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

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      open_limit 3
   6 /* SUMMARY
   7 /*      set/get open file limit
   8 /* SYNOPSIS
   9 /*      #include <iostuff.h>
  10 /*
  11 /*      int     open_limit(int limit)
  12 /* DESCRIPTION
  13 /*      The \fIopen_limit\fR() routine attempts to change the maximum
  14 /*      number of open files to the specified limit.  Specify a null
  15 /*      argument to effect no change. The result is the actual open file
  16 /*      limit for the current process. The number can be smaller or larger
  17 /*      than the requested limit.
  18 /* DIAGNOSTICS
  19 /*      open_limit() returns -1 in case of problems. The errno
  20 /*      variable gives hints about the nature of the problem.
  21 /* LICENSE
  22 /* .ad
  23 /* .fi
  24 /*      The Secure Mailer license must be distributed with this software.
  25 /* AUTHOR(S)
  26 /*      Wietse Venema
  27 /*      IBM T.J. Watson Research
  28 /*      P.O. Box 704
  29 /*      Yorktown Heights, NY 10598, USA
  30 /*--*/
  31
  32 /* System libraries. */
  33
  34 #include "sys_defs.h"
  35 #include <sys/time.h>
  36 #include <sys/resource.h>
  37 #include <errno.h>
  38
  39 /* Application-specific. */
  40
  41 #include "iostuff.h"
  42
  43  /*
  44   * 44BSD compatibility.
  45   */
  46 #ifndef RLIMIT_NOFILE
  47 #ifdef RLIMIT_OFILE
  48 #define RLIMIT_NOFILE RLIMIT_OFILE
  49 #endif
  50 #endif
  51
  52 /* open_limit - set/query file descriptor limit */
  53
  54 int     open_limit(int limit)
  55 {
  56 #ifdef RLIMIT_NOFILE
  57     struct rlimit rl;
  58 #endif
  59
  60     if (limit < 0) {
  61         errno = EINVAL;
  62         return (-1);
  63     }
  64 #ifdef RLIMIT_NOFILE
  65     if (getrlimit(RLIMIT_NOFILE, &rl) < 0)
  66         return (-1);
  67     if (limit > 0) {
  68         if (limit > rl.rlim_max)
  69             rl.rlim_cur = rl.rlim_max;
  70         else
  71             rl.rlim_cur = limit;
  72         if (setrlimit(RLIMIT_NOFILE, &rl) < 0)
  73             return (-1);
  74     }
  75     return (rl.rlim_cur);
  76 #endif
  77
  78 #ifndef RLIMIT_NOFILE
  79     return (getdtablesize());
  80 #endif
  81 }
  82