src/util.c

   1 /* util.c -- utility routines for vlock, the VT locking program for linux
   2  *
   3  * This program is copyright (C) 2007 Frank Benkstein, and is free
   4  * software which is freely distributable under the terms of the
   5  * GNU General Public License version 2, included as the file COPYING in this
   6  * distribution.  It is NOT public domain software, and any
   7  * redistribution not permitted by the GNU General Public License is
   8  * expressly forbidden without prior written permission from
   9  * the author.
  10  *
  11  */
  12
  13 #if !defined(__FreeBSD__) && !defined(_GNU_SOURCE)
  14 #define _GNU_SOURCE
  15 #endif
  16
  17 #include <stdlib.h>
  18 #include <stdarg.h>
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <errno.h>
  22 #include <time.h>
  23
  24 #include <glib.h>
  25
  26 #include "util.h"
  27
  28 /* Parse the given string (interpreted as seconds) into a
  29  * timespec.  On error NULL is returned.  The caller is responsible
  30  * to free the result.   The argument may be NULL, in which case NULL
  31  * is returned, too.  "0" is also parsed as NULL. */
  32 struct timespec *parse_seconds(const char *s)
  33 {
  34   if (s == NULL)
  35     return NULL;
  36   else {
  37     char *n;
  38     struct timespec *t = calloc(sizeof *t, 1);
  39
  40     if (t == NULL)
  41       return NULL;
  42
  43     t->tv_sec = strtol(s, &n, 10);
  44
  45     if (*n != '\0' || t->tv_sec <= 0) {
  46       free(t);
  47       t = NULL;
  48     }
  49
  50     return t;
  51   }
  52 }
  53
  54 static GList *atexit_functions;
  55
  56 typedef union
  57 {
  58   void *as_pointer;
  59   void (*as_function)(void);
  60 } function_pointer;
  61
  62 void vlock_invoke_atexit(void)
  63 {
  64   while (atexit_functions != NULL) {
  65     function_pointer p = { .as_pointer = atexit_functions->data };
  66     p.as_function();
  67     atexit_functions = g_list_delete_link(atexit_functions,
  68                                           atexit_functions);
  69   }
  70 }
  71
  72 void vlock_atexit(void (*function)(void))
  73 {
  74   if (atexit_functions == NULL)
  75     atexit(vlock_invoke_atexit);
  76
  77   function_pointer p = { .as_function = function };
  78
  79   atexit_functions = g_list_prepend(atexit_functions, p.as_pointer);
  80 }
  81