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     int failed_to_lock = 0;
  27
  28     /* No context in use -- silently ignore any changes! */
  29     if (!ctxpath)
  30        return;
  31
  32     if (!(ctxflags & CTXMOD))
  33         return;
  34     ctxflags &= ~CTXMOD;
  35
  36     if ((action = m_chkids ()) > 0)
  37         return;                 /* child did it for us */
  38
  39     /* block a few signals */
  40     sigemptyset (&set);
  41     sigaddset (&set, SIGHUP);
  42     sigaddset (&set, SIGINT);
  43     sigaddset (&set, SIGQUIT);
  44     sigaddset (&set, SIGTERM);
  45     sigprocmask (SIG_BLOCK, &set, &oset);
  46
  47     if (!(out = lkfopendata (ctxpath, "w", &failed_to_lock))) {
  48         if (failed_to_lock) {
  49             adios (ctxpath, "failed to lock");
  50         } else {
  51             adios (ctxpath, "unable to write");
  52         }
  53     }
  54     for (np = m_defs; np; np = np->n_next)
  55         if (np->n_context)
  56             fprintf (out, "%s: %s\n", np->n_name, np->n_field);
  57     lkfclosedata (out, ctxpath);
  58
  59     sigprocmask (SIG_SETMASK, &oset, &set); /* reset the signal mask */
  60
  61     if (action == 0)
  62         /* This must be _exit(), not exit(), because the child didn't
  63            call unregister_for_removal() in m_chkids(). */
  64         _exit (0);              /* we are child, time to die */
  65 }
  66
  67 /*
  68  * This hack brought to you so we can handle set[ug]id MH programs.
  69  * If we return -1, then no fork is made, we update .mh_profile
  70  * normally, and return to the caller normally.  If we return 0,
  71  * then the child is executing, .mh_profile is modified after
  72  * we set our [ug]ids to the norm.  If we return > 0, then the
  73  * parent is executed and .mh_profile has already be modified.
  74  * We can just return to the caller immediately.
  75  */
  76
  77 static int
  78 m_chkids (void)
  79 {
  80     int i;
  81     pid_t pid;
  82
  83     if (getuid () == geteuid ())
  84         return (-1);
  85
  86     for (i = 0; (pid = fork ()) == -1 && i < 5; i++)
  87         sleep (5);
  88
  89     switch (pid) {
  90         case -1:
  91             break;
  92
  93         case 0:
  94             /* It's not necessary to call unregister_for_removal(0)
  95                because the child calls _exit() in context_save(). */
  96             break;
  97
  98         default:
  99             pidwait (pid, -1);
 100             break;
 101     }
 102
 103     return pid;
 104 }