usr/src/lib/krb5/ss/pager.c

   1 /*
   2  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 #pragma ident   "%Z%%M% %I%     %E% SMI"
   7
   8 /*
   9  * Pager: Routines to create a "more" running out of a particular file
  10  * descriptor.
  11  *
  12  * Copyright 1987, 1988 by MIT Student Information Processing Board
  13  *
  14  * For copyright information, see copyright.h.
  15  */
  16
  17 #include "ss_internal.h"
  18 #include "copyright.h"
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <sys/types.h>
  22 #include <sys/file.h>
  23 #include <signal.h>
  24
  25 static char MORE[] = "more";
  26 extern char *_ss_pager_name;
  27 extern char *getenv();
  28
  29 /*
  30  * this needs a *lot* of work....
  31  *
  32  * run in same process
  33  * handle SIGINT sensibly
  34  * allow finer control -- put-page-break-here
  35  */
  36 void ss_page_stdin();
  37
  38 #ifndef NO_FORK
  39 int ss_pager_create()
  40 {
  41         int filedes[2];
  42
  43         if (pipe(filedes) != 0)
  44                 return(-1);
  45
  46         switch((int) fork()) {
  47         case -1:
  48                 return(-1);
  49         case 0:
  50                 /*
  51                  * Child; dup read half to 0, close all but 0, 1, and 2
  52                  */
  53                 if (dup2(filedes[0], 0) == -1)
  54                         exit(1);
  55                 ss_page_stdin();
  56         default:
  57                 /*
  58                  * Parent:  close "read" side of pipe, return
  59                  * "write" side.
  60                  */
  61                 (void) close(filedes[0]);
  62                 return(filedes[1]);
  63         }
  64 }
  65 #else /* don't fork */
  66 int ss_pager_create()
  67 {
  68     int fd;
  69     fd = open("/dev/tty", O_WRONLY, 0);
  70     return fd;
  71 }
  72 #endif
  73
  74 void ss_page_stdin()
  75 {
  76         int i;
  77 #ifdef POSIX_SIGNALS
  78         struct sigaction sa;
  79         sigset_t mask;
  80 #endif
  81         /*
  82          * Close all fd's, excepting stdin/stdout/stderr
  83          */
  84         closefrom(3);
  85
  86 #ifdef POSIX_SIGNALS
  87         sa.sa_handler = SIG_DFL;
  88         sigemptyset(&sa.sa_mask);
  89         sa.sa_flags = 0;
  90         sigaction(SIGINT, &sa, NULL);
  91 #else
  92         (void) signal(SIGINT, SIG_DFL);
  93 #endif
  94         {
  95 #ifdef POSIX_SIGNALS
  96                 sigemptyset(&mask);
  97                 sigaddset(&mask, SIGINT);
  98                 sigprocmask(SIG_UNBLOCK, &mask, (sigset_t *)0);
  99 #else
 100                 int mask = sigblock(0);
 101                 mask &= ~sigmask(SIGINT);
 102                 sigsetmask(mask);
 103 #endif
 104         }
 105         if (_ss_pager_name == NULL) {
 106                 if ((_ss_pager_name = getenv("PAGER")) == NULL)
 107                         _ss_pager_name = MORE;
 108         }
 109         (void) execlp(_ss_pager_name, _ss_pager_name, (char *) NULL);
 110         {
 111                 /* minimal recovery if pager program isn't found */
 112                 char buf[80];
 113                 register int n;
 114                 while ((n = read(0, buf, 80)) > 0)
 115                         write(1, buf, (unsigned) n);
 116         }
 117         exit(errno);
 118 }