external/ibm-public/postfix/dist/src/util/close_on_exec.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      close_on_exec 3
   6 /* SUMMARY
   7 /*      set/clear close-on-exec flag
   8 /* SYNOPSIS
   9 /*      #include <iostuff.h>
  10 /*
  11 /*      int     close_on_exec(int fd, int on)
  12 /* DESCRIPTION
  13 /*      the \fIclose_on_exec\fR() function manipulates the close-on-exec
  14 /*      flag for the specified open file, and returns the old setting.
  15 /*
  16 /*      Arguments:
  17 /* .IP fd
  18 /*      A file descriptor.
  19 /* .IP on
  20 /*      Use CLOSE_ON_EXEC or PASS_ON_EXEC.
  21 /* DIAGNOSTICS
  22 /*      All errors are fatal.
  23 /* LICENSE
  24 /* .ad
  25 /* .fi
  26 /*      The Secure Mailer license must be distributed with this software.
  27 /* AUTHOR(S)
  28 /*      Wietse Venema
  29 /*      IBM T.J. Watson Research
  30 /*      P.O. Box 704
  31 /*      Yorktown Heights, NY 10598, USA
  32 /*--*/
  33
  34 /* System interfaces. */
  35
  36 #include <sys_defs.h>
  37 #include <fcntl.h>
  38
  39 /* Utility library. */
  40
  41 #include "msg.h"
  42
  43 /* Application-specific. */
  44
  45 #include "iostuff.h"
  46
  47 #define PATTERN FD_CLOEXEC
  48
  49 /* close_on_exec - set/clear close-on-exec flag */
  50
  51 int     close_on_exec(fd, on)
  52 int     fd;
  53 int     on;
  54 {
  55     int     flags;
  56
  57     if ((flags = fcntl(fd, F_GETFD, 0)) < 0)
  58         msg_fatal("fcntl: get flags: %m");
  59     if (fcntl(fd, F_SETFD, on ? flags | PATTERN : flags & ~PATTERN) < 0)
  60         msg_fatal("fcntl: set close-on-exec flag %s: %m", on ? "on" : "off");
  61     return ((flags & PATTERN) != 0);
  62 }