/*      $OpenBSD: hack.pager.c,v 1.25 2019/06/28 13:32:52 deraadt 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 <libgen.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "hack.h"

extern int CO, LI;      /* usually COLNO and ROWNO+2 */
extern char *CD;
extern char quitchars[];

static void page_more(FILE *, int);

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

        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) {
                                        len = strcspn(buf, "\n");
                                        /* bad data file */
                                        if (len == 0)
                                                continue;
                                        buf[len] = '\0';
                                        /* Expand tab 'by hand' */
                                        if (buf[1] == '\t'){
                                                buf = bufr;
                                                buf[0] = q;
                                                (void) strncpy(buf+1, "       ", 7);
                                                len = strlen(buf);
                                        }
                                        pline("%s", buf);
                                        if (buf[len - 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;

void
intruph(int notused)
{
        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;
        sig_t prevsig = signal(SIGINT, intruph);

        set_pager(0);
        bufr = (char *) alloc((unsigned) CO);
        while (fgets(bufr, CO, fp) && (!strip || *bufr == '\t') &&
            !got_intrup) {
                bufr[strcspn(bufr, "\n")] = '\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 */

/* 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(char *s)              /* returns 1 if we should quit */
{
        extern char morc;

        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, 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 = (struct line *)
                alloc((unsigned)(len + sizeof(struct line) + 1));
            tl->next_line = 0;
            tl->line_text = (char *)(tl + 1);
            (void) strlcpy(tl->line_text, text, len + 1);
            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)) {
                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))
                hackbell ();
        if (!strchr(quitchars, c))
                (void) page_file((c == 'l') ? HELP : SHELP, FALSE);
        return(0);
}

/* return: 0 - cannot open fnam; 1 - otherwise */
int
page_file(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 == -1) {
                if(!silent) pline("Cannot open %s.", fnam);
                return(0);
        }
        if(child(1)){
                extern char *catmore;

                /* 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 {
                        execlp(catmore, basename(catmore), (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")))
                        execlp(str, str, (char *)NULL);
                else
                        execl("/bin/sh", "sh", (char *)NULL);
                pline("sh: cannot execute.");
                exit(1);
        }
        return(0);
}
#endif /* SHELL */

#include <sys/wait.h>

int
child(int wt)
{
        int status;
        int f;
        char *home;
        gid_t gid;

        f = fork();
        if(f == 0){             /* child */
                settty(NULL);           /* also calls end_screen() */
                /* revoke privs */
                gid = getgid();
                setresgid(gid, gid, gid);
#ifdef CHDIR
                home = getenv("HOME");
                if (home == NULL || *home == '\0')
                        home = "/";
                (void) chdir(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 */