155 lines
3.2 KiB
C
155 lines
3.2 KiB
C
/*
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* Pager: Routines to create a "more" running out of a particular file
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* descriptor.
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*
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* Copyright 1987, 1988 by MIT Student Information Processing Board
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose is hereby granted, provided that
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* the names of M.I.T. and the M.I.T. S.I.P.B. not be used in
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* advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. M.I.T. and the
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* M.I.T. S.I.P.B. make no representations about the suitability of
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* this software for any purpose. It is provided "as is" without
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* express or implied warranty.
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*/
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#include "config.h"
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef HAVE_ERRNO_H
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#include <errno.h>
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#else
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extern int errno;
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#endif
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#include "ss_internal.h"
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/file.h>
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#include <signal.h>
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#ifdef HAVE_SYS_PRCTL_H
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#include <sys/prctl.h>
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#else
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#define PR_GET_DUMPABLE 3
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#endif
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#if (!defined(HAVE_PRCTL) && defined(linux))
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#include <sys/syscall.h>
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#endif
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static char MORE[] = "more";
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extern char *getenv PROTOTYPE((const char *));
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char *ss_safe_getenv(const char *arg)
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{
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if ((getuid() != geteuid()) || (getgid() != getegid()))
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return NULL;
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#if HAVE_PRCTL
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if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
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return NULL;
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#else
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#if (defined(linux) && defined(SYS_prctl))
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if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0)
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return NULL;
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#endif
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#endif
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#if defined(HAVE_SECURE_GETENV)
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return secure_getenv(arg);
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#elif defined(HAVE___SECURE_GETENV)
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return __secure_getenv(arg);
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#else
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return getenv(arg);
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#endif
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}
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/*
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* this needs a *lot* of work....
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*
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* run in same process
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* handle SIGINT sensibly
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* allow finer control -- put-page-break-here
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*/
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#ifndef NO_FORK
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int ss_pager_create(void)
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{
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int filedes[2];
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if (pipe(filedes) != 0)
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return(-1);
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switch(fork()) {
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case -1:
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return(-1);
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case 0:
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/*
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* Child; dup read half to 0, close all but 0, 1, and 2
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*/
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if (dup2(filedes[0], 0) == -1)
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exit(1);
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ss_page_stdin();
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default:
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/*
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* Parent: close "read" side of pipe, return
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* "write" side.
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*/
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(void) close(filedes[0]);
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return(filedes[1]);
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}
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}
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#else /* don't fork */
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int ss_pager_create()
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{
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int fd;
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fd = open("/dev/tty", O_WRONLY, 0);
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return fd;
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}
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#endif
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static int write_all(int fd, char *buf, size_t count)
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{
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ssize_t ret;
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int c = 0;
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while (count > 0) {
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ret = write(fd, buf, count);
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if (ret < 0) {
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if ((errno == EAGAIN) || (errno == EINTR))
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continue;
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return -1;
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}
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count -= ret;
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buf += ret;
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c += ret;
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}
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return c;
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}
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void ss_page_stdin(void)
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{
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int i;
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sigset_t mask;
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for (i = 3; i < 32; i++)
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(void) close(i);
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(void) signal(SIGINT, SIG_DFL);
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sigprocmask(SIG_BLOCK, 0, &mask);
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sigdelset(&mask, SIGINT);
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sigprocmask(SIG_SETMASK, &mask, 0);
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if (_ss_pager_name == (char *)NULL) {
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if ((_ss_pager_name = ss_safe_getenv("PAGER")) == (char *)NULL)
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_ss_pager_name = MORE;
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}
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(void) execlp(_ss_pager_name, _ss_pager_name, (char *) NULL);
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{
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/* minimal recovery if pager program isn't found */
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char buf[80];
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register int n;
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while ((n = read(0, buf, 80)) > 0)
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write_all(1, buf, n);
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}
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exit(errno);
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}
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