diplodocus.org Git - nmh/blob - sbr/context_save.c

   1
   2 /*
   3  * context_save.c -- write out the updated context file
   4  *
   5  * $Id$
   6  *
   7  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   8  * COPYRIGHT file in the root directory of the nmh distribution for
   9  * complete copyright information.
  10  */
  11
  12 #include <h/mh.h>
  13 #include <h/signals.h>
  14
  15 /*
  16  * static prototypes
  17  */
  18 static int m_chkids(void);
  19
  20
  21 void
  22 context_save (void)
  23 {
  24     int action;
  25     register struct node *np;
  26     FILE *out;
  27     sigset_t set, oset;
  28
  29     if (!(ctxflags & CTXMOD))
  30         return;
  31     ctxflags &= ~CTXMOD;
  32
  33     if ((action = m_chkids ()) > 0)
  34         return;                 /* child did it for us */
  35
  36     /* block a few signals */
  37     sigemptyset (&set);
  38     sigaddset (&set, SIGHUP);
  39     sigaddset (&set, SIGINT);
  40     sigaddset (&set, SIGQUIT);
  41     sigaddset (&set, SIGTERM);
  42     SIGPROCMASK (SIG_BLOCK, &set, &oset);
  43
  44     if (!(out = fopen (ctxpath, "w")))
  45         adios (ctxpath, "unable to write");
  46     for (np = m_defs; np; np = np->n_next)
  47         if (np->n_context)
  48             fprintf (out, "%s: %s\n", np->n_name, np->n_field);
  49     fclose (out);
  50
  51     SIGPROCMASK (SIG_SETMASK, &oset, &set); /* reset the signal mask */
  52
  53     if (action == 0)
  54         _exit (0);              /* we are child, time to die */
  55 }
  56
  57 /*
  58  * This hack brought to you so we can handle set[ug]id MH programs.
  59  * If we return -1, then no fork is made, we update .mh_profile
  60  * normally, and return to the caller normally.  If we return 0,
  61  * then the child is executing, .mh_profile is modified after
  62  * we set our [ug]ids to the norm.  If we return > 0, then the
  63  * parent is executed and .mh_profile has already be modified.
  64  * We can just return to the caller immediately.
  65  */
  66
  67 static int
  68 m_chkids (void)
  69 {
  70     int i;
  71     pid_t pid;
  72
  73     if (getuid () == geteuid ())
  74         return (-1);
  75
  76     for (i = 0; (pid = fork ()) == -1 && i < 5; i++)
  77         sleep (5);
  78
  79     switch (pid) {
  80         case -1:
  81             break;
  82
  83         case 0:
  84             setgid (getgid ());
  85             setuid (getuid ());
  86             break;
  87
  88         default:
  89             pidwait (pid, -1);
  90             break;
  91     }
  92
  93     return pid;
  94 }