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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* util/ss/pager.c - create a "more" running out of a 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
*/
void ss_page_stdin();
#ifndef NO_FORK
int ss_pager_create()
{
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]);
set_cloexec_fd(filedes[1]);
return(filedes[1]);
}
}
#else /* don't fork */
int ss_pager_create()
{
int fd;
fd = open("/dev/tty", O_WRONLY, 0);
if (fd >= 0)
set_cloexec_fd(fd);
return fd;
}
#endif
void ss_page_stdin()
{
int i;
#ifdef POSIX_SIGNALS
struct sigaction sa;
sigset_t mask;
#endif
for (i = 3; i < 32; i++)
(void) close(i);
#ifdef POSIX_SIGNALS
sa.sa_handler = SIG_DFL;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sigaction(SIGINT, &sa, (struct sigaction *)0);
#else
(void) signal(SIGINT, SIG_DFL);
#endif
{
#ifdef POSIX_SIGNALS
sigemptyset(&mask);
sigaddset(&mask, SIGINT);
sigprocmask(SIG_UNBLOCK, &mask, (sigset_t *)0);
#else
int mask = sigblock(0);
mask &= ~sigmask(SIGINT);
sigsetmask(mask);
#endif
}
if (_ss_pager_name == (char *)NULL) {
if ((_ss_pager_name = getenv("PAGER")) == (char *)NULL)
_ss_pager_name = MORE;
}
(void) execlp(_ss_pager_name, _ss_pager_name, (char *) 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);
}
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