/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Pager: Routines to create a "more" running out of a particular file
 * descriptor.
 *
 * Copyright 1987, 1988 by MIT Student Information Processing Board
 *
 * For copyright information, see copyright.h.
 */

#include "ss_internal.h"
#include "copyright.h"
#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/file.h>
#include <signal.h>

static char MORE[] = "more";
extern char *_ss_pager_name;
extern char *getenv();

/*
 * this needs a *lot* of work....
 *
 * run in same process
 * handle SIGINT sensibly
 * allow finer control -- put-page-break-here
 */

#ifndef NO_FORK
int ss_pager_create(void)
{
        int filedes[2];

        if (pipe(filedes) != 0)
                return(-1);

        switch((int) fork()) {
        case -1:
                return(-1);
        case 0:
                /*
                 * Child; dup read half to 0, close all but 0, 1, and 2
                 */
                if (dup2(filedes[0], 0) == -1)
                        exit(1);
                ss_page_stdin();
        default:
                /*
                 * Parent:  close "read" side of pipe, return
                 * "write" side.
                 */
                (void) close(filedes[0]);
                return(filedes[1]);
        }
}
#else /* don't fork */
int ss_pager_create(void)
{
    int fd;
    fd = open("/dev/tty", O_WRONLY, 0);
    return fd;
}
#endif

void ss_page_stdin(void)
{
        int i;
#ifdef POSIX_SIGNALS
        struct sigaction sa;
        sigset_t mask;
#endif
        /*
         * Close all fd's, excepting stdin/stdout/stderr
         */
        closefrom(3);

#ifdef POSIX_SIGNALS
        sa.sa_handler = SIG_DFL;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = 0;
        sigaction(SIGINT, &sa, NULL);
#else
        (void) signal(SIGINT, SIG_DFL);
#endif
        {
#ifdef POSIX_SIGNALS
                sigemptyset(&mask);
                sigaddset(&mask, SIGINT);
                sigprocmask(SIG_UNBLOCK, &mask, NULL);
#else
                int mask = sigblock(0);
                mask &= ~sigmask(SIGINT);
                sigsetmask(mask);
#endif
        }
        if (_ss_pager_name == NULL) {
                if ((_ss_pager_name = getenv("PAGER")) == NULL)
                        _ss_pager_name = MORE;
        }
        (void) execlp(_ss_pager_name, _ss_pager_name, NULL);
        {
                /* minimal recovery if pager program isn't found */
                char buf[80];
                register int n;
                while ((n = read(0, buf, 80)) > 0)
                        write(1, buf, (unsigned) n);
        }
        exit(errno);
}