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

   1
   2 /*
   3  * context_save.c -- write out the updated context file
   4  *
   5  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   6  * COPYRIGHT file in the root directory of the nmh distribution for
   7  * complete copyright information.
   8  */
   9
  10 #include <h/mh.h>
  11 #include <h/signals.h>
  12
  13 /*
  14  * static prototypes
  15  */
  16 static int m_chkids(void);
  17
  18
  19 void
  20 context_save (void)
  21 {
  22     int action;
  23     register struct node *np;
  24     FILE *out;
  25     sigset_t set, oset;
  26
  27     /* No context in use -- silently ignore any changes! */
  28     if (!ctxpath)
  29        return;
  30
  31     if (!(ctxflags & CTXMOD))
  32         return;
  33     ctxflags &= ~CTXMOD;
  34
  35     if ((action = m_chkids ()) > 0)
  36         return;                 /* child did it for us */
  37
  38     /* block a few signals */
  39     sigemptyset (&set);
  40     sigaddset (&set, SIGHUP);
  41     sigaddset (&set, SIGINT);
  42     sigaddset (&set, SIGQUIT);
  43     sigaddset (&set, SIGTERM);
  44     sigprocmask (SIG_BLOCK, &set, &oset);
  45
  46     if (!(out = lkfopendata (ctxpath, "w")))
  47         adios (ctxpath, "unable to write");
  48     for (np = m_defs; np; np = np->n_next)
  49         if (np->n_context)
  50             fprintf (out, "%s: %s\n", np->n_name, np->n_field);
  51     lkfclosedata (out, ctxpath);
  52
  53     sigprocmask (SIG_SETMASK, &oset, &set); /* reset the signal mask */
  54
  55     if (action == 0)
  56         /* This must be _exit(), not exit(), because the child didn't
  57            call unregister_for_removal() in m_chkids(). */
  58         _exit (0);              /* we are child, time to die */
  59 }
  60
  61 /*
  62  * This hack brought to you so we can handle set[ug]id MH programs.
  63  * If we return -1, then no fork is made, we update .mh_profile
  64  * normally, and return to the caller normally.  If we return 0,
  65  * then the child is executing, .mh_profile is modified after
  66  * we set our [ug]ids to the norm.  If we return > 0, then the
  67  * parent is executed and .mh_profile has already be modified.
  68  * We can just return to the caller immediately.
  69  */
  70
  71 static int
  72 m_chkids (void)
  73 {
  74     int i;
  75     pid_t pid;
  76
  77     if (getuid () == geteuid ())
  78         return (-1);
  79
  80     for (i = 0; (pid = fork ()) == -1 && i < 5; i++)
  81         sleep (5);
  82
  83     switch (pid) {
  84         case -1:
  85             break;
  86
  87         case 0:
  88             /* It's not necessary to call unregister_for_removal(0)
  89                because the child calls _exit() in context_save(). */
  90             break;
  91
  92         default:
  93             pidwait (pid, -1);
  94             break;
  95     }
  96
  97     return pid;
  98 }