;
        static int      linect;
        struct line    *tl;

        if (mode == 0) {
                texthead = 0;
                maxlen = 0;
                linect = 0;
                if (text) {
                        cornline(1, text);      /* title */
                        cornline(1, "");        /* blank line */
                }
                return;
        }
        if (mode == 1) {
                int             len;

                if (!text)
                        return; /* superfluous, just to be sure */
                linect++;
                len = strlen(text);
                if (len > maxlen)
                        maxlen = len;
                tl = alloc(len + sizeof(*tl) + 1);
                tl->next_line = 0;
                tl->line_text = (char *) (tl + 1);
                (void) strcpy(tl->line_text, text);
                if (!texthead)
                        texthead = tl;
                else
                        texttail->next_line = tl;
                texttail = tl;
                return;
        }
        /* --- now we really do it --- */
        if (mode == 2 && linect == 1)   /* topline only */
                pline("%s", texthead->line_text);
        else if (mode == 2) {
                int             curline, lth;

                if (flags.toplin == 1)
                        more(); /* ab@unido */
                remember_topl();

                lth = CO - maxlen - 2;  /* Use full screen width */
                if (linect < LI && lth >= 10) { /* in a corner */
                        home();
                        cl_end();
                        flags.toplin = 0;
                        curline = 1;
                        for (tl = texthead; tl; tl = tl->next_line) {
                                curs(lth, curline);
                                if (curline > 1)
                                        cl_end();
                                putsym(' ');
                                putstr(tl->line_text);
                                curline++;
                        }
                        curs(lth, curline);
                        cl_end();
                        cmore(text);
                        home();
                        cl_end();
                        docorner(lth, curline - 1);
                } else {        /* feed to pager */
                        set_pager(0);
                        for (tl = texthead; tl; tl = tl->next_line) {
                                if (page_line(tl->line_text)) {
                                        set_pager(2);
                                        goto cleanup;
                                }
                        }
                        if (text) {
                                cgetret(text);
                                set_pager(2);
                        } else
                                set_pager(1);
                }
        }
cleanup:
        while ((tl = texthead) != NULL) {
                texthead = tl->next_line;
                free(tl);
        }
}

int
dohelp(void)
{
        char            c;

        pline("Long or short help? ");
        while (((c = readchar()) != 'l') && (c != 's') && !strchr(quitchars, c))
                sound_bell();
        if (!strchr(quitchars, c))
                (void) page_file((c == 'l') ? HELP : SHELP, FALSE);
        return (0);
}

/* return: 0 - cannot open fnam; 1 - otherwise */
static int
page_file(const char *fnam, boolean silent)
{
#ifdef DEF_PAGER                /* this implies that UNIX is defined */
        {
                /* use external pager; this may give security problems */

                int             fd = open(fnam, O_RDONLY);

                if (fd < 0) {
                        if (!silent)
                                pline("Cannot open %s.", fnam);
                        return (0);
                }
                if (child(1)) {

                        /*
                         * Now that child() does a setuid(getuid()) and a
                         * chdir(), we may not be able to open file fnam
                         * anymore, so make it stdin.
                         */
                        (void) close(0);
                        if (dup(fd)) {
                                if (!silent)
                                        printf("Cannot open %s as stdin.\n", fnam);
                        } else {
                                execl(catmore, "page", (char *)NULL);
                                if (!silent)
                                        printf("Cannot exec %s.\n", catmore);
                        }
                        exit(1);
                }
                (void) close(fd);
        }
#else   /* DEF_PAGER */
        {
                FILE           *f;      /* free after Robert Viduya */

                if ((f = fopen(fnam, "r")) == (FILE *) 0) {
                        if (!silent) {
                                home();
                                perror(fnam);
                                flags.toplin = 1;
                                pline("Cannot open %s.", fnam);
                        }
                        return (0);
                }
                page_more(f, 0);
        }
#endif  /* DEF_PAGER */

        return (1);
}

#ifdef UNIX
#ifdef SHELL
int
dosh(void)
{
        char           *str;
        if (child(0)) {
                if ((str = getenv("SHELL")) != NULL)
                        execl(str, str, (char *)NULL);
                else
                        execl("/bin/sh", "sh", (char *)NULL);
                pline("sh: cannot execute.");
                exit(1);
        }
        return (0);
}
#endif  /* SHELL */

static int
child(int wt)
{
        int             status;
        int             f;

        f = fork();
        if (f == 0) {           /* child */
                settty(NULL);   /* also calls end_screen() */
                (void) setuid(getuid());
                (void) setgid(getgid());
#ifdef CHDIR
                (void) chdir(getenv("HOME"));
#endif  /* CHDIR */
                return (1);
        }
        if (f == -1) {          /* cannot fork */
                pline("Fork failed. Try again.");
                return (0);
        }
        /* fork succeeded; wait for child to exit */
        (void) signal(SIGINT, SIG_IGN);
        (void) signal(SIGQUIT, SIG_IGN);
        (void) wait(&status);
        gettty();
        setftty();
        (void) signal(SIGINT, done1);
#ifdef WIZARD
        if (wizard)
                (void) signal(SIGQUIT, SIG_DFL);
#endif  /* WIZARD */
        if (wt)
                getret();
        docrt();
        return (0);
}
#endif  /* UNIX */