lib/util/system.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba system utilities
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Jeremy Allison 1998-2002
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22 #include "system/network.h"
  23 #include "system/filesys.h"
  24
  25 /*
  26    The idea is that this file will eventually have wrappers around all
  27    important system calls in samba. The aims are:
  28
  29    - to enable easier porting by putting OS dependent stuff in here
  30
  31    - to allow for hooks into other "pseudo-filesystems"
  32
  33    - to allow easier integration of things like the japanese extensions
  34
  35    - to support the philosophy of Samba to expose the features of
  36      the OS within the SMB model. In general whatever file/printer/variable
  37      expansions/etc make sense to the OS should be acceptable to Samba.
  38 */
  39
  40 /**************************************************************************
  41 A wrapper for gethostbyname() that tries avoids looking up hostnames
  42 in the root domain, which can cause dial-on-demand links to come up for no
  43 apparent reason.
  44 ****************************************************************************/
  45
  46 _PUBLIC_ struct hostent *sys_gethostbyname(const char *name)
  47 {
  48 #ifdef REDUCE_ROOT_DNS_LOOKUPS
  49         char query[256], hostname[256];
  50         char *domain;
  51
  52         /* Does this name have any dots in it? If so, make no change */
  53
  54         if (strchr(name, '.'))
  55                 return(gethostbyname(name));
  56
  57         /* Get my hostname, which should have domain name
  58                 attached. If not, just do the gethostname on the
  59                 original string.
  60         */
  61
  62         gethostname(hostname, sizeof(hostname) - 1);
  63         hostname[sizeof(hostname) - 1] = 0;
  64         if ((domain = strchr(hostname, '.')) == NULL)
  65                 return(gethostbyname(name));
  66
  67         /* Attach domain name to query and do modified query.
  68                 If names too large, just do gethostname on the
  69                 original string.
  70         */
  71
  72         if((strlen(name) + strlen(domain)) >= sizeof(query))
  73                 return(gethostbyname(name));
  74
  75         slprintf(query, sizeof(query)-1, "%s%s", name, domain);
  76         return(gethostbyname(query));
  77 #else /* REDUCE_ROOT_DNS_LOOKUPS */
  78         return(gethostbyname(name));
  79 #endif /* REDUCE_ROOT_DNS_LOOKUPS */
  80 }
  81
  82 _PUBLIC_ struct in_addr sys_inet_makeaddr(int net, int host)
  83 {
  84         struct in_addr in;
  85         struct in_addr in2;
  86         in = inet_makeaddr(net, host);
  87         in2.s_addr = in.s_addr;
  88         return in2;
  89 }
  90
  91 /**************************************************************************
  92  Wrapper for fork. Ensures we clear our pid cache.
  93 ****************************************************************************/
  94
  95 static pid_t mypid = (pid_t)-1;
  96
  97 _PUBLIC_ pid_t sys_fork(void)
  98 {
  99         pid_t forkret = fork();
 100
 101         if (forkret == (pid_t)0) {
 102                 /* Child - reset mypid so sys_getpid does a system call. */
 103                 mypid = (pid_t) -1;
 104         }
 105
 106         return forkret;
 107 }
 108
 109 /**************************************************************************
 110  Wrapper for getpid. Ensures we only do a system call *once*.
 111 ****************************************************************************/
 112
 113 _PUBLIC_ pid_t sys_getpid(void)
 114 {
 115         if (mypid == (pid_t)-1)
 116                 mypid = getpid();
 117
 118         return mypid;
 119 }